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l0b95m | Why do ads load and play quickly and smoothly, but actual content is super slow and laggy? | Technology | explainlikeimfive | {
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"Ads are hosted on fast, distributed servers that are made to handle lots of requests per second. Google serves a large share of ads, and their servers are all over the world + they're super beefy. When the content itself loads slower, it might mean the server(s) it's hosted on is underpowered or its network connection isn't good enough to handle the amount of requests coming in."
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l0cwtd | How did our ancestors figure out the concept of glasses to improve eye sight for someone who has crappy eye sight? | Glasses have become such a staple for today’s modern life. How was this figured out in the past? Why did they use glass early on and not plastic like some glasses are made today? Why do we still call them glasses if the lens aren’t always made out of glass? | Technology | explainlikeimfive | {
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"We've had a good enough understanding of how optics work for quite a long time. Ptolemy, who lived in the 2nd century BC, even wrote a book about optics. From there, it wasn't a huge jump to start shaping glass to magnify an image and start holding it in front of your eye. By the 1300's, Venice even started regulating the eyeglass market. They used glass instead of plastic because the first man-made plastics didn't appear until 1862, and they're probably still called \"glasses\" because that's what we're used to calling them."
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l0ewbo | Why do black and white photos look better compared to color during the 70s/80s? | Technology | explainlikeimfive | {
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"Im sure someone here will have a more detailed answer, but generally speaking the black and white film is simpler and had been perfected (as a mass-produced consumer product) many years earlier. They were still improving color film through the 90s, and it switched to digital shortly after. Black and white film is much simpler on a chemical level. One variable: light exposure. How much did this spot get exposed to? Once you start introducing color you have multiple wavelengths of different energies, multiple chemicals to produce different color prints, balancing performance with cost with the type of colors consumers are likely to be using, etc. Plus black and white photography had been around for decades at that point, so long-term issues had been identified and corrected. Consumer-level color photography was still relatively new, so issues like fading hadn’t been identified yet.",
"Partly because the color chemicals aren't as stable and fade and partly because black and white film is more sensitive and only one color so it can have a finer grain.",
"B & W are shot and developed with a simpler chemical process, and this process is more age-resistant. You need 2 colors — white you get from a transparent film, and black you get from a silver coating after a chemical reaction. Color photo is based on the pigments/dyes of different colours. Said pigments are less age-resistant, make the shooting and developing process harder, and the technology wasn't at it's top in the 1970's. Cheap film? A little over/underexposed? Developed for 30 seconds more? Results won't be the best. Source: I shoot and develop film."
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l0k5l5 | How can I be sure that even if I do not consent, a website won't continue gathering my data? | I would expect a company to have as much respect for the "Reject" and "Accept" choices on data collection prompts as a kid has for the "I am over 18" button on popups on porn sites. | Technology | explainlikeimfive | {
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"You can't. You can examine your cookies and check if the site has set a cookie with a long expiration time that looks like some sort of ID, but there are other ways of tracking people online besides cookies.",
"You can either: * Go to the section of your browser that lists cookies stored and see if any are set to that specific website, albeit that doesn't cover third party cookies that may appear in multiple sites or * You can disable cookies in your browser preventing sites from setting them to begin with. Outside of that it's just gentleman's agreement and the very slim risk of someone lodging a complaint. However if a site really wants to there is very little the end user can do to prevent some data collection.",
"> I would expect a company to have as much respect for the \"Reject\" and \"Accept\" choices on data collection prompts as a kid has for the \"I am over 18\" button on popups on porn sites. Not exactly a fair comparison. You put your trust in other people and other companies all the time. You trust the staff at the restaurant isn't writing down the info on your credit card and using it to make online purchases. You trust the car mechanic isn't rifling through your belongings and siphoning away your gas when you leave your car with them. Or taking your car for joy rides. You trust the coat check person isn't searching your pockets, etc. At the end of the day, you can't \"be sure\" they still aren't gathering your data, but at that point it's illegal and companies at least try to minimize the illegality of their actions. At least companies that have a vested interest in maintaining a positive reputation."
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l0pmls | How did our eyes ever think 240p was crystal clear? | I tried to watch an old skate video from 2007 on YouTube and it was only available in 240p which obviously looked terrible. But once apon a time 240/360/720p resolutions were as crispy to us as 4k is today. What's the trick behind this? | Technology | explainlikeimfive | {
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"Keep in mind that you are viewing these videos on a much higher resolution device. If you view a 240p video on an 4k monitor, without zooming it, it'll be like 1/10th the size of the screen. If you view the same video on an SD TV it'll take up much more of the screen without having ot stretch. When you stretch it to say 720p \"size\"... It's going to look way way worse.",
"You pretty much answered your own question almost. If it's the only thing to exist why wouldn't it look amazing back then? Just like how N64 games or PS games looked amazing back in the day. You'll probably look at something from now ten years from now and it will also be shit in comparison.",
"Your brain does an excellent job of filtering information. Low resolution video is similar to watching a black and white movie. You notice it at first, but once you start focusing on the story, characters, action, etc. your brain just focuses on the data, not the bandwidth. Also, back in the day, you likely weren't looking at 240p videos on a 4k flat screen monitor that's optimized for high resolution content."
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l0vmnc | When seeing how old a spear/ arrow head is how do they know the age of when it was carved/made and not how old the rock itself is? | Technology | explainlikeimfive | {
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"Usually they can find other materials that are buried at the same level that they can to date by measuring decomposition of isotopes in carbon",
"Most fossils and tools are found at certain levels in the ground. This is a good starting point for age verification but it’s never 100% perfect which is why we say “dated to be between X age and Z age”",
"There is a saying in archaeology: If it is outside of a context, it is worthless. So yes, more or less, it is difficult to date object itself, especially stone one... Sometimes you make an educated guess based on style or material, but in most cases you rely on context."
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l0wxna | If our phones can have such small cameras yet retain good image quality, why are security cameras so large yet have relatively bad image quality? | Technology | explainlikeimfive | {
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"It just takes a massive amount of data to record all the time so they compromise resolution to keep storage manageable.",
"A number of factors like cost, it is too expensive to by a good quality camera or to pay for high quality storage. Storage doubles as the second factor in that storing HD footage takes significantly more space (and more money) this second reason is usually the main one that is they don’t store the video in HD One more and this isn’t backed up by real world knowledge but something to consider which is age of the camera. Most security cameras probably don’t get upgraded very often which could contribute."
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l0y3j0 | Why did we more widely adopt carrier grade NAT instead of IPv5? | Technology | explainlikeimfive | {
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"Well technically it's IPv6 that's been accepted onto the greater internet. There was an IPv5 created but it didn't take off, and the number has technically been claimed even if it is considered a failed project. But the problem is there's no backwards compatibility. If a program wasn't written to support IPv6, it won't run IPv6, period. Besides old software and video games and stuff, that potentially includes routers which may need a software (or hardware!?) upgrade. New DNS record types need to be added. Management and accounting by the ISP needs to be done for their whole network basically from scratch. It's a lot of work. Much of it has been done, but IPv6 just has so much momentum. CG NAT is the easier, if horrible and shorter term, solution."
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l181os | why cant we actually permanently delete files on a computer? | Technology | explainlikeimfive | {
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"text": [
"Unless you potentially had a government with unlimited resources to throw at you, a single pass with new data (or just a solid state drive's garbage collection) is more than enough to prevent recovery attempts."
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l19003 | What is an API? | Technology | explainlikeimfive | {
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"It stands for Application Programming Interface. Basically, it's a set of rules (and the code that supports those rules) that allow for two programs to talk to each other. A very common application for an API is to allow people to query a database in particular ways without actually writing SQL or having formal access to the database. For example, in my day to day work life, I use lots of data from the census bureau. They have all sorts of datasets available from their surveys. You can often find these data as downloadable excel files by navigating their site, but this is really inefficient and cumbersome to do when you know the data really well and know precisely what you want. Census, of course, has all of these datasets in a database where it would be easy to grab what you need, quickly. However, they're not just going to let everyone access the database, itself. As such, they basically set up a small web page where the URL you enter gets turned into a query for the database. When you go to that URL, the computer running that web page talks to the database and runs the query for you and takes the results and sticks them in the web page it sends back to you. This web page is an APi. It allows a script that, say, gets data from a web page to talk to a database. This constitutes a very lightweight, secure* way to make databases accessible to lots of users and is a very common use for an API. I can just have a script say \"get the data from this particular URL\" when I want some data from Census, rather than having to actually find it on their site. *Secure if done right!!",
"An Application Programming Interface is a front for a program which other programs can interact with without interacting directly with the code. For example, Reddit lets you post posts. However, they don't want anyone to directly open the database of posts and insert their posts there. Instead, they made an API that lets other programs (like browsers and apps) send a \"post this\" signal, with the subreddit, account, contents etc. and the API then transfers that information with the backend, where the post is actually added to the database."
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l1ay8d | Why are satellites visible at night with our own eyes? | Childhood me would like to know why every time I pointed to a star someone would tell me that one was in face man made. | Technology | explainlikeimfive | {
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"Satellites are bright from reflected light and pretty close to the Earth (compared to stars), so they are very noticeable. Some, like the ISS, are also very noticeably moving across the sky, which draws your attention. Lastly, since they are brighter, they are more likely to be visible in situations where you have light pollution or the sky isn't pitch black.",
"If the sun is just below the horizon then there is a small timeframe (maybe an hour) where a satellite high above you is still in the sunlight even though you are in darkness on the ground. This makes the satellite shine brightly against the dark background of the sky. If around that time of night you see a STEADY white light cruising across the sky, then you are probably seeing a satellite. If it is flashing other colors then it is probably an aircraft. If it is sitting still and not moving then it is probably a star or planet.",
"Also, What you are seeing are Low Earth Orbit (LEO) satellites that orbit the earth about 2,000Km up. The satellites that are used by DirectTV, Dish, Sirius/XM and the like are in a Geosynchronous orbit (GEO) and are 36,000Km above the equator."
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l1gp8m | Do nukes really split an atom to explode? | Technology | explainlikeimfive | {
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"If it's a fission explosion then yes. There are isotopes of atoms (they have the same number of protons but different number of neutrons) that are very unstable and they are just itching to reach a stable state. When they're hit with a high energy particle they break up to try to reach that stable state - they break into other elements and also release a ton of energy in the process."
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l1h9bu | Why do we sometimes get multiple captchas (sometimes even "infinite" to the point where you simply quit) and other times only one? | Technology | explainlikeimfive | {
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"If the website has extra spam protection system that consults the spam database and the IP of your pc is toxic and listed in those databases it ll keep on showing you the captcha even if you solve it correctly. this happens alot with dynamic ips as they are usually being used by more than one person and chances of someone spamming are higher. If the website uses just uses recaptcha without any extra spam protection measures. , it ll let you pass on you solving the captcha."
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l1hahi | = How does an atomic clock work? | Technology | explainlikeimfive | {
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"Atomic clocks take a very pure substance, typically cesium or rubidium, and energize it with microwaves. These microwaves raise electrons in the cesium atom to a higher energy level. When the electrons return to their preferred energy level, they emit a radio frequency photon. The frequency of this photon is extremely precisely known. By measuring the radio signal, you can have an extremely precise signal at this specific frequency, thenyou just count up the oscillations to get the time."
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l1hyvu | how information is stored on CDs | How does a smooth little piece of plastic hold possibly like 150gb, it's not like a hard drive or usb, it's just a piece of plastic right? | Technology | explainlikeimfive | {
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"Nope, it's two smooth pieces of plastic with a layer of super-thin aluminum between them. This aluminum has \"holes\" punched into it, so that it either reflects light (no hole) or it doesn't reflect light (\"hole\"). This lets the disc encode 0 and 1 binary bits in the series of holes/not-holes.",
"There is a reflective surface on the back of the CD/DVD/BluRay. Pits are made in the plastic on that back side, and a laser is bounced off the reflective surface through the pits and to an eye. The eye reads the pits, and knows what binary data is suppose to be there (1's and 0's). Think of it like old movie film. You sign a light through it, and the image is projected on the screen. Except it's happening with very narrow beams of light (lasers) and is bouncing off a reflective surface back to an electric eye watching."
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l1l5ck | When two people are on a call, how does one mobile phone block the system/app sounds from the phone (but not the caller's voice)? | Technology | explainlikeimfive | {
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"text": [
"Most phones nowadays have multiple mics Let's say. mic 1 picks up your voice + background noise. Mic 2 picks up background noise only Your phone now knows to do mic 1 noise minus mic 2 noise = clearer voice"
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l1o0cw | With all the amazing advances in technology, why is there not a smartphone that can take a selfie without reversing everything in the image (writing on shirts, etc.)? | Technology | explainlikeimfive | {
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"There's an option for that in the camera settings. In mine, its called 'Mirrored Selfie', might be a bit different in yours. Just turn it on and all writings will appear the correct way."
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l1q2vm | How do lasers cut through wood without making it catch fire? | Technology | explainlikeimfive | {
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"Lasers vaporize the material they are cutting by using a focused beam of infrared radiation. Wood can definitely catch fire while being cut with a laser. To keep it from catching fire lasers use a stream of air directed at the cut point - called \"air assist\". This prevents a flame from flaring up and also helps to keep the cutting area free of smoke that could otherwise block a portion of the beam. If you forget to turn on the air assist you can very much expect the wood to catch fire when lasering. Source: I have cut literally tens of thousands of things with lasers.",
"It's basically the same reason you can't (easily) directly light a log on fire, you have to start with something really small like kindling. When you're cutting wood, the surface exposed to the laser is \\*very\\* small (that's part of how the laser works) so it's like trying to light a big log with a really tiny match. If you try to cut really thin materials, so the size of the hot spot is \"large\" relative to the wood around it, you can set it on fire."
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l1t8im | how can they continue to cram more and more memory into tinier and tinier spaces? | I suppose you’ll need to start with a basic explanation of how memory takes up space in the first place, and then how they can keep shrinking that space. You may even need to explain this like I’m 3. I’m not so smart. | Technology | explainlikeimfive | {
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"We're reaching the limit actually. There are two types of informations. RAM (Random access memory) and ROM (Read Only Memory). Ram is the memory you computer use when it work. As the name imply, whenever your computer need to store something to use a few seconds later, it ask the RAM \"Hey, where can I put it? It takes X amount of space\". RAM, as the name imply, then take a random spot in its memory that is available and tell the computer to store his stuff there for the time being. This memory rely on very thin strip of materials that will simply allow or prevent current from going through. Something like tiny electric switches. It's easy to work with, but it rely on constant electricity to work. As soon as you shut the electricity, all the switches stop working and reset to not working. ROM unlike its name CAN be written to. It's your hard drives, SSD, USB, etc. It's the memory that can actually store information for long term. For hard drive, it's a bunch of polarized disks. By applying a current to that part of the disk, you change the polarization of that part of the disk. When you want to read it, you simply check how the polarization at that place is going. Even if you shut the electricity, the info remain, because polarization doesn't need constant electricity. You only need electricity to read or write. On the other hand, it makes the hard drive sensible to magnets. I'm sadly not knowledgeable on SSD behavior, so I'll leave that out for now. First of for ram. It used to be some big lamp that would turn on an off. Eventually, we realized that the lamp was useless, all we needed was the electricity. So we created these nice little switch that would turn on an off. The big issue with changing size is timing. Computer go really fast, and it's reached the point where the speed of electricity matter. So when you shrink stuff, you speed your computer, but you need to make sure the rest of the hardware can handle the speed. Nowadays, we've kept on shrinking more and more material, to the point that these \"switches\" are just a couple of micrometers. Now we're hitting a physical barrier. We CAN'T shrink anymore simply because we can't ensure reliable transfer of electricity with less material. We're at a point were we need a whole new technology, as we've shaved off most of the material we could. For Ram, it's partly similar, but we had a couple of other things. The concept has remained relatively similar. But by improving precision, we didn't need to put as much space between each polarization. So we could store more on a same surface. There is also making thinner and thinner disks. As they are thinner, you can put more. And finally, we learned to put on both face of disks. As long as we can keep making the writing tools more precise, and maybe if we find a material that we can make thinner, it can still be improved."
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l2205q | What is so amazing about the F35 to warrant its $1T budget? Do the benefits really justify the R & D costs? | I've read a number of different estimates for the F35 project but everything seems to fall in the ballpark of $500B to $1T. I've seen some pictures (renderings?) and it just looks like another F16. What in the world is so great about this jet to justify this amount of R & D expense? | Technology | explainlikeimfive | {
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"A major thing that continually gets glossed over by people citing the $1 trillion figure; that's the **lifetime** cost of the project. By comparison, the airframes that are being replaced by the F-35 would have had a combined cost somewhere on the order of $1.8 to $3 trillion over the same time frame that the F-35 is expected to run in, but those costs don't get talked about nearly as often because they're in smaller, more manageable chunks. Making one airframe that is (largely) the same across all three of it's variants makes it considerably cheaper from an upkeep and manufacturing perspective, because you can take advantage of economies of scale to crank out loads of parts for the aircraft. By comparison, we currently need completely separate lines for the F-16, the F-15E, the F/A-18E/F, the A-10, and the AV-8B; a manufacturing line for one of those aircraft can't easily (or quickly) be retooled to make parts for the others, but the majority of the F-35 parts are shared across all three variants. The F-35, counterintuitively, is rather cheap on a per-unit basis (hence why it costs less than the competitor Rafales and Eurofighters that it's actually superior to), but it's a *huge* program, hence why it has such a large overall price tag.",
"The main reason that the F-35 program's total cost is so high is that it's a huge project intended to make a whole ton of planes; F-35s of various versions are going are supposed to replace huge sections of the Air Force, Navy and Marine fighter fleets. The has undoubtedly been bloat and cost overruns, but the current cost per aircraft isn't that much higher for a F-35 than for a new production legacy fighter like the F-16.",
"The F-35 is not a single airframe but rather three different airframes which have different capabilities. This is so that they not only replace F-16 but also F-18, F-15E, Harrier, A-10, among other different airplanes used today. The US Air Force is putting all their money into making the ultimate fighting aircraft that can be configured to do anything. Just like the US Army did with the development of the Bradley Fighting Vehicle. Edit: list of aircraft it replaced were corrected.",
"In addition to the other comments about why it's a huge program that isn't really directly capable, to directly answer your question of why it's not just another F-16... It's far stealthier. It's not quite F-22 stealthy but, compared to any legacy fighter, it's still stealthy. That's a huge deal for modern operations in \"contested airspace\" (where you don't have air dominance, like the US is used to). It can operate from carriers, the F-16 can't. The VTOL variant can takeoff and land vertically, the F-16 can't. It has a \\*vastly\\* superior sensor suite. Not just radar, but optical and electronic. And a far more capable network/datalink system so it can share all that information with other aircraft and units in real-time. An F-35 is like a tiny AWACS. An F-16 has nothing like that capability to coordinate or inform on what's happening. F-35 carries more than 2x the fuel with a larger payload, for double the combat range with more weapons."
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l24q13 | How do satellites and the ISS correct their orbit in space? | I know that the International Space Station (ISS) and man made satellites often have to move to make small orbit corrections, but since they have no fuel, no aerodynamic and no oxygen, how exactly do they do this? | Technology | explainlikeimfive | {
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"They have fuel and thrusters to make small corrections to their orbit. You might think satellites are just out there flying through space doing nothing, but in reality, they are making small corrections on a daily basis and are actually being 'flown' by a team on the ground. They only have a limited amount of fuel though, so once they run out... thats probably gonna be the end of the satellite. The often will save just enough fuel to de-orbit it either into a \"graveyard\" orbit, or back into the earth to burn up in the atmosphere. Many satellites are only expect to have a lifespan of 10-25 years, for many reasons, with fuel obviously being a concern"
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l258b8 | does radiation from an outside source effect radio waves? And if so how was nasa able to talk to their astronaught on the moon from earth with all the radiation In space between earth and the moon? | Technology | explainlikeimfive | {
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"text": [
"Because photons do not interact with each other. If you send radiation from two sources and the streams colide the direction of the radiation won't change. So they can send radio waves back and forth without any disturbance."
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l25vnf | The first humans made crude stone tools 2.5 million years ago, but our recorded history is only 5000 years old. Wtf did we do for 24,995,000 years? | Was it only recently that we started to build cities? Did something snap inside us 5k years ago, and we were like, "Alright, time to start civilization." Why did it take our ancestors, people with very similar brains to ours, so long to start making real strides in community building? Are their Forrest cities that just vanished in time? I know this question sounds incredibly stupid. I'm just really curious about pre-history. | Technology | explainlikeimfive | {
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"It was a long, slow buildup. We're used to history moving *FAST* because we have a globalized civilization with excellent record keeping, near instant access to huge amounts of data, and perfect communication. For the vast majority of human existence \"civilization\" was the 100 or so people you would ever meet in your life, records were whatever the oldest person could remember, data was whatever you personally could remember, and communication happened at walking pace. With those conditions it takes a long time for the right resources to come together to increase the complexity of your society and technology.",
"Well, 2,495,000 years. It’s a long technological jump from a stone picked up off the ground to break open bone marrow and a Clovis point arrow head. You have to also have the right kind of stone. Each advance requires someone unhappy with the current situation and willing to improve it. We’d still be using house phones if it weren’t just so very much more useful to carry a phone in your pocket. Also, taming fire is more like 100,000 to 200,000 years ago. And that is probably the invention that triggered some modernization. Then there’s farming. Once we decided to farm instead of forage, things really took off about 12,000 years ago.",
"The general answer is \"roaming around in small bands of no more than a couple hundred and hunting and foraging for food.\" However, the reason it took so long to develop complex social structures and agriculture (the real sufficiency conditions for civilization as we know it) is a whole field of study for historians, anthropologists, and biologists. I would note a couple of big things, though, the domestication of animals and plants was a looooooong term process and it was only after they had happened that agriculture became a viable option. Secondly, in the early days there were only a select few locations that were really amenable to early civilization. It's not a coincidence that every place that independently developed agriculture happened to be a regularly flooding river valley with grains that grew in the area. Again, though, this is a big question with lots of answers.",
"For most of prehistory, a hunter-gatherer lifestyle was just more practical. Trying to settle down in one place usually just plain meant death. Civilization was largely able to start because of the invention of farming, which is really not an intuitive thing to do. But once it was finally figured out, people suddenly had surplus food and didn't have to keep moving around. And even after that, writing wasn't invented until much later."
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l289ea | Why in video games do bodies of water look so real but liquid in a drinking glass looks so fake? | These days in video games, rivers, streams, oceans etc look so ridiculously realistic that you could swear you were looking at the real thing. But if a character pours a glass of scotch, they might as well be pouring a glass of light syrup. What’s the reason for this disconnect? | Technology | explainlikeimfive | {
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"Large bodies of water are usually not interactive, developers can make a flat plane texture that looks really good with minimal work. Liquid in a glass has to move in real time with a moving container, and is just a much smaller asset. This is especially hard if you can hold and manipulate the container in any way you want. Both can look better with things like real-time physics simulations, but large bodies of water are usually worth more attention and work than drinks in cups. Related, Polygon just did a video about Half Life Alyx's bottles - the liquids inside are simulated WAY better than most games. If you're interested enough to pose this question you'll probably enjoy the video",
"The mundane task of drinking is not an artistic focal point. Sailing on the sea as a pirate on the other hand, makes the sea very important."
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l2aufo | How do scalpers buy up goods online in seconds? | So I've been trying since the release date of the xbox series x to get a console for my nephew but everytime new shipments arrive they are gone in seconds wouldn't buys of this magnitude flag the credit or debit cards associated as fraudulent and not allow the transaction to process? | Technology | explainlikeimfive | {
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"They're not fraudulent transactions, they're real. The retailer doesn't care who they're selling to, they care about selling the product. If they have 1000 and they sell 1000, they're happy and the buyer is happy. Something in really high demand might have millions of people trying to buy at once, it's easy to sell out in a few seconds. Popular concerts see the same thing with ticket sales (in the beforetimes). If they have terms of service specifically to prevent scalping then they might be able to do something, but why would they care? The ire is usually directed at the console maker, not the retailer.",
"Simple answer is monitors. I do some reselling for side money and there are plenty of paid discord groups called \"cook groups\". The entire purpose of these discords is to provide people with information on all things reselling. They also have what are called monitors. They are web scraper bots that detect when items restock on specific websites and relay the link to the discord. Some people try to buy them manually by just clicking the link and others use software specifically for buying in mass quantities very fast that are just called bots. As for the fraudulent charges aspect. Credit and debit cards detect fraud mostly based on purchase history patterns so if someone is spending tons of money consistently then the charges will not be flagged. Also if you're wondering why websites can't just ip ban the people purchasing tons of the same item it is because bots use what are called proxies. Proxies are able to change the apparent location of all the virtual \"people\" trying to check out for that person's bot. It's all very complicated and bot devs are constantly updating their software to combat websites antibot strategies."
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l2b8d2 | Why can't Flight Traffic Controllers remote control Airplanes in Emergency Situations? | So I just learned that all the new, big airplanes can basically do everything on auto pilot, even land and stop the plane. So why can't they just program the auto pilot remotely if e.g. the pilots passed out? | Technology | explainlikeimfive | {
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"> So why can't they just program the auto pilot remotely if e.g. the pilots passed out? Because both pilots becoming incapacitated pretty much **never** happens, so it's not worth the effort to establish the necessary infrastructure",
"The risk of that system being compromised and used for evil grossly outweighs the incredibly tiny fraction of times you’d need it. This isn’t new to new airplanes, large jets have been routinely capable of auto land for about 50 years."
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l2gqyn | I have 8GB RAM on my phone, why is it that usually only 4GB of that is available? What is it using the other 4GB for if i don't have any apps in the background? | Technology | explainlikeimfive | {
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"Your phone itself, cellular signal, WiFi signal, Bluetooth signal, etc.. all these things and more take up RAM while your phone is running.",
"If it always shows as having exactly 4GB the manufacturer probably locked 4GB of ram for OS and hardware uses and then lets apps use the remaining 4GB. If it usually shows as having close to 4GB available but can vary between 4 and higher numbers like 5 or 5.5 then your phone probably just has a really inefficient version of android installed or some other custom OS that has not been well optimized.",
"Another factor is graphics memory. Phones don't have dedicated memory for its GPU so a certain amount of RAM is reserved. Otherwise, keeping things in memory allows things to be opened faster. It doesn't consume any more power, RAM is always powered regardless of capacity used. I imagine all phone OEMs are keeping camera apps in memory to get those booted up faster."
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l2igc0 | How are fireworks designed? How do theyake the fireworks into shapes when it explodes? | Technology | explainlikeimfive | {
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"There are a few different types of ways to make fireworks. But for the starshells that you often see in fireworks display creating the pretty patterns they are basically a big ball of gunpowder with smaller \"stars\" in them which glow in different colors when ignited. When the fuse runs down and ignites the gunpowder it explodes creating a loud bang and throwing the stars out in all directions igniting them at the same time. The stars that are towards the edges of the shell will be thrown the furthest and the stars in the center of the shell will be thrown the shortest. So the stars end up in about the same relative position to each other as they were in the shell. Fireworks manufacturers use this to make sure the stars are placed neatly in certain patterns within the shell and stay in place embedded in the gunpowder until it explodes. By being careful when you launch the shells into the sky you can also keep its orientation as well."
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l2ll75 | Even battery packs consist of many cylindrical cells making a bigger battery, why are they not in a cuboidal shape so there is no space between cells and can store more of the chemicals for a battery which lasts longer? Why is cylindrical the standard? | Technology | explainlikeimfive | {
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"Batteries are actually made up of thin layers of foil. The more you can compress these together the higher energy density you will get. There are currently two common ways of doing this. First is to roll the foils up into a very tight roll and then encapsulate it in a cylinder. The other is to fold the battery in multiple layers so that you end up with a flat rectangle that is then pushed into a box. This is for example how cell phone batteries are made and you would expect that this would be more efficient for large batteries as it can fill the entire volume while cylinders needs space between them. But the problem is that in order to get the best density you need to compress the foil very tight together. However if only one part of the foil gets compressed too much it will catch fire. This was the reason for the public recall of certain cell phones a few years back. To avoid this you need the plates used to push the foils together to be very strong so they do not flex. And this takes up both space and volume. However the cylinder shape is much stronger then a plate and will apply an even pressure over the entire content. So the walls of a cylindrical battery can be made much thinner then the walls of a flat battery. And this makes up for more then the lost volume by using the cylindrical batteries.",
"Some electric vehicles do use prismatic cells. Cylindrical cells are very efficient in their manufacture and energy density, so there is no guarantee that a prismatic cell has higher volumetric energy density than a set of cylindrical cells. Further, there are considerable challenges of removing heat from large battery packs, and having air or fluid flowing between the small cells is a useful way of achieving this."
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l2m2m9 | Why do we have to purchase website names why can't we just have a system like usernames on sites? Like whom are we even buying from? What stops us from just straight up using it for all I know internet is free right? | Technology | explainlikeimfive | {
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"Let's say the post office was an entirely private operation, and would only send and deliver mail to people who were customers. So you sign up to have your address added to their list of customers so you can do this \"mail\" thing- otherwise, you just flat don't exist for mail purposes. You're buying recognition from the companies that route and sort electronic traffic (the equivalent of mail in the postal service example) when you buy a website name.",
"In addition to what u/ShalmaneserIII correctly pointed out you may consult [this]( URL_0 ) if you're interested in the more technical background. Also keep in mind that you're generally not **buying** domain names from accredited registrars. You're **renting** them."
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l2m9yx | 2020 rover system specs. | Why does the 2020 rover have such weak system specs? For example my pc has 16 GB ram and 4.0 ghz cpu. Meanwhile this multi million dollar machine that is meant to travel to another planet only has 2565 megabytes of ram and a 0.2 ghz cpu. & #x200B; [reference]( URL_0 ) | Technology | explainlikeimfive | {
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"Why does it have to have strong system specs? Is someone going to be playing games on it? These are optimized to be as resistant to radiation as possible and to make sure their computations are accurate. 200 MHz is plenty for what it needs to do.",
"They don't build these from off the shelf hardware. They build them from very well known, very well tested, radiation hardened hardware. If your CPU is bad you send it back and get a new one. If your rover's CPU is bad there isn't a service center on Mars. And with radiation it turns out the more gates you stuff into your CPU, the more it suffers from radiation. So you don't want the latest Threadripper, that would die there in 5 minutes. You want the simplest CPU with the least amount of delicate bits that will get the job done. Then there's that it doesn't really need to do all that much. It has to drive around, control instruments and send stuff back to Earth. There's no reason to do any heavy processing on Mars when we can do it here, where we can have huge datacenters dedicated to it if we need.",
"You can not launch any consumer electronics into outer space. It will just get damaged by the radiation and stop working after a short time. You need to have electronics that use different transistors and with a lot more checks in place. So what they do is that they take a processor architecture that is already out and modify the design to be able to withstand the harsh radiation and temperatures of outer space. This might take a couple of years and is a quite expensive process as you need to test it in various different conditions to make sure it works as expected. Then new space project can start designing their computers around this new processor. But they will not be lanuched for another few years. Especially for a high profile mission like a Mars rover it takes a lot of time between selecting a design and actually launching the mission. In addition due to the costs of the processor development they do not come out with new editions every year, it is more like every decade. In the case of the Perseverance rover it is actually more of an upgraded Curiosity rover and is therefore using much of the same computer systems which includes the processor. Curiosity used the latest and gratest hardened processor on the market at the time, the IBM RAD 750 which was based on the PowerPC 750 from the late 90s. But even though the technology is over two decades old it is perfectly fine for the task it is designed to. But do not fear though because newer spacecraft is designed with more modern technology. The latest and gratest in the RAD series includes fancy features like up to 1.4GHz clock frequency, 64 bit instruction set, DDR3 memory and up to 4 cores. And yes, it is based on a decades old technology but we do now finally have a tested hardened design that have been incorporated into new spacecrafts so you will soon see it launch for the first time."
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l2mcmq | How do they shoot those scenes in movies where the camera is moving around a scene frozen in time? And how do they sometimes put the same characters in that same scene more than once and show it all in one camera panning? | Technology | explainlikeimfive | {
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"The way they did it in The Matrix was by surrounding the scene with cameras which all took a picture at the same time (or in quick succession if they want slow motion). See [this video]( URL_0 ) for example.",
"The Matrix I believe was the first movie to popularize shots like this. So if you want to see some detailed information on it, check out the making of that movie. But I'll summarize here: There are a couple of tricks they can do to do a shot like that. Like multiple cameras set up around the subject and then smoothed out in post to give the appearance the camera is moving. They could even have a camera on a rig that moves super fast around the subject. But usually both of these require the use green screen and cgi."
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l2po0e | How do smartphone and other devices know what time is it even without internet connection? And even when they were turned off and then turned on. | Sorry for my bad English. | Technology | explainlikeimfive | {
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"Your English is fine. Most wireless electronic devices have a little quartz crystal and battery (much like a watch) to keep time. The battery charges the crystal, the crystal vibrates at a certain frequency, and the frequency is used to measure time. This isn't always 100% accurate, so over time, the longer you keep your phone disconnected from the network, the less accurate the clock might become.",
"> And even when they were turned off and then turned on. The power button doesn't turn everything off. The clock keeps running as long as there is a battery. > How do smartphone and other devices know what time is it even without internet connection? Smartphones (and many other digital devices) can also get the time from the cell network and/or GPS."
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l2swtk | What do people who rely on medical equipment, both at home and in hospital, do when the power goes out? | Technology | explainlikeimfive | {
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"text": [
"Hospitals have generators private citizens may have generators as well. Also if you rely on power for certain medical devices many utility companies will know this and prioritize you for repairs."
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l2tolh | why the size of online games is so big? | when someone installs an online game (WoW, FF XIV, etc), the game usually downloads \~30 GB, if I can't play offline and can't see the models, what are these files, do I really need \~30 GB to make the connection? | Technology | explainlikeimfive | {
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"The files are the game, all of the art assets, the code that says how it's run, etc. When you play online games basically what happens is that you send a very small message to the server, and the server then sends you back a very small message of what files to load on your computer. If you see a monster, it's because the server told your computer to load those files and display the monster, it didn't actually send you the file for that monster. & #x200B; That's why if you have ever played one of those games and disconnected while playing, it looks like you can keep playing for a few seconds but nothing \"new\" happens monsters will keep doing their animations, you can move your character, etc. All of that stuff is on your computer and until your computer hears from the server it will just use those local assets. & #x200B; tl;dr, you arent streaming all the visuals.",
"> if I can't play offline and can't see the models, what are these files, do I really need ~30 GB to make the connection The files *are* the models and textures and everything else that you have no business downloading every single time you connect. If you *didn't* have those files locally, you would need to stream them to your computer on-the-fly. Not only do you likely not have the internet speed to do this as quickly as would be necessary, but you may not even have the available bandwidth on your internet. Imagine if every time you connected to WoW, you had to sit at a loading screen for 15 minutes while your game loaded all the models of the city you were in, except you logged on to go to another city to do something, so now you travel there and hit another load screen and wait another 10 minutes to load (less time because some of the content was reused). You do what you wanted to do so you close the game for the day, oh but wait you forgot to turn in a daily quest that will expire if you don't do so before tomorrow....time to load the game up again *and wait another 15 minutes for it to load*. EDIT: You also totally *can* see the models and such offline. That is, if you have a program that can extract them from the data files. If you do enough research you an even write this kind of program yourself - but there's little need to do so because the game client does this for you when you connect online.",
"When you install an online game, it is optimized for performance so you can play. In order to do so, they download all assets to your local PC. All visuals, all graphics, all program code, etc. So that when you play the game, the only thing going over the Internet is your computer telling their servers what you are doing, and their servers telling your computer what else is going on. If you didn't optimize like this, you would not be able to play online games with any speed or decent graphics. There just isn't enough bandwidth to support downloading all the assets in real time or before each match. Think of it this way. You ride a bike to work and back. Would you rather have your bike all assembled every day safe in the garage, and just be able to hop on and go? Or would you rather have it that every time you want to use your bike, you have to assemble it from scratch? Assembling it from scratch would obviously take way more time than just hopping on and going."
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l2vbh0 | What makes Google search results better than Bing or DuckDuckGo? | I've been toying with other search engines for the past week or so. DuckDuckGo, Bing, Ecosia... The one thing I notice is that no matter what, my results on Google are just \*better\*. I'm wondering why that is. Is it just because they've been tracking me my entire life so they know how to curate my search results properly? Or is their algorithm just better? And in that case, why can't other search engines just copy their algorithm? | Technology | explainlikeimfive | {
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"I want to add to the discussion that duckduckgo is actually Bing. All they do is take your query, make it anonymous and then give it to Bing in order to return the results generate by Bing to you.",
"Algorithms can be copywritten, not to mention the money that Alphabet can afford to give companies for incentive that some companies just don't. in the case of Bing, Microsoft doesn't treat Bing like Alphabet treats Google search",
"> Is it just because they've been tracking me my entire life so they know how to curate my search results properly? Or is their algorithm just better? Both. Google personalize results based on location, and they probably use other data have about you although it's really hard to know. But they also have so much more money to invest into making the search algorithms really good. > why can't other search engines just copy their algorithm? Making a search engine is incredibly difficult. So difficult that only Google, and maybe Bing, have been successful at it. Duckduckgo and Ecosia both license results from Bing. Google and Bing keep the details of their search algorithms very secret, so you can't copy it, although many have tried."
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l2yahj | Why is it that computers apparently can't run Crysis? Can they run it now? | Technology | explainlikeimfive | {
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"Modern machines generally wouldn't have trouble running Crysis. When the game was released in 2007, however, it was incredibly demanding and only high-end machines could run it well. So, for quite a while 'can it run Crysis?' became a shorthand for whether a machine was a quality gaming machine. If it could run Crysis, it could run basically anything."
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l3205d | Is theoretically any device connected to the internet vulnerable to attacks from hackers? | Technology | explainlikeimfive | {
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"Security researcher here: Theoretically? No. Practically, absolutely. If there's a device out there connected to the internet, it likely has some services running on it, and due to the complexity of software development/networking/much more, no one person knows everything a device is doing. This is where criminal hackers come into play, by applying common research techniques as well as reverse engineering skills, they are able to develop exploits that take advantage of flaws in software and services. The general rule in security is that \"everything can be hacked\"\\*, but the defensive idea is to make it so time consuming and not worthwhile for criminals to try and attack. No one wants to spend 2k hours trying to make your smart fridge warm(Well, at least most criminal hackers, I'd like to imagine(though I'm sure there's a few out there!)).",
"Yes, theoretically and practically any device connected to the internet can be hacked, whatever level of security you use there is always a higher level hacking method maybe not figured out yet.",
"My father once told me ' the only computer thats safe from hacking is one that runs on batteries and sits in the middle of a large desert. ' this was in '92.",
"This question makes me curious whether, conversely, it is possible in actual practice to 100% secure a device that is connected to the internet against hackers?",
"Short answer? Yes. Long answer? Yessssssssssssssss. But for real any device can be breached if there is access to it and a vulnerability. That could just be an exploit that hasnt been patched or even just a user doing something dumb like setting a password to \"password\". It extends beyond just internet connected devices. Open Bluetooth? If someone is in range they might get into it."
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l320j1 | How are non-contact thermometers able to determine temperature? | I just cannot understand how a device that does not come in contact with a object is able to determine the temperature of that object. | Technology | explainlikeimfive | {
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"text": [
"Because hot objects glow a colour that gives their temperature away. You can see that with red-hot metal, for example. If you could see in the infra-red, you could tell the temperature of cooler objects in the same way.",
"Everything radiates energy. A rock in outer space is radiating a small amount of energy. Non-contact thermometers work by measuring the amount of radiation coming off an object. That radiation is infrared light, the same thing that warms you when sitting by a fire. Some things will start to glow with visible light when getting very hot, like steel that is heated by a torch (red hot). However, a piece of aluminum heated by a torch to the same temperature will not glow at all. They both will will be radiating a lot of infrared light that we cannot see, but the sensor in the infrared thermometer can see it."
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l34ipu | How do authorities track down someone using Wickr or other encryption chats? | Technology | explainlikeimfive | {
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"text": [
"Answer: So security and encryption are only as good as the users who use it. In theory, if you never share any other personal details, no, you shouldn't be able to track someone. However, the more you share, the more likely you are to be found through other means. For instance, let's say you always show pictures of your lunch at a certain time, well, then we can narrow down your timezone based on where the time you share is likely around lunchtimes for people. Then you may say you work at a \"large software company\" and now maybe there are only a couple of those in your timezone. If you share other pictures, you may be able to reverse websearch those pictures and find them on a user's non-encrypted social media platforms (A lot of people will use the same selfies for everything). Even other details in pictures can be used to potentially track you such as landmarks or buildings in the background. If you say you graduated in X year, we can narrow down your age. Most of the time people are sharing way more than they think that they are, and a lot of small things that would never identify you individually, will identify you together."
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l357sm | how does Bluetooth work? | Technology | explainlikeimfive | {
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"It’s just another wireless technology. A transmitter translates data into zeroes and ones, and pulses them out on a specific radio frequency. A receiver listening on that radio frequency catches the zeroes and ones, recompiles them into information, and passes the data onto the computer’s processor. Every wireless technology uses the same essential methodology, and then differs in frequency and encoding of the data."
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l37dy9 | How does RADAR work? | Technology | explainlikeimfive | {
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"A radar antenna is both a transmitter and a receiver. First, it sends out a powerful directed beam of radio waves. Then, it waits for that beam to bounce off things (planes, ships, etc) and return. In short, it listens for an echo. The longer it takes for the echo to return, the farther away the thing causing the echo is. A computer uses the direction of the antenna and the delay of the echo to draw a map.",
"You shoot a radio wave at a certain frequency at a target or in a general direction. Based on when you get a \"return\" (from the wave hitting various objects and bouncing back), you can tell how far away it is. If you have multiple receivers, you can also do some trigonometry to find out what direction each \"return\" is coming from, based on when each receiver hears that \"return.\" If you do two quick pulses, you can calculate the change in the distance that each \"return\" generated in order to find the speed of an object."
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l39gaa | How do refrigerators work? | Technology | explainlikeimfive | {
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"Usually heat only wants to flow from a higher-temperature area to a lower-temperature area. But something neat happens to gases when they compress and expand. Compressing a gas makes its temperature rise. Letting a gas expand makes its temperature lower. So if you compress a gas, it will get hot. But what if you then take that hot, compressed gas, and let it cool down? Well, then , you have some cool, compressed gas. Now, if you let the gas expand again, it will get cold! Much colder than it was when you started. So the trick is, you compress the gas over here outside the to make it hot, and then let it radiate all that heat away through the grille on the back of the fridge. Then you bring that compressed gas back over there to the inside the fridge, and then let it expand, and it gets very cold, and the cold gas is warmed up when heat flows into it from, say, your vegetables. The fridge achieves all this by pumping the gas, called a refrigerant, through a closed circuit of pipes. (It's actually not always in the gas phase; usually it condenses into a liquid for part of the cycle, but that's not really important to the basic principle here. Refrigerants are generally fluids which boil and condense at just the right temperatures and pressures to make this process most efficient.)"
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l3bkz0 | Why is it that you can keep a house phone on it's charging dock for years and it doesn't destroy the battery where as a cellphone will eventually wither over just a couple years if you charge it for too long everyday? | Technology | explainlikeimfive | {
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"Cell phone battery decays as each cell has its charge life and they die after a number of times it is charged. It's your assumption that house phone batteries do not get spoiled. They too get spoiled but probably the storage capacity of their batteries is larger and due to it the frequency of times you charge it is less compared to how you charge your cell phone. Hence the damage is not so quickly noticed.",
"Im guessing that the house phone’s battery would eventually wither too. but the device needs so little energy throughout the day that the battery comes under less strain overall so it ages slower",
"Short answer is, different battery chemistry. Not all batteries work the same way. Some batteries like to be fully discharged before recharging and recharging these types of batteries from halfway charged damages them. Others are damaged by being fully discharged. And all types of battery prefer to be trickle charged rather than fast charged. Cordless phone cradles are generally trickle chargers. Mobile phones use lithium batteries because they have high capacity at a very light weight. Lithium batteries hate being charged all the way from flat. It damages the battery quite a bit. But most people routinely let their phone get very flat before recharging. Moral of the story, recharging your phone too long isn't hurting the battery. Using it too much in between charges is why the battery fries itself. You should charge it all the way up and recharge it before it drops to 50%. If you are running it flat and then not fully charging it up because you are afraid to leave it on the charger too long, you aren't doing it about favours. Also, if you want to maximize battery life, charge it slowly. A charger that takes 10h to charge your phone is going to damage it much less than one that can do the job in 90 minutes. Even if you are charging from 50%, slow charging is much better fit the battery."
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l3frk3 | It's been more than 40 years since the first successful space shuttle launch. However, as we saw with the recent NASA launch, we still have launch failures. Why is it so tough to achieve reliability in space shuttle launches? Does this apply to all space technology? | Technology | explainlikeimfive | {
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"\"It's Rocket Science\" is a meme for a reason. To get maximum efficiency, rocket designers are pushing the limits of human technology. Sure, we could more reliably use old technology, but it's not affordable.",
"Rockets are extremely restricted by weight, much more than most other technologies. IIRC the Saturn V was something around 3000tons and only delivered a payload of a few single or double digit tons. If the rocket was 1% more heavy it would have basically lost all its cargo potential. The result is that rockets operate on much lower safety margins than other means of transport. Everything is designed to be just barely strong enough for the expected loads and redundant systems aren’t always possible or particularly practical. A single sensor failure can lead to the loss of the entire vehicle. IIRC there was a proton rocket that just flipped upside down and exploded because a sensor was mounted the wrong way around. Another aspect is that there is only limited ways to test your product in realistic scenarios. Rockets are crazy expensive and until recently they were entirely expendable devices. „Test flights“ aren’t really a thing when your vehicle has no way to land. The engineers must rely on in flight telemetry which makes it hard to spot faults unless you have a sensor specifically monitoring that part. There was an arianna rocket which exploded because its control software was partially copied from an earlier generation of the rocket. The newer rocket was faster and as a result a sensor ( I think it was an altimeter) exceeded its range of valid values during the early phases of the launch. This wasn’t an issue on the old slower rocket because the system was shut of before it ever flew that high. It never happened during tests because all tests were performed on the ground. And lastly rocket failures are always spectacular because rockets are basically a giant fuel tank with some high tech strapped on the top and bottom. If it goes wrong it goes wrong with a big boom. In retrospect it’s often a small „silly“ thing, but every part is critical in the rocket.",
"The reason why we have failures so often is because the technology and the physics are incredibly complex. When you’re launching a rocket, you need to make sure that the three ignition systems are working perfectly, that there isn’t a single screw out of the tens of thousands loose, that the weather could not possibly pose a problem. There is so much that could go wrong, and so much at stake (even if there aren’t people on board, launches are unbelievably expensive) that launches get cancelled quite frequently. However, there are so many variables that sometimes one gets missed, something goes wrong, and the launch fails",
"When/if you watch programs showing factories producing things you rarely, if ever, see anything going wrong. In reality, there are problems ALL the time, and things are having to be corrected on a regular basis. Stands to reason things will go wrong with rockets aswell. Only difference is, instead of a small pile of food on the floor, you get an impressive big bang.",
"\"However, as we saw with the recent NASA launch, we still have launch failures.\" - What launch are you referring to?",
"There are some quality responses here; but a point the other posts dont emphasise is the very narrow specialist nature of the technology. While there is some overlap with military applications - which have tens of trillions of dollars thrown into them over the last five decades. Arguably up until recently, **manned space flight is not actually a well funded mainstream industry.** It has a (proportionally) tiny budget, for what is effectively a continued series of research experiments (the launches included). If major world economies *chose* to throw more time, money, and effort at the technology - you would rapidly see a significant reduction in cost, and an increase in reliability (all the listed problems notwithstanding). This is what we are finally starting to see with the privatisation of space flight.",
"Many people here are talking about the difficulty of rocketry, which is huge, but I think many people are forgetting a big piece: sample size. There are very very few things in this world that happen as infrequently as a space launch. There have only been \\~200 crewed flights by NASA and \\~5,000 orbital launches by the world. Cars produced: over 1 billion TVs produced each YEAR: \\~200 million Aircraft flights per year: \\~10,000 No matter what you are doing, if you don't do it enough, you'll never become an expert at it, and until you become an expert at it, you can be rest-assured you will have issues.",
"For uncrewed launchers, you wouldn't want extremely high reliability. Extremely high reliability means making things more robust and heavier. It means adding redundant systems that weigh a lot. Weight that you add to the launcher is weight you have to remove from the payload. I've no idea how the economics pay out for any specific launcher, but if they just plain never fail you've built them too strong. Obvs all this goes out the window for crewed launchers.",
"Rockets are very complex and operate as close to the limit of their materials as we can. That means there are both more things that can break and they're more likely to break since they're under a lot of stress. That's why we have so many launch aborts. If there's a minor failure that mission control can't work around, it's better to scrub the mission and try again later. Otherwise, it risks a failure in flight which is often catastrophic. A rocket isn't like an airplane that can fly with an engine out or an instrument failure.",
"The forces involved are huge, and the machines have to be as light as possible. You can't \"over engineer\" due to the weight requirements, and even slightly \"under engineered\", or even a tiny flaw in the materials, can cause failure. \"Just right\" is a thin line.",
"I’m currently working on a university liquid rocket team. Even in their simplest form, liquid rockets are hellishly complex. Not only is everything hugely weight-optimized, but it has to be weight-optimized over a large range of temperatures and conditions. Finding the failure load for a strut at room temperature in air is easy; finding the failure load for a strut with one end connected to an injector plate and one end connected to a tank of cryogenic liquid oxygen under vibrational and transverse loads is less easy. Of course, this doesn’t even get to the hardest part, which is handling the fluids. Not only does everything have to be compatible with liquid oxygen and impeccably clean (like seriously, a single drop of cutting fluid can ignite an entire aluminum tank) but you often have to predict the properties of multiphase flows in non-trivial geometric arrangements, which even computers have trouble with. This isn’t even getting into turbopumps and the associated headaches with them. Seriously, every time you look at a liquid rocket it seems like the number of potential problems has tripled. When I look at a successful rocket launch, I wonder how the hell they got 1 out of 100 launches to work let alone 99 out of 100. Additionally, a lot of stuff is found through testing because there’s no good way to model it, which won’t necessarily reveal all possible issues. For instance, the F-1 engine team for the Saturn V brute-forced their injector development, by testing 600 subscale injectors (which are often among the most costly and expensive parts) until they found one with suitable performance, and IIRC they didn’t even find out about the combustion instabilities until they tested the full scale version. A flaw that made its way to the final Saturn V was an instability called “chugging” which caused engine thrust to oscillate back and forth. The cause? The mounting plate flexed slightly which subtly altered geometry of some pipes which altered turbopump inlet pressure which altered injector pressure which altered mass flow rate into the engine which altered thrust. *Everything* in a rocket is interconnected in extremely non-obvious ways that often aren’t evident until the thing flies."
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l3g6e7 | Why did you need to hide under a blanket like object when taking pictures using an old school camera? | Technology | explainlikeimfive | {
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"Nope to these \"answers\". View cameras (which still exist – I own one) have lightight plate holders to protect the plate (or \"plan film\" nowadays) from light. The problem is composing the shot on a ground glass: the objective gives only a dim image which would be swamped by ambient light. So the photographer hides, with the ground glass, under a kind of dark \"tent\" to be able to see the image on the glass, orienting the camera, setting the focus, & c. Once this is done he removes the veil, removes the ground glass and replaces the latter with a plate holder. The objective gets closed with a cap (or just a hat in ancient times, or an inbuilt shutter) and the plate holder opened – it's either a sliding piece of metal or a kind of blind you have to move. Now the plate can be exposed just by removing the objective cap (or hat, or triggering the shutter). Once this is done the shutter is closed, the plate holder is closed too, removed from the camera and stored in the bag you have to drag along with all that gear. Most holders have a place where you can write a pencil mark so you don't mix up exposed and fresh plates. It's all a bit technical, but here's a picture of a plate/film holder: URL_1 And here's a view camera from the back where you see the ground glass and the projected image on it: URL_0",
"When you look at the back of an old school camera, the image of what you're looking at through the camera lens is projected onto a piece of opaque glass (it's not clear like a window, but white), and that image is not very bright. It's not very bright because the only light you're seeing is what's allowed to shine through the small opening of your lens. Covering the camera and shielding it from the outside light makes the image easier to see for composing your shot and getting it into focus. You can see how this works yourself by turning down the brightness of your phone and reading it while out in bright sunlight, then cover yourself and your screen with a dark cloth to get the same effect. TL;DR: It's how you turn up the brightness on an old school camera by blocking out the sun.",
"With a traditional SLR style camera, the photographer composes the image by looking through the viewfinder of the camera, where they see the image as seen through the cameras lens. Traditional view cameras don't have a viewfinder, what they use instead is a ground glass plate - this is slotted into the camera where it forms the back of the body. The cameras lens then projects the image it sees onto this glass plate which the photographer can look say to frame and focus the camera correctly. To take a photo, the ground glass plate is removed and a holder containing a piece of film is put in its place and a photo can be taken. The reason for the cloth covering is that the images you see on the ground glass is very dim and quite hard to see in bright light. By covering yourself with the cloth you block out the light behind you which makes it easier to see the image."
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l3hdam | How do air-fryers work? | If you’re using oil, I assume it heats then atomizes the oil so it cooks the food item in hot oil by coating it with a mist rather than the traditional method of dunking it in liquid oil, but it says on the box you can cook many items with no oil.. so how is this different from just baking/roasting them in a traditional oven? ETA: Thanks everyone! | Technology | explainlikeimfive | {
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"Air fryer = convection oven, with a fancy name. If you have an oven with a convection setting, you have an air fryer. Convection ovens come with fans that help circulate the hot air around the oven to uniformly cook the food. It's great if you're cooking in large batches; all the food will cook at the same speed.",
"Like the others have said, air fryers are essentially scaled-down convection ovens. However, there are a few crucial differences: - air fryers don't get as hot (mine tops out at 400F/204C) - air fryers have a much higher fan speed than most convection ovens - air fryers don't need to preheat in the same way (you only need to wait for the heating coils to warm up, no need to warm the basket itself) Before air fryers were introduced, there was an appliance called the NuWave that was essentially the same thing, but with multiple tiers like an oven or dehydrator instead of the basket you'll find in most air fryers. The surface of foods cooked in the air fryer are a bit more dry than what you'll get out of a traditional oven or deep fryer. That's sometimes a good substitute for the crispiness you get from a deep fryer, but an air fryer can't achieve the \"bloom\" that you get from deep fryers, which relies on a rapid transfer of heat between the cooking medium (oil or air) and the surface of the food. (Fun fact: Food in a deep fryer is essentially \"steamed\" by its own moisture while the surface is fried; properly fried foods will have relatively little oil remaining on the surface.)",
"Like a regular oven, it just heats the air and circulates it around the food. If there’s oil on/around your food, it’ll be heated as well, but nothing atomizes the oil to spread it around, that’d be extremely dangerous and inefficient for heat transfer.",
"If your oven has a “convection” mode, it’s literally no different. Air fryers/convection ovens use fans to circulate the air around whatever you’re cooking. The convection feature on ovens isn’t the default setting because it’s loud, uses more energy, and doesn’t make a difference if you’re making lasagna or a casserole or whatever. But most ovens have it. If you baste or spray whatever you’re about to cook in an air fryer/convection oven in oil, it comes reasonably close to the taste of deep frying. But a lot of people are using them for health reasons and avoiding oil altogether. Without oil, it’s still better to use the convection setting for certain things as it can make them crispier. Counter-top air fryers are just for convenience, similar to a rice cooker. You can make rice on the stove but if you have the space, a rice cooker makes it super easy and frees up your stove for cooking other parts of the meal."
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l3lnah | Between the time I open a webpage and the time it takes for the option to pop up to accept or deny cookies, what happens to my cookies? | When I opened a news site today and it asked me about consenting to cookies, it made me wonder what happens to my cookies before I deny or accept it? Are the cookies being monitored up until that point? What happens if I never click deny or accept? | Technology | explainlikeimfive | {
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"There is probably no cookies. The website won't automatically write cookies just because you visit it. It probably writes it's first cookie when you click \"accept\" storing that you clicked accept. If you never click anything, it will just wait for your input.",
"Hi, so the answer depend on where you are in the world. For example with GDPR (in a nutshell the european law on cookies) an european website SHOULD wait for you to click on \"YES i accept\", before droping a cookie. On a \"less protected\" country or on a website that does not respect the rules; they often drop the cookie on the instant of your arrival. So even before the \"YES i accept\". Hoping it was clear enough ☺️"
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l3temz | Why can't we just read the secret ingredients of coca-cola off the ingredient label on the back of the can ? What's secret about it ? | Technology | explainlikeimfive | {
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"The process in which you make things can drastically change the results. Their “secret” ingredient could be something special they add to the process that isn’t necessarily an ingredient. This is more a chemistry aspect then an ingredient aspect. Temperature, speed, time and a ton of other things can affect this, I can’t guarantee this is the reason why but it’s a possibility.",
"One of the ingredients is \"natural flavors\" which could be any combination of barks, spices, roots, fermentation products, buds, vegetables, fruits, or yeasts.",
"If you look at the recipes for Coke (and Pepsi) 'do it yourself' plans you will see that the flavor comes from a pretty complex mix of quite a few flavor ingredients. Even if they published what they were trying to get the precise combination in the precise amounts would be very difficult.",
"I will only give you 65kg of Oxygen, 18kg of Carbon, 10kg of Hydrogen, 3kg of Nitrogen and 4kg of ‘other stuff’. Now that you have all the ingredients, make a human.",
"I had a friend in sweet beverage industry. What he told me is that recepy for Coca-Cola is not a mystery for the last 20-30 years. It was reversed long time ago, however noone wants to face Coca-Cola law team. There are laboratories all around world specialized for \"taste\" formulas for food industry - they make industrial formulas for samples you deliver."
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l3vqh7 | How do mood rings transition from color to color? | Technology | explainlikeimfive | {
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"Mood rings contain a liquid crystal that basically works similarly to a thermometer. Or in other words, the liquid crystals reflect different wavelengths of light at different temperatures.",
"Body temperature. I realized this by wearing mine while wetting my hands, cooler water made it turn lighter colors, and warmer water scorched it and now my ring doesn't work anymore."
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l3wfgb | What is so bad about the waste of nuclear power plants? Why are many governments so against it? What is so hard about storing the waste in a safe place? | Technology | explainlikeimfive | {
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"I'm a nuclear engineer. Elements can have different weights when they have different numbers of neutrons in their nucleus. A reactor is a neutron throwing machine. Certain atoms split into pieces when it absorbs a neutron, making smaller atoms, while others hold onto the neutron and get bigger. Generally, more neutrons make the atom radioactive, meaning it spits out energy and/or parts of the atom to be more stable, like a ball rolling down a hill. So, after running for 3-4 years, nuclear fuel has made some of every element in different weights. That includes toxic metals, which makes it chemically toxic, and many radioactive versions of atoms. People have long been conditioned to be afraid of radiation, though compared with most industrial hazards it is pretty easy to manage. In fact, the atoms that decay slowly (\"they last for hundreds of thousands of years\") release radiation slowly, and is of little risk. The real problem ones last a hundred to two hundred years, which is relatively easy to store. The short answer is fear and lack of perspective. Basically, reactors make a chemical soup that is capable of putting out a lot of energy for a couple hundred years, and after that you're left with a weird mix of elements. We have multiple techniques for reusing, recycling, and safely storing the used fuel, but fear keeps hitting those ideas down and we're left in a weird limbo as an industry. Essentially, a technically challenging but solved problem is being confused with the politically challenging and unsolved problem.",
"The waste from current nuclear power plants is highly radioactive and also toxic. It is stored on site under a pool of water until the worst of the radioactive isotopes have decayed but some of the particles will have half lives in the thousands to hundreds of thousands of years. This means the waste remains dangerous for thousands of years. Finding a place which is safe to store it is difficult, convincing locals to let you build that storage is even more difficult and then you have the cost of actually building long term storage.",
"Old reactors worked this way, definitely - they made spent fuel that is hard to safely store. Modern reactors don't. Heck, some modern reactors can use old-school spent fuel as secondary fissile (fuel) material! And then the waste they produce is pretty inert (harmless), edit: at least the waste we don't recycle, I should say! In short, nuclear science had come a long way, and modern reactor waste is not remotely as dangerous as old-school spent fuel.",
"Not here to argue. But I would like to share [this article here]( URL_0 ) Just scroll down to read the radioactive waste from a coal plant, and compare it to a nuclear plant. That said? Green all the way. Nuclear would be a *great* step away from coal though to help bridge the gap as far as carbon emissions go however. The article I'm sharing though is just to illuminate *how insanely bad coal is* compared to literally the most though of radioactive producer that actually isnt. Nuclear power just concentrates it incredibly. Now, compare coal to green, and ask yourself why people still argue for coal....",
"Nuclear waste is radioactive and harmful to people. Bad particles come out of it and if they hit you, they can really hurt your body. Because of this, many people are scared of it. And it’s right to be scared of nuclear waste, it’s dangerous. Thankfully, scientists have have worked really hard to make new technology so that the waste isn’t as dangerous. Nuclear reactors are more efficient now and we have storage containers that can stop the bad particles from getting out. The waste is still dangerous though, so we have to be really careful.",
"What really needs to happen: refine it, reuse it. This is possible and would save loads of money and prevent further spent fuel needing to be stored. This is completely possible and done in some countries-France for example, and should be an environmental priority.",
"There's been serious talk about having absolutely huge sites deep under ground near bedrock and have different types of signs that will be understood by people 100.000 years from now. That no treasure or valuables are buried here. Only death that will get worse the closer you get to it. And possibly even make a sort of religion around it to pass the knowledge to future generations.",
"Nuclear waste stays radioactive for a REALLY long time. During the first hundred years this presents little or no problems. BUT, after a while the drums sealed in concrete can and will begin to leak. Any leakage not only contaminates the the outer container but any surface the containers are in or on. That means you have to dig up the floor or dirt in the facility and recontain it and the original containers. This isn't a big deal in the short term but over hundreds and hundreds of years it's going to be a big problem! If 1 tom of waste is produced in the first years and each year there after: Year one = 1 ton of waste. Year two= 1 ton plus one ton equals 2 tons, Year three= 1 ton plus two tons, plus 2 tons, year four = 1 ton plus 3 tons equals four tons of stored waste. Still not a big deal, eh? Okay, lets say an accident occurs on year 8 and 44 tons of contaminated waste needs to be stored. Suddenly you have 54 tons of store waste!. Now, repeat this cycle every 20 years and by year 100 you have hundreds of tons of radioactive waste to watch over, contain and monitor. If an earthquake hits and damages the storage site you could have thousands of tens of thousands of tons of radioactive waste to contend with. Politicians can safely say \"they\" have nothing to worry about whole ignoring the radioactive legacy they leave for our descents to live with. Edit. These numbers are not consistent over the years and may decrease or increase depending om many factors. I was simply illustrating the concept.",
"Where do you think the nuclear fuel comes from? It's mined from the ground. The ground is radioactive. Coincidentally, but unrelated, the sky is too. Bananas are radioactive. So are people. You are radioactive. (Go ahead and google something like \"How Much Radiation Does the Human Body Emit?\" if you're curious.) It's totally natural and nothing to be concerned about. The problem with nuclear waste is just that it's concentrated. It just so happens that it's easy to concentrate, and that's what we do to get power out of it. You have to concentrate it for that. If you concentrate any dangerous thing (like a poison), then it's not easy to dispose of safely. One accident with a concentrated poison could get into the groundwater and contaminate the drinking water for an entire region. And that's exactly the fear of nuclear waste. Radiation isn't dangerous in natural amounts (well, it is, but no more so than just being in nature), but concentrated it can be much more dangerous. And we have to concentrate it to get that value out of it. The other aspect is how long can it be safely stored? It can take a long time for radioactivity to degrade. And we're a \"buy a new phone every two years\" society. We're not really good at long-term projects that can be secure for multiple generations. There's nothing technically stopping us, but human nature and our culture tends to ignore and neglect things that are old. We're fully capable of containing it safely, but not quite mature enough to do so.",
"Several items we call waste. First off the fuel which is highly radioactive is placed in dry cask containers, welded shut and filled with helium as a heat transfer medium. Casks are placed outside to continue to decay and you can walk right up to them. This is done all over the world. In the US there was discussion to consolidate the containers but currently the casks are stored on site. This is not hard and has been done for twenty years here in the US. Second by product is contaminated waste which includes old components, consumables for service work. These get packaged up and sent to a burial site where they are sorted. Some of the old components are stored on site as they are too large to move so utilities make a bunker and let the part cool off radiologically. All of the waste is monitored and disposed of safely and correctly with very few exceptions. The largest risk of nuclear is not really the waste. It is the potential for a large scale issue like Fukushima which could impact the area.",
"unrational fear of the people, and government workers are generally directly or indirectly elected by the people. Older people know of chernobyl and younger people learned of it, and then saw fukushima, even though they are not related in the slightest. They also see the direct deaths of chernobyl and not the indirect deaths of coal miners, oil harvesting and all the other side affects of dirty power. So people are afraid, thus government has to act afraid, even though it would be better and much much safer. Waste is not an issue, the world has thousands of sites we could easily store waste, and the waste created is very small amount.",
"> What is so bad about the waste of nuclear power plants? It doesn't take much place, but it's dangerous for a long time. Like 100,000 years. > What is so hard about storing the waste in a safe place? It's easy to store it for a short time, but harder to store it for a long time because in 100,000 years languages change, culture changes, even ground changes. You need to keep it in a very stable place like some mountains. > Why are many governments so against it? People are afraid of anything related to radiation. > Unasked question: [can we shoot it into the sun/a black hole?]( URL_0 ) It's hard and expensive. It takes *a lot* of energy to shoot things into the sun. And if the rocket explodes or falls down to earth, the dangerous waste is spilled all around. > Unasked question: is storage the only option? No. The \"waste\" is mostly good fuel, just with some dangerous isotopes in it. [Fast-neutron reactors]( URL_3 ) can use this waste as fuel and produce energy plus much less problematic waste which only needs to be stored for about 300 years. That's much easier. Nuclear waste can also be made less problematic in a process named \"[transmutation]( URL_2 )\". This is expensive though and doesn't produce energy to pay for itself. See also: [List of radioactive waste treatment technologies]( URL_1 ) on Wikipedia.",
"The waste is not that difficult to manage. It is small and easily stored. The problem is that it has a half-life measured in tens of thousands of years in some cases. So where do we put it that will be safe for that long? The benefits of nuclear also relate to the waste. Nuclear waste is small and easily stored, easily sequestered, unlike the waste of fossil fuels, which we puke into the atmosphere and which will take billions of years to clean up. (Life on earth has been sequestering carbon from the atmosphere for 2 billion years. We are putting it back into the atmosphere in a few hundred years). The resistance to nuclear power is an exercise in what-about-ism. Nuclear is cleaner, safer and cheaper than fossil fuels, and more practical than wind or solar for now. It is not perfect, and it will be overtaken by solar. It is marketed as an alternative to coal, not solar power.",
"URL_0 This is a brilliant and very short (6 minutes) video that EVERYBODY should see. The worst thing about spent fuel is peoples perception. In fact, it is the best kind of \"waste\", it is of low volume and has a half-life. It also has lots of energy left, and can be reused in advanced reactors or recycled. Chemical toxins do not have a half-life, they are poisones indefinitely, like cadmium in solar panels. Nuclear \"waste\" is great.",
"Half-Life of 24,000 years. It's fucking Pandora's Box. NO human enterprise can keep its shit together for that long. And then twice that again. The literal dawn of reason in humanity was 10,000 years ago, when we know they had oral traditions from the Vedas. This kinda shit right here is why the quote: **Paleolithic Emotions, Medieval Institutions, God-Like Technology** Is meaningful. EDIT: Some helpful information: [ URL_2 ]( URL_3 ) [ URL_1 ]( URL_1 ) [ URL_0 ]( URL_0 ) Thanks to /u/dbdatvic for the heads up I might want to include this, since my view is sounding perhaps a bit alarmist. I DO think that there is a lot of things we don't know, as the public, and I believe more my friend [Helen Mary Caldicott]( URL_4 ) than I do more governmental agencies, but take it as you will.",
"Going to attempt an eli10 on this: The waste is like the sun. It puts out light, and things like light, that you can't see, and that light can hurt you just like too much sunlight can. Big governments aren't as much against it as little governments are, like towns and councils, because people don't want to hold onto it or have it stuck in the ground near their homes. Remember those X-rays you got? If you got way, way too many of those, you could get sick. That's why doctors leave the room while they take the X-ray, because they might do a lot and be close to a lot, but you only get a couple a visit. The X-ray is actually a lot like the stuff that comes out of the waste, and not just for how it can make you sick. We can block it with lead, and we can block it with other stuff as well. Water is pretty popular; it's cheap, and it works pretty well for what we're trying to do. Another way the stuff it makes is like light is that it gets dimmer the farther away you go, and there's only so much the source can give before it burns out. So, you can dig a big hole in the ground, build basically a big swimming pool, seal it to prevent leaks, put the waste in, and cover it with water. Then we watch it from a small distance to make sure nothing happens to it, and we let it burn itself out over time. After about 150 years, barely 3% of the waste is still dangerous. Once the material burns out, we can reuse it. The hardest part in the whole thing is getting someone to agree to put such a pool in their town, because people mostly don't know how it works, so it makes them afraid, but if the government wanted to pay me to hold onto it, and they gave me the money to dig the hole, build the pool, stick it all in, and then babysit it, I would. I worked with this stuff in the Navy. It got less radiation working in the plant than the guys working on the flight deck, because they were standing in the sun and I was deep below in the ship, surrounded by metal above and shielding around. The next-hardest part is about making something that'll last for that long without anything leaking, but that's why we have to watch it and check it to make sure it doesn't. We're great at building stuff good enough for people that'll last for hundreds of years, but not as good at building stuff that won't ever spring a leak for that long. That's one of the reasons why we have to watch it after we put it in the pool. The water itself doesn't become *very* dangerous, but if we're being responsible we have to make sure nothing corrodes and gets into water... But that's an engineering problem that you solve by building stuff, moving stuff, and being responsible. You can check how much radiation is coming off of the waste with a bunch of different detectors, the way the TV has a detector that checks for the signal coming off of the remote. That's the biggest danger out of all of them: People need to be responsible while they hold onto the stuff. It's not anywhere close to as bad as you see on TV or in your games, but you can't be stupid or careless with it either. It's fine. Like I said, I'd put some of it in my backyard if they gave me enough money to build what I need to build, and if they paid me to keep an eye on it."
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l3wlvm | What is the internal difference between a CPU and GPU? | Technology | explainlikeimfive | {
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"The CPU has a relatively small number of cores - up to 4 in home computers, and up to 32 in high end workstation CPUs. Each of these cores if very fast and can do lots of different kinds of calculations. Meanwhile, a GPU has a large number of relatively weak cores, which specialize in calculations that are used mainly for displaying graphics. A single GPU core is much slower than a CPU core, but there are literally hundreds or even thousands of cores in the GPU, all calculating at the same time.",
"A CPU is like a pocket knife and a GPU is like a surgeons scalpel. The CPU is designed to be decent at pretty much everything. The GPU is designed to be really really good at it's one specific purpose, which in the case of GPU os doing lots and lots and lots of fairly simple and extremely similar calculations in very little time."
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l3x0p9 | when Adobe Flash ‘died’, why did it cause every Flash program to stop running? | I don’t really have much of an understanding of computer programming, but I thought that Flash was just another program that was installed on a computer to access content. I read a story about how it caused a Chinese railway to stop running which is just mind boggling, but for simpler things like games and other interactive content, why can’t you still access them? | Technology | explainlikeimfive | {
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"Flash applications won't run anymore because Adobe time bombed Flash player so that it would not run after 12 January. Microsoft and Adobe distributed these updates over a long period of time, which meant they were installed on the majority of computers. So, on 12 January, Flash stopped working on most computers. This approach was taken because Flash was never designed with security in mind and as a result was very, very insecure with no possibility of fixing it. The decision to do this was made, and announced over three years ago. It has been announced over and over again so nobody should have been surprised when it stopped working. But of course some people don't take warnings seriously.",
"Adobe specifically included a kill switch in all Flash updates since they decided to finally end it for good, in order to avoid a Windows XP/Internet Explorer 6 kinda situation. The browser maintainers also did this separately, so browser refuse to load the Flash plugin. This is very rare to see for this kind of program and only goes to show how huge a security threat the existence of Flash was. If you *must* run a Flash SWF file, there is an open source player called Lightspark."
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l3xzp8 | Why are sinking ships in movies portrayed with metal screeching sounds while going under? | Technology | explainlikeimfive | {
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"There are stories (true) about submariners who would listen to the ships sink after torpedoing them - the sound of a ship dying underwater is haunting to fellow mariners even in war time. It was also true of the surface fleet - as they could hear and confirm a kill by the sounds of the sub coming apart. So the noise it real - Hollywood obviously enhances it - like most everything else. The structure of a hull is designed to resist the forces of the water being applied to it - this is what buoency is. The moment it stops resisting is when the sea wins. This resistance is along the entire length of the ship and although it is a very dynamic load (load of the ship, waves, rise and fall, rolling etc) these loads are designed into the structure. But when that structure fails then you have loads applied that are not designed for or that exceed the strength of the material and it fails - violently. Like ripping itself apart or snapping. And this material is metal - so the sounds of metal grinding onto itself, snapping and ripping open is like a soda can x1000 being crushed.",
"To make it sound more dramatic, of course. Same as with crashing aircraft typically featuring Jericho trumpet sounds - which, in reality, were a fancy little gadget Nazi Germany planted onto its Stuka dive bombers as a literal terror weapon. Additionally, do bear in mind that water actually weighs a lot. So if one \"half\" of the ship is rapidly flooding while the other half is still dry, it *does* put a considerably amount of stress on the ship's structure."
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l415ag | How did we get to the point where a smartphone cost more than a laptop? | Technology | explainlikeimfive | {
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"There are plenty of smartphones that cost less than a laptop, and plenty of laptops that cost more than a smartphone. But if you compare a *high end* smartphone to a *low end* laptop, then yes, the smartphone would cost more.",
"A high-end smart phone does not cost more than a high-end laptop, and a low-end smart phone does not cost more than a low-end laptop. I reject your premise. If you want to know why smart phones _can_ cost as much, it’s because of miniaturization.",
"I get you OP. My iPhone costs a grand but my laptop costs $400. I believe we got here because people now spend more personal time on their phones, which can do some of the same functions as a laptop. I use my personal laptop maybe 8-10 times a year. I use my phone 8-10 times an hour. If I were gaming or working from my personal laptop, I would buy a more expensive one. I compromised and invested in the platform I use the most.",
"Customer demand for smartphones vs. laptops. People will still line up to pay $1000+ for smartphones.",
"Well, that isn't always the case as already pointed out, but fundamentally a modern smartphone has pretty much all the same components as a laptop (screen, CPU, memory, storage) along with stuff that a laptop typically \\*wouldn't\\* have (GPS and mobile network connections). So, even though the smartphone is smaller it's arguably more complicated and thus harder to manufacture.",
"It’s harder to engineer and manufacturer on smaller scale. It’s easiest to fit the necessary components into a desktop computer. Harder to make them smarter and fit just right into a laptop. Much harder still to do so into a tiny smart phone. The processing, storage capacity, etc are not that far off between a laptop and smart phone in spite of size differences"
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l426oy | how is the bottom of the ocean mapped and how accurate are the results? | Technology | explainlikeimfive | {
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"Mostly they use a form of radar/sonar but water can cause issues with mapping. Results are pretty accurate. But the ocean is just big and it takes time"
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l42qav | How does a trunked radio system work? | please as basic as you can lol | Technology | explainlikeimfive | {
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"The simplest way it was explained to me is to think of a bank. Each teller is a different frequency. You stand in line. When you transmit, you go to the first available teller/frequency. You stand in line again. When you transmit again, you again go to the first available teller/frequency which may be a different teller because another person is using the previous teller/frequency to talk with their dispatch from another agency."
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l45qd9 | how does a country like the USA produce exactly as much electricity as needed at all times. Where does excess power go when not needed? | Technology | explainlikeimfive | {
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"One one side, you regulate the output of your powerplants to meet demand. That can be complicated with some plants, so the system is set up that you have base load plants, that will essentially run at constant production, mostly nuclear and coal, and peak load plants, which can react quickly to changing demand, that is mostly gas. On another side, you can store excess production. That's done with pumped storage plants. Excess energy is used to pump water into an uphill reservoir, from which it can be quickly released downhill through a water turbine to produce electricity again when the need is there. Overall, it's a fine balancing game between all the different sources and the changing demand. But the folks running that game have lots of statistical data on how demand changes over time and can predict what they have to do based on that.",
"Used to operate a gas power plant. A large power company has a central control center. They predict and react to demand and direct starting and stopping of units. Any plant with variable load will likely have an automatic control that can change a plants megawatt output remotely. In the US like other countries our grids are very large and interconnected, like multiple states and parts of canada for the west coast as an example. Power companies buy and sell power/reserve from other companies on the grid as needed. The control center was pretty good at their job, but we dont always produce exactly enough. This mostly results in frequency and voltage changes on a grid, but you'd need a large surplus or deficit for this to be a big issue....generating units like steam turbines will trip on overspeed or underfrequency to protect themselves if the load is too imbalanced. Other issues include things like lines overheating and transmission equipment tripping. You can use things like pumped storage to help use grid load, and can cut power to certain areas to help lower grid load.",
"In addition to what these other smart people have said, it's important to understand that we don't produce exactly as much electricity as needed at all times. We try to keep up with demand, but that doesn't always work. Prime example, summers in CA. They've been plagued with rolling blackouts for years in CA due to demand exceeding supply. They max out all the generation facilities but it just isn't enough. So they have to shut down parts of the electrical grid to make sure they don't go into an overload state. It would be nice if we had a way of storing power for an emergency at a large scale, but we don't. As others have already said, it takes a ton of monitoring and constant adjusting to ensure the power grid generation closely matches the need. Another thing to note is that the USA isn't one large power grid. Its many many many many small grids interconnected at times. So where I live in Oregon, my power mainly comes from hydroelectric with some other sources as needed. If my area had a huge power spike, the power would come locally. It's not like some big all equaling grid where power from other places automatically rushes in to fill the demand. We have the ability to move power to other areas, in fact Oregon sells a ton of power to California when needed, but it's very inefficient. The further distances you send power the more you lose. So in general, power is generated very close to the consumer. It'd be cool if this wasn't the case, because we could put all the power generation plants some places where nobody care, like the middle of the desert. But alas, this isn't the case.",
"Excess power goes into main power frequency, which fluctuates slightly. The power regulation system needs to stay into certain frequency range around 50 Hz (60 Hz in US). In Europe there was a power generation problem in Serbia few years ago. Since many clocks use the frequency from the main to keep clocks, they were getting slower because they were not generating enough power. URL_0",
"By starting up and shutting down power plants as needed. And computers. And lots of smart engineers watching it 24/7. It's a clusterfuck really, and nothing but a miracle that it works as well as it does. > Where does excess power go when not needed? It makes the generators in the powerplants spin faster, increasing the net frequency. Which you REALLY DONT WANT. It's imperative that there is no \"excess power\". Electrical energy isn't really stored at large scale (yet). There are a few battery facilities, and a few pumped hydro (think of it as a reverse hydro plant, which consumes energy to pump water up a mountain) stations, but nothing large scale. If we can accomplish that, it's a huge leap forward especially for unpredictable power plants such as wind and solar.",
"It actually does not. You will find that the grid frequency fluctuates all the time, it‘s just that it fluctuates very tiny amounts. If you pull more energy out of the grid than you supply, the frequency drops, and vice versa. As a first line of defense, the rotational inertia of the big turbines in the power plants buffer the changes, just like a heavy truck will react less quickly to pressing the accelerator than a light sportscar. Then you have power plants that are quick to regulate, like smallish gas plants, those get adjusted constantly in a matter of (mili-)seconds to follow demand. Coal plants are sort of in the middle, while nuclear power plants are extremely slow to adjust and wind or solar are depending on weather rather than energy demand. That‘s why we have stuff like pumping stations, which will store excess energy by pumping water up to a reservoir on a hill and release that energy later when it is needed.",
"USA also imports power from Canada. Quebec and Ontario for example. The US grid is tied in with Canadian grids",
"Power producers can only control their output voltage and frequency. Power generating stations produce high voltages which are eventually reduced to somewhere between 108-127V at your residence wall outlet. Sensitive equipment and other devices (wall clocks) rely on a constant frequency at 60Hz but are designed to accommodate fluctuations in voltage (108-127V). The generators constantly vary their output voltage to maintain a constant 60Hz output. This results in variations in your residential voltage which may cause your lights to shine a little brighter or dimmer or you coffee maker to heat a little faster or slower."
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l4ccff | How do people gain access and leak CCTV videos? | I go on 4chan a lot and see threads of gore and "rekt" and continuously find myself wondering, "where do they get these videos? Who is giving these people tapes of random maimings and such?" I know that they probably **find** the video on liveleak or some other gore site but how does the footage itself make it on the internet? Edit: Why the downvotes? | Technology | explainlikeimfive | {
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"Someone who has access to the source files initially leaks them. It's really that simple. There's also a chance, if the CCTV system is networked, that it is compromised and hackers go through the files for a bit of fun and come across it. Then *they* leak it."
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l4dlbt | what happens if I connect my power bank to itself? Will it explode?? | Technology | explainlikeimfive | {
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"Many power banks will disable the outputs when connected to a power source, but otherwise the entire contents of the battery would slowly be lost to heat as it attempts to charge itself from its own batteries.",
"No, unless it's very poorly designed. It will slowly discharge itself. It's not some sort of power increasing perpetual motion machine."
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l4jjto | How and why 6gb, and 12gb RAM sizes came to be in smartphones? | With RAM sizes, I have seen them going up by doubling, for example 1- > 2- > 4- > 8 etc. So why and how some smartphones come with 6, or 12gb of RAM? Is there any specific reason for this "odd" amount of RAM? | Technology | explainlikeimfive | {
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"Memory in pcs always come in powers of two because of the architectural design. Ie dual channel, requires it to be even. And since the dimm dimensions are also strictly defined its just been convenient. For phone memory, the architecture is different so they could plop in whatever GBs they wanted since ram is soldered on and space is more important as well so they stick on the bare minimum they think they can get away with based on modern usage scenarios. In terms of memory controller design. Ram has a row and column address and the number of rows and columns is in powers of two (because binary) so making 6GB ram doesnt leave any unused addresses. But 5gb will."
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l4ox0m | What are the differences between Hertz in electricity, in the electromagnetic spectrum, in processors, in displays and in sound? | Technology | explainlikeimfive | {
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"Nothing. A hz is a cycle per second. If your screen is 120hz, then it refreshes 120 times per second. If your power is 60hz (A/C) then it cycles 60 times per second Your cpu does ghz or 1billion cycles per second. Each cycle is a chance to do something.",
"Hertz is a unit of frequency: a measure of repetitions per second. Lots of things repeat. In processors, there is a \"clock signal\", a signal that repeatedly turns on and off at a regular interval in order to keep the sub-components of the processor in sync. The frequency being measured is how many times the clock signal switches on and off per second. In a display, the screen displays a still image several times a second to create the appearance of motion. The frequency measured in a monitor's quoted refresh rate is how many times a new still image is displayed a second. Higher refresh rates means more images or \"frames\" per second, which means smoother motion. In alternating current, the live wire's voltage cycles from positive voltage to negative voltage, and the frequency is how many times it cycles per second. In sound, a passing sound wave changes the air pressure changes the air pressure in a spot, cycling it from high pressure to low and back. The frequency being measured is how many times per second the pressure cycles. In electromagnetic waves it is the same as sound waves, except the quantity that is varying isn't pressure, but the energy in the electric and magnetic fields. Hertz are generally only used to measure the frequency of things which periodic (that happen at regular intervals). Other things happen at random intervals, but with a predictable average frequency, like radioactive decay, which has its frequency measured in Becquerels rather than Herts, even though they both mean \"number of times per second\".",
"Hertz is just a measure of inverted seconds. Often times the thing being measured implies some other measurement. If I have a 5 gHz CPU, then what that means is I have 5 billion operations *per second*. If I have 6.5 * 10^14 Hz light, then that light is oscillating 6.5 * 10^14 times *per second*. If I have a sound at 200 Hz, that means the sound waves are oscillating at 200 times *per second*.",
"Hertz is just a measure of frequency, specifically how many times something happens per second. All of the things you list have some property which fluctuates in a measurable way, and the frequency of this happening is shown as hertz, kilohertz (thousands of times per second), megahertz (millions of times per second) or gigahertz (billions of time per second).",
"do you remember when we went to the playground last week? do you remember swinging back and forth on that big swing? we kept counting \"one, banana. two, banana. three, banana....\" and so forth. i was counting how long it took you to go from where you could touch my hands with your toes, swing all the way back away from me, and then swing all the way back to where you could kick my hands again. i was also thinking about how \"often\" or how \"frequently\" you were swinging back and forth. it took you one second to complete one full swing--front to back and front again. in science, we measure how \"often\" or how \"frequently\" it takes for something to repeat itself for lots of stuff--car tires rolling around, waves out on the ocean, a guitar string vibrating, and lots more stuff. we had to pick a unit--kinda like a foot, an inch, or a millimeter, or meter--for this. so, scientists named it for a guy who studied very tiny waves that make x-rays, microwaves, and things like my bluetooth earbuds. his name was heinrich rudolf hertz. he lived a long time ago. yeah, his name does kind of sound like \"hurts\"--just like when you skinned your knee at the playground. yep, i bet it still hurts--or hertz! ha! so these days we can measure all kinds of stuff like electrical current flipping back and forth or tiny waves like gamma rays--y'know like the kind that made dr. bruce banner become the hulk--and sound waves from stuff like a piano string or a speaker using \"hertz.\" do you remember back to your swinging on the swing? it took one second for you to complete one whole back and forth. you're swing was one hertz. if the swing had a shorter chain, you would've swing back and forth more often. you would've had a swing of more than one hertz. if the swing had a longer chain, you would've swing back and forth less often. it would've been less than one hertz. some waves can go very often or frequently. like the note \"c\" on a piano. when you press that key, the string inside the piano wiggles back and forth over 260 times every single second! some stuff like computer parts can wiggle almost two billion times every single second! but when we watch that scary dinosaur movie and the big speaker next to the tv makes a low, rumbly booooom, booooom sound that's a low frequency sound--maybe only 50 or 100 hertz. so, sometimes stuff can move back and forth (or even up and down) very often or frequently. that's a very big hertz number. but, sometimes stuff can wiggle back and forth (or up and down) not very often or not very frequently. that's a small hertz number. we can use hertz to measure all kinds of stuff that repeat their motion. (for older learners: frequency is made up of 1/T. that T stands for period. a period is how long it takes to complete one full back and forth cycle. so mathematically, a big period means a small frequency. think \"less frequently means small frequency.\" for example, a wave that takes 2 seconds to repeat means 1/2s = 0.5 Hz. a small period means a big frequency. think \"more frequently means big frequency.\" a wave that takes 0.2 seconds to repeat means 1/0.2s = 5 Hz.)"
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l4pvsn | Why is it that when we watch footage from the 70s a lot of times it looks better than footage of the 90s? | Technology | explainlikeimfive | {
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"Older stuff is more likely to be captured on film, while newer stuff is more likely to be captured on videotape. Images on film are captured at a higher resolution and can be restored more easily and to a higher degree.",
"The quality of old film recording was more limited by the technology playing it back than recording it. We can play back old film content with extremely high quality. The quality of digital recording is primarily limited by the technology that recorded it. We cannot add detail that wasn't captured at the time.",
"To add to the \"it's film, not video\" chorus, here's some numbers: 1. The resolution of the NTSC VHS standard (which would have been used to \"videotape\" many things from the 90s) is 333×480 pixels. If you were thinking about this as a digital camera, that would be a total of less than **0**.16 megapixels. Importantly for your question, *that's all that video captures.* There is no \"hidden\" detail we can go extract from an old video tape. 2. The resolution of 35mm film (which would have been used -- at least as a professional level -- to film many things in the 70s) is estimated in the *range* of 100 megapixels. Every film stock is different and it's not possibly to actually measure megapixels on film, so this is just a rough justice estimate, but you can - again, rough justice - calculate that film has somewhere on the order of 500 times more resolution than video. This also makes innate sense -- film was (prior to the last decade-ish) used to shoot movies which we went out and watched on giant movie screens. And it looked great. Video was never intended for anything more than your dinky at-home TV, *before* they got bigger and we switched to HD standards. Video was used when it was available because it was dirt cheap and had instant turnaround -- film was more expensive and required development. What this means now is that the stuff that was captured on video is forever limited to video-grade quality. Stuff that was captured on film (even if it looked shitty when broadcast on TV in the 70's), we can go back and re-scan the film at modern resolutions and it will look great. It's far more likely that stuff from the 70s exists on film than stuff from the 90s, which is the answer to your question.",
"Everybody is explaining it all, so I'm gonna say it in a very basic way. Film is 4k. People just didn't have ways to display 4k quality images in their homes in the 70's",
"If it was filmed in the 70's, it was on film. In the 80's-90's, there were lots of camcorders filming on VHS tape or other tape that got converted to VHS, which wasn't as high quality and degrades over time."
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l4sj5b | What does a CGI (Common Gateway Interface) do? What is its part in web servers? | This isn't the "CGI" they use in movies. It is a term from computing but I don't quite get its function. | Technology | explainlikeimfive | {
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"It’s the original server side scripting platform for web. Before PHP and ASP, this was how you would run custom scripts at the server side.",
"CGI defines a set of rules for how an application can communicate with a web server to handle incoming requests. The web server sets up various [environment variables]( URL_0 ) based on the incoming request and then executes an application with that environment. The application can look at those environment variables to determine what the request was for and process it accordingly. The application then outputs a response to the web server which will forward that response to the end user. By implementing CGI applications and web servers can be paired together to create dynamic websites.",
"CGI -the Common Gateway Interface- is an agreed-upon standard by which Web servers can, rather than serve static files, run separate programs on the server. Mostly it's a means of specifying which aspects of the server get put into the program's environment variables just before running them. The first Web-based mail forms and discussion forums were CGI scripts. Perl was the most popular language for writing them, but you could use any language as long as the server had some way to run it. True CGI scripts aren't all that common anymore. Part of this is due to the potential for security problems, but it's also a question of performance: starting up and tearing down a program every time the server has to run the script takes time. The usual practice nowadays is to embed a language into the server itself (often via plugins, as with PHP and Java servlets) and run that instead: this gives the server more control over what can and can't be done in code, and it also cuts out the overhead of running a new process every time. But these scripts are still sometimes called CGI scripts for historical reasons."
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l4zgl0 | Why do most telephone calls still sound so terrible? | Technology | explainlikeimfive | {
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"One issue: keeping everything compatible with everything else. HD voice can't be used for all cell phone calls since there are still a lot of devices relying on 3g networks for voice calls, as an example."
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l5an70 | how do modern cars have parking cameras view of the car from all angles? Like from the top, view of the whole car? | Technology | explainlikeimfive | {
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"Composite images. Many images combined into one. Including radar data for accurate distances."
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l5gtol | Why do bank transfers take ~3-5 working days to complete? | Why does it take so long? With current technology I don't understand why it takes a whole 72 hour minimum? What happens in the background? It sounds reasonable for pre-computer era but nowadays? & #x200B; EDIT: In the US, guess today I learned in other countries this is instant haha. | Technology | explainlikeimfive | {
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"Transfers can be handled by two methods in the US, Automated Clearing House “ACH” or wire transfers. ACH operates in batches, 3 times a day. The sending bank gathers all the transactions and a final total of money (here’s 62 credits, 72 debits, for a total of $123,456.23) and sends it to the clearing house. The clearing house then batches things up for each bank as well and sends those transactions and final overall total to the receiving bank). Each of those batches takes time. Funds availability depends on the receiving bank’s policy. My bank gives me credit for the incoming money as soon as they get the notification from ACH. Other banks wait until the notification and the actual funds are transferred to give you credit. Wire transfers use FedWire. The money is taken out of your account immediately and send via the Federal Reserve banking network directly to the receiving bank. Because it’s not as efficient as batch processing ACH transactions, there’s a higher cost associated with the transaction. But it is nearly instantaneous.",
"They don’t; in most of the world they take seconds; in Canada it takes < 10 minutes for an account to account transfer to be processed and show up.",
"Historically it came from the cheque clearing time. This is Uk. The cheques would be manually input at the branch level of bank A, then all the cheques sent to Bank A's clearing centre for processing, then each individual entry is routed to the issuing banks clearing centres for input into their system, and finally on the relevant branch. Similar time for standing orders/direct debits etc -hope this paints the historical side a bit for you. Present day transfers are pretty instant if staying within the same country (ie UK here) but most companies (not banks) who say it will take 3-5, or up to 7 days to processes your refund or whatever are saying this because that is their own administration timelines, not the actual banks timelines."
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l5h24y | Why is there a file size limit on emails? | Technology | explainlikeimfive | {
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"Short version: you don't know what kind of mail server any particular email address is supported by. When you send files over a shared platform like WhatsApp, both you and the recipient are on the same platform. It doesn't even really need to send the file itself, you just upload it and it sends a link to that same file to the recipient, so there's no concern that there might not be enough space, that the recipient can receive it, etc. That is \\*not\\* generally true of email servers. You have no idea if you're sending to an enterprise-level datacenter backed set of servers, like a Microsoft or Google, or some guy running a mailserver on the side in his home office. Virtually all mail servers (Google included), impose a quota on the mail store size but you have no idea what the quota is of the address you're sending to or the bandwidth that server has. If you send a 4GB 4k video to someone it's entirely possible you'll tie up their entire bandwidth and mail server for hours, preventing \\*everyone\\* on that server from getting or receiving email, and potentially locking their account if you blow through their quota. Think of it like the difference between sending a postcard and sending a shipping container, without knowing what the destination physically looks like. Everyone can receive a postcard; not everyone can receive a shipping container."
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l5l22d | why do websites load more and more cookies to the browser with each passing year? | I still vaguely remember a time when I could surf the web without worrying to have my browser loaded with cookies. Then cookies started appearing. I'm so old I still remember having sites that proudly announced they cleared the cookies as you logged off. Nowadays, it is as if without cookies the entire internet will break. | Technology | explainlikeimfive | {
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"Companies figured out that user info is valuable. Usage behavior patterns are valuable both internally and externally and can be sold for revenue.",
"I can answer a slightly different but perhaps just as useful question: \"What do browsers do behind the scenes with cookies and other technologies, and why do they do this?\" Cookies are sent up to a website with each web request (well, essentially). This allows a server to say whether this user is secretly the same as that user. Aside from social media tracking (which most people have heard about) there are many reasons for websites to do this: * Tracking how a website is used: if there's a bug on the website only affecting some users, it can help the developers and maintainers to know how those users have been browsing their site. Does the bug only occur after browsing this particular order of pages? (Related: which parts of the site are people actually using, and do companies want to pay developers to maintain parts of a site that aren't actually popular?) * Anonymous browsing (ironically): a common example is when you can build a shopping cart on an online store without having to log in until you pay. Without that cookie, the server cannot know which anonymous cart belongs to whom. * Easy to access settings: if you want to change the theme on a website, it's easier for the server to let the website handle that sort of trivial setting. So the cookie stores a name of the theme you're using (maybe \"dark mode\" or something.) As for why (and why it is increasing), it's a combination of even more reasons: * Users expect websites to do more. Websites back in the nineties weren't very dynamic and didn't have as much functionality. Now we expect our inboxes to load emails live, to be able to chat with customer support in the browser, to view a map on one website that's secretly embedded from another website, etc. * Users are addicted to social media: cookies, and other background processes that you don't see, are essential for those simple buttons that let you share content with facebook, instagram, etc. * Advertisers are willing to pay for information about what you do: Websites can now show ads for products if you visited other websites that mentioned those products, for example. Does that answer your question? I guess it's not very ELI5. Cookies are not poisonous, and in fact most are relatively benign, but some are certainly used to manipulate you into voting a certain way, buying certain products, or agreeing with certain ideals. Source: I build web-based dashboards for a living, and have built social websites previously.",
"In the olden times webpages didn't have to warn you about cookies, they could just dump them on your ass without a word. Then the EU said that you need to be notified of it, so sites started telling you.",
"It's not that cookie use is increasing; it's because several countries (notably, the EU) have passed laws requiring websites to disclose to you that they are using cookies. Before, they just did it silently and you had no idea. EDIT sources for the downvoters: URL_1 URL_2 URL_0"
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l5ldes | What happens when you pair and/or reconnect bluetooth devices and why does it never work reliably? | What's the internal process like and how can I ensure it to work as expected. I work in IT, but in general, it's arcane witchcraft to me.. | Technology | explainlikeimfive | {
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"There’s no way to ELI5. This is just way too complicated. Google “frequency hopping spread spectrum”. Bluetooth basically acts like a radio where both the receiver and transmitter are randomly changing channels constantly, in sync with each other by clocks. It’s really a miracle it works at all.",
"It's reliable for the devices I have. However, it's true that it's often unreliable because the BT spec is complicated, and you have inexperienced BT firmware developers in third-world countries that barely know what they are doing cranking out code on the cheap without any quality control."
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l5ly3c | Spam advertising bots. Why is it so hard to prevent them? Especially ones stealing content from other users. | Technology | explainlikeimfive | {
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"I know Reddit as a whole, and many subs, put in a lot of work to prevent spam and bots from ruining the experience. I searched for an answer before writing this post and almost every result was about getting banned by mistake by over sensitive filters, so I can see there are filters out there trying to catch spam accounts. I don’t have a background in computers or programming so this might be a stupid question, but why is it so hard for Reddit to catch profiles like this who steal other user’s nsfw content and spam it out as an ad for a porn site? Especially with reverse image search software and when they are making whole subreddits just for cross posting. Example: URL_0 URL_1"
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l5obf7 | Why does the wifi signal strength frequently change and sometimes disconnects, when the router and the laptop are both always placed in the exact same locations ? | The indicator is usually a dot and three curved bars that determine the wifi signal strength on windows laptops | Technology | explainlikeimfive | {
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"It's just a radio signal. Anything radio on the same frequency (2.4GHz or 5GHz) will interfere with it. Echoes of its own signal, other devices in your own house or nearby houses, people in cars driving past with their phones on, wireless devices like Bluetooth, doorbells, video senders. Hell, even microwaves. It's just a digital radio modem, in effect. Any radio interference on those channels will affect the strength and will vary quite considerably over time. Even your own devices are dialling up/down their speed as per their current requirements/battery status all the time which will affect the signal. You're sharing the airwaves with anything nearby that uses those same frequencies, basically.",
"WiFi these days operates at a fantastically high data rate, so the signal is pretty delicate. I worked on the earliest WiFi adapters, and given all the trouble we had in 1998 I'm astonished at how fast and how far WiFi now goes, and with very little set up. And so cheap! But it's easy for nearby electronics and the RF environment to interfere with a packet here or there. The software automatically re-sends these packets once the receiver figures out something is missing and lets the sender know, but that takes a few milliseconds, which is a hundred years in computer terms. Add to these that WiFi is a frequency hopping technology. Invented by actress Heddy Lamar (no joke), frequency hopping means that each WiFi channel is actually a set of frequencies the radios can use, and the hardware automatically hops between them to whichever is working best at the moment. So it's a very dynamic system of moving data.",
"The signal strength depends on the environment. Obstacles can degrade the signal. Other objects can also stand in such a way that they reflect the signal in a favorable direction. The signal strength can also simply depend on the weather or the air. Cold humid air absorbs more of the radiation you receive as WLAN than dry warm air."
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l5oov7 | How does darkweb work? Why do onions work on tor but not on other browsers? Does it mean tor know of all the .onions that exist? | Technology | explainlikeimfive | {
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"Darkweb contains a lot more then just the onion services. Tor is an anonymization service composed of lots of different voulanteerely run nodes around the world. These nodes works as routers and when you send encrypted traffic to them they will decrypt it and pass it on. Most clients will encrypt the traffic three times with the keys of three different nodes so that the traffic will be sent around the network through a path controlled by them before entering the global Internet. In order to connect the source and destination an attacker have to have compromised at least two of the three nodes. The onion services works using the same network. But instead of sending traffic out on the Internet they have their own servers to answer the requests. As the encryption key is used as the address for the service this often becomes quite long and unreadable. But even though the traffic is sent through the nodes in the onion network they do not know which nodes are services and which are just passing the traffic along to other nodes and they can not see any traffic because it is encrypted."
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l5tkac | Noise Cancellation in the AirPods Pro: How Does it Work? | Technology | explainlikeimfive | {
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"It sends out opposite sound waves. When sound waves hit your eardrum, they vibrate it and you hear the sound. A opposite exact sound wave hitting your eardrum at the same time, will prevent you eardrum from moving, so you don't hear either sound. It only prevents your eardrum from moving for the intended sound though, so you still hear other sounds, like the music. Think of the opposite of a double bounce on a trampoline. Someone lands at just the rint moment and you dont bounce back up, or how you stop yourself from bouncing, by pushing back in just the right timing to stop it from bouncing.",
"Sound waves are picked up by a microphone, and turned in to electrical signals. These electrical signals have been combined with whatever music you are listening to (or silence if you are not listening) and turned back into sound in the tiny earbud speaker. What you \"hear\" at your eardrum is the sum of the sound from the earbud speaker and the sound coming in from the outside of the ear. The sound from the speaker is the opposite of the sound from outside, so they cancel out. Thus \"noise cancellation\"."
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l5vsbb | How do advertisers determine my preferences by using internet cookies? | Would cookies be defined as personal data? If so, can the user deny cookies and still surf the webz without issues? | Technology | explainlikeimfive | {
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"Imagine your parents are tracking your iPhone location. While you’re moving around freely, they know where you are. Your mom can look and see you’re at the park. Because your mom knows you’re at the park she sends you a photo of a squirrel with the caption “deez nutz”. You’ve received the text but all you can say is OK. You can delete the text, but you can’t un-receive it. You = you. iPhone tracker = cookies. Squirrel = ad. Your response “Ok” to your mom = cookie banners (they usually don’t do anything)",
"Cookies are one way that a website can use to offload some storage onto a user. This can be incredibly useful -- for example, if you have a website you use daily, you can habitually close the browser tab for a day or two between sessions and the next time you navigate to the site you'll still be logged in. The website hasn't \"remembered\" your session, the website gave you a cookie that's essentially a \"I was just here a few days ago, please log me in\" pass, and your browser hands the website that cookie when you connect to it. That's all a cookie is, it's just a piece of data that the server sends to your browser, and your browser by default will dutifully send it back every time you revisit the website until the cookie expires. The way a tracking cookie works is primarily only notable for extremely large corporations like Google and Facebook. They offer services to other websites, usually for free, that help make hosting that website easier. If you've ever seen a \"log in with Google/Facebook\", that's one example. They do this, and in exchange, Google and Facebook now have bits of them embedded into a HUGE chunk of the web. It's hard to visit a popular website these days that doesn't have at least one of these players wormed into them. What Google and Facebook then do is give your browser a cookie that's essentially just an ID card. Every time you connect to a website that has one of these embedded bits, your browser will \"phone home\" to them and present your ID cookie. Instantly, that company now knows that your ID visited the page you're looking at. Collect enough page hits from enough users and you can get a pretty good idea of what people are into."
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l5y19x | How was the first computer software coded? | Technology | explainlikeimfive | {
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"The very first programs were written directly in machine code - that is, they told the processor exactly what to do at each step through instructions mechanically fed to the processor via punch cards. The first compiler (thing that translates human-readable source code into machine code) had to be written that way, too - but once one compiler existed, you could write a new compiler using the language of the old one and bootstrap your way all the way to complex modern languages."
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l604ko | why do cross-platform PC games become increasingly harder to run during a single console generation? | i mean, the console specs remain the same, so do they just stop caring about pc optimisation later in the generation? | Technology | explainlikeimfive | {
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"Games developed for a given console tend to become better and better during the span of that console generation, as studios accumulate specific experience on how to best exploit the HW, the quirks, and the possibilities afforded by that console (including ones initially unseen or overlooked by anyone). (They also become more confident of being able to avoid the pitfalls, and so willing to push it nearer to the edge). This can make the games increasingly harder to adapt to different HW."
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l60qtg | How can an adapter convert Usb to HDMI? | Like why do we even need an HDMI port then | Technology | explainlikeimfive | {
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"The usb adapter contains a 'mini video card'. It registers to the operating system as a video card and is treated by the OS as such. It is terribly limited in speed.",
"These devices are little external \"graphics cards\". They get the data via USB and render themselves a signal for the monitor. They are very low power, so probably very bad for fast moving things like watching videos, but for a powerpoint presentation they will do. This is because of the limitations of USB, inside a PC, the graphics card is connected via a very capable connection making it possible for even 3D stuff to be fluid. HDMI only carries the image information itself, not the data out of which the image is drawn.",
"This devices is not a simple adapter that just converts between two different plugs carrying the same type of signal. For example a USB-C to USB-A adapter does not have any active components and just connects the two together directly. But an USB to HDMI adapter is an active adapter with its own microchip inside it that communicates with the computer and the monitor using two seperate protocols. To the computer it looks like a video card but does not have any GPU so it can not render anything but full frames. This means that another GPU on the computer can transfer fully rendered frames over the USB line to the adapter. When the adapter receives such a frame it stores it in its internal memory and then continuously outputs it on the HDMI cable as a HDMI signal. You will often notice the difference between passive and active components in its price and its features. A passive adapter is just a few bucks but an active adapter is significantly more expensive. And while a passive adapter usually supports all the features of the underlying protocol as it does not touch any of the signaling an active adapter may be limited in bandwidth or capabilities."
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l61z7d | Why do some websites punish you for using ad blockers? Why can you get free stuff in games just for watching ads? What do these people gain or lose from the simple fact of someone staring at their ad for 30 seconds? | Technology | explainlikeimfive | {
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"The advertising industry works like this. I want to sell something, I pay someone to put my ads everywhere, hoping I gain a lot more (because my ads convinced someone to buy my stuff) than what I pay for. The websites are being paid for putting those ads. If everybody starts using ad blockers (and refuses to set up exceptions), the whole thing is completely useless, because no one even sees the ads, so there's basically no chance for the whole ad concept to even work. And if this doesn't work anywore, they (websites hosting ads) lose a significant part of their profits. Hence why they \"punish\" you."
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l62vj4 | ; Why do halogen lights get burning hot but LEDS don't get hot at all? | Technology | explainlikeimfive | {
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"Different method of operation and different efficiency. Halogen lights are just producing light by making a wire get very, very hot to the point it gets white hot, same as old-style incandescent bulbs--so most of their output is actually heat. LEDs produce light via semiconductor interactions in a diode junction, and are far more efficient, so most of what they produce is light rather than heat. That doesn't mean they don't produce heat at all--depending on how your LED lamp is constructed it may have an aluminium heatsink behind the LEDs to soak up the generated heat and allow them to last longer, or the newer \"filament\" style rely on the gas in the bulb to carry the heat away.",
"It's about how efficient you can turn electricity to light. Halogen light bulbs work by heating up a filament inside. What’s different from regular light bulbs is that halogens ones can recycle the vapors of the tungsten filament inside - the filament gets “fixed.” However it works, it still works by making a metal very hot. So, what about LED? LED uses electrons, or more specifically, photon emitting electrons, to produce light. How can it force electrons to only produce visible light (well, more than light bulbs, at least)? Well, here’s the answer. There’s two semiconductors. When a current flows through it, electrons goes from one to another, releasing energy as photon during the process. Now, why does it release electrons? So, semiconductors are usually made of silicon and another material (more in that later). Now, silicon has 4 electrons on its most outside shell. It bonds with each other using covalent bond, by sharing electrons and getting 8 electrons (the number of electrons that is most stable for that shell). Now, add an atom that has 5 electrons on its outer most shell. When it bonds with the silicon, you have 1 electron that is not used in the bond. Ok, we have a semiconductor that has 1 free electron (of course, it’s not only one but go with it). Next, we make the same conductor but this time the atom you add has only 3 electrons. Now, it needs 1 more electron to make 8 (the stable amount). So, we have one semiconductor with a free electron and another semiconductor that needs 1 more. That free electron moves to the other semiconductor to fill the hole. Yeah, but why does it release a photon? Energy difference. Only electrons with a certain energy level can be in a shell (well, orbital to be exact). Different shell have different energy levels. That means, if the electrons need to have an energy level of 1 to be in that shell, the electron needs to have an energy level of 1, not 1.1. The free electron has more energy than the hole requires. So what does it do? The electron releases energy, in the form of light. By the way, the energy difference between the semiconductors determine the color of the LED. If you want a blue LED, you’ll need a energy difference bigger than a red one.",
"Head on over to r/flashlight and check out the holes they've burned in things with LEDs yo.",
"OP, it's a common misconception that LED light sources run without producing heat. It's simply not true. Yes, they do run cooler compared to a halogen light source, but a LED does run hot.",
"Halogen lights are actually designed to run hot, hotter than normal incandescent bulbs. Filament bulbs in general produce light by heating the tungsten wire to white heat but that means there is waste heat which makes them inefficient. There is also a limit to how bright they can be before the wire burns out because the metal evaporates. Halogen bulbs have a small amount of iodine or bromine inside which deposits evaporated tungsten back on the filament so they can be brighter and not burn out too soon. For that chemistry to work the inside of the \"glass\" (fused quartz not ordinary glass) has to be quite hot which is why the bulb is usually fairly small and burns you."
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l6h29t | How are songs remastered? | It seems that on Spotify all the Beatles songs are remastered. What exactly is a remastered song, is it not just re-recording a song? | Technology | explainlikeimfive | {
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"Remastering basically has two components: reworking the mix and \"restoring\" the audio. Studio gear, even back in the day, typically records each instrument and vocals onto separate tracks. That's re-balanced, along with often having some equalization applied, to provide a \"polished\" final sound for various audiences. FM isn't very good at transmitting the highest and lowest audible frequencies, and back then a lot of audio gear wasn't good at reproducing the highest frequencies either. So an old FM mix tends to have boosted bass around 80hz and treble somewhere in the 7k-10k range to give the impression of a \"full sound\" where a vinyl production wouldn't have those boosts. Things like that. So in a remaster they re-work the balance between those different studio tracks (where it's still available) and tweak the equalization to match modern tastes. For \"Restoring\" the audio, there may be loss from the recording material, the microphones themselves weren't great at recording the highest end and some things like that. We have algorithms now that are intended to bring out or clean up missing or distorted sounds from technological differences, degraded recording media and so on. It may be cleaning up static or trying to restore the very upper end \"sparkle\" to things like cymbals or sibilance to the \"s\" sound in vocals. Bringing out that kind of thing is more art than science and is a lot about taste. So...that's what a remaster is for, adjusting the mix to modern tastes and playing around with some equalization/digitization magic to try and make it sound like a brand new recording on the best gear.",
"Songs aren’t just recorded at once, on one microphone. Each instrument and singer usually has their own microphone and are frequently recorded separately so that each of those elements can be mixed together by the band and producer. Remastering a song involves going back to those original recordings and mixing them again. This could mean any number of things like boosting/lowering the relative volume of individual elements to emphasize different aspects of the song, applying or removing EQ or other effects like reverb, or simply creating a stereo mix from a mono recoding. Often times for older songs it involves re-digitizing the master recordings at a higher quality than was previously possible too.",
"It is not in fact re-recorded! Imagine a song being a car. In the old days, when you bought it, a red car was all the rage but through the years, the color has faded, the polish doesn’t look as fresh anymore and the red color is not modern at all now. You don’t build a new car from similar materials, because you like the car. You take your car to be sanded down to the metal, and then you have it repainted in a new sparkly and much more modern color, and you add a nice new polish so it really shines and looks as it was a brand new car. Basically when a song is mixed and subsequently mastered, the raw sounds recorded such as the drums, vocals or sounds from the amplifiers, are edited to fit better together. This is done with a range of tools such as reverb, delay, saturation, compressors, limiters or even equalizers to highlight certain frequencies of an instrument or the whole song, and in general setting the volume of one instrument compared to the others. Some mix engineers prefer specific parts of a song to be louder and quieter than others for example how much the vocals are in front or ‘hidden’ deeper in the mix. When all of that sounds good, the song is mastered to ‘glue’ the whole song together and make sure that it is at a specific volume matching all other songs out there so there isn’t a big difference in volume when the radio or Spotify switches from a Beatles song to a Katy Perry song. But why do it again now, so many years later? There can be many reasons, but for example with The Beatles, they were some of the first to record electric guitars so since then we have learned a lot about recording, mixing and editing electric guitars. They may be very rough on the original songs and generally not ‘pleasing’ to listen to. The equipment we use today has also evolved a lot so everything is much more clearer now. Something that a mix engineer couldn’t hear 40-60 years ago can much more easily be heard on modern studio monitors and seen with modern visualization tools. That way we can now control the frequencies much tighter. Song is mixed and mastered depending on the primary listening medium. If you mix/master for vinyl it is going to sound different from streaming, simply due to different storage methods. The old Beatles songs were recorded on an analog medium (tape) and has since been converted to a digital media to use on Spotify, and surely some quality would be lost in that conversion. So in short, a remaster *may* also mean it has been re-mixed (not remixed), but it could also just be only the final polishing of the song to ensure it has more clarity and fits better with our modern ways of listening to music. An engineers job is always for the music to sound as good as it can on as many devices as possible - some people have hifi speakers worth thousands, others will listen on their smart phone speaker.",
"So essentially all of the raw vocal and instrument tracks were recorded one each to a \"track\" which was literally a track on a tape. You've heard of a 4-track or whatnot, it means that tape deck could record 4 different tracks. Nowadays, each \"track\" or if you want a mic or a line in from an instrument gets recorded digitally. So the process of \"mastering\" is how you go from those raw tracks to the single finished \"master\" track i.e. what gets sent to the record/tape/CD factory. It involves mixing all of the tracks together at one of those mixing consoles with all the knobs, controlling fade, echo/reverb and a bunch of other effects, relative volume, left/right/fade etc. to get the desired effect. Back then, lots of times a lot of compromises are made in the rush to get an album made - studio time wasn't cheap (and very few artists had all the mixing and recording gear at home). Plus you needed a skilled recording engineer ($time) etc. Maybe your engineer didn't make your hot guitar solo sound the way you wanted, but you ran out of time. Maybe the keyboard synth was too loud and you couldn't hear the wicked bass line. Maybe you always wish you'd put a cool reverb on the vocals of a chorus but you didn't have the equipment to do it. Maybe the sound mix just was muddy and uck, maybe the master tape sent to the record factory was mistakenly one of the bad tapes and the vinyl sucked because of it. Maybe the lead singer never liked the album version of his singing because he had a sore throat that week at the studio, he/she might actually re-record that song's vocal tracks. Who knows? Remastering all these old tracks are going back to the raw tape recordings where they exist and rebuilding, remixing the entire song from the ground up. Its a bit like a movie director putting out a \"Director's Cut\". Its how the artist really really wanted the song to sound but didn't get it right back then. To give an idea of what that might look like, check this post out. A recording engineer \"remixes\" a song by Def Leppard: URL_0 Each channel or vertical bank of controls/meters/sliders corresponds to one of the raw recordings (guitar, each drum mic, vocal mic, each keyboard etc.) Ill be curious to see how remastering albums trends in the future now that good quality audio equipment can be had for home studios and with computers you can pretty much go back and fix whatever you like whenever you like.",
"You basically take the original, highest quality recordings and then redo the final \"mastering\" process of the songs, except this time it's for a new medium. You also might need to redo part of the mixing stage, which is a bit more complicated. Mastering is the final stage of music production, you send the mixed song off to an audio engineer and they make it sound as loud and clear as possible for the intended medium (be it vinyl record, CD, etc), all while testing it on different audio setups, removing certain resonances and audio hiccups and such. Remasters usually try to make songs sound better for modern audiences and streaming platforms, following all the suggested guidelines regarding volume and such. Songs from the 60s, etc, were meant to be listened to on vinyl record or the radio, not headphones in a pristine digital audio stream. So the mastering engineer's job (or even mixer if the songs need to be mixed again) is to make the songs fit this new world, to squeeze all the new juice they can from those original super high quality recordings they've got stored somewhere. If you're also remixing (which is quite common), you'd also be redoing parts of the mix itself to fit modern sensibilities and such, maybe the song is very old and the drums are too quiet/badly mixed, who knows! anyways, hope this helps!",
"Often in posts like this there is one reply and then the next reply contradicts it, and so on. I’m very pleased that here the replies agrees with each other. Bravo! You all got my upvote."
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l6k2h0 | Loudness in regards to music production. | I've been reading about the "Loudness War" and the "wall of sound" approach with sound mixing and I can't really conceptualize what means. For me loudness is determined by the volume knob regardless of how the song was mixed but this is clearly not what they're referring to. So what is "loudness" in this context and how does it affect the sound on the listener's end? | Technology | explainlikeimfive | {
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"When music is recorded there is an absolute minimum and maximum value for volume that can be stored on the media. Think about the minimum as the floor (zero feet) and the maximum as the ceiling (10 ft) and the song volume as jumping in between the two during quiet (floor) and loud (ceiling) parts of the song. Lets say that you have a song where the loudest part is a 7 as played but when you record it you want it to sound like a 10 so its louder than other songs, that’s OK, you can just bump up all parts of the song by 3, so your 7 becomes a 10, the 6 becomes a 9, the 5 is now an 8 and so on. Then on the next release you want it even louder so you bump up all parts by another 3, the problem is that the parts of your song at a 10 can’t go any higher, 10 is the max. Furthermore other parts of the song that were at a 7,8,and 9 are now also all at a 10 for volume! So when the song is played those parts of the song which were originally at different volumes are now all equally loud (technically called “clipping”). This ruins the soundscape of the music because parts which were originally louder and quieter relative to each other are now all at the same level of loudness.",
"Let's listen to a song. It starts off quiet, but becomes louder as it picks up. Do you change the volume knob during this process? The song starts with a specific loudness, and the volume knob then multiplies this. That way, quiet moments stay quieter and loud moments stay louder. So, what if instead, we made the whole song a 'loud moment'?",
"Let's see if I can keep it ELI5: Let's take for example Led Zeppelin's Stairway to Heaven. It starts out softly, just acoustic guitar and a flute comes in. These sounds, as you'd expect, are soft. The song builds, bass and drums come in, and then acoustic turns into electric guitar and bombastic vocals. It's LOUD! Now, this is great for critical listening: Under quality headphones, or on your couch listening through a hi-fi setup, which was popular and common when the song was released in the 1970s. But, if you're listening in your car, the soft parts might be too soft for you to hear the music over the road noise. So you turn up the intro. Then, damn the loud parts are so loud that the sound gets distorted, it hurts your ears, and you end up turning the loud parts down. Then came the 1980s when cassette Walkman players became popular with their open-air mini headphones. Now the outside sounds of the bus, cars, whatever are intruding on your soft music. So again you're turning the volume up and down again. So, sound engineers came up with a solution: Remaster the song with the soft sounds turned up, and the loud sounds limited so they're not too loud or overdrive your amplifier, even if your amp is a cheap Walkman or factory car stereo. The result is what we audiophiles call \"brickwalled.\" If you look at the song on a graph of loud vs. soft, the original has soft parts and loud parts, but the brickwalled version looks equally loud throughout the song. [Here's an article]( URL_0 ) with a graph to show what I mean. So while this may help you enjoy the song in your car or over a Walkman, when you critically listen through your $10,000+ home hifi system, it sounds horrible. The dynamic range (differences between soft and loud) is gone. The loud parts might be squashed to the point where it just sounds terrible. In our Stairway to Heaven example, the opening softness drawing you in, with a crescendo to a glorious loud, bigger-than-the-sky sound...it's just gone. The excitement has been taken out. We people with good audio systems hate this.",
"Without going into the physics of it - the \"wall of sound\" is basically cranking the volume up and removing all dynamics - as in, the difference between quiet notes and loud notes. Think of a piano recording, or even an orchestra. It's not all 100% loud, right? You want to hear the quiet moments, you want to hear the loud moments. The wall of sound removes that difference and just has it all at the \"loud notes\" level. This is very popular in pop music, or the kind of music you'd expect to hear on the radio anyway.",
"Can I recommend that you listen to some symphonies (any, choose randomly) to feel the power of good dynamics? Quiet notes add suspense, anticipation. Loud notes are exciting, satisfying. New music is a lot of instant satisfaction, but there's not much build up. It's just BAM tune! then over. One example of a similar scenario is yummy food. Sure, it's good to eat. It's amazing to eat yummy food. But to smell it cooking beforehand adds anticipation and makes actually eating it feel even better. I think of the quiet notes as smelling food cook. You know what's coming and you develop a taste for the flavor, you start anticipating it. Then the orchestra crescendos, the tune climaxes in full volume, and you eat while your taste buds dance for joy and satisfaction. In the 80s, music producers started only being loud, the value of soft notes seemed to be lost. People noticed. Maybe things will turn around, and full range of dynamics will come back to modern music."
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l6l2fi | What's the difference between extracting a zip folder and just opening it? | There doesn't seem to be a difference between just opening a zip folder (navigating inside) and using its contents and extracting them to the folder it's located in. What's the difference, if there is one? | Technology | explainlikeimfive | {
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"Windows extracts or expands the file you select within a zip file in the background. It is actually written to the drive in a temporary folder and then executed or opened.",
"when you only open it, everything is stored in RAM, not to disk. If you extract it, the extracted files in their full form are stored to disk",
"If you browse the content without extracting and open a file, it will unzip itself anyway, but only that specific file and in a temporary way (cache) that doesn't require disk space. The problem is, sometimes complex files like applications and design assets are linked to other ones in the same folder, so if you only open one it may not work properly.",
"The zip file contains two things. First, an index of files that it contains, and second, the contents of those files. When you open and browse around a zip file, you are just navigating that index. If you have an application that supports opening files from the zip, then all its doing is extracting the file into a temporary path and opening it, and then later cleaning up."
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l6m0ip | App developing and patenting | What’s the deal. You have a great idea you want to make an app. How does one regular ol’joe shmoe go about creating and patenting an app/idea ? | Technology | explainlikeimfive | {
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"If you don’t know how to do it yourself, you hire someone who knows what they’re doing. if you want to patent something, hire a patent attorney.",
"Oh hey, I can answer this one! I’m a UX/UI designer at a software dev company and custom designing apps for people is our entire trade. When you work with a company on something like this, they’ll be able to provide you with custom design & development and you still keep intellectual property (well at least that’s how my company does it). If you’re serious about your idea feel free to ask me anything!"
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l6mopr | How come in TV shows they always make a huge deal about the victim saying they “don’t want to push charges” when in reality, the system can still charge them for the crime? What does a victim “pressing charges” actually mean? | Technology | explainlikeimfive | {
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"On TV, its a trope to push the drama. In real life, it is extremely more difficult to convict someone of a crime if the victim doesn't testify, or if the jury thinks they're unwilling to testify",
"Depending on the crime, an uncooperative victim can make it difficult for the state to successfully prosecute a crime. So if I’m a victim and “pressing charges” basically what it means is that I’m accusing someone of a crime and willing to testify or provide evidence."
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l6n191 | what the hell is geomining? | Technology | explainlikeimfive | {
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"Geomining is the collection of location data. Currently, apps like Google maps on your mobile device track where users are at any given point in time. This data is anonymous but can be sold to companies interested in knowing traffic patterns. This can be used to target advertising in high traffic areas or to route shipping to avoid high traffic areas. There are probably a ton of other uses for the data as well, but those are two of the most obvious. The ads you are likely seeing are from companies trying to build a location database. In exchange for anonymously tracking your location, they offer rewards."
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l6tgo2 | Why aren't more video games distributed on cartridges (SD Cards etc)? | I recently bought a Micro SD card and it got me thinking, these things can hold a ton of data nowadays (even more than a Blu-ray!) so why is it only the Nintendo Switch uses carts (which I assume are some sort of SD card) when they can conceivably fit any AAA title on them now? | Technology | explainlikeimfive | {
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"Because games are mostly distributed via the internet nowadays. For consoles you *could* make a case for using SD cards (and I think the Nintendo cartridges are indeed such but with a larger case so they fit the cover art and don't get lost easily), but the Xbox/Playstation has inertia behind using DVD/BluRay drives. Indeed, one of the Playstation's features is serving as a BluRay player to watch movies. Disks are also quite a bit cheaper since they contain no electronics while an SD card is actually a tiny computer that communicates with the reader over a serial port.",
"in short. they cost more to manufacture. to put it in comparison, you can get a 50GB BD-R disk (blu ray writeable) for about $1.50-$2. and a 32gb sd card costs like $5-$10. because carts use flash memory. and flash memory is a lot more expensive to make than \"mostly\" plastic disks. there's no practical reason to have xbox or ps use carts b/c there's plenty of space for a blu ray or diskless. but the switch's format basically requires it to use a more portable format."
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l6vdz7 | Why is medical software so bad? | Many of my friends and family work in the medical field and no matter what software they use, they all complain about the same things: Sluggish performance, outdated GUI, extremely complicated menus, no ease of use, etc. How does that happen? Why can't medical software follow the same standards as B2C apps for our phones? | Technology | explainlikeimfive | {
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"[Sturgeons law]( URL_0 ) 90% of medical software is bad because 90% of software is bad source: I'm a software dev",
"Medical software isn't bad. I've worker in that field and there is plenty of up to date software out there. The problem is companies in general, and maybe medical companies in particular, hate spending money on stuff that basically does the same function as stuff they already have and isn't broken. This means stuff that doesn't wear out over time tends to get used well beyond its recommended use period and software is one of those top items.",
"It takes a lot of time and effort to update software which costs. Given that the market for it isn't huge the payback doesn't justify frequent revamping. Plus it is tried and tested, introduce new software and you end up with a whole new load of bugs and a lot of staff to retrain.",
"Developing software for the medical field is a very misserable thing. Firstly there is usually not a lot of clients as there is not a huge number of hospitals you can sell to. And these hospitals tends to prefer to use their money elsewhere then on software. So improvements such as performance and usability improvements is very hard to sell. On the other hand if the software fails then people will die. There are several examples of this happening. So when you write medical software you have to spend a lot of resources testing, verifying and documenting all your testing. This leaves very little available resources for improvements to the software. Especially if there is some software which have already been tested and approved as any changes means it is no longer approved and all test results are void. Even changes which would be standard in any other industry such as upgrading hardware or applying patches from third party vendors can be a pain to get approved in the medical field. So if a piece of medical software feels like something built in the 90s and never upgraded it is probably because this is exactly what happened.",
"A few things that affect the software prices are: * Design: the software is not something that you can just buy (like Microsoft Office) or download (like an app). The software is a database at its core (Microsoft SQL Database, Oracle, etc.) and then \"business logic\" must be custom-made on top of the database, to translate the doctors and nurses' needs into the database format. The devs can do this in-house up to a certain point, but the last parts of it, the finishing touches, they must send a team out to the hospitals to actually LOOK at what the doctors and nurses need, and program all of that into the software. * Certification: Once installed, *someone* must verify that all the menus and all the functions and every single screen actually behave as intended, so that data isn't lost or misplaced. Someone must sign a declaration that this was checked and the software is behaving as intended. Scripts can be used to do all the checking, but this is \"taking responsibility\" is a legal thing and so the devs will charge money, to offset the risk of lawsuits and financial loss. Because bugs happen. * Training: Everyone in all the hospitals using this software must be trained. It's not simple, they can't \"just learn it\" from use, they must be trained. The training programs for so many users cost money, as you can imagine. All in all, you're looking at millions (maybe tens or hundreds of millions) of dollars in costs to install and use this software, but it's *mandated* by government regulations, so basically there's huge financial pressure to use the cheapest possible software out there, and also to NOT upgrade it every year or whatever, keep using it for as long as it works.",
"Let me summarize the other answers lol. I think this is the case with the old joke: Pick 2 out of 3: Cheap, no bug, good user experience bad user experience = \"Sluggish performance, outdated GUI, extremely complicated menus, no ease of use\" Since budget are limited, they pick cheap. Since the people who decide which software to buy don't actually use the software themselves, they don't pick user experience. And besides, the have to pick no bug, or else, people will literally die.",
"I'm a programmer who has, on previous occasions, worked in medical software. There are several reasons: * Programmers are not doctors. They have no understanding of the needs and ways of thinking of the medical field. They also have a deep-seated disdain for anyone who is not a programmer. Why should they listen to some stuck-up doctor? They could be working on their next startup! * Doctors are not programmers. They have no understanding of the constraints and ways of thinking of the computing field. They also have a deep-seated disdain for anyone who is not a doctor. Why should they take the time to explain all this to some scruffy hacker? They have patients to see! * Bureaucracy. There is always requirements that forms must be submitted in a certain way, that patient consent must be recorded in a certain way, that records must be stored in a certain way, etc, that were put in place long before modern computers were invented and nobody can even remember the reason for but nobody has the authority to change. * Legacy. Often there is an existing system which all the important data is stored in, so the programmer has to spend a lot of time making his new program interface with the old system. Often the program has to interface with some piece of medical hardware that uses an undocumented protocol over a bus that stopped being produced in 1998. * Price. A lot of medical software is bought according to guidelines that require the buyer to choose the lowest bidder. You can imagine how well that works for software. So the winner is someone who promised to do a project that will really cost 1,000,000 dollars for 2,000 dollars, then hired a bunch of fresh-out-of-college programmers in Bangalore.",
"US Army vet here - I've moved to the civilian world and have had to use \"legacy\" systems in my job. * A lot of programs were \"form over function\" - 'who cares how it looks? It works!' * There were standards and formats that were either mandated by law or were traditional. * And yes, you can't just stop using a piece of software and replace it. A program that's in a \"mission critical\" application (medical, military, law, etc) is in a situation where it has to be used consistently with little downtime. In many cases, new features are built on top of the old software or the new software was made \"good enough\" to do the job. Just like how the missile radar I used to work on couldn't stop for a software update, a hospital can't stop admitting patients so it can use a new app. New software has to be tested, be compatible with old formats and old software AND still be in compliance with all the laws and regulations. A little hospital in some smol town may be used a software package 10-20 years out of date because that's all they can afford. They still have to be able to talk to that big city hospital, insurance companies, and governments at various levels."
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l6vutm | why is it when a 3rd party app uses the camera i.e. messenger, viber, etc. The picture quality it takes is significantly lower? | Does the app interfere with the software? I thought it merely asks permission to use that hardware | Technology | explainlikeimfive | {
"a_id": [
"gl2ybra",
"gl3e25w"
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"text": [
"90 percent of this is because of 2 things: 1. Picture size. That really adds up and if you let people post pictures at the native quality of their phone. This becomes limited to DRASTICALLY reduce drive space. 2. Uniformity. Once one resolution is set, everyone's pictures have the same level of quality.",
"On android in some apps like instagram or WhatsApp the app is just taking a screenshot if you use their camera function that's why it seems as their camera is weirdly bad, but if you use the phones camera app it's the normal quality. I don't know if you meant that but additionally are photos that you post or send often compromised (less pixel)."
],
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7,
5
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l6w38n | File extensions vs File format? | Technology | explainlikeimfive | {
"a_id": [
"gl2zmam",
"gl2zuhe"
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"text": [
"A file extension is basically a tag to tell programs what to expect from the data inside the file. That is, how it is organized and what it represents. There's nothing stopping you from giving a file an extension that says it's something else. You can call a plain text file a .mp4. Just don't expect a video player to know what to do with it. The format of the file is how it's actually, in fact, organized.",
"file format is the format of the file, is it a text file, or an image, or a video, etc. (It also goes deeper than that, like, what kind of video is it.) But life is kinda hard right if you don't know what is the format of a file. I give you a file and you don't know what to open it with. Okay, so what if we invent a way so I can tell you what kind of file it is, maybe on the file name, maybe by using some kind of acronym after a dot. That's what file extension is. It is just the few characters after a dot in the file name, telling what format it is."
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l6xljn | Why did ancient technology develop so similarly around the world despite societies living remotely from one another? | Technology | explainlikeimfive | {
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"Examples? What comes to mind is common needs and maybe even sharing of technology. The Bronze Age and later eras were pretty interconnected.",
"It didn't really. Much of the similar tech through Europe, Asia, the middle East and North Africa is just the same stuff passed around. The entire Eurasian continent was in contact throughout history and before. If one person in one part of it came up with an innovation it would spread through trade and conquest and migration to anywhere were people would find it useful. You can also look at cultures separated from that like the pre-columbian people of the Americas. They didn't have access to the same resources and were not exposed to the same idea and ended up doing some thing quite differently. For example swords. Swords were fairly universal in the old world that you had examples of the basic idea all the way from Japan in the east to the Iberian peninsula in the west adapted to local circumstances. They didn't have anything like that in the Americas, the closest anyone came to was putting some shards of volcanic glass on a wooden stick. Some ideas like piling rocks up in a pyramidical shape to create a building that is tall and won't fall over are universal and easy to come up with other require the right sort of resources to develop and some might seem easy, but are actually quite hard to come up with individually and were mostly just copied."
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l6xpew | why car rims move so smoothly on video? | When you see a car ad, when the car is going fast the rims move very smoothly and with a certain harmony that makes them look like they’re “disconnected” from the car. If you look at it in real life it’s completely different but then again, if you capture the movement with a camera and watch the video later you can even see the design of the rims. Why? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Has to be with the camera shutter speed. Since the wheels are rolling very fast, the shutter speed on your camera can make it seem like it's rolling slower or is even frozen in time. If you set your shutter speed very low like 1/1000 for fast moving objects, they will appear to move slower.",
"In video, you take individual snapshots very quickly and play them back very quickly. Let's look at a traditional 30 FPS video. That means you get 30 of those snapshots (or Frames) per second. Each frame represents 1/30th of a second. Now let's imagine how fast a wheel is moving. A car wheel might have 360 rpm. Over 60 seconds, it has 360 revolutions. This means over 1 second, it has 6 revolutions. That means in 1/30th of a second, it has 1/5th of a revolution. Thus, if you were recording it at 30 FPS, you would see in every frame that it moves about 1/5th of the way around. Now it just so happens that this wheel also has a 5 spoked design, so even though it moves 1/5th around, it still looks the same. Thus, every shot seems to capture the wheel in the exact same position. Now if you speed it up just a bit, rather than the wheel looking like it's in the same spot, it'll actually look just a bit ahead (i.e., 21% of a turn instead of 20%). This makes it look like it slowly creeps forward rather than turning very quickly. Likewise, if it slows down, it'll look like it's slowly spinning backwards."
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l717hz | How come taking screenshots of video was difficult back in the day? | In the 2000s I remember when I had video players playing a file, trying to take a screen grab of it made a "hole" where the video was. It was pretty nuts, when I pasted the screenshot into Photoshop the hole showed areas of my video player application itself behind it. Does anyone know what I'm talking about? | Technology | explainlikeimfive | {
"a_id": [
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"* Most applications that want to show something on the screen have to give the data for that thing to the operating system. * The OS gathers this data from each app and also keeps track of which app is open \"over\" another app, and which are \"behind\". * Once it sorts all that out, it sends everything that is \"visible\" to the video card and the video card sends it to your monitor. * However back in the day, full motion video was super hard to render and it really could only be done by the video card. * So instead of giving that video data to the OS, it say hay, make a hole where the video is, and I'm going to send it directly to the video card. * When you take a screen shot, that comes from the data the OS has access to. * So it couldn't capture the video because that data went straight to the video card. * So instead you saw everything the OS had including the hole it made for the video."
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l71hac | why do apps consume more memory the longer you have then open all else being equal? | On my Mac key apps just start consuming more and more memory the longer they are open even if not used (eg no new tabs added for a browser but after a week it’s sucking gbs of memory) | Technology | explainlikeimfive | {
"a_id": [
"gl41vt9"
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"text": [
"* Those apps are poorly coded and don't properly return unused memory to the operating system. * It's like a child who keeps wanting another glass of milk. * Instead of reusing the glass they have, or washing it when they are done, they just put it aside and grab another glass."
],
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7
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l72m4g | Virtual Machines | My college has a virtual lab where you can run programs that you don't have downloaded on your computer. How does this work? | Technology | explainlikeimfive | {
"a_id": [
"gl4fm0e",
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"text": [
"The concept behind a virtual machine is to simulate a computer within the resources of another computer. So for example suppose you want to give some students access to a computer with 4 CPU cores, 8 GB of memory, and 500 GB of hard drive space. You might want to do this for various reasons, like in your case allowing students to run programs without needing to pay for licenses for every student. To do this the organization can simulate those computer resources within a much more powerful server system. They might have hundreds of CPU cores available for use, terabytes of memory, and hundreds of terabytes of storage space available. When a student wants to work on a virtual machine the software sets up a simulated file system and allocates the necessary resources to running it. For the student it will behave much like a normal computer, but the server can run many of these virtual machines at the same time. In this case the college is likely benefiting because they can pay for only a few licenses and only start that many virtual machines on the server. If another student wants to run the program after you are done the server can simply reset the environment and allow the other student to access the virtual machine you were using.",
"When you interact with your computer, like by typing or moving the mouse, you're sending a series of signals to a processing unit. The processing unit then responds, like by darkening some pixels on the screen in the shape of 'a' or by starting some calculation. There's no particular reason that set of signals needs to be sent only to a processing unit that is close to you. With the right software and an internet connection, you an instead send those signals to some other processing unit far away, which can then send back the results to be shown on your screen. This is not ideal - there may be lag or connection issues - but it can be useful if the far-away unit has programs/data/processing power that your local machine doesn't. As a side note, this may well be the future of video game technology. Products like Stadia run games on powerful computers in their facilities. You send them inputs over the internet, and they send you back a feed of the game. With a good enough internet connection and some technical refinements, it could be just as good as having that powerful machine in your living room."
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8,
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l7axly | How does a 3D cinema movie get translated into a 2D movie you can watch at home? Do they show you only one eye perspective or do they film a separate 2D version? Or is it something else? | Technology | explainlikeimfive | {
"a_id": [
"gl5o5nd",
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"text": [
"Sometimes they rework some special effect shots, but usually you're just seeing the left eye view.",
"Many movies aren't really shot in 3D, they're shot in 2D and post-processed to create a 3D image. So a 2D movie existed before the post-processing. URL_1 URL_0"
],
"score": [
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"text_urls": [
[],
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"https://en.wikipedia.org/wiki/2D_to_3D_conversion",
"https://realorfake3d.com/"
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|
l7e4cu | This may sound dumb, but why can’t a phone charger take more electricity from the outlet and charge your phone faster? | Technology | explainlikeimfive | {
"a_id": [
"gl666d8",
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"text": [
"The charger isn’t the problem, the charger can supply plenty more power if designed to. The battery is the main problem, the battery cannot charge faster without causing degradation.",
"Mostly it's because of the battery, if you charge a battery too fast it will break. And that can be as mundane as \"it don't work no more\" all the way to \"it exploded and then burned down my house.\" If you got rid of the batteries and use capacitors, which are a completely different type of technology that can also store electricity, you would be able to charge a phone nearly instantly. But capacitors simply can't store that much electricity without being massive.",
"Think of electricity like a water hose. There's voltage, or how big an opening your hose has, how \"thicc\" it is. And amperage, or how fast the water is moving. If you have a really small hose but the water is going ***really*** fast, it will break apart anything it hits, like how a Power Washer works. You don't want that to happen. So you get a really thick hose, but the fast water is *still* too strong. Now you have a fire hose. That's bad, too. Now, picture a battery as like a bucket. You want to fill the bucket, but you don't want to spill. Spilled water, in our example, means something gets damaged or destroyed. Electricity going somewhere you don't want it to is *bad*. If you try to fill up a bucket with a thick hose of fast water, you'll knock the bucket out of your hands and down the block. If you try to fill up a bucket with a thin hose of fast water, you'll bore a hole through the bucket, spilling everywhere. If you fill it with a thin hose of slow water, you can fill it easily- it just takes some time, sure. If you use a thick hose of slow water, you can fill it faster- but it'll be harder to not *overfill* your bucket. EDIT: got my terms switched. It's fixed now."
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l7hmzf | Why did CRT televisions have curved screens? | I was born in '99, so I grew up in the last age of CRT TVs. I'm wondering why they were built to have curved screens. It's not like flat screens weren't a thing, because films were projected onto flat screens in movie theaters until IMAX became a thing. But I wonder what about cathode rays made curved screens a necessity until plasma, LCD, and LED televisions came about. | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"There was a combination of factors. First, spheres are stronger against implosion. A totally flat screen would be too weak to hold vacuum. Second, maybe most important, the electron beam is more like a water hose than a laser beam. An electric field focuses it to a point, and that point needs to coincide with the CRT inside surface. The focus electronics is simpler for a spherical surface because the beam length stays constant. Thirdly, for a similar reason, the scan/sweep electronics had to account for non-spherical beam lengths in order to maintain a constant transverse speed. Interestingly, they could also have moved the beam source farther back from the screen so the beam length was more constant. In other words, larger spheres have flatter surfaces. However, the market wanted thinner TVs they could set closer to the wall.",
"Because they were lit by a beam of electrons, and the aiming mechanism is a powerful magnet. Having the screen equally distant from the beam point was the best way to get it focused on the screen. I realize this isn't \"ELI5\" ish, but....I couldn't think of a way to explain it better."
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l7i4h3 | How were video games in the late 80s/early 90s animated before huge digital advances were made? Additionally, how was music added? | Technology | explainlikeimfive | {
"a_id": [
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"they had very little resources to use, so the resources were used sparingly. Mush was 8bit and limited to the notes they could use. Graphics were re-used (for example, in Super Mario Brothers on the original NES, the clouds and the bushes were the same graphic, just some were green and some were white.",
"So adding onto the other comment, shortcuts like that were used a lot. Any and every way to save a little space was often used it they could get it to work. Music is an interesting one. So how it used to work, was, if I’m remembering correctly, actual hardware made for making what we traditionally associate with 8-but music. The midi sounds. Instead of having an entire audio file, which could take up a lot of space, the game instead had directions for the hardware which allowed it to output the music without having an entire song saved. Soundtrack files are a HUGE component of what takes up space in a lot of modern games nowadays. An entire symphony worth of musicians and more. Lots of long, complex pieces, etc. You can’t just tell the game to “loop X sounds until Y action/part of map” or whatever the same way we used to.",
"In case you're interested, there are some incredible resources for making 8 bit games on retro systems available for free. Arcade Game Designer (AGD) for the ZX Spectrum is particularly fun. Highly recommended!",
"Earlier games like Pong and Elite used vector drawn lines to create the scene, but in the late 80's early 90's, a lot of games were made on custom workstation PC's that were purpose made for graphics workloads. Sprite editors were pretty far along by then though, so not all game graphics required these advanced workstations. As to music, prior to digital sound and the CD-ROM based multimedia revolution, most music used MIDI files. FM synthesis was also used by most sound cards of the time period for sound effects and some music, but MIDI was easier to work with. So to answer your real question, the types of computers the developers of those games used were not the same as the ones the final game ran on. They were a lot faster and purpose built for the task of creating graphics, or music.",
"Game consoles of the 1980s and early 1990s didn't have lots of storage or processing power to handle large amounts of data, so there was a strong focus on making everything as efficient as possible. In many early consoles, such as the NES, graphics is stored as small tiles, with each pixel in the tile only having a few options for colors, to minimize the amount of data required. To produce images, these tiles are combined together in groups, and to produce animations, the tiles were moved around or replaced with other tiles. That's why backgrounds and objects tend to look similar or have repeating patterns. Lots of strategies were used to minimize the amount of tiles required; [this video]( URL_0 ) shows some some of these strategies. For music, rather than storing an audio file containing the music, the game would store instructions for playing a song as a sequence of notes on a few basic audio channels. The limitations of hardware greatly restricted the complexity of music; the NES can only play up to 5 notes at a time for example."
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l7iwhx | How does an EMP work, and why does it disable only certain kinds of electronics but not others? | I'm deeply curious about how EMP's work (I'm hoping to learn more for a story I'm writing), but I don't really understand what they do or how they do what they do. I'd also be very interested to know what kinds of technology they affect and which kinds they do not, as well as the extent to which said technology is disabled (and for how long). I tried searching for a lot of these answers on Google but I couldn't find anything adequately specific enough or clear enough to get into my layman's head, so here I am! | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Electromagnetic Pulses are bursts of energy radiating out from a high-energy event, like a lightning strike or nuclear detonation, or even just switching on a strong enough power source. Just throws Electromagnetic energy out everywhere, messing with magnetic fields and electrical circuits. EMPs don't temporarily disable things, they break them. Wires and circuits are made to handle a certain amount of energy. If the pulse is strong enough, it simply overloads the conductor and burns it to a crisp. Your tech stays down until you can replace the wires/solder contacts/whatever. Equipment can be shielded from an EMP by surrounding it with conductive material that directs the energy away from the vulnerable equipment."
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