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ds4xqd | Why is there still a delay in broadcasting on the news while people are being interviewed? | Technology | explainlikeimfive | {
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"Because broadcast quality video from a remote location is usually done via satellite, which is a 45,000 mile round trip. Have you ever tried to setup a video-conference with 5 people? 90% of the time something is fucked up and you have to dial in again, or restart something, or Lydia has echo on her end. That's annoying for a weekly meeting, for a national TV broadcast that costs huge $$. The tried-and-true satellite technology is much more reliable in many cases than using the internet.",
"The delay is usually intentional as a precaution to give them time to censor anything they aren't allowed to show. Additionally the \"almost no delay\" in your video games is probably worse than you think. Most online games have some form of compensation running on the server to minimize the effects of the delay, but round trip from you, to the server, to the other player can be a half second or longer depending on many factors (which doesn't sound long, but it's an eternity in highly competitive games)."
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ds5e7s | Why do paper back and hard back cover books exist? Why not just one type of book? | Technology | explainlikeimfive | {
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"Hardcovers are much more durable than paperbacks. This is why you see school textbooks with hard covers, and, say, practice workbooks with paper ones. Hardcovers are supposed to last for years and years, at the cost of a slightly elevated price. Paperbacks are cheaper, but they're more prone to damage.",
"Paperback books are cheaper to make, so they can be sold for less. They dont hold up as well as hard cover books (covers tear more easily and then pages get damaged) so the more expensive hardback books are also still made for people that want something more durable.",
"Cost and weight. Hard copies are better quality but they're heavier and more costly to make and buy. So you get 2 options depending on what matters more to you",
"Hard cover books are stronger and not so easily damaged. However they are heavier, cost more and are not so flexible. This is why paperback is also sometimes called pocket books as they can more easily fit in a pocket and be carried around. You can make the same comment as to why you need both a laptop, tablet and smart phone.",
"Books used to be expensive to produce so they were made hardcover to protect them. In the 1920s books started to be printed on cheap paper with paper covers. These were pulps because the cheap paper was called pulp. This was only done with lower class books such as westerns and fantasy. In the 1950s, paperbacks started being printed for what were considered good books. These were sold to schools in huge numbers because they were cheap. There was clearly an audience for cheaper paperbacks but book sellers made less money off of them. So publishers publish first in hardback and charge a lot. Then months later they release in cheaper paperback. There are people who prefer hardback books, but for the most part now it is just to charge more."
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ds6z97 | How do targeted ads cross unconnected devices? | Can someone please explain how ads on my personal cell phone match with something I purchased for work on a work computer? | Technology | explainlikeimfive | {
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"What do you mean my targeted? “Dan, it’s been a while, so here’s 25% off at Home Depot” indicates you have a cookie sync situation going on, in some way, as others have suggested. “Here’s 25% off at Home Depot” when you happen to be a guy who is DIY-y is targeted at your general demographic (taken from browsing history, other ad trackers) and can be very accurate even on a single machine. I work as a product manager for an internet marketing company.",
"Facebook, Google, Amazon. They all keep personal data on you. All it takes is for you to log into one of their website and that device will be linked to your other devices."
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ds7leg | how was the sextant used in navigation how does it work? | Technology | explainlikeimfive | {
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"It is used to measure the angle between the horizon and some consistent celestial body. For example, it can be used to measure the angle of the sun to the horizon at noon. By knowing the angle of the sun for that time of year at various latitudes, you could use that measurement to determine your latitude. Likewise at night you could use it relative to stars to narrow down your location."
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ds8168 | why does the quality of a picture seem to get worse when something is screenshot? And continue to get worse as others do the same and share it. Shouldn't it stay the same since its quality is good when the first screenshot was taken? | Technology | explainlikeimfive | {
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"It’s because of compression. Compression reduces the size of an image at the expense of some quality. Each time someone edits and image, it gets compressed again, resulting in blemishes known as compression artifacts. This type of compression is known as “lossy” because some of the data is lost when it’s compressed. Alternatively, using a lossless compression algorithm, no data will be lost. However, the trade off is that the resulting file will not be as small.",
"Different displays have different resolutions, pictures often end up being scaled to fit in the chat or wherever they're supposed to be. If we scale down a picture we lower its resolution, worse quality."
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ds9fto | How does waving my phone in figure 8's calibrate the GPS/compass? | Technology | explainlikeimfive | {
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"The phone compares the data from its accelerometer to the data from its compass. When the accelerometer says the phone has changed direction by ninety degrees, the compass should say the same thing. The figure eight produces a smooth change in acceleration that is easier to do math with than a sharp back and forth.",
"Others have laready answered, I'll just add a small addition: It will calibrate the compass, it won't do anything with the GPS. The GPS gets its position from very precisely measuring distance to satellites with a well known position, there is no need to calibrate it.",
"Moving the phone in different directions while level will create different voltages depending on the orientation of the device according to the [Hall Effect]( URL_0 ). The earth is a big magnet and when the device moves across it, different voltages are produced, allowing the device to know where true north is pointed."
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dsc8dm | How do ISPs limit speed? | Do they just give you x MiB and then wait with transmitting more until the second has passed? | Technology | explainlikeimfive | {
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"Think of your internet connection like a garden hose. Your speed is how much water is flowing. The ISPs control the valve at the other end, and by closing or opening that valve they can control your internet speed. On the technical side they have a device the limits how fast data can travel back and forth. It takes about 5 seconds to change the speed you receive. There are a number of reasons for rate throttling both technical and financial. Edit: funny spelling error"
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dsiuid | Can WiFi be used for nefarious reasons? | Technology | explainlikeimfive | {
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"Yes. They can log when your cell connects or disconnects from the WiFi, they can also monitor your network traffic to an extent....they can't see everything you do but they can see any DNS requests you send, which means they know which websites you browse to but not specifically where you go on the website if it uses HTTPS. So they would see you went to URL_1 but they can't see you went to URL_0 However - unless you give them information that ties your device to you specifically, they probably can't tell it's *you* on the WiFi, just that someone has a Galaxy Note 8 or whatever using the WiFi and going to specific websites.",
"Your IT department (system administrators) are almost definitely able to monitor what you do when you are connected to the office Wi-Fi. They can definitely see what sites you're going to, they can definitely see the IP address of any remote server you have to connect to, and can almost certainly record all that data to personally identify you. They can definitely see which apps are currently in use by your phone (even in the background), they can definitely see when you opened them or how long you used them for. They can potentially see what data is being sent or received to those apps. Your phone is constantly pinging outside servers for information, and all that data is sent through the company Wi-Fi. They probably won't be able to install anything onto your phone without your knowledge. **Never, under any circumstances, should you install an app on your personal phone/computer that your employer requests you to install.** Don't get the corporate email app, don't get the corporate messenger app. While generally harmless, these apps can very sneakily gain access to parts of your phone that you don't want your company IT department to know anything about (an HTTPS certificate, for example, would allow your company to decrypt otherwise secure traffic, like your personal email account details/emails)."
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dsjncr | Why are we evolving technologies at such a fast pace now a days, when contrasted to the thousands and thousands of years it took humans to move on from stone tools? | Is it just like a big domino effect? | Technology | explainlikeimfive | {
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"A lot of answers missing the point here. Technological advancement isn't magic, where the more that has been invented, the more will be invented. The driving force is the availability and spread of information. Thousands and thousands of years ago, hardly anyone could read and even fewer people could devote their time to writing, and if you were a professional scribe, the only people willing to pay you to write were merchants needing receipts, clergy needing holy texts, and nobility who needed to send messages. With the introduction of printing technologies and recently things like the internet, along with the explosion in literacy rates over the past couple centuries, the flow of information has allowed so many more people to learn, experiment, and innovate than was even imaginable ten generations ago.",
"It's basically an exponential process. That is, earlier gains make future gains easier. Figuring out how to do more things make it easier to gather enough food for folks, makes it easier for them to communicate, etc. This frees up more time for people to come up with new ideas and makes it easier for them to collaborate, etc.",
"It's worth noting that there are many more people alive and inventing now than at any point in the past.",
"Technology is exponential. The more new technologies that are invented, the more tools you have to create never ones. Everything we have now relies on several inventions, cultural changes and scientific discoveries, but you can't start at the wrong end. You have more avenues to explore, more options, more ideas that can be made reality when you have industrial society than when you had barely figured out metalworking.",
"Technology is slowing down in many regards. What many people view as \"technology\" is actually just globalisation. For example, in the 1960s we landed on the moon. Everyone thought we'd have flying cars by the year 2000. Instead, we have Twitter. Computers arent new technology, they're just getting smaller, faster, and more powerful. But it's just improvement...not new. I know this is a contrarian view, but I find it to be worth noting."
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dsjtfy | How do large area WLAN networks work? | For example the WLAN in a Uni or in a convention center. Are there like 50 routers with the same Login data? How does your phone know to switch to a different WLAN source? | Technology | explainlikeimfive | {
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"exactly like you suggested. There are a lot of Access Points (not routers) that broadcast the same network (ESSID), with the same security settings. Every Access Point has a unique ID (BSSID), which a client also sees. So your PC or phone or whatever notices that the same network is broadcasts by different devices. It then choses the one with the best signal. Your phone constantly checks whether it sees a different access point with a better signal. It then switches the acces points it connects to without you noticing."
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dsjz4a | Why are RGB values out of 255? | Technology | explainlikeimfive | {
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"These values are (or at least used to be) stored as 8 bit integers. That is, they are sequences of 1's or 0's that are 8 digits long. There are 2^8 or 256 such sequences. These then correspond to a value from 0-255.",
"That's how many numbers can be displayed in a byte (0-255). The shorter way to display it is in hexadecimal, which is why you'll see some colors described using 6 digits of hex (2 for red, 2 for green, 2 for blue, like 0A552F)",
"A little background on binary numbers - you probably learned decimal numbers by thinking of each digit in a column, from right-to-left, which tells you how many units, tens, hundreds, thousands, etc there are. We have 10 digits, so each column is 10x larger than the previous one. In binary numbers, because we only have the digits 0 and 1, the columns are instead how many units, twos, fours, eights, etc. Each column is 2x the one before. Now in computing, binary is usually grouped into sets of 8 digits, or bits (binary digits). This group of 8 is called a byte, and we use 3 of these bytes for 24-bit colour - one for each of red, green and blue. 255 is the largest number that can be written with 8 bits: 128 + 64 + 32 + 16 + 8 + 4 + 2 + 1."
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dsl45o | How did our species manage to go 100,000+ years without ready access to clean water and/or sanitizers/soap etc.? | When I go camping it's already a nightmare having to bring extra hand sanitizer, wet-wipes etc. And that's with modern amenities like water bottles handy, lighter to make a fire (to boil, sterilize water) etc. As a germaphobe I'm always paranoid about washing my hands. Wouldn't our germs have nearly constantly wiped out entire communities? How did we not all get sick... I can't even think of a way to easily and quickly wash my hands or sterilize something 200 years ago.... let alone for millenia | Technology | explainlikeimfive | {
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"*Our* germs barely make us sick. Almost all of them are known as the \"common cold\". The diseases that kill communities - influenza, plague, cholera - all come from other animals. *Domestic* animals. Which we didn't have until the advent of agriculture. Besides, all you need for humanity to survive is about one in ten live births making it to 20, and outside of cities (which, again, didn't exist before agriculture) this is almost guaranteed to happen.",
"A lot of sex. Large families. Live hard die young and all that. The world population didn't even hit 100 Million until about 500BC and before that there were A LOT FEWER people, like the population is thought to only have just about doubled about every thousand years from 10000BC on, and there is thought to have only been around 4 million people on the whole planet then. To go from 4 million to 8 million in 1000 years means most people born, died before they had kids.",
"Some societies had things in place which created better hygiene systems as a by-product. Rome's aquaducts are a famous example. Building these massive water transport systems to easily move water from the mountains into the city meant that Rome's water was never stagnant making it difficult for bacteria to proliferate unlike other places which relied on wells or transporting and storing water in clay vessels etc. The Aquaducts not only supplied water to communal access points but also wealthy people would have clay pipes feeding into their homes providing them with running water and communal toilets had a separate system to deal with human waste (essentially these toilets had people doing their business into a gutter with a constant flow of water which carried the waste away immediately). Having this fantastic access to a constant supply of water allowed for regular bathing. And of course, soap has been around for a long time. Even perfumed varieties. The Greek's and Roman's had ready access to it and there are accounts from around 300bc that describe watching the soap making process which indicate that soap had been around for a long time before that too. The best soaps at the time were said to be from Germanica and Gaul so it was something that was quite well spread as well",
"People back there were exposed to more bacteria, viruses, etc and their immune systems reflected that. Sure, many more died due to disease, but those who didn’t were often stronger for it. The same things still happen today. If you live in the US and have access to clean drinking water but go vacation in Mexico and drink the tap water there, you could get “ Montezuma‘s revenge”. But the local populace, having been raised exposed to the water, can drink it with no ill effects."
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dso5qn | Why are we building brand new electric vehicles instead of fitting existing vehicles with solar or electric power? | Technology | explainlikeimfive | {
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"The cost to retrofit a combustion vehicle is too high. You’d have to buy the solar cells the batteries move the engine and all it’s various components. So forth and so on Then you’d have to connect all the new stuff and stuff it for safety",
"The battery pack of a Tesla Model S weighs about 1200 lb, so even if you could find enough space for it in a regular car, it would be unsafe to add that much weight to it. Unless the car was designed to be electric from the beginning, you're going to be limited to small battery packs that don't provide much range, and going to all this trouble doesn't really make sense if at the end of it you get an electric car that can't even go 100 miles on a charge."
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dsorhe | Wouldn't it be more efficient for an electric vehicle to utilize a conventional transmission, as opposed to running direct drive? | Technology | explainlikeimfive | {
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"Every transmission system has losses, the one with the least losses is direct drive. Since electric motors have high torque at low revs a gearbox is unnecessary.",
"Yes, but not by much. [This]( URL_0 ) is what the efficiency map of an electric motor looks like. It's most efficient (96%) at medium speed and medium load, and the efficiency drops down to 82% at low load levels and low speeds. Now look at the efficiency map of an internal combustion engine: [ URL_1 ]( URL_1 ) At medium speed and high-ish load it burns 250 grams of fuel to produce 1 kw-hr, but at low loads it burns nearly twice as much fuel (475 grams) to produce the same output. If you don't keep an internal combustion engine inside its speed/load sweet spot, you may almost double its fuel consumption. If you don't keep an electric motor inside its sweet spot, its electricity consumption only goes up by a few percent. A transmission with multiple gears is very important to run an internal combustion engine efficiently, but an electric motor doesn't really gain much in terms of efficiency, and the gains would probably be offset by the extra weight, friction and cost of the transmission, so there's not much point in having one, unless you have specific requirements, like being able to achieve very high vehicle speeds.",
"Electric car are not in general direct drive. They have have gearboxes. Look at [this video]( URL_0 ) of the read drive unit of a Tesla model S. Notice that the electric motors are not inline with the wheels but offset from them. There is gray metal part that connect the rear axis and the electric motor that is a gear box. It is a 1-speed fixed gear (9.73:1) as stated on the wiki page for the car. It is a fixed gear system but that is still a gear box."
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dsoyml | how does a yeti cooler keep things colder for longer than other coolers? | Technology | explainlikeimfive | {
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"It doesn't. There are several good YouTube videos out there if people testing them. And in general while they are really good coolers they do about the same as a good igloo cooler at 1/4 the price. So if you buy Yeti stuff you are paying for the name."
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dspc0i | how do web crawling servers work? | Technology | explainlikeimfive | {
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"This is a very broad question but the basic idea is that you create a program to download web pages. Once a page is downloaded the program can do whatever sort of analysis you want with it. Strictly speaking you could give a crawler a predefined list of links but it's usually more specifically a \"spider\" where you give the program a starting page. It downloads the page, looks for links, adds them to a database, and then starts downloading pages from the database of previously-found links, looking for more links and adding them to the database."
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dsr303 | What is the difference (in terms of music format) between a wireless headphone vs. a wired one? The information that they receive is the same? | Technology | explainlikeimfive | {
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"Well it's not the same. A wired connection can transfer data more efficiently and quickly than a wireless one. To make up for this, a wireless headphone has to have that data compressed before receiving it. That compression degrades the quality of the music data, leading to \"worse\" sounding music. This is of course a bit subjective as most people don't use the highest quality files to begin with and probably would never notice the difference. There are different compression methods formats. The most popular being * SBC (Most basic and worst of them) * AAC * Aptx * Aptx HD * LDAC (proprietary sony format and considered the best) For Android users, all android phones running 8.0 or higher can output LDAC but you do need a receiver or headphones which are compatible with the format",
"Wired headphones are just speakers attached to wires, which are attached to a jack connector. They recieve a power-amplified signal from a power amplifier. Wireless headphones recieve audio over radio waves, which don't have enough energy to drive speakers. For this reason all wireless headphones contain a power amplifier to drive the speakers. If the audio signal over the radio link is digital, it will be decompressed (if it is compressed) and converted to analog by a digital-to-analog converter (DAC). Assuming the source is a music app running on a phone, the most common setups nowadays are: **Wired** Music app - > codec in phone to decompress - > DAC in phone to convert to analog - > power amplifier in phone to drive headphones - > headphone jack - > headphone cable - > headphone speakers **Wireless** Music app- > transcoder to convert to different compressed format usable by headphones - > encoding for sending over wireless link - > radio baseband - > radio modulator - > radio power amplifier - > radio transmitter antenna in phone - > air - > radio antenna in headphones - > radio receiver preamp - > radio demodulator - > error correction for corruption in transmission - > decompression of digital audio - > audio DAC to convert to analog audio - > power amplifier to drive speakers - > headphone speakers."
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dstvmq | How do phone batteries and things like headphones stop charging when they are full and not just explodes as some phone's like the Samsung. Never really understood the reasoning behind that. | Technology | explainlikeimfive | {
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"there is an extra circuit on the charging module to measure the amount on energy stored in the battery. whenever a specific value is reaches, the control circuit reduces/stops the electrical pass through. like a bouncer who controls the entry of a nightclub and decides when its time to stop people from entering the club."
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dstz5d | How are windows made | My friends car window got smashed and 99% of the pieces are little 1x1mm square glass , is glass made up of small pieces or is this just a strange coincidence? | Technology | explainlikeimfive | {
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"This is called tempered glass: [ URL_0 ]( URL_1 ) It is produced by rapidly cooling glass during production to give it different tension on the surface and the inside of the glass, it's made to shatter just like this instead of forming big sharp edges that probably would be more dangerous than the smaller pieces. Check out \"prince rupert drop\" for some cool videos explaining this better than I am :)",
"Glass for vehicle windows is tempered glass and is actually multiple layers of glass with a plastic laminate between. These factors help it to break into small, relatively unsharp pebbles instead of sharp shards that could do real harm in an accident."
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dsu77t | How are there brain scans that show brains that have mental disorders, yet there’s no way to “prove” we have mental disorders? | I just saw a Photo of different brain scans and some of the brains are of proper with OCD, schizophrenia, etc However, I’ve seen multiple posts saying that we’ll never be able to “prove” anyone has a mental disorder and we go based off of what people are saying and just believe them when they say they have depression or are having hallucinations. So what exactly are brain scans for? If we think someone has OCD, why can’t we just scan their brain and see if they do or don’t? | Technology | explainlikeimfive | {
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"These images that you're referring to are not diagnostic of mental disorders. They seem compelling, and very sciency, but there are no reliable biological tests for schizophrenia, OCD, depression, anxiety disorders, eating disorders, etc., etc. Diagnosis is made based on the client/patient's self-reported symptoms as well as any signs that the clinician observes. Collateral information and psychometric assessment can be useful additions. The images you're referring to are usually fMRI images that are very carefully tuned to exaggerate very small differences, that do not reliably differentiate between individuals with/without the condition. TL;DR: \"Brain Scan\" images are not capable of reliably diagnosing most mental disorders. The most reliable methods remain clinical interviews (often structured interviews) combined with psychometric (i.e., questionnaire) assessment. & #x200B; EDIT: Spelling error",
"Because these brain scans can only show the momentarily activity of the brain (region). Based on this we can make assumptions about what is going on but we can't be sure what causes it",
"There are several different ways to answer this question. First, as many people have said, many mental disorders aren't diagnosed based on biological correlates, but rather on self-reported problems. For example, major depressive disorder is diagnosed in part by having depressive symptoms more than 80% of the time for 2 weeks or more. This diagnosis is independent of what's going on in the brain. The fact of the matter is that many neural correlates to mental disorders are simply correlational. Individuals with depression, for example, have smaller hippocampi (the hippocampus is a structure in the brain implicated in learning and memory), but that doesn't necessarily mean that all individuals with depression have small hippocampi, or that any individual with a smaller hippocampi is depressed. The brain is a highly complex organ, and mood and mental disorders have highly complex syndromes. They're often not able to be diagnosed by just \"looking\" at the brain, since we don't know what is going wrong in the brain; we just know what differences are seen between healthy individuals and sick individuals, but, again, these differences are largely correlational. Second, even if disorders are caused by specific physiological symptoms, they're often not due to *structural* changes in the brain, and the vast majority of brain imaging techniques focus on **strucutre**. For example, Tourette's Syndrome is highly correlated with overproduction of the neurotransmitter dopamine in a network of structures called the basal ganglia. Unfortunately, right now our imaging techniques can't tell us about specific neurotransmitters. An MRI is not much more informative than an X-ray of the brain. And just like an X-ray isn't going to be able to spot that you've got the flu, and MRI isn't going to be able to see at the level of neurotransmitters. Other techinques, like fMRI, only tell you WHERE the brain is active. But fMRI doesn't tell you how structures or active, or what exact neuronal populations. It simply gives you a rough estimate of what general areas of the brain are more excited than other areas, but it doesn't get into why that may be. As an analogy, think about seeing a crime map of the United States. You may see, for example, that lots of people get killed in Detroit, but that doesn't tell you very much useful information about WHY that's the case, or how to solve the problem."
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dsxejw | Why don’t photographers always use the fastest shutter speed? | Technology | explainlikeimfive | {
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"Because the shorter the exposure the darker the image. If i use a fast shutter speed like 450/1 i crank my ISO up. But if i have too high ISO (light sensitivity) more and more digital \"noise\" appears.",
"Faster shutter speed means less light hits the sensor so the image gets darker. You can fix this by increasing the apature size but that means your depth of focus decreases causing objects in the foreground and background to be out of focus. This is why you see sports photographies with very blurry backgrounds. You can also get more light by using a bigger lense but this is more heavy and also have issues with image quality for complicated reasons. A third option is to shoot the image too dark and then increase the light sensitivity in the sensor or brighten the image digitally in post processing, however you will also brighten the background noise of the sensor so the resulting image gets more noisy then usual. Part of being a good photographer is to be able to select the right shutter speed, apature size, lense, sensitivity, etc. for each photo to get the image you want.",
"Cameras are a lot like your eyes. If you keep your eyes shut, flick them open for a split second then close them again, that's basically the shutter opening to let light into the device. All the time you're eyes are open, photons are hitting the detector, same with the camera. If you open your eyes longer, you'll take in more photons, shorter will be fewer. So try looking in a random direction with your eyes closed, opening them then shutting them again really quickly, you'll find it hard to describe in detail what you see.",
"My camera goes up to 1/4000 of a second. If i were to shoot in anything other than bright daylight at the lowest aperture, i'd be underexposed. Also camera lenses tend to get some weird distortions at their lowest f numbers, especially for fast lenses. If you can trade some shutter speed to go up a couple stops, you'll have a technically better image. More to the point, a good photographer can keep the camera steady down to around 1/20th of a second (i personally always spring for 1/40 at the expense of ISO because i'm shakey)",
"I'm going to answer your question, but it's going to take me a bit to get there. This may be a bit above ELI5, but enjoy! TL:DR - Yes you are correct, but there are additional variables that dictate what your picture looks like. A camera is a balancing act between 3 primary attributes. * **Shutter speed:** This is how long the camera's lens is open to absorb light. * **Aperture**: This is how wide the hole is on the lens to allow the light to come in to hit the senor (or film). * **ISO**: This is the senor, of films, sensitivity to light. To get a good picture, you need to balance these items. * If your shutter speed is too slow, you get trailing. * If your aperture is to low or high, you modify your field of depth. * If your ISO is to high, the picture will come out grainy. Depending on what you're taking a picture of will dictate which levels of shutter speed, aperture, and ISO you'll use to get the picture. **Some Examples**: * For well lit sporting events, you'll want to use a quick shutter speed (because there's a lot of action), and higher aperture (to let enough light in) and a medium setting for ISO (\\~800) * For a poorly light night even...if they're mostly stationary subjects you can use a long shutter speed, and use a middle-ish setting for your ISO/Aperture. If there is a lot of moving around, then you'd want a quicker shutter speed, and you'd offset it by increasing your Apeture/ISO."
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dszxuq | how does camera capture rate change depending on the amount of light being let in? | If you have seen the video of the ruler being flicked in the shade vs the sunlight that's where my question stems from. | Technology | explainlikeimfive | {
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"It's about shutter speed, or its set to auto. If it's shutter speed the difference is the amount of motion blur. The longer the shutter speed, the more light, the more blur. If it's set to auto the camera automatically switched to a higher capture rate because: If you have a shutter speed of 1/40th of a second you can have a max frame rate of 40. Or rather a bit less. This is in low light where the camera has to capture more light per frame If the shutter speed goes to 1/800th now, because it's brighter and the camera does not have to capture so much light you can have a video at as high as 120 frames per second or higher."
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dt0y4o | how does a Fitbit measure and record sleep? | Technology | explainlikeimfive | {
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"it guesses. it knows how much you're moving around, because moving around moves it. it can track your heart rate pretty accurately. it uses the combination of those two things - are you moving around? are you calming down? to try to come up with some kind of guesstimate about how well you're sleeping and if you're sleeping.",
"There is currently a [class action lawsuit]( URL_0 ) regarding the accuracy of this feature. As others stated, it doesn't. It makes a wild guess based on how much your arm moves.",
"I worked for a company that manufactured a similar device and we based our measurements on [Actigraphy]( URL_0 ) which is not exactly a total guess like others in this thread have mentioned. I assume Fitbit uses this method, but I might be wrong.",
"During sleep you go through a natural cycle of approximately 90 minutes from light to deep and back to light sleep. During deep sleep your body stops from moving. When you leave deep sleep and are lighter your body may move around. The Fitbit or other sleep trackers measure the number of transitioned, how much they are spaced, how slow or fast the transition occurs, etc. To give a calculation of \"sleep quality.\" *Fixed issues with descriptions",
"As someone who did tech support for \"a multinational mobile phone company\" (NDAs amiright?) I can tell you the technology used on those smart watches is actually very dumb. It tracks heart rate and movement pretty well (although I would regularly get calls from people who said their smart watch showed a massive heartrate spike while they were sitting down and totally calm. Something my superiors told me was a feature to detect heart attacks, as opposed to the obvious software bug it actually was) and then makes wild and often inacurate guesses based on that information. It's not to be taken seriously, cause there is little to no scientific testing done on these devices before they get shipped out, and faulty hardware or software is passed off as \"features\" introduced after a problem has been detected. don't take these readings seriously! They are mere guidelines that are relatively accurate for most people, but have major flaws that make them generally unreliable",
"The same way it measures steps - it's just a guess based on movement of the arm. People tend to move less when they fall asleep, and even less when they are in deep sleep. Apps can use this info to make educated guesses. Some apps even use the microphone for this. They guess your sleep by the sounds you make (caused by movement). I have one and it's pretty accurate IMO, it also lets you listen to how you snore. Pretty fun.",
"Lol somehow my fitbit tells me my heart beat is in low 70s then steadily rises to 110 then gradually lowers to low 80s and repeats.",
"Everyone keeps mentioning movement, which is one of the main signals. But there's another one you can use, if you have something that can reliably measure heartrate, which Fitbits aren't terrible at. To demonstrate: sit down in a quiet place and take your pulse manually for a minute. If you breath normally, you will notice that your heart speeds up slightly when you inhale, and slows down when you exhale. This is called Heart Rate Variability and can be used as a somewhat accurate way to determine how fast you're breathing, if you have no other way to sense it. Your breathing rate and heart rate variability also differs some between sleep phases. It's very slow in deep sleep, and faster in REM and when you're awake. So you can kinda guess at sleep phase by looking at these. But these differences in breathing and heart rate are higher for people in good shape, meaning its not as accurate in non-athletes. You can't diagnose a real sleep phase disorder this way, because you have to take a lot of averages over time. Given deep and REM sleep can normally only be like 20% of the night, being off by even 5% (which sounds pretty good) is enough to misdiagnose someone. You really need brainwave monitors to know for sure.",
"Sleep scientist here who has worked on studies comparing the validity of fitbits and other sleep devices, fitbits and similar devices use movement and heart rate variability at certain thresholds to determine if you are sleeping. Unfortunately fitbits are not terribly accurate at this, and their algorithms are proprietary and have not been validated. Sleep/wake data is considered within an acceptable margin of error, but their sleep stages are a pile of shit. They also only output sleep data after it has been scored by their algorithm, meaning a trained technician cannot access the raw data. Most actigraphy devices use movement and light (photoreceptor) to decide if you are asleep, and also allow trained technicians to analyze raw unscored data to make their own determination. Please let me know if you have any questions!"
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dt2eqb | How do players and computers read CD's and DVD's? | I'm just wondering physically how is it possible? Why is it that if I wanna pick one song from the CD the player 'knows' where the song I want is? | Technology | explainlikeimfive | {
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"Nobody answering the question OP asked. A CD, or any optical media is made up of a continuous spiral of 1s and 0s represented as reflective flats, and non reflective pits. At the beginning of the disk is a table of contents of sorts. It tells the system where physically on the media a particular file is. It basically tells the drive that file x starts at sector 423. The drive knows roughly where the laser is physically on the disk, so in order to \"seek\" to a particular file, it can move the laser and count how many tracks of the spiral it passes over. Once it's close, it slows down and reads the whole spiral searching for the start of the file. Once the start is found, the data begins to stream from the drive out to the system. From there the file can be played or loaded into memory wholesale and worked on locally.",
"The backside of the label is made of a reflective coating, so that when light is shone through the plastic of the disc it is reflected back out. A laser shines upwards through the disc. In the plastic of the disc there are microscopic dimples or *pits* that change how the laser light is reflected. Specifically, they cause the waves of light to overlap in a way that causes destructive interference, which means no light reaches the detector next to the laser emitter. So either there's a pit, or a land. Light enters the detector, or it doesn't. The 1s and 0s of binary are encoded in the pits and lands. It is *not* that a pit or land is a 1 and the other is 0. Instead, a 1 is when the laser detects a *change* from land to pit or vice versa. The laser follows tracks, like the grooves in a record. A chip precisely controls the position of the laser, so the player knows exactly where on the disc the reader is. That means it also knows precisely how fast the disc is turning. It uses that to calculate the clock rate, or how fast 1s and 0s should be happening. DVDs use a more precisely controlled reader and more sensitive reader so the pits can be smaller and closer together, which means more data can be packed onto the disc. The format of the data is also different. Blue ray players use a blue laser, which has a smaller wavelength. That means it can read smaller pits, so they can be even smaller than in DVDs and pack in more data. Blue ray players and HD-DVDs both have multiple layers, too. The laser has a lens to change the focus to ignore or pick up different layers."
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dt3axn | How do scales that are capable of measuring incredibly tiny amounts of things actually work? | Technology | explainlikeimfive | {
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"I believe that most scales contain a piece of metal with a precise thickness/strength (called a load cell). Placing an item on the scale bends that piece of metal *very* slightly. By measuring how much the metal bends, you can figure out how much the item weighs. *How* that measurement is made is a little beyond ELI5, but it's done electrically by passing voltage through a set of resistors attached to the metal whose value changes when they're bent. By precisely measuring the voltage changes across those resistors, you can measure the distortion of the metal and thus calculate the weight. To measure smaller things, you need a smaller load cell (that will bend more from less weight) and very precise calibrated electronics capable of accurately detecting equally tiny changes.",
"All the other answers are great; they describe practical scales that measure in the sub milligrams. But to give you something even deeper, some specialized scales can actually go to higher resolutions, measuring picograms, and more recently down to the yoctogram resolution (10^(-24) grams) which is basically the mass of a single proton. They essentially work using a very basic law in physics. They have an oscillating beam (for the yg range, they use nanotubes for beams). Without getting too much into detail, if something is oscillating, it has a given natural frequency (a rate at which if you move it at, it will produce maximum deflection or amplitude). When you apply a force, no matter how tiny, to this oscillating structure, its natural frequency will change. This sounds insane to measure but it's not, because measuring frequency is like counting, and we have very advanced technology for this (think atomic force microscopy). So now, if you put a mass on this oscillating beam, and you measure how much it's natural frequency changed, you can calculate the mass of the object you added. This actually measures the inertial mass, but let's not get into that. Of course scales in your everyday scientific lab or kitchen or gold shop don't use this technique, they use what other comments mentioned like magnetic methods. Edit: English",
"When measuring incredibly tiny things, we use balances to find the mass. Modern day balances use magnetic force restoration. First you zero the balance. This tells the balance where the plate is without any additional mass added. You put your item you're measuring on the plate. The balance then calculates how much mass would be required to return the plate to its original position using electromagnets. This allows us to measure very minute displacements of the plate. Meaning we can measure very tiny amounts of things :)",
"Generally, small pieces of metal that bends to the weight of an object on top, called load cells, are inside. This load cells have small \"bending sensors\" stick to their sides, those are called \"strain gauges\" A special \"amplifier\" chip is commonly used to read the signal of an arrangement of those sensors and give a value to those tiny amounts of deformation of the load cell. Then a small \"computer\" chip can make a relation between the deformation and the corresponding weight, even taking many measurements, and finally display the information on a screen",
"In the kitchen... Scales use sensors that change when pressure is applied: **Piezoelectric** Effect is the ability of certain materials to generate an electric charge in response to applied mechanical stress. The word **Piezoelectric** is derived from the Greek piezein, which means to squeeze or press, and piezo, which is Greek for “push”."
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dt3v8k | Why Li-ion batteries have reduced capacity over the usage cycles. | With so much in advances in technology why have we not been able to make batteries that retain the maximum capacity. Is it theoretically possible in future? Given global shift towards clean energy, wouldn't in time of century or so there would be massive 'Battery graveyards'. | Technology | explainlikeimfive | {
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"Due to lack of comments so far, here is my amateur understanding. Li-ion, and almost all other rechargeable batteries, use chemical processes to store charged molecules in the battery liquid. When a current runs through it the molecules discharge and become neutral. When you charge a rechargeable battery, this process is reversed. However, no chemical process is 100% reversable. Therefore, all batteries based of this interaction, which all commercial batteries are, will always lose capacity over time."
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dt8v3i | How is a scammer able to spoof a phone number so that even the exchange points are unable to know the real number a call is originating from? | Technology | explainlikeimfive | {
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"Spoofing is fairly easy to do with some easily obtainable equipment that a nefarious user has no problem obtaining and setting up. The current, and long in place phone system is not built to explicitly prevent this, as its pretty old. In the current system, the system inherently \"trusts\" that the phone is reporting its correct number to the system. Id the phone number I'm calling from I say is 123-4567 the system doesn't verify it, it just passes it along to the next step and assumes its legit. Yes, this is a problem that needs to be solved. Its not new, its been a known issue forever, but the telecoms haven't really been too interested in making the expensive and time consumer changes to the system to fix all the methods of spoofing, both known and currently not known."
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dtareb | How can computer parts like a graphics cards get updates to get faster when they are still the same hardware? And why are there soo regular? | Technology | explainlikeimfive | {
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"The same way you can get where you are going faster by using better directions, even though the car is the same. Devices like graphic cards have software called *device drivers* that communicate between it and the rest of the computer. Updating those drivers can give them more efficient instructions, and it can also fix bugs and security holes.",
"Its not the cards themselves that get the updates, but rather the software on your computer which tells it how to interact with the card."
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dtb3z0 | which is more deadly, direct or alternating current? | I’m in the middle of ‘AC/DC: The Savage Tale of the First Standards War’ by Tom McNichol which is very interesting. Proponents of each form of consumer electrical power had different claims. But which was right, scientifically? | Technology | explainlikeimfive | {
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"Despite what the others here have said, my training has always been the opposite AC holds while DC throws. Most people will never come in contact with DC voltages high enough to make a difference. Because Edison was and always will be a fucking moron. But if you were to come into contact with a high voltage DC situation, it had always been told to me that it would throw you across the room. Sort of like being hit by a train. AC on the other hand does cycle from high to low. This acts on the muscles by contracting them during part of a cycle then releasing briefly, only to have them contract again I was an electrician and the stories have always been about people unable to let go of something energized. For what it’s worth I also have an EE degree. I have been shocked a few times and my initial reaction is to pull back. Never been hung up. I’ve felt 277v which does indeed feel much different than 120v. I do not suggest it. But I think it will always be situational no matter what. It’s not a guarantee one voltage will always force a hold or throw. Just my thoughts"
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dtdtaq | What is the difference in audio over different wireless transmission methods (Bluetooth, Wifi, Radio, Phone, etc.)? | Technology | explainlikeimfive | {
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"* One of the specific uses of Bluetooth is to transport digital audio, so it has several data compression schemes that alter the audio as it moves from the source device to the listening device. * WiFi is just a data transport. It doesn't alter the audio in any way, it just moves the audio data from one place to another. * Radio is a broadcast medium that can transport audio in either a digital or analog format. Both of those standard allow for very high fidelity audio to be broadcast, however radio stations tend to use audio compression to decrease the dynamic range in audio signals. So while this does technically alter the audio signal from its original sound, it's not a consequence of being broadcast, but rather a choice the radio stations make that just happens to be pretty universal. * \"Phone\" is not a way to wirelessly broadcast audio so I can't answer that one. I can try if OP gets more specific.",
"How the signal is transferred, how fast it can transfer, and how far/ what can interfere with the signal."
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dteqsn | why does the wifi drop when in certain situations. Like the way you sit or direction you are facing | Technology | explainlikeimfive | {
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"Your body attenuates (reduces) WiFi signal strength. Depending on where the WiFi signal is coming from, your body would be in between the phone and the signal thus reducing it. The position of the WiFi antenna location within the phone can affect things too. My last phone I could watch a noticeable drop in signal strength holding the phone in landscape vs portrait mode because my hand would cover the antenna.",
"Think of your router as a very bright light bulb. WiFi signals shine throughout your house in the same way light does. Objects in the way of the light cast shadows and your device will register these shadows as low signal. The difference between real light and WiFi is that many objects which block light are clear in varying degrees like glass to WiFi light. For example, microwavable plastic containers are 100% clear to WiFi (same kind of light your microwave uses to cook). This is how a single light bulb of WiFi can been seen shining by your device throughout your house, but the more objects it needs to go through the dimmer the light is. Your body also casts shadows, and could cause lower quality depending on how dim the area already is.",
"IIRC, it’s because WiFi is almost like a contained radio signal that’s made to only span the size of your house. Anything in-between the signal output and the signal receiver will cause the signal to lose strength. (Usually more drastically through walls or thick metal) Edit: wording"
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dthuhm | How do contactless payments through a phone work without service or WiFi? | Technology | explainlikeimfive | {
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"Your phone creates a \"virtual card\" of sorts. Your normal card is just a collection of data like serial numbers, account number etc that tells the card reader how to withdraw money. Your phone simply creates similar card, that effectively functions same way. Your card doesn't need internet access to work, and so neither does your phone (for this purpose). The card reader does, however, require network connection - to actually contact the bank etc. Regardless of whether phone or card is used."
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dtkzn4 | Web Servers | From what I have read throughout the last couple weeks trying to understand this, it seems that when you go to a web page like Youtube or Reddit, you are essentially just accessing the files found on what is basically a computer Youtube or Reddit administrate. Is this correct? | Technology | explainlikeimfive | {
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"Yes the role of a server is to store and distribute things such as data or images or whatever you want Édit: a server is nothing different from your basic computer it’s just not used the same way",
"Not quite. Servers like Reddit have to **generate** lots of stuff for you to view. While simplest servers just have ready-made html page that you just download and browser shows(for sites like imgur this is close to being the case tho), more complex processing is required for sites like reddit. To give you view of the page, you have to find comments on that post, what their upvote count is, if you have upvoted any of them(to display orange or blue arrow correctly), figure out which comments you can edit etc. This means that while the skeleton of the page exists, there are multiple steps between acquiring that skeleton, and actually fleshing it out into an actual page ready for you to download. Basically, your browser and server do a bit of negotiation about what page you should view, and after that's done, server prepares that page(which might basically be entirely made from what was negotiated), and then allows you to download it. From your browsers/computers perspective, the result looks the same as if server simply had the files ready for download anyway, but from server point of view the difference can be huge. Anyway, in general page is only generated when you request it, but in the simplest instances the \"generation\" step just means fetching the corresponding file. With file host servers this simplest case is closest to being true. With sites like reddit, not so much. Servers therefore are just computers that are configured to listen for these requests. With lots of added complications for complex sites like Reddit."
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dtps62 | After dialling a phone call, why does the dial out ring you hear before a person picks up often differ in tone and frequency? | Technology | explainlikeimfive | {
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"Remember, the phone system is ancient. The electronics that generate the ring signal you hear when you call a phone number is not the same as the electronics that generate the ring signal that the person you are calling hears. For example, one might be Sprint, the other might be AT & T. One might be a cell phone, and the other a land line."
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dtq3ao | Why are electronic payments universally trusted, but electronic voting largely viewed as a crazy idea? | Technology | explainlikeimfive | {
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"Its not trusted. That's why banks have massive fraud departments. Why you're given a free credit report yearly in America and everyone stresses protecting your identity",
"Divergent goals and requirements. With electronic payments, you record \"Alice transferred $200 to Bob at 2:15pm\" With electronic voting you need to explicitly *not* record that Alice voted for Bob (secret ballot), but you need to be able verify that Alice voted at most once, that her vote wasn't tampered with, that the number of votes cast is equal to the number of voters, etc. Satisfying those contradictory requirements is basically impossible to do electronically, but pretty simple using paper ballots."
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dtqc62 | How Did Humanity First Make Bronze? | I just watched a cool video from HTME that got me thinking. How did the bronze age come before things like paper, wheels, written language, etc? I don't understand how people would've thought to mix and melt some random ores. | Technology | explainlikeimfive | {
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"The first bronzes were made not with tin, but with [arsenic]( URL_0 ). Arsenic occurs naturally near some copper ores, and preserved bodies from that era such as Otzi have significant arsenic contamination. If fire is your main transformative technology, you will burn a lot of stuff and heat it as much as you can; evidence for gold mining goes back some 7,000 years as well.",
"In all honesty, the ELI5 here is: people are inventive and experimental; people burn stuff. The vast majority of inventions up until very recently in human history happened because someone was bored and did something a thousand times, until something interesting happened. Quite a lot of the time, they were actually trying to do something completely different and thought: \"I wonder what would happen if I did $this with $that?\" It is of course also how homo sapiens happened. Some**thing** thought: \"I wonder what would happen if I did $this with $that?\"",
"Luck, but not as much as you might think. Gold, silver, and copper occur in their pure form naturally, and of those, copper is best suited for most tools and weapons. These metals are more easily extracted and work when hot, so putting metal in fire wasn't a crazy thing to do. Lead and tin don't occur in pure form, but have low melting points and can be smelted at campfire temperatures, at some point someone probably threw an ore bearing rock in a fire and useful metal oozed out. Rocks, fire, metal, they all went together. The first bronzes were simply copper with natural impurities, the earliest bronzes contain arsenic instead of tin. People eventually figured out different impurities resulting in different properties and worked out how to add those impurities themselves."
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dtue2n | Is it possible to permanently shut down the entire internet? Maybe like an internet kill switch or is it too complex than that to explain. | Technology | explainlikeimfive | {
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"Not easily. The internet is a bit like a road network. If you close one road people will go around it by using another road.",
"The Internet is pretty much a network of smaller country networks, so it would be almost impossible to kill them all at once. Some countries have tried to legislate and implement their own [kill switches]( URL_0 ) for massive cyber attacks etc. The closest thing to killing the whole Internet might be to [shut down the 13 root nameservers]( URL_1 ), but it wouldn't be instantaneous.",
"\"the internet\" is not in one place, it's a interNET of computer, when you go on a website you ask a computer placed somewhere if you can have that page, if you go on a different website it is very likely it will be on a different computer somewhere else, In conclusion you either switch off the whole world electric power supply, or you will always have some computer still up",
"Pretty much, no. The internet in its original form (ARPANET) was a mechanism to allow communications to stay up between American cities where any multiple of them could be completely wiped out with nukes. Its called the World Wide Web because like a web there is no central pillar, everything connects to its neighbors and to get from one spot to another you move along whatever route of connections can take you there. By design there is no one thing you can hit which would take it down. There are some central pillar like structures out there. Things like DNS and timekeeping servers come to mind. But there are a lot of these scattered around the world, it would truly be a near impossible task to do that all simultaneously, and knocking them out wouldnt actually stop traffic from flowing it would just be a major disruption as the the way things work currently assumes they exist to verify against rather than *relies* on it."
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dtvb3g | Why do game makers use fake textures instead of pictures of real life objects? | Technology | explainlikeimfive | {
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"Game textures often do come from pictures of real objects. But mapping a photo to a texture for a 3D object isn't always easy, so it takes a lot of work to make it look right. A photo only show the object from one point of view. Even when it's for a mostly flat surface that isn't ideal because it doesn't capture how the light bounces off it when you look around it in 3D. So the game will usually apply techniques like normal mapping to make it look more like it would in real life. Also sometimes it's not feasible to use unique photos to texture everything. You need a repeating texture for the ground, walls, etc. Quite often they will be based on real photos of grass or brickwork, but they need to be adjusted so they can be repeated. But sometimes repeated textures are offputting if it's too obvious, so they might blend other textures in to hide the repetition, which takes it further away from a real photo.",
"The technique of mapping real life photos onto 3D computer models is called photogrammetry. The only game I'm aware of that used this extensively is The Vanishing of Ethan Carter. It was a beautifully immersive game. I think ultimately the problem with photogrammetry is it is cost prohibited compared to traditional graphics."
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dtvnm2 | What part of the eye does an eye scanner scan and register? | Technology | explainlikeimfive | {
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"text": [
"^(typically the iris-- which is the colored bit around the pupil. there are lots of ridges and variabilities in the surface which makes it unique to the person like a fingerprint.)"
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dtwy4i | How come lots of online services still subscribe you to their newsletters though you didn’t tick the option to do so when signing up? | Technology | explainlikeimfive | {
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"text": [
"Most of the times the \"receive our special offers and newsletters\" box is already checked automatically and you have to uncheck it before accepting. Just pay close attention when agreeing to services theres always tricks in place to get subscribers."
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dtxk4q | if UV light and infrared lights are invisible to eye, why we see blue light in uv light torch or red light in infrared lamps used in certain physiotherapy?? | Technology | explainlikeimfive | {
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"Sources of light rarely, if ever spit out a single pure wavelength. LEDs get the closest and have the narrowest output, and using special equipment you can filter out light you don't want to get a very narrow band. But for the most part, all lights are going to give off *some* extra photons in frequencies outside of the range that you want. For example, all lights designed for perfectly normal visible light also put out infrared at the very least. Fluorescent lights actually start with putting out mostly UV that is absorbed by a phosphor inside the tube, which absorbs the UV and converts it down to visible wavelengths. In any case, the point is that a UV bulb doesn't *only* put out UV, it also puts out a tiny bit of very high frequency blue light, and most infrared lamps put out a fair amount of low frequency visible red light. There's no need to filter that visible light out so they don't, so it's visible.",
"I think this is an added light just so you can see that this is infrared light and this is uv light are on/off and so you can aim with it. It’s hard to aim with an invisible thing"
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dtyb2r | Modeling plasticity | I know that our artificial neural networks have been inspired by our brain One of the mechanisms that I know that occurs in our brain is plasticity where our neurons are forming new connections. This enables learning. I know that our neurons can also break off existing connections - pruning. I am interested in comparing this approach to how our artificial neural networks work I know in our artificial neural networks, there is a process called backpropogation where a connection between is strengthened or weakened based on how it contributes to the solution we want. This connection can ultimately reach 1 or 0 in a sense that represents the connection being fully on and off(perhaps breaking off) What are the main differences between the two processes? In our brain I suppose that any neuron can establish a connection with any other neuron. Is there a neural network that simulates plasticity to more what happens in our biological brains? | Technology | explainlikeimfive | {
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"This is going to be a tough eli5 but I'll give it my best shot! & #x200B; Neural networks are loosely based on biological neurons, but not exactly. They weren't modeled to fit exactly, and we actually don't want this. For example, our memories fade over time, which is not something we want with a neural network, where a neural network will be consistent. A neural network consists of a bunch of mathematical functions that are connected to each other instead of biological neurons. Each neuron has several parameters associated with it. Simple neurons will have a weight and a bias, which describe how strong the connections are to each other (weight) and how strong the neuron is on its own (bias.) More complicated neurons will have other parameters such as convolutional windows, strides, etc. There are also 'special' neurons that transform the data in other ways (max pooling, dropout, etc) that are out of the scope of an eli5. The key similarities are that neurons are connected to many other neurons, and that the network is able to 'learn' from seeing examples. For example, consider a network is supposed to determine how to steer a self driving car. The network receives its input from the sensors on the car. Then, the input is passed through each neuron and the output is eventually turned into a value, such as the angle to turn the steering wheel. Let's assume that this is the only thing we care about for now. At first, the network has never driven, so it pretty much steers the car randomly. During training, the network is told the real value that should be used. For example, if the road curves left, and the network tells the steering wheel to the left, there is no problem, and nothing happens. However, if the network steers the car to the right, there is a problem. This problem is turned into a quantity called 'loss,' which numerically describes how far off the steering wheel is from the actual 'best' value (note that the 'best' value is provided by humans and is therefore subjective!) This is where backpropagation comes into play. The network is a VERY complicated function (as many as 100,000,000 parameters) so it cannot directly calculate how to adjust the parameters to get the best steering performance (lowest loss.) However, as it turns out, the network can compute the gradient of the loss for each parameter. This tells us the parameter adjustment that will increase the loss the most. For example, continuing to steer to the right will result in more loss. By going in the opposite direction, the network can adjust the parameters to decrease the loss, and begins to turn the steering wheel to the left. To do this we can only make small adjustments to the parameters. If the car turns the steering wheel all the way to the left when the road curves slightly, it will still not drive well. Therefore, for each training example, only a small adjustment is made. & #x200B; After being shown lots and lots of training examples, the network continues to learn. This takes the form of strengthening and decreasing the connections between neurons. Note that the connections are never cut off completely (ie the architecture of the network is constant) but if the weights are adjusted to near 0 then the connection won't contribute to the final result. This is similar to pruning. Connections can also be strengthened by increasing the weight. Hwoever, neurons cannot form new connections entirely as this makes everything more complicated AND changes the performance of any neuron downstream of the new connection. This is a difference from plasticity as you described in biological neurons. & #x200B; As an additional detail, some networks may take advantage of a feature called 'dropout' during training, which actually does disconnect random neurons temporarily. This allows the network to perform as multiple different networks with different connections, and can improve the results. However, during actual predictions (not training,) all of the neurons are still connected."
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dtz1v2 | In terms of computer's RAM(SSD, HDD) - what is a cache and how does it work? | Technology | explainlikeimfive | {
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"One of the basic rules of computing is that performance costs money. We know how to build faster hdd's and memory, but it is often cost prohibitive to do so. But with some clever engineering we can use a small amount of expensive and high performance storage to improve the performance of slower storage. Think of a cache as a sort of middle man between slower storage and the rest of the computer, allowing the computer to interact with the cache at high speed while the slower and cheaper storage catches up.",
"There are various levels of memory in a computer. The types of memory that are closest to (or in) the central processing unit (CPU) are the fastest; however they are also small. Because you can’t store much data in those faster regions, a computer needs to move to the next fastest area to retrieve data. In the CPU there are “registers” which may only hold a couple of numbers or letters at a time and are used to actually do the math/work that a CPU does. There is also a CPU “cache” which are very small (a couple of megabytes) data that the CPU is about to use is stored here. Approximately 1,000 times more data can be stored in the cache than in a register. Outside the CPU your computer has random access memory (RAM), and also commonly referred to as “memory.” An average computer these days may have between 8 and 32 GB of RAM. Therefore you can put 1,000+ times more data in RAM than a cache. Next you have hard drives. Hard drives can be spinning disks (hard disk drives, HDDs) or solid state drives (SSDs). Hard drives these days can be 8TB or larger. Therefore you can store 1,000+ times more. Then you have the Internet. It is the slowest data to access because it’s the furthest from your CPU. It contains an endless amount of data, most of which you shouldn’t trust because there are anti-vaxxers out there and people that think Epstein killed himself.",
"think of it like the book return at the library. shelving books is *slow.* the librarian has to run all over the library and can't be of much help to anyone else while they do it. so when the library is being used, the librarian merely documents what books have been returned, puts them behind the desk, and carries on helping customers. if another patron needs the book right away, the librarian has it on-hand. if not, the book stays behind the desk until the librarian has no other duties and can shelve it.",
"Cache can either refer to hard drive cache or CPU cache. Hard drive cache (found on all types of drives, SSDs, BD-ROM, mechanical hard dirve, etc) is usually just a small amount of RAM (a few MBs to 128MB) that stores memory that is about to be written to the drive, but the drive cannot write it quickly enough. CPU cache is memory that is directly on the CPU that runs at the same frequency as the CPU, it is extremely fast memory that the CPU has direct access too that it doesn't have to go find in RAM. On older computers the CPU cache sometimes off the CPU and ran at 1/2 or 1/3 the speed."
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dtzr9l | how does crack in games works and why? | Technology | explainlikeimfive | {
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"A game crack is disabling of the copy protection. So what you do is change the game program so when if for example check with steam if you own the game you add some code that fake a response from steam and say that you own the game. So cracking a game is examining the program by decompiling it and checking the code and to run and check where it try to access something to determine if it is a legitimate copy. You might the just change the code so the check is never done and the game run just like if there was not code to check it if was legitimate at all. It get a lot harder if the game communicate to some server and part of the game is executed there or stuff that is needed is downloaded on the fly. You can create code that do what the server do and copy what is downloaded and lot is locally but it is a lot harder. Online gams where you play with other on a server that the publisher own can't be cracked because the check is on there server and you can change them without hacking into them. That is hard, can be fixed and a a crime that is a lot easier to trace back to you so it is not done."
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du0dcp | Why do monitors appear in negative colors when you look at them from a lower angle? | Technology | explainlikeimfive | {
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"You mean LCD monitors? That's because of light polarization. I am no expert but in general it works like this: there are simple LEDs behind, in front of them is a layer of liquid crystals, and in front of that layer is a polarizing film filter. The liquid crystals polarize the light emitted by the LEDs, so that a dark pixel makes a light wave \"twisted\" in one direction, a white pixel is in another direction, a grey is in-between. Yes, light can be \"twisted\" and it actually has to do with quantum physics. When light passes through an incredibly thin and dense grid cut by laser (in a film polarizing filter) or micro prisms made of liquid crystals it gains special properties. This effect is invisible to a naked eye unless another micro-grid or micro-prisms are put in front of such a light. Light wave can also be forced to rotate - that's called circular polarization and it's used, for example, in 3D glasses used in cinemas. So basically the liquid crystals turn in one direction when they are black and in another when they are white under the influence of electric current, depending on polarity. The LED light passes through them and becomes polarized either in one direction or another. Then comes the outer polarization layer which cuts the light from the black pixels and lets the white pixel light through. In LCD monitors the polarization is made in the horizontal axis, because the screen is wider in that direction and we're more often move our head horizontally rather than vertically. That's why when you change the viewing angle it changes the pixel intensity, up until the moment when you're crossing the polarization angle and see the \"other side\" of the liquid crystals. You have probably seen some clock radios which have white digits on a black background, that's just because the liquid crystals have their structure turned 90 degrees, as well as the polarizing film in front."
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du1g2d | How processing power increases? | At the very basis, it's all binary and electrical signals, so what has allowed processing power to increase so drastically? Is it the hardware that improves? Number of transistors? Is it programmers' abilities to manage the binary in different ways? I'd like to know! Computers and code have always fascinated me so much... it blows my mind that electrical signals create all of this. | Technology | explainlikeimfive | {
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"Most of the things you mentioned, plus more. But the biggest driver over the last half-century or so has been making transistors smaller. This allows more of them to be put on a chip, and makes the circuitry faster (up to a point). As we've been able to pack more transistors on an integrated circuit, there have been major architectural improvements (ways that the different circuits work together), wider data busses, bigger on-chip caches, etc. Programming has also improved, with a lot better tools having been developed, libraries of functions created, etc. But the biggest driver has been shrinking the transistors. See \"Moore's Law\" or \"Dennard Scaling\". When I first started working on microprocessors back in the early 1970s, there were hundreds or thousands of transistors on an IC. But with the doubling of transistor density about every 18 months, there are now *billions*.",
"It comes down to two things: How many times a second your transistors can switch, and how efficiently you use those switches. By making your transistors smaller, they switch faster, but you can also get more. More transistors means you can switch more every second, since you can switch more than one at a time. Also, by arranging them right, we can actually have multiple calculations being done by the same set of transistors, since it takes time for the signal to propagate from the input to the output. Meanwhile, with creative programming and timing, we can squeeze more processing power out of the same number of transistors."
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du639s | How does power-cycling a router fix connection issues? | Technology | explainlikeimfive | {
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"Sometimes things just get out of sync or there’s a bug that causes the router/modem to lock up. Power cycling forces a start from a known state.",
"Sometimes the ISP (internet service provider) wants to get an IP address freed but the router does not respond correctly. Sometimes its the other way around that the router requests a new IP, but the ISP refuses. Sometimes powerusers trigger a state where the router can not handle more connections and hangs."
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du6rsi | What makes electronics break when water gets in them? | Technology | explainlikeimfive | {
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"Unless it is absolutely pure distilled water, water conducts electricity. Most electronic devices have many different uninsulated components close to each other. Water causes a short circuit between these components, effectively causing electricity to flow into components where it shouldn't, for example, if you have a 12v power lead near a grounded component that is designed for only 5v, the water can cause the 5v component to receive more voltage than it can deal with. Sometimes if you get an electronic devices wet, it will stop working and appear to be dead, but can actually be saved. This happens because, although there was a short, it didn't damage anything. If you completely dry it inside and out it could be fine.",
"Water contains impurities that conduct electricity. When this water contacts electronic components, it shorts them out and they can not function. It would be like placing bare wires all over the circuit board."
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duag3a | When we switch off a phone and switch it back on after say 5 hours, the clock has automatically set according to the time, how is this possible? If it didnt have power how did it have memory? | Technology | explainlikeimfive | {
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"Like computers, cell phone have a Real Time Clock RTC. Even when turned off, there is a tiny amount of power used to count the seconds/milliseconds. When you turn it back on, the network also provides timestamps to the device to synchronize time. On computer motherboards, there is even a small battery that keeps the RTC going even if the PC is unplugged.",
"Most phones have a very very small secondary battery inside just to keep the little internal clock going. The battery is just powerful enough to keep the clock ticking, but nothing else!",
"If the battery goes fully dead and even the real time clock powers down, it will then get the time from the network as soon as it starts up. Before then, it may have the time set to a default value - 1 of January 1970 is common, or a time just before the release of the phone - or it may start up with the time still set to what it was when the phone turned off."
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duaj2k | How do people make mods for games? | Technology | explainlikeimfive | {
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"There are in general three *types* of games in regards to modding. Some games encourage modding to the extent of releasing developer tools, giving players proper access to the game and makes modding about as easy as it would be for proper developers. Imagine a car that arrives with a proper manual, allows access to all parts of the car, and comes shipped with all the tools you need to properly fix, alter or modify your car as you see fit. Other games encourage modding, but don't release tools for it, only opening up access to the core loop. Modders thus have a way of interacting with the underlying core of the game, but have to find their own way if it were. The game might have a specific \"mod\" folder that it looks in to find new mods, but you can't just open a special modding program for that game released by the developers. Imagine a car that doesn't come ship with tools to fix it, but you can easily open the hood, unscrew all parts if you want, and could reasonably figure out how to do what you want to do if you study it a bit. The last category of games is closed off, not being built for mods at all. Modders have to go poking around in the game files, reverse engineering the games program, applying cracks to allow for an access point, and so on and so forth. This is the hardest type, as you're essentially trying to force a game to change that doesn't want to. This is a car that arrives with the hood sealed, the engine covered with an irremovable plastic cover, and proprietary parts that you don't know how to operate. You *could* break open the car and try to see how it works and apply changes to it, but it's a difficult process that takes a lot of guessing and trial and error, reading trough obscure forum posts and old car manuals to see what connects where.",
"That varies from game to game. Some games, like Skyrim, release tools to allow players to more easily modify and tinker with the world with plugins that don't overwrite the base code but just tell it to take the changes over it. Other games, many more games, that don't release modding tools have to be reverse engineered in part, or have access to what is called the source code (effectively the files that make the game the game without encryption etc), and poke at it to see what each part does/read the notes to see what's what. Then rewrite said code as needed.",
"It's either the use of developer tools(released or leaked) that are what the devs used to make the game to begin with. Or some really dedicated turbo autists that have studied the game with the fervor of monks to find ways to make it run custom code through means that are more akin to magic then science."
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dub3v5 | In cartoons/animations, objects that are about to move are coloured differently, usually are brighter. | Technology | explainlikeimfive | {
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"text": [
"Because the artists would draw the background (like, a beach with towels and umbrellas and maybe some buildings). That background doesn't change. Next, they draw the non-fixed objects (characters or things that have to move, like an umbrella the character knocks over) on a transparent sheet that goes on top of the background. The colors used for the animation sheets are usually richer / more saturated, and they will naturally contrast against the background picture.",
"Hand drawn animation is incredibly tedious. You'd need to redraw an entire scene 24 times a second for every little movement. So animators cheat. They only redraw the parts of the scene that actually move. They do this by on layers of transparent sheets called cels. If you've used layers in Photoshop or GIMP, then you're already familiar with the concept. The static background of a scene will be on the bottom, and moving objects will be layered on top of it. These cels aren't perfectly transparent though. So the more layers you add, the duller the bottom layers will look, while the ones closest to the camera will look brighter. I think someone else mentioned they use more vibrant paint as well for foreground objects.",
"> I always thought it was so that the kids knew where to look on the screen when a character gets buried in rocks and stuff there is a philosophy in animation that says priming the audience for what you are about to do next can only help your animation, so that could be a reason why animators often didn't go through the expense of matching moving animation with the static background."
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dufmsl | How are laptop components (web cams, microphones etc.) so, relatively, easily exploited and hacked? | Technology | explainlikeimfive | {
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"text": [
"It's not the components that are hacked, but they are usually the final target. A system needs to be compromised first in order to access the components. So basically the system itself is hacked by some means with the intention to retrieve data, and perhaps record audio or video and stream it back to the hacker for intel or blackmail purpose. It's not the components, it's the operating system, or the hardware."
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dufsik | What makes the TV do the clicking/crackling noise when you switch it on? | Technology | explainlikeimfive | {
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"Most likely relay switches. When the TV is turned off or on, these mechanical switches will open or close some of the unit's more high powered circuits and produce an audible click in the process. As for the crackling, I didn't know modern TVs crackled (mine doesn't). Are you referring to the crackling of CRT TVs?",
"If you're referring to old tube TVs, they operate by actually firing a stream of electrons at the viewing surface to light it up. So the front actually has a bit of a static electrical charge, and you can hear that as the electricity builds up as the crackling. On both flat panel and CRT/tube TVs, they still use a lot of electricity so there's a mechanism to open/close the major flow of power to the electrical components using the most electricity and you can hear it click on/off. A lot of electrical devices do that. Probably the biggest thing you have doing the same thing is a car - can you hear clicking noises that are not the key turning as you turn it on but not started the engine yet?"
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dukdvb | How does a device keep the correct time even after being without power and without any internet connection or signal? | Technology | explainlikeimfive | {
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"Most devices have a capacitor or small battery to maintain the settings and real time clock. Very little power is required to maintain the energy to power a chip.",
"Many electronic devices keep a separately powered circuit to maintain an internal clock (or other system functions) called a CMOS. Because of the very low power requirements it can maintain the system clock for a very long time. If it's not charged 6or replaced (like the button battery on a PC motherboard) it will eventually stop keeping time and reset when powered up again."
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dukkeb | How does Google maps know if a road is closed or traffic is slow? | Technology | explainlikeimfive | {
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"Google does a lot of tracking on user's phones, and they also own Waze. Between those data sources, and others, they know when multiple users are moving more slowly than usual on a given road, or if no users are on a given road. they're also connected to multiple departments of transportation and receive notifications of road closures and other activity.",
"Most users having GPS location tracking on when using Google Maps. If they've planned a trip in the app and parts of it take longer than expected, it'll send the info to Google and tell others where the longer parts of the trip were, giving everyone access to info about the delays."
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dum7wf | How Exactly Are Smartphones Designed For Planned Obsolescence? In Terms of Hardware. | I get that with software, companies could just stop supporting old phones with new software, and possibly slow them down, but how are phones manufactured for Planned Obsolescence? | Technology | explainlikeimfive | {
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"\"Planned Obsolescence\" is a poorly misunderstood term. Many people seem to think it refers to evil corporations trying to milk the public by having their products self-destruct in some fashion. In reality, it's reflective of the fact that when you engineer *anything*, you need to make decisions about how long it needs to last. It makes no sense to spend money ensuring one part will last 100 years when another critical part only lasts 6 months. The reason the products you buy today are so cheap is largely a result of designing products with a more precise sense of how long they'll last - and calibrating that time against the standard use of the product. With your cellphone, the product lifetime is normally determined by the battery. Batteries only have so many recharge cycles and the cost of increasing the number of recharge cycles is prohibitive. If you know how long your battery is likely to last, then you can select components that last a similar amount of time.",
"It doesn't need to be done with hardware, but making batteries not user replaceable is one example. All they need to do is no longer provide software updates for the product."
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dumksr | Why does pushing an earbud into your ear make the music significantly more quiet? | Technology | explainlikeimfive | {
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"You're probably pushing it at an angle that causes the speaker to partially push against the wall of your ear canal, muffling the sound",
"My guess is that you're restricting the available space and/or air pressure for your eardrum and/or the speaker membrane to vibrate within."
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dupvrl | How do cultures without electricity store their crops to prevent winter starvation? | Technology | explainlikeimfive | {
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"Grains and legumes (beans, peas, lentils etc) can be stored for years in a dry place. They just need to be turned over occasionally. In a wet climate, they would use rooms or vessels that were raised up from the floor, so that moisture can't get up. Vegetables were often salted, or fermented to turn sugar into acid like sauerkraut and kimchi. Some vegetables such as onions and carrots can also simply be left out in the field during winter. There are also some which simply last for a long time without spoiling, for example red cabbage. In warm climates, it was also common to dry some fruit until they became so acidic or sweet that they didn't spoil. For example dates, figs and persimmons. And once sugar became abundant, they could be preserved with sugar. Meat and fish meanwhile were often salted and dried. If the weather wasn't warm enough for that, they could hang the meat under the roof, where the warm air from the fire pit dried and smoked it. They could also use more salt instead of heat, which was used a lot by scandinavian fishers, who exported their catch all across Europe.",
"Dry them out, roast them, salt/brine them, bury them, in honey, in cool caves or cellars, there are lots of more or less common techniques depending on the temperature, humidity, altitude etc."
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dutino | If the Hindenburg disaster hadn't turned public opinion against airships, would they have been an efficient form of air transportation or were they mostly novelty? | Technology | explainlikeimfive | {
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"Probably not. If not the Hindenburg it would be something else in the future. If they just naturally swapped to helium without a disaster they’d just deplete global helium supplies faster. Currently we’re getting close to the point where it’s becoming a scarce commodity and harder to find.",
"They were on decline before the Hindenburg as airplanes became more practical. Airplanes can be plenty comfortable, are much faster, and are easier to supply since they don't need a lfiting gas. They weren't really a novelty at first since they were around before planes, but eventually a plane would've just been better for pretty much anything an airship was functionally useful for.",
"The writing was on the wall for them. Airships really just aren't an efficient form of personal travel, and even in their heyday airships were noted as being pretty spartan in terms of their accommodations (entirely because they had to shave so much weight in order to work)."
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duu9j4 | how does a phone stylus work? | How does a phone stylus still register on a screen when something like an eraser, which feels somewhat similar, doesn't? What allows some materials to register on a screen, and others not to register? | Technology | explainlikeimfive | {
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"Touch screens generally work due to \"capacitance\". That is the ability for a material/object to store an electrical charge. The human body is reasonably good at this, due mainly to containing a large amount of water. Water molecules are [slightly more positive on one end and more negative on the other.]( URL_0 ) If you expose them to an electrical field (a voltage), the water molecule will rotate a bit. In this way, it's storing a bit of energy. If you remove the voltage, it will go back to moving around more freely. Touch screens work by putting a tiny voltage on the screen (in many places, one after the other, very rapidly) and detecting if there's a tiny current flow. If there is, something with capacitance has touched or come near the screen. Like a human finger. But it doesn't have to be the finger itself, it can be something electrically well connected to that finger. That will form a conductive path to the finger and it's almost as good. And that's what a phone stylus does. It is conductive, and it therefore provides a \"virtual finger\" that increases the capacitance at the screen where it touches. If a material is not very conductive, or not in electrical contact with something with high capacitance, it won't register on the screen."
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duuzbp | Why does battery powered electronics (such as a remote or an electrical toothbrush) lose power as the battery is weakened and not work at full power till the battery is dead? | Technology | explainlikeimfive | {
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"A battery's voltage decreases as it is drained of energy. Think of voltage (electrical potential) as water pressure. You hang up a bucket of water and open a hole on the bottom to shower. The water pressure at the start is strong from the weight of water pressing down. However, as the water drains, the pressure weakens and it gets more difficult to wash yourself. This is the same thing that happens with the motors and lights powered by batteries. As the battery drains, these parts lose power gradually until they stop working. One way to prevent this is to put in regulators that fix the pressure/voltage at some level rather than have it decrease over time. Newer electric toothbrushes have this. They will run at full power and only start weakening when they are low on battery.",
"If the question wasn't too understandable (English is not my native language), what I was trying to ask is why i.e. when your remote's batteries are almost dead the signal weakens instead of working full power until there is no power left in the battery?"
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duwd6d | How did people begin to disprove the geocentric model? | Technology | explainlikeimfive | {
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"Early evidence: the visible planets follow bizzare paths across the sky that are difficult to explain with the Earth at the center. Mercury and Venus never leave the Sun's proximity, the others lazily wander through the sky on multi-year cycles that confounded early astronomers. Eventually (1500s) telescopes got good enough to resolve details about the planets, and astronomers noted that Jupiter had objects that seemed to orbit it instead of Earth and that Venus went through distinct moon-like phases. This suggested that Venus was orbiting the sun and not simply moving in some bizzare path ahead or behind it, and that it was possible for objects to orbit other things. Taking that observation and making a model with the Sun in the center produced a much cleaner series of nice circular orbits instead of labyrinthine explanations of retrograde motions, and it soon became the established teaching (despite some infamous early resistance from religious figures)",
"[Summarized from this really good article here:]( URL_0 ) The most important discovery involved the phases of Venus by Galileo in 1610. This gave direct evidence that Venus was sometimes farther than the Sun, and at other times closer. This disproved the Ptolemaic model that had all the planets orbiting Earth. However, Tycho Brahe had a geocentric model that involved all the planets orbiting the Sun, and the Sun and Moon orbiting Earth. The important thing is that if you just consider objects within the solar system, this model is pretty much indistinguishable from a heliocentric one. The key problem with a heliocentric theory was lack of stellar parallax. Kepler several years before Galileo's work had published his now famous laws of planetary motion, but for whatever reason they were largely ignored for a few decades. However, in 1687, Newton develops his theory of Gravity. This provides a theory in which the Kepler model *ought* to be true. From this point, no one really questions the heliocentric model even though they still can't find the stellar parallax. In 1728, stellar aberration is discovered. While not exactly parallax, it does prove that Earth is moving relative to the stars. In 1806, stellar parallax is observed. In 1835, an illusory optical phenomena (Airy disk) was identified that causes stars to appear more disc-like in telescopes. This explains the erroneous calculations Galileo's contemporaries made that suggested stellar parallax should be significantly larger than it actually is (thus they thought that they should be able to see it when it was actually too small)."
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duxbow | Why is salt mined when there's a bunch of it available in the ocean? | I'm sure its harder than mining, but how and why? | Technology | explainlikeimfive | {
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"Sea salt takes a lot of space and time to produce. You have to be able to flood huge fields and then you have to wait for evaporation to remove the water and leave the salt behind. So basically you need a hot, dry country, a coastal area that can be turned into salt fields and quite a lot of time and effort. Mining is a lot quicker, takes up less space, and can be done in countries with colder, damper climates. Obviously there are pro’s and cons to both which is why we see so many different kinds of salt production.",
"Taking the salt out of the water requires an Evaporation process or “train”. The reason it is harder is because of the energetic demands vs the amount of salt obtained.",
"Water loves salt. Getting water to give up salt is hard, so if you can find a place where past sunlight drove the water off to leave salt that saves process energy.",
"It take _a lot_ of energy to boil water. One BTU is the amount of heat energy required to raise one pound of water by 1ºF. Water weighs 8.33 pounds per gallon so we can calculate that one gallon of water requires 8.33 BTU to raise the temperature 1ºF. So, to raise water at \"room temperature\" of 70ºF to boiling it takes 1,182 BTUs of energy. Seawater is about 3.5 percent salt by weight, which means a gallon of water (eight pounds) should yield about 4.5 ounces of salt. So, excluding the costs of gathering, filtering and collecting the salt, it would take ~260 BTU to get one ounce of salt. Now, that isn't that much - about 1/3 of a cent per ounce (based on using natural gas at about $15 per 1M BTU) - but that is still much more energy than it required to just mine salt in salt deposits - which are plentiful. **Edit**: While 1/3 of a cent doesn't seem like much, it is a lot when you factor in how cheap salt is. A 40lb (640 oz) bag of salt costs about $5, which works out to a little less than 4/5 of a cent per oz. The cost of energy to boil seawater would be almost half the cost of the salt alone if we extracted from sea water This is the same reason that desalination plants aren't used to get drinking water in areas near the ocean - while it _can be_ (and sometimes is) done, it is usually much cheaper to just pipe water in from other places than expend the energy required."
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duzkw2 | what’s actually meant when an album is re-released as “remastered” | Technology | explainlikeimfive | {
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"the mastering and perfecting of audio has come along way in recent years, so they revisit old classic albums and tune the tracks and EQ them give a more expansive sound quality.",
"**During the process of mixing and mastering an album, each sonic quality of the recordings is considered and adjusted both to best fit the desired effect of the music and retain that effect on the medium it is intended to be distributed on. If you want to make a change to that originally distributed master, you're going back to the original tracks and cutting a new master via computer editing - this is** [remastering]( URL_0 )**.** & #x200B; For example, an analog medium such as a cassette tape tends to be what is often described as \"warmer\". This usually means there is less \"high-end\" (treble) clarity. Therefore when you cut your master for release to cassette tape, you may have taken care to adjust your mix in such a way that you achieve your desired effect best when listened to via a \"warmer\" medium. 10 years later, CD becomes the household standard, and now you are working with a digital medium with a much \"flatter\" (not really leaning towards bassier or trebblier) sonic property. But because you mixed for \"warmer\", your music does not achieve the desired effect that you had achieved on cassette tape (perhaps those highs that you had to really emphasize for clarity on cassette tape now come through as harsh or shrill). Now you've got to remaster your album. Even if no significant changes are made, you've still got to cut a new digital copy of a analog master. Another example may simply be that the tastes or means of the artist have changed over time. Perhaps you recorded your album on low-quality gear or hired a cheap studio engineer and you always thought the album could sound better. Or maybe your ear has \"grown\" and you want to make changes that you think would enhance the quality of the album. In either case, your taking your original recording and remastering them via software. & #x200B; For all of the above examples you could theoretically re-record an album, but that would be expensive and time consuming, and would not be considered a remaster. [\"Remastering\" is to create a new master of, especially by altering or enhancing the sound quality of, an older recording.]( URL_1 )"
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dv0nol | Where are backdoors /security flaws from ? | Technology | explainlikeimfive | {
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"Backdoors and Security Flaws are ways to circumnavigate normal digital security or access permissions to get access to data that you shouldn't have direct access to. The difference is backdoors are intentionally created or left there at the request of a government or other authority so that the \"good guys\" will always have a way in if they need to get someones information. This is very obviously not great as it is very hard to prevent backdoors from getting leaked or abused like the reports of NSA agents caught with people's nude photos from iCloud and other cloud storage platforms. As to where they come from, security flaws are generally oversights in the software design just like locking all the doors to your house but leaving a window unlocked. As far as an example, as to what a flaw \"really\" is, as always there's a [relevant XKCD]( URL_0 ) about the HeartBleed vunerability.",
"Computer systems are very complicated, but the computers that run those systems take things literally. Clever people take advantage of those complicated systems to make the computers do what they're asking and not always what the program writers intended. My favorite example of a flaw or \"hack\" comes from the early 2000s and doesn't involve computer systems at all. It used to be that with a cell phone, you could sign-up for a plan where the nights and weekends were free but you paid by the minute during the day. Someone in the US on the west coast figured out that if they registered with an east coast address, their nights and weekends would start three hours earlier at 2:00 PM instead of at the intended 5:00 pm because of the differences in time zones. The employees that came up with or \"wrote\" the nights and weekends plan did not expect someone would lie about where they lived, and thus a hack was born. Computer systems behave just like this, and they take things like dates, times, and locations exceptionally literally. Someone skilled in the art can understand where likely flaws are, and then press on different defects (sometimes combining multiple flaws together) to get the result they want.",
"ELI5: Backdoor: You have a lock on your house. The previous owner (or government) have kept a key, just in case... Security flaw: You have a lock on your house. It looks good, but it's actually a crappy lock you can open with a bent paperclip if you know how.",
"A backdoor is an intentional security flaw built into a system by a programmer with the intention of being used to allow them access to the system while bypassing regular security. Hence the term, they are entering through the back door instead of the front door. This is either done for troubleshooting purposes, or it's malicious to allow them unauthorized access to the system. An example would be building in a master password hidden in a program that always works even if the account doesn't exist. Generally speaking a backdoor in a program is a bad idea no matter how well intention. Because sooner or later someone else will find it and abuse it."
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dv20hs | Why does a laptop say it's at 6-8% charge, and then it dies, but when it's at a higher charge, going from 60% to 59% takes a while? | EDIT: Wow, I did not expect this to gain so much traction. Thank you to everyone who responded with such helpful insights. I certainly do understand this now! | Technology | explainlikeimfive | {
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"Most laptops shut down long before they reach an empty battery, mostly to preserve your work and system when the battery is low.",
"Because it's an estimation. The computer doesn't actually know how much charge is left. Batteries are direct current, that means as the battery discharges the output voltage changes. Through battery testing they're able to determine a reproducible voltage curve. Then they assign percentage of charge to voltage. By measuring the voltage the computer can estimate the amount of charge left. As the battery ages the chemistry changes making the voltage curve not as predictable as programmed. That's why the battery will die at 6%. Then when you plug it in it says 0%. Voltage curve: URL_0 In the image it starts at 1.5 V then gradually decreases to 1 V then suddenly goes to zero. When rechargeable batteries age the sudden drop in voltage drifts to the left due to changes in the battery chemistry. So instead of suddenly dropping to zero at one volt it'll do it at 1.2 volts. The computer thinks 1.2 V is 6%, so it says 6% battery life left. Then the sudden drop occurs and the battery dies.",
"You probably have your laptop configured to begin shutting down when it has some power left over (perhaps 5%), to avoid it losing power while doing something important. It shuts down when it's hit that preset limit, not when it absolutely can't run any more.",
"It is an estimate and as batteries get older/weaker anything below 10% should be considered 1% unless you enjoy living on the edge.",
"Because the battery is old. **Edit: here's a water analogy**: The battery is like a tank of water connected to a pipe with a valve at the end. The laptop adjusts the valve in order to keep the appropriate amount of water flowing (power) to supply the laptop. As the tank drains, the pressure drops, and the laptop opens the valve further to keep the same amount of water flowing. When the battery is old, the pipe is all rusted up and full of gunk. When the tank is full, the pressure is still enough to keep the water flowing at a sufficient rate. But as the tank drains, the pressure drops lower, and the laptop has to open the valve up more. Eventually, even though there is still water in the tank, the gunk in the pipe causes the pressure at the valve to be too low. Even with the valve open all the way, the water flow is insufficient to power the laptop, and it shuts down, even though there is still water in the tank. If you use the laptop heavily (like playing games), you need more water flow, and it will shut down at a higher percentage because the tank can't keep up even if it isn't empty. If the laptop is idle and the display is at a low brightness, you need less water flow, and it will more likely drain smoothly until the tank is really empty (0%). **Original explanation**: The laptop measures the charge in and out of the battery in order to estimate how much remains; simple. They can even compensate for how batteries have less usable charge if you discharge them faster (some is wasted). However, that is not quite all that goes into how batteries work. Batteries have a property called *internal resistance* that increases over time as they age. Internal resistance is public enemy #1 for batteries. The higher the internal resistance, the more heat is emitted by the battery when you use it, which means energy is wasted. But it gets worse: as internal resistance increases, the more current you use from the battery, the lower its voltage drops. And the lower the voltage drops, the more current you need to sustain a given power level. You might be able to see where this is going. As the battery runs out, its voltage drops. To compensate for this, the laptop needs to pull more current from the battery to keep running - it can't really decrease its power consumption, since that just depends on what you're doing with it, so it needs to do whatever it can to sustain the amount of power required. Now, if the battery is brand new, this isn't a problem: the internal resistance is low, and as the current increases, the voltage stays roughly the same. Cool. But now you try this on an older battery, and there's a problem. As the laptop pulls more current, the voltage drops. Then the laptop tries pulling more current to compensate, and the voltage drops more. It still can't get enough power, so it pulls more current. Now the voltage drops below the minimum level at which the laptop's power supply can run, and your laptop shuts down. Hard. No warning. If the power management system is smart, it might be able to catch that this situation is about to occur before it becomes unsustainable, and then jump straight to indicating 0% charge, and trigger a proper shutdown. Effectively, internal resistance sets a *limit* for how much power you can pull from a battery, and this limit varies depending on how charged the battery is. Your battery might have 20% charge remaining, but if it's old and you try to pull 40W from it and it can only sustain 30W at that point, then it might as well have 0% charge remaining. You can't use that extra charge. You can see this by running down your battery to, say, 10%, and comparing how long it lasts with the laptop totally idle and the screen at a low brightness (low power), vs. with the laptop running some benchmark or something that uses a ton of power. If the battery is old, chances are it will still last a while and trickle down to 0% in the first case, while it'll crash and drop to 0% (or die instantly) in the second case. You can see why this is also a user interface problem. Even if the battery controller knows all about internal resistance, what is it going to tell the user? \"If you use your laptop lightly, you have 10% charge remaining; if you try to max out the CPU, you have 0% charge remaining\"? There's no good way of indicating this problem to the user, because \"how much charge remains\" isn't a single number!",
"Weird how it feels like the opposite with most cell phones (that I've owned). I'll start using my phone at 5% just to kill it and be scrolling for a couple hours",
"The power supplied by a battery is non-linear. We do our best to linearize it to make it intuitive to use but it isn't easy especially not when you're using the cheapest sensors known to mankind for the measurements. Pretty impressive all of them don't just explode.",
"Voltage drop under load and allowable voltage tolerances of devices. ELI5: You’re drinking a juice box and super thirsty, but if you suck any air your head explodes. If the box is full you can drink as fast as you want. But if it gets down low you have to sip really slow or your head will explode. You’re going along just fine riding in a car but getting a little low on juice, but you’re oblivious because the scenery outside is awesome. You grab the juice box and drink like normal, forgetting you’re getting low, and your head explodes.",
"Not sure if this is the correct answer but I heard batteries take longer to charge the more juice they have. It's like stacking bricks, at a certain height.. it takes more time and energy to stack it there. So maybe the same goes for how the power is used and the last 10% deplete faster.",
"Knowing how much battery is surprisingly hard. The easiest way is by reading the voltage, but the voltage only varies when [almost empty and almost full]( URL_0 ). This means that between \\~10-90% the computer has no easy way of knowing how much power is left. To know how much battery is left between 10-90% a power counter is used, which literally counts how much power is consumed, since you already know how large the battery is and you know how much power has been used you know how much is left. The problem is that batteries degrade with time, and the counting always thinks the battery is perfect, so there is a point where the counting thinks its above 10% (so the voltage should stay stable) but the voltage starts falling, so you either see the battery dropping very fast, or the computer over-reports how much battery is left.",
"Probably bad algorithm to estimate battery life. Batteries tend to discharge in non-linear fashion, but it's easier to estimate battery life linearly.",
"This is a two pronged answer. (i added a bit in the second part in italic to make more sense & #x200B; > **Why does a laptop say it's at 6-8% charge, and then it dies** Most, if not all laptops, especially windows, have a setting in the power settings that will automatically shutdown the computer at a certain percentage. You could set the percentage to 1%, but that would be harmful to the battery over its life time. & #x200B; > **Why does a laptop ... going from 60% to 59% take a while,** *but going from 9% to 8% takes a shorter amount of time?* & #x200B; Batteries are similar to water pressure, like a lemonade jug. If you've ever filled up up a lemonade jug/water jug with a spigot, you'll know that it will fill a cup much faster when its full of liquid, and takes longer to fill a cup when it gets empty. Batteries have a similar effect; going from 100% to roughly 25%, you will get relatively the same amount of \"bang\" for your battery percent. But as the battery gets empty, it has less \"oomf\" to push the juice out, and in order to maintain the same amount of flow (power), it ends up using more relative battery percentage for the same tasks. that last sentence is a bit oversimplified and possibly slightly out of context, but its the best ELI5 i could do, assuming your 5 year old has worked a lemonade stand or two.",
"It seems there are a lot of detailed explanations. Here's the simplest I can think of it. A battery is like a tank of water, you can suction out the water at one end and for a brief moment (Longer in batteries) the water level is lower on that end, and must settle to get an accurate reading on the water level across the entire tank. In a battery, it's very similar but much slower, so realistically there's no real way to tell how much battery life is left. The reason it jumps so much is things that read the level are mostly guessing. However, it's in my personal theory, that for the energy in a battery to \"Settle,\" is near impossible, because batteries do slowly leak their charge. While we can get good estimates based on voltages, they can be easily thrown off or wrong.",
"Many battery indicators are not well calibrated. Battery monitoring circuits measure the voltage and the current coming from a battery, but do not directly see the amount of charge in the battery. Software programs estimate that from the voltage and the current measurements, but doing so is somewhat of a black art. Good software algorithms keep records of past performance of the battery to estimate the charge state more accurately, but when a battery can be changed, it may take some time to recalibrate the algorithms. Laptops (as with other devices) require a certain amount of power to operate, and when they sense the battery is nearly empty, attempt to shut down in an orderly way. Older batteries may take longer than new batteries to charge up, and may not hold as much charge. Battery charging circuits may push a lot of current into a battery that's nearly completely discharged, then reduce the current as the battery approaches maximum capacity. Devices may also measure the temperature of the battery to best charge the battery without damaging it by overheating. (Off topic observation: Tesla cars use battery power to warm the battery itself, as well as a cooling system to keep the batteries from getting too hot.)"
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dv3yee | Why many android devices with more CPU's, clock speed & much higher amount of RAM are still superseded by Apple chipsets with far less? | Technology | explainlikeimfive | {
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"text": [
"Well, first. Apple is a monster when it comes to SOCs and has been for years; the idea that Android features better CPUs isn't really accurate. URL_0 URL_1 specifically this, benchmarks aren't everything but they're a good baseline. Secondly, Android is doing a shit load more behind the scenes than iOS is. So that extra RAM is already seeing a lot of consumption before you actually start doing anything. Third, Apple is pretty much alone in device manufacturers in controlling both their software and hardware. They design the hardware and have it built to their specifications, and they design the software to get as much out of said hardware as possible. Samsung and Huawei ((iirc) both build their own SOCs and most of their own hardware, but don't get to control Android in the same way. Now. The performance differences aren't necessarily going to be anything particularly noticeable except in pretty extreme cases, like a Nokia 2.1 and an iPhone XS or something like that. Just an FYI."
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dv526l | SSDs /single/dual core/quad core | In this buying guide, there are multiple SSDs with single, dual and quadcore configurations? I cant find an appropriate explanation for it? [ URL_1 ]( URL_0 ) | Technology | explainlikeimfive | {
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"text": [
"You're connecting unrelated things. \"cores\" are an unrelated concept to SSDs. Cores are a technical spec of CPUs (you can google for info since your base question is off anyways). SSD's are storage devices and there is no concept of \"cores\" on these in any possible sense. I'm not even sure how you ever combined these items."
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dv6yun | How do wireless non-battery pens (for Wacom & Gaomon tablets) always work and never need to be charged? | Technology | explainlikeimfive | {
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"f7b0igv"
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"text": [
"All the good stuff happens on the tablet. The pen though does have reactive electronics thats powered thru the tip. The tablet emits a electric field and the receiver in the pen picks up that minute power and does simple logic and retransmission"
],
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dv96n0 | How does an old rotary phone work and how does it register the numbers you put in? | Technology | explainlikeimfive | {
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"Rotary phones don't use the tone based dialing that more modern phones use. They use what's called pulse dialing. Essentially an electrical pulse is sent down the line every time a number is \"passed\" on the rotary dial. So if you wanted to dial 9 for example you turn the dial to nine and let it go and it would click over 9 metal plates and thus send 9 pulses, telling the equipment on the other end that you are dialling a \"9\". The long pause between dialling denotes the end of one number and the start of the next. Tone based dialling works essentially by playing a sound that the other end can recognise and a particular sound represents a specific number. Old dialup modems (and fax machines) use a similar principle. Sounds are used to represent data in some way that can be reversed. Termed modulation and demodulation (hence mo dem)",
"The dial actuates a switch when it spins backwards to its original position. That switch essentially 'hangs up' the phone for a fraction of a second a certain number of times, and the phone exchange will count how many times that happens and recognizes that as a number. So instead of dialing a 5 on the phone, you can actually tap the hook that the handset is resting on five times very quickly, and that will be recognized as dialing a 5. Technically you don't even need the rotary dial at all. If you have a bit of practice, you can just tap the 'hang up' switch repeatedly to dial numbers. Tapping it 10 times is a 0, tapping it once is a 1 and so on."
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dvc59u | why do speakers from smartphones sound terrible while earbuds can sound good with much more bass? | Whenever I listen to music using my phone's speakers, the quality is terrible and has no bass at all however when I listen using earbuds the sound is much more clear and has a lot more bass. Why is this? Is it because earbuds work in a sealed environment? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"an earbud only has a tiny volume of air between itself and your eardrum. It has almost as direct a connection to your eardrum as it's possible to have, so it can move it easily, right down to low frequency rich full bass. A phone speaker is sending its sound (which are just air pressure waves) out into the air, and they have to reach your eardrum intact and still move it. Bass is relatively slow changes in pressure, low frequency and the problem with a speaker is the little ripple it's making in the air dissapates quite quickly, because a little speaker just can't get much air moving. Higher frequency waves are a lot easier for a smaller speaker to create, and get to travel through the air. That's why on a loudspeaker, the bass speakers are larger than the treble speakers. Phone speakers just haven't got the oomph to send out low frequency waves into the air and have them maintain power till they reach your ear. Earbuds don't need power to do that, because they're already right against your eardrum nearly, and only have to act on a relatively tiny amount of air."
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dvguu3 | What prevents computers to pretend to be other IP addresses? | Technology | explainlikeimfive | {
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"text": [
"It won't work. If I send a packet that says my IP address is 1.2.3.4, which I totally can do, then when the server computes my answer, it's going to send it back to 1.2.3.4. Since that not me, it's going to end up at some computer that's going to say \"I didn't want this!\". If I want the message's replies to get back to me, I have to fill in the \"from\" field with the right answer, because the protocol uses that value."
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dvkhzv | how do they make keyboards for languages like traditional chinese, which has over 3000 individual characters? ive seen mandarin typewriters, and theyre pretty cool, but how do laptop keyboards work? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Other than pinyin, which romanized the pronunciation of the character. There is also the wubi system which codifies the sequence of strokes of the writing of the character. To put it into English sense, the letters a-z are typically treated as atomic elements. You describe 'a' as just 'a'. Nothing less. The wubi system would break apart the writing of the 'a' into: ccw circle, then right-down sweep. 'b' would be: vertical stroke, cw circle. 'c' would be: ccw semicircle. 'd': ccw circle, vertical stroke. 'e': horiz, ccw semicircle Etc etc. Now you can see there's alot of common elements. ccw semicircle, verticals, horizontals. There going to be also left diagonals, right diagonals, hook left, hook right. Each of these can be a key on a keyboard and you can type out the sequence of how to write a letter. once you have each letter's strokes codified, you can then bucketize them by how many strokes it takes to write that letter. 1 stroke letters, 2 stroke letters, 3 stroke letters, 4 stoke letters. now you have a system",
"The keyboards are just like any other keyboard, perhaps with a few extra special keys. The magic is in software called an IME (input method editor), which takes characters typed in some kind of phonetic representation (e.g. pinyin in mainland China, bopomofo in Taiwan, romaji in Japan) and shows the user what words match that reading, letting them choose from a list. Therefore, writing these languages is a much more interactive process than writing romance languages, since you need to pay attention to the IME."
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dvl88i | With deepfake voices now sounding almost indistinguishable from human voices, why do computer voices (TTS, Google Maps, etc) still sound like garbage? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Because they're not deep-fake voices. They're deliberately kept out of the uncanny valley by remaining obviously computerized. That way, nobody gets weirded out by an almost human voice.",
"There are a couple of factors at play. First off, think of the sheer volume of things that these voices have to figure out how to say, on the fly. Travel through America and you'll run into all sorts of oddly named streets. Then take into account how much local dialect plays into street names. For example I've spend most of the year in Nashville for work, and drive by the \"Grand Ole Opry\" on a daily basis. Siri insists on pronouncing it \"Oo-Pree\". With that kind of variety, it's going to be more focused on being easily understood, than sounding human. Second, we don't want it to sound human. A truly human sounding voice would be off-putting. Meanwhile the fancy computer voice on Star Trek didn't sound human, it sounded like a computer. If Alexa talks to me like a human, then I don't feel special. Sound slightly like a computer, and I feel like I'm living in the future."
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dvmvxj | Why is broken glass not recyclable when in the recycling process, it is crushed into cullet? | I have just watched this video: [The smashing story of recycling Glass.]( URL_0 ) Normal bottles and jars are still crushed into cullets. I've read that broken glass is not recyclable. Some sites claim the strength of broken glass is reduced ([A confusing article]( URL_1 )). Many say it's dangerous for workers. Providing if we can get broken glass into recycling plants safely (without harming waste handlers), is broken glass still recyclable? Or because it was broken not accordingly to the recycling process, it would never be recyclable again? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Short answer, it is. Long answer, it is recyclable, just people don't want to touch it. Picking through recyclables(cardboard, glass, metal, cans, boxes, bathwater) is difficult and time consuming. The material it self is reformed through the manufacturing process, not the recycling process. All in all its a load of shit companies tell you to not break bottles. Its just harder to grab a little sliver of glass than a whole bottle.",
"Glass can be recycled pretty much as many times as you want to. Melt it down and reform it into whatever you want and it is just as strong the 20th time as it was the first time. I would say the big issue with broken glass is just the safety side of things for the handlers.",
"I understand the safety side for sorting, however, at the recycling depots here, you sort for them. They have these big bins for different things - one for jars, one for dishware, one for styrofoam, etc etc etc. When you put things into the bins, it’s IMPOSSIBLE not to break the jars, because you’re literally dropping glass onto glass. And yet it says no broken glass right on the outside of the bin. Like what? It can’t be broken until after it falls in? 🙄 I don’t get it."
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dvq28s | How are products registered into a stores "inventory"? | How do stores register all products that enter them? Like when a grocery store receives a pallet of a certain product, how do they register all of the products in the pallet into their system so that they aren't confused with similar products bought elsewhere? Say like if you have a soda with you into a store that you've bought somewhere else. | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Stores usually have a computer system that keeps track of how many items they have in their possession; when something is scanned at checkout, the scan subtracts one from the system. There is nothing on or in a soda that tells you whether or not it \"belongs\" to the store. If you bring a soda into the store, and the store carries that soda, the staff will either assume you already own the soda (perhaps because they saw you walk in with it) or ask you to pay for it, in which case you tell them you walked in with it.",
"Normally a portable scanner (or handheld) is used to scan in all the boxes (the info is prepoulated so scanning in one box of xyz adds x amount of xyz to inventory) or pallets coming in. The reverse happens when scanning them out for buyers. The store staff will not be able to receive foreign stock as the barcode will not be recognized by their system, but depending on authorization, may manually enter it after scanning"
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dvuhb6 | Why do speakers in a very cold car project a different quality of sound? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"You got it exactly right. The sound is created by deformations in the speaker cone. If it's extremely cold the material stiffens up."
],
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dvumqz | How come when your phone dies, you can constantly turn it on and itll show you a logo and then turn off again? Is there another aspect to battery that powers basic function? If so, how long can you go until your phone is completely dead? | I can explain further if needed. | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"If the battery is run completely dead, it can't be recharged. The phone manufacturer knows this, and programs the phone to shut off before it gets ruined. When you restart it without recharging it first, it takes a little time for the circuitry to detect this and shut off itself to protect the battery. You can do this over and over until you ruin the phone, but that's not a good idea."
],
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dvvisg | What exactly are my cable modem and router doing in the minute after being reset? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Booting. They both run some form of linux. And, frankly, neither will have many hampsters under the hood CPU wise for computing power (you don't need a massive CPU for essentially packet shovelling), so booting up - even a stripped down embedded version like these will have - an operating system takes some time. Then they have to launch whatever routing/modem control services, firewall services, DHCP and DNS services, and then the little webservers that provided your admin/control app. The OS kernel itself is probably booted up in under 20 seconds, the rest of the junk can take upwards of a minute.",
"Analogy time - imagine you are opening an sandwich shop for the day. You unlock the shop and switch on the lights. Are you now ready to flip the closed sign to open and start serving customers? Probably not. You may still need to switch on the cash register, maybe warm the oven, defrost some stuff on the fridge, mop the floor, prepare your display cabinet, etc. In router/modem terms (general computing devices), before the devices are ready to perform its job (such as to receive electrical signals from a wire and send them to the correct devices on your wireless network), it needs to do some setup first, such as loading the instructions of the wireless communication algorithm from disk to memory, or detecting which devices it can connect and route to, etc (“exact” steps are too complex and varies by product). All these takes time because it takes time to read and write data to a disk, perform calculations with the CPU and read/writing to its memory. Sometimes it takes times only because it is waiting for a response from the network, eg checking if you are a valid customer. It may execute very fast but the millions of instructions and steps add up to significant microseconds."
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dvwuxm | How does a speaker produce multiple sounds at the same time? Do they just play the average tones of all information given at a time? | Technology | explainlikeimfive | {
"a_id": [
"f7f7oj1",
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"text": [
"Take a look at [this picture]( URL_0 ). When playing a 100 Hz tone, the membrane of the speaker would move as indicated by the upper waveform, and when playing a 500 Hz tone, it would move as indicated by the waveform in the middle. Now if you want to play both tones at the same time, you would add both waveforms and the speaker membrane would move as indicated by the waveform at the bottom. It moves back and forth slowly to play the lower tone, and on top of that it moves back and forth quickly to play the higher tone.",
"Can I tack on to this and ask how a speaker produces different tone? Like I get how when I sing a Beyoncé song I don’t sound like her, how does a microphone pick up or better yet a speaker put out the differences?"
],
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"https://www.mq.edu.au/about/about-the-university/faculties-and-departments/faculty-of-human-sciences/departments-and-centres/department-of-linguistics/our-research/phonetics-and-phonology/speech/acoustics/speech-waveforms/assets/waveadd01.gif"
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dvyekt | Movies have conditioned some of us to think that cars, airplanes, jet engines, blowtorches - basically anything that runs on fuel, can explode. If so, why are 'explosions' quite rare (only occur in case of severe accidents). How are machines designed to be safe from exploding? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"> Movies have conditioned some of us to think that cars, (...) can explode The Mythbusters tested this by repeatedly shooting a gas tank with incendiary (iirc) rounds. They were able to light the contents on fire, but the rate of combustion was limited to how fast air could move through the bullet hole. No explosion. > How are machines designed to be safe from exploding? They use a fuel which requires an oxidizer to burn and don't carry an oxidizer, instead using atmospheric air for that. The exception is spaceships which do carry an oxidizer and do explode spectacularly if anything goes wrong. The biggest risk of explosion from cars is if their fuel is brought to it's boiling point, resulting in a steam explosion (of superheated flammable liquid), but this requires an external heat source."
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dvyxnm | How does a USB hub work? | How do they manage to combine 4 or 6 USB signals into one USB cable? | Technology | explainlikeimfive | {
"a_id": [
"f7fltb8"
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"text": [
"USB is a packet based communications bus. To send data between the devices the data is gathered into a suitable packet of data and then transmitted over the wires. When the packet have been sent the device will switch over to listening for incoming packets from the other device. As USB was designed with USB hubs in mind each packet have a device ID marker on it so that the hub is able to send it to the correct device. There is also a way for the hub to send a message back to the device when there is an incoming packet saying it is busy with another packet and that the data packet can not be forwarded at this time."
],
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dw03c4 | Bandwidth speed tests (ie speedtestdotnet)--how do they work? Does it measure total bandwidth including what's being used or only the free bandwidth? | Technology | explainlikeimfive | {
"a_id": [
"f7fttl5"
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"text": [
"They just download (and uploads files as fast as they can and measures how long it takes on a millisecond-by-millisecond basis, wait for the speeds to settle in, and report what they're seeing. Generally the bottleneck will be your modem but ISPs with problems may see overall slowness during busy times caused by problems within their infrastructure. If your internet is in use while running such a test, the results will likely be inaccurate and whoever else is using the internet while you run the test will whine and complain about \"the internet going down again\". :)"
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dw0xmr | When a phone is on speaker, why can't the person on the other line hear themselves? | Technology | explainlikeimfive | {
"a_id": [
"f7fzose"
],
"text": [
"There is a special circuit that takes the input from the local side and filters it out of the incoming audio to prevent feedback and echo from just such a thing. It is called \"Acoustic Echo Cancellation\" or AEC."
],
"score": [
18
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dw3211 | How does a digital projector work? | I understand that old style projectors would go frame by frame at a high speed with a magnifier and a bulb, but how does a digital projector work differently? | Technology | explainlikeimfive | {
"a_id": [
"f7gcv11"
],
"text": [
"There is a bulb, of sometimes 3 bulbs, and a modulator and 3 color filters. Some modulators are LCDs that absorb light to make a pixel darker. Other modulators are micromirrors that reflect away light to make a pixel darker."
],
"score": [
3
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dw33my | how do streaming music services know what music to recommend to me? If I like song “x”, how does it know I might also like “y”? | Technology | explainlikeimfive | {
"a_id": [
"f7gckgq",
"f7gg68e"
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"text": [
"They collect data on what everyone listens to. If the people who listen to X also listen to Y, they calculate X and Y go together.",
"My recommendations usually never make sense. Because you like “Thy Art is Murder” maybe you’ll like “Poppy”"
],
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dw3fj9 | What is the silicon lottery (jackpot) | Technology | explainlikeimfive | {
"a_id": [
"f7gfec0"
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"text": [
"Computer hardware is so extremely small and delicate that no one even tries to make it perfectly right. Every chip past a certain complexity is broken in one way or another, but that is fine and every design is made to have parts of the chip that can run too slow or too hot or be broken and still have that be okay. If your chip can't run at 3ghz, then you sell it as a chip that runs at 2ghz, if the math coprocessor in broken on half the chips you just sell it as a version without a coprocessor. A lot of products are actually the same product but \"binned\" into different categories by how well the thing actually came out. The magic about this is that it means every bit of equipment is of unknown quality. And some of them happen to be just, really really good. Like maybe the chip won't run at 3ghz, but it will run at 2.999ghz but is sold as a 2ghz chip for a much lower price, maybe it'll run at 3ghz but just not with the cooling the testing process uses, maybe it'll run at 4ghz but they don't sell a 4ghz chip with the other specs it has so you got yourself a chip that runs faster than anything officially on the market. etc. But it's a gamble, you might buy a 2ghz chip and find out yup, it's a 2ghz chip. You might try and unlock some cores on a graphics card and find out they are all actually broken for real, or find out they seem to work fine and it's not even clear why they disabled them. It's like a lottery."
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} | [
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|
dw5j2r | How are night sky pictures with nebulas and lots of stars taken? | Technology | explainlikeimfive | {
"a_id": [
"f7gr77d",
"f7gr6si"
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"text": [
"A dark clear sky, Tripod, Long exposure time up to a min, and photo editors like Adobe Photoshop. Use URL_0 to find the least amount of light pollution. Tripod to eliminate shake. Long exposure to allow enough light to come in. Photo editor to enhance your photos. That is exactly what I did in the Great Sand Dunes National Monument.",
"The first thing is \"light pollution\" most all of us live way to close to population centers with a lot of lights. This washes out what we can see in the sky. To get a photo like this, you have to get far away from artificial light. Then, just a good camera lens with a low aperture number that allows a lot of light to reach the film or sensor. There are parks in the US designated as \"dark skies parks\" that are far from artificial light and have light restrictions. Interestingly enough, I was just researching some of this earlier and learned Florida actually has one about 2 hours from me, so it's on my short list."
],
"score": [
5,
3
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"text_urls": [
[
"darksky.net"
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[]
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"url"
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|
dw7n53 | What kept us from creating the USB-C we have today 10/20 years ago? | Technology | explainlikeimfive | {
"a_id": [
"f7h16oc"
],
"text": [
"There have been lots of improvements in transfer rates in a number of areas. The issue with high data rates was that if you sent data too fast then the individual bits you sent down the line would interfere with each other and end up just a blur on the receiving end of the cable. Today we have a lot better knowledge of how this happens and what we can do to prevent it or interpret the blur so we get the data through. In addition we have found out what kind of cable works best and how to make it on the cheap. The issue was that USB did not use that cable or connector. So while other technologies like PCIe, SATA and HDMI were able to use the new technology as it came out USB was left behind. The USB 3.x standard was designed almost 10 years ago but it required new connectors, new cables and new controller chipsets. Thus it took some time to become common."
],
"score": [
5
],
"text_urls": [
[]
]
} | [
"url"
] | [
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|
dw8ytk | Color grading is an essential part of digital filmmaking nowadays, but how did people “color grade” film in the pre-digital era? | Technology | explainlikeimfive | {
"a_id": [
"f7h97c1"
],
"text": [
"They didnt. They just made sure the lights on set (as in, physical lights) and colors etc that actors wear matched well together. It was a lot of effort to ensure all the lights, colors etc matched the mood well. Fun film fact: Adams family (yes, the black and white original) was actually shot in very bright colorful colors - because they translated to black and white shades much better than actual black and white materials. Another fun film fact: During filming wizard of the OZ, there's a moment where Dorothy transitions from B & W Kansas into colored wonderland. There was no technology that would allow them to seamlessly switch between B & W footage and colored, so both the actress and entire set were actually black and white, except for the Wonderlands \"portal\" which was properly colored."
],
"score": [
8
],
"text_urls": [
[]
]
} | [
"url"
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"url"
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|
dw92ne | You know those times when you enter your password in a website, it tells you it's wrong and asks that you reset it, but tells you that you cannot use your old password as your new password? What's all the confusion? | I design computer software, but I do not have experience working with databases or online forms, so this confuses me a lot. | Technology | explainlikeimfive | {
"a_id": [
"f7h9osw"
],
"text": [
"The confusion is that you entered your current password incorrectly, but then either entered it correctly when changing a password, or used a password that was even older that gets rejected."
],
"score": [
13
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
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dwfysj | How come old Gameboys looked great in direct sunlight but modern screens are unusable in bright conditions? | Technology | explainlikeimfive | {
"a_id": [
"f7ivfgr",
"f7iw3bn"
],
"text": [
"Old gameboy did not use back lighting and they were designed for the light to be provided externally. Modern screens use backlighting and are designed for the light to come internally. As a result excessive external light will cause glare on newer devices. Back lighting is when the light source for the screen is provided from behind the screen.",
"The original Gameboy's screen had no backlight. It acted kind of like a piece of paper, requiring light to reflect off it to be able to see it. Images were made on the screen by blocking light reflecting from active pixels, similar to how when you draw on a piece of paper with a pencil, the pencil marks block light from being reflected. Modern screens have backlights. They don't reflect much light, instead light shines through the screen from behind. The pixels act as colour filters, only allowing light of a certain colour to shine through that part of the screen. If the environment is very bright it just overpowers the light coming from the screen so it's harder for your eyes to see it properly."
],
"score": [
46,
7
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
dwgtlo | Why doesn’t NATO or the UN control/deploy a Global Positioning System | Technology | explainlikeimfive | {
"a_id": [
"f7j3kyl"
],
"text": [
"NATO has no real need for a separate system, as there's not too many plausible scenarios in which they don't have access to the US system. The UN isn't something that can really do something like that. When the UN has things like peacekeeping forces, they're really just forces \"on loan\" from one or more nations, a \"UN GPS System\" would be the same thing, just putting a coat of \"UN\" paint on a US or Russian or whatever satellite system, which doesn't gain you much."
],
"score": [
5
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
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|
dwhn8w | why do some games tie physics to framerate? why does going over 60fps cause some games to bug out? | Technology | explainlikeimfive | {
"a_id": [
"f7jdene"
],
"text": [
"So the core of games tends to be an infinite loop that checks for changes to the game-state; so every \"frame\" you get is typically one loop of the game loop, and in each loop it does things like detecting collision and updating the position of things based on new inputs, existing velocity, etc. Depending on exactly how it's coded, if the game was coded and tested on nothing but 60fps max, because that was the usage they had envisioned, then certain values may get weird and unexpected results, if the developers make the assumption that, say, every loop will be 1/60 of a second, and calculate velocity of objects based on how far they have moved between frames. In an extreme example, when I was much younger my family upgraded the family computer from an old IBM 386 to a Pentium 166mhz chip, and some of my games ran so fast they were literally unplayable. There was this old Terminator game that was made to run on even older PCs, and it would install and run, but the game timer would run so fast that as soon as I exited the starting menu screen the Terminator would find me and kill me before I could react, and that's because one of the game's assumptions was that the processor could only go so fast. In a more famous example: Space Invaders originally wasn't supposed to speed up as you killed enemies, but the hardware couldn't run the code fast enough to make it run at the speed you see in the last couple enemies or so; however they found that it made the difficulty curve scale really well as a happy accident, so the feature has been added to ports ever since."
],
"score": [
4
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
dwm1s9 | How do scientists shoot the neutron, I know how they colldct them, but how do they shoot them? Is it electromagnetic or something? | Technology | explainlikeimfive | {
"a_id": [
"f7k9boe",
"f7k8tv6",
"f7k6d2u",
"f7k9i5f"
],
"text": [
"Neutrons are largely unaffected by electromagnetic forces, and cannot be accelerated directly like protons or electrons. There are two main ways to \"shoot\" neutrons. You can take a radioactive element that decays by emitting a neutron, and put it in an enclosed container with a long, narrow tube. The container will absorb most of the neutrons, but a few will shoot on in the desired direction long the tube. The other way is to accelerate protons with neutrons attached to them and smack them together in a way that knocks neutrons loose.",
"You don't accelerate the neutron by itself. You accelerate a deuterium ion, which has 1 proton and 1 neutron. You smash that ion into a tritium atom, 1 proton, 2 neutrons. This produces an helium atom of 2 protons and 2 neutrons and 1 accelerated neutron.",
"They really don't accelerate neutrons from what I gather. It has to be a charged particle like a proton or electron. And there they use EM fields, radio frequency cavaties and magnets to accelerate and control them. Neutrons can be accelerated to an extent but not nearly to the speeds of the LHC for example.",
"Neutrons themselves are not electrically charged, so can't be directly controlled magnetically or electrically. However, if they are attached to stuff that is charged, protons and electrons, then the whole atom can be accelerated. If you take Hydrogen-2 (hydrogen with 2 neutrons), and strip it's electron off (making it positively charged), you can easily use the magnetic force to accelerate it. If you then smash it into Hydrogen-3 (hydrogen with 3 neutrons), they will collide, producing helium, and 1 free neutron. This extra neutron can then fly off creating the neutron beam."
],
"score": [
8,
4,
3,
3
],
"text_urls": [
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
dwmcta | why would laptops and phones interact differently with a speaker? | My roommate brought home a Bose bluetooth speaker for the living room. Both of our laptops need to be up close to the speaker or else the music (via YouTube and Spotify) skips. And yet, both of our phones can stream just fine from across the room. Why would this be? | Technology | explainlikeimfive | {
"a_id": [
"f7ka8l4"
],
"text": [
"It'd just be the strengths of the devices' Bluetooth adapters. The laptops were likely designed with the intention of only using Bluetooth for mice, headphones, etc. that would all be used in relatively close proximity, whereas phones are more likely to be used further away"
],
"score": [
13
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
dwojzj | In Stranger Things S3, how did Dustin and Suzie manage to sing a song over CB when if one is transmitting, that it cannot hear the other? | Technology | explainlikeimfive | {
"a_id": [
"f7khwn0"
],
"text": [
"Plot magic. I've heard that that kind of tech was possible in the '80s, but it's extremely unlikely they would have had access to it. The writers/directer must have thought it was just too cool to not include."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
dwqm52 | the difference between a front vs top load washer | I've read a few tech reviews that seem biased and paid, so I want facts the differences between the two. I am gathering that all front load washers are HE; is this a by-product of design or an intentional design? It mentions that they clean more; how so, and is this inferred or actually proven that they clean better? | Technology | explainlikeimfive | {
"a_id": [
"f7ks0um",
"f7kt4lc",
"f7ksos7",
"f7m4brz",
"f7kta31",
"f7ma6iz"
],
"text": [
"Front load washers are by design HE; they don’t need to fill the whole drum with water to soak your clothes and the clothes actually move inside, as opposed to “oscillating” in place while the water around them gets agitated.",
"Front load allows the clothes to tumble with less water. And the tumbling action in a top load requires more water and back and forth of the drum. And many top loads have a center agitator - to better facilitate the tumbling needed. But this center agitator can also cause more stress on clothing and cause them to wear out more quickly. (And some top loads have no center agitator b/c their goal is to \"mimic\" the front loading system better.) I have used both and find the efficiency of the front load spectacular. But when I have occasionally wanted more water or more agitation for dirtier loads the front load had few options for that. I could sometimes trick the machine by wetting items before they went in so they were heavier and tricked the sensors into thinking it was a heavier load. This way it would add more water. With the top load the major downside seems to be that the weight of individual items impacts the agitation. All the items kind of need to be similar in size and weight. If there is something heavy it may end up on the bottom and lighter items don't move as much. Having to pay so much attention to what goes in can be a little annoying. I may have a load full of cotton t-shirts. But the heavier/thicker cotton seems to weigh down thinner jersey. I know when I have had a more \"traditional\" top load - the kind that fills with water - this is still a problem, but I've never pulled something out and felt like it got missed completely. My super low-water top load sometimes gives me that impression.",
"Front load is able to clean with less water. The clothes only need to be soaked, not completely submerged. Front loaders suffer problems of mold growth and seal failures which top loaders don't have as much just by design. Top loaders don't need big door seals, gravity keeps the water inside. Top loaders also have advantage of being able to add clothes mid cycle.",
"TIL that top loading washing machine means different things in different parts of the world. In my country and I assume in most of Europe toploaders work on the same principle as frontloaders. The toploaders just have door in the side of the drum to allow access from the top, but the drum still rotates in a vertical position. The only time I've seen a US style top loader was in a hotel in South Korea.",
"Efficiency is determined by how much water the washer uses. All the mechanical work that's being done doesn't take much power. Heating the water is where the vast majority of the energy goes. Top loaders need more water because all the clothes need to be more or less submerged. When the drum of a front loader rotates slowly, it lifts the clothes out of water and them drops them again, but the ones that used to be at the top are now at the bottom and vice versa. That means even though the water level inside the drum isn't high enough to submerge everything, everything will still come into contact with the water. As a result they need to heat up a lot less water overall, and that's why they use less electricity.",
"The UK mostly uses front loaders and I believe the same goes for most of Europe. The washing action is actually a softer approach to the old manual process whereby the clothes are bashed against each other, the agitators and the drum by the tumbling action. As such suds are a reduced necessity as they are only used to capture whatever grease does not get broken down by the enzymes etc. However, a thing to consider is that in North America where top loaders prevail some clothing may not be able to stand up to the front loaders washing action. So you might want to use gentler wash cycles for T-Shirts and the like. I base this on some Nike T-Shirts I received from the US which whilst extremely soft and light (100% cotton) started to show small holes post washing whereas no others do. Spin speed may have a difference as well, mine has 1800 but I rarely set it that high as drum perforation has a greater effect on water extraction than spin speed does. If you buy a washer with a highly perforated drum it is able to extract more water at lower spin speeds and so drying time is decreased meaning more efficiency."
],
"score": [
29,
5,
4,
3,
3,
3
],
"text_urls": [
[],
[],
[],
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} | [
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"url"
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dwra3m | what is electromagnetically induced transparency? | Technology | explainlikeimfive | {
"a_id": [
"f7kvmqg"
],
"text": [
"Things are transparent because they let the light go through themselves. They let light go through themselves because of how the molecules are arranged in the material. Some materials change the arrangement of their molecules if their electromagnetic charge changes. So they can be transparent or opaque depending on whether they are electromagnetically charged. So we induce transparency via electromagnetism. Electromagnetically induced transparency."
],
"score": [
4
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
dwtcwk | How is there so much carbon in the air? | Technology | explainlikeimfive | {
"a_id": [
"f7lcik4"
],
"text": [
"Carbon is put into the air through a whole variety of processes. We pay a lot of attention to carbon produced through combustion - e.g. the CO2 from cars, power plants and industry. These increase the levels of Co2 in the atmosphere significantly, but it's not the only source - it's perfectly natural for CO2 to be in the atmosphere from forestfires, the natural decomposition of carbon from dead plants and animals, the exhalation of oxygen dependent lifeforms like us. The release of these and then recapture of it by plants and other life is referred to as the \"carbon cycle\". Humans have greatly increased the rate at which carbon is released into the atmosphere and slowed the degree to which it is recaptured resulting in an increase in the CO2 levels in the atmosphere."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
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