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lm2l0q | Technologicsl development in previous civilizations | Hey, I was wondering how previous civilizations have been praised to be super intelligent (ex; Greeks) but never managed to come to bigger technological advancments? Was something holding them back, what was it? How come some of the large advancements only happened during the Industrial Revolution? I know they were really far for their time, of course they made some advancements and nowadays we probably aren't at our biggest potential but we will advance much faster than back then. In summary, what held previous civilizations back from making bigger and faster technological advancements? | Technology | explainlikeimfive | {
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"> what held previous civilizations back from making bigger and faster technological advancements? Simply put, time, resources, and previous knowledge. The way I think of it is, we are only where we are, because of them. We still use \"ancient\" practices and devices today. If we had to start where they started, I doubt we would be any more \"advanced\". We joined the snow ball while it was already rolling. So we may have progressed quicker in a shorter period of time, but we had 60-70 more lifetimes of knowledge to assist with that.",
"The speed of technological development is heavily correlated with the ability to share ideas. Three main inventions, and this is not an exhaustive list, that helped accelerate technological development: 1. Patents. Instead of innovative technologies being trade secrets that died with the proprietor they could be published, the inventor got a payout, and everyone else got access to the benefits of the idea and could then look at it and find new ways to improve it. 2. Printing Press. Prior to the printing press if you wanted to make copies of your research or ideas you needed to pay people to transcribe it by hand. Every single copy. So someone researching in London could only know of what another researcher in Paris had found if the Parisian researcher had had a copy of their work transcribed and then sent to London, or if the researcher from London traveled to Paris. This obviously is not a particularly efficient way to get a new idea out there and save everyone from trying to invent it multiple times. Being able to mass produce copies of manuscripts changed this dramatically. 3. Telecommunications. This is an extension of the printing press - today a researcher is able to readily find out about whatever is going on in their field and communicate with other researchers with phenomenal ease, this greatly helps innovation - the more people who are aware of an idea or invention the more people there are who might have an idea on how to improve it or apply it to a previously unconsidered application.",
"I think when we talk about an ancient civilization being “advanced” we are comparing it to other cultures around the time of that civilization. A quick google search tells me that the ancient Greeks developed geared mechanisms, bronze casting, and steam power. While these seem outdated to us, you have to keep in mind that no one had done those things before them. Geared mechanisms are ubiquitous today, but being the first to come up with, develop, and implement a new technology is really hard. Especially when put in the context of what tools and techniques were available at the time. I’d highly recommend checking out the channel Clickspring on YouTube. For the last few years he’s been slowly trying to recreate a working replica of the Antikythera Mechanism, (one of the earliest known geared calendars) and is trying to learn about how they could have made such a precise mechanism by only using handmade tools and materials that would have been available at the time. Edit: typos mostly"
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lm4z2k | - Why does different software drain my mobile phone battery vastly differently, even if doing the same thing? | Looking at the battery drain statistics on my phone. Since the start of this week, I have apparently spent 3 hours watching Disney Plus, and 4½ hours watching YouTube. I never changed my screen brightness and all of this was done through wired headphones at the same volume. But YouTube has apparently used up 25% of the battery, while Disney Plus has used 54%. Why is the drain so vastly different, despite the two apps both performing the same basic function (video streaming)? | Technology | explainlikeimfive | {
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"Different video codecs and qualities require more CPU power to process. In addition, Disney is going to be sending a stream that is protected by HDCP (basically encryption that goes all the way through to the monitor, preventing software from just copying it). This requires extra CPU power beyond just the quality/codec changes.",
"Different frameworks, design patterns , use of GUI and phone sensors and resources will greatly affect your power drain. Som apps are built with HTML and some apps are build in phones native code that could be a huge difference",
"Different video qualities or codecs requiring more/less resources to decode, different amounts of time just having the app open or a video paused versus actively playing, more or less efficient processes, the potential for additional processing from tasks like submitting information on viewing habits, bugs causing unnecessarily high CPU/GPU load... etc etc etc."
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lm6478 | Water resistant electronics | How do things like iPhones and new technologies that have charging ports and other parts out in the open able to resist water damage? I dropped my phone in a puddle a few weeks ago and all I did was shake the water off and there was absolutely no damage. | Technology | explainlikeimfive | {
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"The charging port has no open holes into the phone for moisture to get in, just contact surfaces. The main culprit for water damage is the speakers which let water in and small cracks where multiple surfaces were put together on the phone. It’s fine for water to touch these contacts because they only accept power, not output power and therefore cannot short circuit.",
"I phones, and other water resistant electronics have essentially a water tight seal around all those sensitive components. Charging ports, speakers, and headphones all have a seal that prevents water from seeping in. Do you know how you have a water bottle with a little rubber seal around the screw on cap? These phones have them too - just around the ports. No air gets in, no water gets out. Except under heavy pressure. You may notice that water resistant devices usually have a rating like \"IP67\". This describes how well protected it is against dust and water getting in. URL_0"
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lm965u | Airplanes and helicopters. How do they stay in the sky? | Technology | explainlikeimfive | {
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"By generating lift with their wings or rotors. Just like a ceiling fan pushes air down, a helicopter pushes the wind the same way. Except with far greater force, enough to counteract gravity. An airplane uses thrust (either from its props or a jet engine) to push itself forward, and has wings that create lift. Pushing air down below them and creating a low pressure zone above them.",
"It's the same principle at work in both cases. An airplane's wing is an airfoil, which is shaped and angled in such away that when air moves across it creates a lifting force (the actual physics behind this effect are actually quite complicated, and there are a lot of misconceptions about it). If the lifting force is more than the weight of the airplane, it flies. The key is that air must move across the airfoil to generate lift. That's why planes must be moving quite quickly to take off, and why they can't hover in the air. In a helicopter, the \"wings\" are the blades, and are moved independently of the body of the vehicle. They can move straight up and down in the sky as long as the blades are spinning, and they move laterally by tilting the rotor disk."
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lmaidn | Why are CD and DVD players not mutually compatible to play each other's audio? | Why can we not put a DVD into a CD player and listen to the film's soundtrack? Or put a CD into a DVD player and listen to it as if it's a film soundtrack with no video? | Technology | explainlikeimfive | {
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"There's two problems, one is physical and one is \"format\". DVD is a much higher density format than CD. A CD can hold about 630MB, a DVD holds about 4GB (about 7 times more). This means the pits (the physical features that encode the \"1\" and \"0\" of the digital data) are a lot closer together on a DVD than a CD. A CD player doesn't have the ability to read the DVD. The reverse is not a true, a DVD player generally can read a CD. The format issue is how the data is stored; an audio CD is just the sound files. A DVD is combined video/audio. As a result, a CD player expects to see only audio. Even if it could physically read the DVD (which it can't), the data it reads isn't what it expects to see. Again, the reverse isn't true, a DVD player generally can read a CD because most DVD players are also setup to \"understand\" CD. Edit:typo",
"CDs and DVDs may appear visually similar to the naked eye however there are hardware and software differences between the formats meaning both the way the data is stored on the disc and the way the data itself is formatted result in incompatability. CDs have a lower data density allowing them to be read with an infrared laser and the audio data is stored as raw uncompressed stereo PCM. DVDs are read with a shorter wavelength red laser, bascially allowing for a sharper focus and therefore higher data density (Blu-Ray discs take this a step further with an even shorter wavelength laser allowing for HD video). Additionally the audio data on a DVD is usually encoded as compressed multichannel audio using the DTS and/or Dolby Digital codecs (similar to MP3), some rare DVDs such as concert videos may use PCM but at a different technical specification. The result of all this is that even if CD players had the necessary red laser optics to physically read DVDs they also lack the appropriate decoding circuitry and firmware to decode the audio data on DVDs. Nearly all DVD players and drives also have an infrared laser and the necessary firmware to read CDs."
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lmdr53 | Why are pipes bursting in Texas but not so much in colder climates? | Technology | explainlikeimfive | {
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"Texas doesn't bury its underground pipes as deep, because digging deeper is expensive, they also don't insulate the piping that needs to be above ground properly because again, expensive. Usually they get away with doing it like that because warm southern climate, but once or twice a decade it bights them in their big Texas Ass",
"I'd assume because Texas doesn't get cold weather, like, at all, so their pipes aren't made for cold climate like in Canada. I'm probably way wrong"
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lmhaif | Should I use the phone while charging? | Is it better to use the phone while charging than using the battery to 20%, charging to 100% and using again? | Technology | explainlikeimfive | {
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"It depends on what you're doing. Purely conceptually, using the phone while it's charging shouldn't affect the battery life. It'll just make it take a little longer to charge since it's draining a little while being charged. Practically speaking, however, using the phone while it's charging can make your phone heat up. Heat is one of the factors that causes battery degradation. So if your phone gets noticeably warm if you use it while it's charging (or it might just get warm while charging, period), best to leave it alone to avoid shortening the battery lifespan."
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lmmht3 | why can’t someone on house arrest cover their ankle monitor in foil then leave | No don’t worry I’m not a criminal / on house arrest I’m just curious because I’ve heard aluminium foil can block micro waves and radio waves . If that’s the case then why can’t wrapping an ankle monitor in foil allow them to trick it ? | Technology | explainlikeimfive | {
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"\"Yeah if you drop off the radar\" they will go to your last know coordinates and start looking. Now you're evading police, tampering with government property, and breaking lawful orders, plus all your other charges that got you out on house arrest now puts you in prison. Bail revoked... I mean really it's up to you if you wanna have a moment of \"freedom\"",
"Monitor is not the actual monitor. It's a transmitter sending message to actual monitor that is located somewhere in or near the house. If the actual monitor doesn't receive it's signal periodically, it will think that the ankle transmitter have left the premise and will alert the authority. If you cover your ankle with foil (that wouldn't actually work you would have to put faraday cage around it), police will be alerted even if you don't leave because the actual monitor will think you did.",
"You are thinking it works on proximity to a receiver, it doesn't, not anymore. It is a GPS on your ankle, the address you are doing your house arrest under is put into a system, that system sets up a fence around the address. Your new jewelry pings the system randomly to see if you are still inside that invisible fence and if you venture outside of the fence it will ping as well. It equally is checking to make sure you are inside the fence as much as it's checking to see if you are outside of it.",
"If the foil indeed blocks the signal from transmitting than that means u will be shown as offline in the system, nd they must have a system that alerts them when someone goes offline abruptly. One will be caught in either case.",
"You're thinking about the key backwards. That's a little bit like saying, if I'm trying to hack into someone's email account, instead of typing in the wrong password, why can't I just hit enter without typing a password and get access? Your notion is that the monitor sits there silently until it's in the wrong spot, and then sends out a distress call. That isn't how they work. They send out constant signals that the person is in the right place. If you covered it with foil, even if you then stayed home, it would stop getting the signals that it's in the right spot, and alert the authorities."
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lmniw2 | Does anyone *own* the internet? i.e. did the people who invented it get royalties? | Technology | explainlikeimfive | {
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"The original technology on which the Internet was based was a product of the US Government/military, and US Government works are not eligible for copyright protection. The part of the Internet that many people commonly think of as \\*being\\* the Internet is the World Wide Web. This was developed in 1989 by Tim Berners-Lee, and he purposefully made the tech freely available - he is quoted as saying \"This is for everyone\". The reasoning behind this is that the Web could only achieve its potential if as many people as possible could use it.",
"No one owns the internet, but there are corporations that steward it and those corporations do get paid for stewarding. As others have said, the underlying technology was developed by the US government for military purposes. When that tech was released to the commercial sector, it was royalty-free. Some of the more modern tech is owned by people and the choice to use that tech does incur royalties, but the underlying technology is still free to use. Now, to actually _get on_ the internet, you require a few things - like an IP address. IP addresses are controlled by a company called IANA - they issue blocks of IPs to Tier 1 ISPs to be dolled out to businesses and customers. These ISPs pay a fee to IANA for the blocks they rent so that IANA can maintain the core infrastructure that keeps the internet functioning. Similarly, to register a domain name (like URL_0 ) you have to lease it from a registrar, and registrars get the rights to lease domain names from ICANN (who also charges a fee for the lease). This again is to fund the core infrastructure that allows the domain name system (DNS) to function."
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lmnjh2 | How do film companies increase the quality of a movie 50+ years after filming? | I see commercials and posts all the time about movies being remastered into a high definition. I’ve always been curious how they can increase that with such old film. | Technology | explainlikeimfive | {
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"Physical film has a very high resolution - from around 4K to 8k+ depending on the size of the film used when shooting the movie. They need it to as they’re looking for a clear image when projecting onto a 40 foot wide screen! But for a long time the distribution media for home consumption didn’t have the storage capacity and playback media didn’t have the resolution - so the quality was downgraded for home use for more economical distribution without really impacting what people could see on their TVs. When they remaster these films they go back and use the original footage and transfer it to current media at the full resolution.",
"They don't. Actual movie film is *very* high quality, much higher than 4k. If the original film still exists and is in good condition they can just rescan it into a 4k digital format. Where you hit problems is with movies where the original film is missing or damaged, or movies that were originally filmed on a digital format."
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lmxkhv | How do phones vibrate? | Technology | explainlikeimfive | {
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"text": [
"The same way everything vibrates - they put a motor in it, that spins an intentionally unbalanced weight. [ Like this]( URL_0 )"
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ln14q1 | What is a fusions reactor and why can't we make one? | How would a fusion reactor work in theory? I hear every few years that fusion energy is in the near future. Though it always seems to be only in the near future. What are the issues stopping us from creating fusion energy? What can we not figure out yet? | Technology | explainlikeimfive | {
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"A fusion reactor fuses atomic nuclei together. The 2 nuclei join to create a new element and a lot of energy is released. The energy given off by this fusion reaction can heat up water into steam which can turn a generator and produce power. Think of the sun. Extreme pressures and heat from the gravitational force fuses hydrogen together to make helium. We can and have made 1 but the energy put in to fuse the particles is still higher than the energy we get out since we need to create extremely high temperatures and pressures for the fusion reaction to happen. Once we get to the point where the energy released from the reaction is much greater than we put in AND we can sustain these reactions for a long period of time, then you will see a lot of fusion power plants popping up around the globe",
"Simply, it’s the idea of shoving two atoms together so hard that they join together, or fuse, releasing huge amounts of heat energy in the process. The problem is that this requires more force than the gravity at the core of Jupiter. It requires forces like the internal pressure of the sun, which is exactly what a star is. A star is a mass of gas with so much gravity that hydrogen atoms fuse to form helium. Recreating those forces on Earth requires huge amounts of energy. So far, it has required more energy to produce the forces than we get back from the fusion reaction. This is the problem we need to solve."
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ln4bhq | Why are keyboards not alphabetical? | Technology | explainlikeimfive | {
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"Original typewriters used an Alphabetical ordering system, but due to the way the arms of the typewriter swung to the paper to print each letter, they would often get tangled as typists got faster. QWERTY was used since the letters were separated in such a way that it was much rarer for several keystrokes to come from the same region, so there would be no damage to the arms Certain letters appear more in language than other ones, and different keyboard layouts are designed to make typing as fast as possible using 2 hands. QWERTY is the most common layout though not the most efficient for top end typing, its just so widely used and known that most keyboards are made with that layout. In the past I converted one of my keyboards to a DVORAK layout as it is supposed to be faster, and its fairly easy to do in Windows, but a lifetime of typing in QWERTY made DVORAK super slow and I didnt have the patience to keep practicing it.",
"Keyboards are set up so that the keys you use the most often are easier to type from the \"home\" position. Keys that are used less often are farther away."
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ln4qyn | How do we have photos from the perseverance rover already? | What’s the transmission medium / technology and how does this transmit photos over that vast distance? Thanks! | Technology | explainlikeimfive | {
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"It only takes about 20 minutes to radio from Mars to Earth. The rover was taking photos during its descent and when its on the ground. About 20 minutes later, we get pictures, via radio transmission. Nothing more to it than that. Its fairly \"simple\" in that regard.",
"I believe there is two orbiting satellites around mars, the rover sends the data to them then they send the data back to earth."
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ln57kd | How was the Texas Grid seconds to minutes to complete failure for possibly months? | Technology | explainlikeimfive | {
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"I don’t know how the Texas generating stations are built but we nearly lost the grid in the Pacific Northwest in the winter of 1983 IIRC. We used to joke that if we tripped the (coal fired) units they would freeze solid into giant icebergs before we could get them restarted. It would be spring before they thawed.",
"Brown outs are actually worse than black outs. Brown outs destroy equipment because they don't have enough power to function correctly. And Texas hasn't been in a situation of complete failure for months, not sure where you heard that. When the storm hit, and the demand went way up for power, and there wasn't enough production, that's when the complete failure was minutes away. That's why they had to shut down grids. It won't take months to recover either. Once they get the power production back online they will start recovering. There will be some time to get all the power lines repaired that have fallen due to trees and such. But the grid will be repaired once power production comes back up."
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ln9ae0 | What is it that makes low budget movies look “raw” while high budget look all more put together? | Every time I start a lower budget movie, I can instantly sense it in the sounds and video that everything just seems more “raw” like it was filmed on an iPhone or something. How come big budget movies don’t generally seem like this, a ton of post processing? Why can’t low budget folks do this? | Technology | explainlikeimfive | {
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"Some of the big differences that are really hard to hide are good quality lighting and sound, a 'cinema' quality camera, and post-production processes that smooth the sound and picture quality (grading and mixing). New tech is closing the gap between low and mid-range budgets as long as you have the know-how. That said, low budget productions are also inclined to lean into the lofi aesthetic, especially if they're making a genre film.",
"There are a number of reasons, some of which have already been covered by u/Blahdyblahblahisme. While the technology is certainly available to lower budget productions, the experienced personal in the field are out of the price range. If you could get award winning camera operators, editors, sound mixers, and colour technicians to work for minimum wage, you could get a professional looking production at a budget price. In fact, one of the professional digital editing packages (Davinci Resolve) is available for free. But the experience and knowledge to get the most out of it, is going to cost."
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lnapmr | Why are RISC processor architectures more energy efficient than CISC | There's starting to be a transition in the laptop space to the RISC Arm architecture from the CISC x86, and new architectures like RISC-V are projected to be even more energy efficient once it matures, but why is this? Wouldn't having more dedicated instructions be more efficient since you don't have to sequentially feed multiple instructions to the processor, and the processor can just handle all the complex multi-step processing in the background? | Technology | explainlikeimfive | {
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"The main problem with CISC is that it's dropping optimization potential. With RISC you basically give the responsibility to build a complex command to the layer above (the compiler), wich can then tailor it to the current needs, skipping parts of it that are currently not needed. CISC isn't \"few big instructions\", it's \"one instruction is actually a whole chain of simple instructions\". So the \"feeding multiple instructions\" part isn't improved with CISC."
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lnbcjr | why does youtube load videos faster than other streaming platforms? | Technology | explainlikeimfive | {
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"UNLIMITED POWER!!! Or something like it. First we need to understand what their service is. You chose a video, send a request for watching that video. The server then send you the first X seconds of the videos. After Y seconds of watching (Y being shorter than X), you ask the server to send you the next X seconds of videos. Y need to be shorter so that you can receive the next X seconds BEFORE you finished the X second you received previously. If everything goes correctly, The video shouldn't stutter nor stop and you should only load the necessary number of seconds and not more. Now, why does all this matter? And why is Youtube faster? It's a matter of server load. Answering a request takes time. It takes time to receive it, to process it and finally to send it back. Which lead to a quite funny conundrum. The less seconds you send each time (so the smaller X is) the more often you'll need to send things (AE, the more often you'll need to receive and process a request). The more seconds you send each time, the less often you'll need to send things, but you'll need to send more which takes more time. The question become is it better to send a lot of small bundle or a little bit of large bundle? Well user retention teach us that lot of small bundle is probably better. Because everytime you leave a video, all those unwatched seconds left (be it the credit, or just you losing interest) are wasted server load. The bigger the bundle, the more you waste. But there is a catch: The more often you request something, the more the server has to receive and treat requests. Which mean you need server that can quickly answer. They need to be fast, powerful and close by. Youtube belong to google. Nobody can match them in that regard. They have servers all over the world. They can receive and treat request faster than anyone else. The issue isn't that much sending the videos(even if it matters, it's not as much of an issue for big companies) but rather that Youtube can optimize as much as possible whereas other do not have the capacity to do so. So most other send bigger bundles and waste a lot things. This mean their server are overloaded with wastes, but if they don't do that, there is a risk that the video won't be loaded on time for the user, leading to stutter and poor user experience. Basically, Youtube is big enough that it can optimize everything. That optimization mean that they get better performance for a lower cost. Others can't achieve that kind of optimization.",
"Youtube has google’s cdn (content distribution network) which is probably superior to most streaming websites which may have only 1 or a few hosting servers. you’ll notice that other major platforms like Amazon prime video and Netflix will usually load just as fast, because they have similar advantages. More basically: Google has more servers that are closer to you than the other streaming services you use."
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lniixk | What do the links that you get through those fraud texts, actually do to your phone if clicked? | Technology | explainlikeimfive | {
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"At the very least they tell the spammer that you click links in emails and texts and that they should continue to send you more as well as try to sell your details to someone else as a “live” target. At worst they can exploit your device, spy on you, steal your data and money, and much more.",
"Used to work in digital forensics. A lot. Clicking a link can send the other side your IP, location, personal information, internet service provider, web history, contact list.... A lot. Dont click links."
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lntmub | Dear homebrew developers why the original Xbox was able to emulate N64 games flawlessly and a twice faster CPU on a Raspberry Pi 3B/3B+/4 (and far more RAM) still can't? | Technology | explainlikeimfive | {
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"It's not just CPU & ram, it's the graphics card and software infrastructure. A video card is basically a second CPU, but specifically designed to do graphical calculations. They are especially important for doing full 3d graphics, which become amazingly slow without them. The Xbox has one while the rasberry pi doesn't. Software infrastructure referrers to all the code and resources required to do the stuff that you want the system to do. Historically, consoles provided almost no infrastructure to the developers. Their code almost directly access the hardware. Most rasberry pis are running a full linux distribution, both allowing it to more easily do more things, but consumes a relatively high amount of resources.",
"Point of order, N64 emulation on XBOX was kinda crap IIRC. Secondly while the clock speed on the Pi maybe be faster by a good bit, it runs on an ARM64 processor which is designed for power efficiency and cost savings over raw compute power. The XBOX is based on an x86 processor which can effectively do more per clock cycle, at the cost of using note transistors and therefore more power. Another problem is that ARM64 is a relatively new architecture. N64 emulation was more popular back in the OG XBOX days, and there was more effort put into optimization for that architecture. ARM64 coming up only fairly recently hasn't had the same amount of optimization/development put into it. Specifically dynarec comes to mind or dynamic recompiling which translates n64 specific code into x86 or ARM64 specific code. It's entirely possible that whatever emulator you used just didn't come with this as a feature by default. (Though it's probably doable with some configuration, seems like someone did manage to write something about 3 years ago.)",
"Mainly because the CPU clockspeed isn't the only factor to consider. E.g A bus and a motorbike can both travel at 100kmh but at the end of the journey the bus will have transported 50 times more people and their luggage. It's the same with CPU's. Different designs (essentially known as architecures) can do more than others. They all perform various calculations on data (essentially known as instructions) but some can have more complex instructions to choose from and so can do more 'work' in less time. That's basically the difference between the Xbox CPU and the Raspberry Pi. It's the CISC (complex instruction set computer) architecture versus the RISC (reduced instruction set computer) architecture. The Xbox uses a Pentium III (CISC) and the Raspberry Pi 3b uses a Cortex A53 (RISC). If you want to get a bit more technical we can take the example of multiplying two numbers. One number is stored in memory location A, the other is stored in memory location B, we want to multiply A by B and store the result back in memory location A again. With the CISC architecture of the Pentium III we just have to tell the CPU to do something like : multiply a, b That's one complex instruction that takes one clock cycle to complete. The Xbox CPU runs at 733MHz so it can do 733 million of those multiplications in one second. (That's not exactly correct but it's ok to think of it that way for the sake of the example). With the RISC architecture of the Cortex A53 we have to tell the CPU to do something like : load a load b product a, b store a That's 4 simple instructions that take 4 clock cycles to complete. If the Raspberry Pi 3b CPU runs at roughly double the clockspeed of the Xbox CPU it would still take twice as long do that multiplication task. (Again that's not exactly correct but think of it that way for the sake of the example). It gets even more technical when you take other aspects of the different CPU architectures into consideration. You can get into things like how many instructions can each architecture execute at the same time (known as parallelism). That's not as simple as how many cores are available, it's to do with how each core schedules and arranges the instructions it's working on at any given moment. It does that because instructions and memory accesses take time to complete, and the CPU can be doing other work while it's waiting for those things to complete. The Pentium III has a superior design in that department compared to the Cortex A53 which further increases the amount of work it can do in each clock cycle. Or you can talk about the size and performance of the cache memory (very fast memory inside the CPU that stores the most recently used data and instructions). That is used to avoid having to load and store the same data from the relatively slow main memory (the RAM). That also allows work to be done more quickly and the Pentium III is better than the Cortex A53 in that regard too. So ... as you can imagine all that extra complexity in a Pentium III makes it more capable, and it also makes it larger and more expensive to manufacture. But that's basically why an Xbox CPU is better than a Raspberry Pi CPU even though it's clockspeed is half as fast, and also why a Raspberry Pi CPU is so much cheaper."
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lnw5nu | Why is it that a new television costs about 1000 dollars, it has android, a chipset, wifi etc, while a phone wich is much smaller, but has also a chipset etc, also costs 1000 dollars ? | Technology | explainlikeimfive | {
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"Smaller, more intrinsic technology to fit in to the space. The quality of the housing, the function. Tiny technology is more expensive to produce than something 20 times its size.",
"For smartphones you are paying for all of the miniaturized tech in a very compact package. Every component of the device is usually cutting edge or groundbreaking in some way, whether it be double the megapixels on the camera over the last generation, a faster SoC that is able to dissipate heat better, a longer battery life, greater pixel density on the screen, wireless charging, the latest wireless radio technology, etc. For televisions you are basically paying for the screen per inch. Some more expensive televisions have some features like localized dimming, better color accuracy, low latency mode for gaming, etc. Sometimes you see new technology like vibrating the screen to produce audio, but mainly it's the screen size that you're paying for. The smart device features that come in your television are usually really low-powered budget android (or other OS) chips from years ago.",
"The short answer: because it's smaller. A slightly more complex answer is because the phone has more components, like front and rear cameras, video and audio encoders, cellular broadcast/receiving hardware, a battery that can power the device for a couple of days, protective glass, touch screen, and more. All that has to be packed into something that fits in your pocket. TVs have a plastic chassis, no space or power limitations. Then there are market reasons. There is less competition in the phone market. There are a gazillion people making TVs.",
"There are several things: * Smaller components are more expensive and it takes a lot more development and engineering to fit them all into a small space * Phones have more components (multiple cameras, bigger storage and RAM, battery, face/touch ID, ...) * $1k phone has the latest high-end components (processor, wifi module, ...), TVs usually use older versions which are way cheaper * Software development (TVs usually have very simple software) * Phones have to be more robust (waterproof, able to withstand a fall, ...)"
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lnx95a | Pixar movie 3D modeling elements | Technology | explainlikeimfive | {
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"Yes they animate it and model it all. In combination with some high tech animation tech. (Like algorithms that animate the hair moving). There’s a reason big hero 6 cost 150 million dollars to make, millions of dollars is spent on computing tech and paying a team of two dozen animators to work on it for months on end. Yes, there’s tech to help make it easier, a lot of it is proprietary and a trade secret, like we know there’s an algorithm to animate hair, but we don’t know exactly what that algorithm is because Pixar keeps it secret. But there’s also a team of people working on it 8 hours a day for several months.",
"The models from previous films are saved and reused, often with some tweaking. Many of the models created for the original Toy Story have been used in multiple Pixar films after being rescaled or retextured. Every film that requires new assets adds to the library of objects. One of the best examples of reuse is the ravine from Bugs Life being reused as the extraterrestrial canyon that Buzz Lightyear flies through in Toy Story 2. The floating rocks were initially a glitch when the ravine was rescaled but the rocks didn't move down to the new level of the ravine's floor. The CG artists were showing the initial rescale to the director and apologetically said they would fix the rocks. The director liked the look and jokingly said he would fire them if they fixed it. Thus, the floating rock space canyon came to be."
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lnyvdw | How do audio feedback loops work? | When using an external speaker and another separate microphone you often get audio feedback loops. From my understanding it's because the microphone picks up the audio from the speaker. Seems simple enough. What I don't understand is how they never occur when the speaker and microphone are connected (like using the built in mic and speaker of a laptop). At first I thought that it was just due to the mic stopping whenever the speaker played, but after some testing I found that the microphone was still able to pick up the audio. Is there some software like noise canceling where it makes "anti noise" to get rid of the feedback loop? Or is it something simple that I'm missing? | Technology | explainlikeimfive | {
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"> What I don't understand is how they never occur when the speaker and microphone are connected (like using the built in mic and speaker of a laptop). The laptop \"knows\" what sounds the speaker is playing. So it \"knows\" what the feedback sounds like (roughly). Therefore it can subtract the feedback from the microphone input. > Is there some software like noise canceling where it makes \"anti noise\" to get rid of the feedback loop? Often yes. It's called acoustic echo cancellation. > Or is it something simple that I'm missing? The concept is simple, but the implementation isn't. I don't know the algorithms, but I'm pretty sure there's no ELY5 for them."
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lnzw1w | Why do phones take so long to charge enough to turn on after dying? | I don’t know if this is exclusively an iPhone thing or not, but every smart phone I’ve had takes a ridiculous amount of time to charge to the point of powering up after it dies. Anyone know why? | Technology | explainlikeimfive | {
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"Rechargeable batteries do not like being completely discharged. If the battery is discharged enough that the phone has to power itself off, the phone is designed to charge up to a certain percent above \"dead\" before it allows itself to be powered back on. That way, if the phone is unplugged, it does not have to shut down right away. Also, forcing the phone to stay off allows it to charge up to the \"power on\" threshold more quickly, since all the power from the charger can go to the battery, and not be split with running the phone as well.",
"Well for one, lithium batteries can't charge as fast when they are super low. It's just a quirk of the battery chemistry. Below 10% and above 90% (ish) they need to charge slower. The other part is that your phone will wait till you get at least a couple percent so that it doesn't just die halfway through, or immediately after booting up. Even when it's plugged in to an adapter if the adapter is, say, just plugged into an old 100mA USB port it's entirety possible that your phone is using more power than the charger can supply and is still draining battery. Most phones will also save a bit of reserve below 0% where it has enough power to safety show you a quick low battery image before blinking off several times. Then below that it will just not respond to the power button press, but this can make people think the phone is bricked when they might just have a bad charger."
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lo187b | What does people mean when they say that a computer system runs on different architecture from another computer? Like when somebody says that an emulator can run N64 games faster theoretically but because of different architecture in practicality it cant? | Technology | explainlikeimfive | {
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"Processors each have their own language. In technical terms it's what's called an \"Instruction Set Architecture\". It defines the words that that a computer uses to do things. For instance one computer might have use \"ADD 2 2\" to compute 2+2. While another computer might use \"SUM 2 2\". When someone writes a piece of software like a video game, it gets compiled for a specific instruction set architecture based on the platform it's going to be used on. When a program is compiled, it gets turned from the programming language (C/C++ for instance) into the language of the processor. You might hear this called \"machine language\". So code that's been compiled for one processor type can't run in a different processor because the machines use different languages. Another way to think of it is you want to tell someone hello. You could chose to say it in either Russian or English. If you say it in Russian, the English speakers won't understand it, but if you say it in English, the Russian speakers won't understand it. Your choice of language is like compiling the software.",
"I'll expand on the language metaphor that others have used. An \"architecture\" determines how the hardware works at a very basic level. It's the language that the computer thinks in. When you emulate another kind of computer, there's basically one level of indirection going on. The emulator is creating a digital version of a different computer, for example a nintendo 64, that has to have all the different hardware of that computer in digital form. The languages that the two computers think in might not have a 1-1 mapping for words though. If I translate english to spanish, I can't just go word by word. I have to consider the different grammar and adjust accordingly. That translation process takes time. Similarly, the digital hardware being emulated has to actually be running on the physical hardware of your actual computer. So the instructions are essentially being interpreted twice. First, they are interpreted by the emulated computer, and then translated to your computers language after.",
"To really get down to five year old level: the actual hardware, the computer chips inside the game consoles, is different. It's designed different, it uses different codes, and it behaves different. Some of those \"cpu architecture\" terminologies are ARM, x86, x64, PowerPC, MIPS, RISC, and more. Less five-year-old stuff: The same programmed source code may sometimes be capable of working on multiple architectures, but once it's compiled for a certain one it's quite hard to decompile or recompile it for another without having access to the source code (which is usually something companies keep closely guarded.) Also it often takes a lot of work to write code that runs well without bugs on different architectures: for example x86 is a \"32 bit\" architecture which means that 4,294,967,295 (about four billion) is the largest number that that architecture can easily handle without lots of ugly workarounds. (If you tell a 32-bit computer to do 4294967295+1 it'll say the answer is 0, and if you tell it to do 0-1 it'll say the answer is 4294967295... unless you have negative numbers turned on but I won't go into that right now.) A 64-bit architecture like x64 however can handle numbers as big as 18,446,744,073,709,551,615 (18 quintillion or 18 million billions) so a lot more math and detail can be handled. In other words, architecture matters and newer architectures help games look good and be fast. One other big reason 64 bit architecture is increasingly popular is because programmers like to store dates and times as the number of seconds before or since January 1, 1970 GMT. (It can be negative to easily talk about dates before then too.) But as of this writing, it's been 1,613,808,415 seconds since 1970. Since it can also be negative, that cuts our available numbers in half, to 2,147,483,647. So we only have 533,675,232 seconds left until we run out, which is just under seventeen years from now. This is called the \"year 2038 problem,\" much like Y2K, so we've got until then to upgrade or patch every single digital device that cares about what year it is. Fortunately with 64 bits, we can count up seconds for the next 292 billion years, so we shouldn't have to worry about that anymore.",
"It's like building a car out of Duplo blocks or Lego blocks. They are both cars made from similar blocks but are entirely incompatible.",
"Hmmm. Architecture is basically how that computer runs at the most basic level. All a computer is, is a bunch of really high tech light switches, on and off. Where it gets complicated is to figure out how they should be flipped and how to convert that into lets say a document, or a picture, or even a fully functioning video game. So to do that we have to give the computer instructions. We would call that a program or a programming language. The catch is, it's really freaking hard to actually tell the computer which switches to flip exactly when. What we do instead is tell it on a more human understandable level what we'd like it to do (do some addition here, print a message here.) When we write those instructions for the actual game, the computer then converts it into what is called machine language, which is basically telling it what switches to flip when. Now here's the catch. In the same way that every car and vacuum cleaner brand are different, so is every model of computer. And in the case of computers, it REALLY effects what order the switches will be flipped in. In some cases, it can be a big enough difference that you can't get old programs to run on new computers. Now this is really a bigger problem with older programs running on newer things, because they were written for older computers which ran on older computer parts that used different machine language. So when we update them for new computers, even though the human readable part of the code works, when it gets translated to the machine code, the newer computer is essentially speaking a completely different language and can't understand the program. So to get it to work we have to make significant and difficult changes to either the program that emulates the software or the software (game) itself. Most people, unless they are the original company who owned the game, don't have access to the human readable code, because companies only sell the games in machine readable form to protect their product from pirates and other reasons. So when you're emulating an old game and it's not working because of the system architecture, it can be a really difficult problem to solve, because you don't always know exactly what part of the program is causing the issue",
"Consider different architectures as different creatures. One (let say it is A-creature) with strong 6 legs and strong 2 arms, specialized to live in forests and climb trees, another one (B-creature) with 2 legs and 8 arms, specialized to live in flatlands. Consider a game is a dance. If a dance invented in B-creatures tribe and is performed heels over head, A-creature may perform this dance, but it will be slower and a bit clumsy, than if this dance will be performed by a B-creature.",
"If you are emulating a cpu that has similar cpu instruction set and functionality as a modern computer then at worst you just map the game instruction to a modern cpu instruction. Some of the late 90s consoles had weird chips and weird ways of communicating between them. Just means you have times where too much happens at once to do all the processes necessary to simulate the state of the chips faithfully. Jon burton that lead sonic the hedgehog game development at one point has some awesome videos explaining some of the weird hardware they had to support in the 90s. URL_0",
"When you were a kid you probably played with some \"construction\" toys, such as Lego, K'nex or Meccano. The idea of the toys is that you have some basic parts that you can combine to build something, like a small vehicle. You can make whatever you like, so long as you can build it with the parts you have and some kind of blueprint to follow. Now, let's say you have a blueprint for a Lego model helicopter, but you and your friends only have K'nex. The Lego blueprint is mostly worthless, but you *could* design something that looks very similar and has the same functioning spinning blade. In order to do this, you need to know how lego works and probably be pretty good with K'nex too, there's no simple way to convert the blueprint. The result might be pretty good, but sometimes, some parts just won't be the same because it's physically not possible. You also need to design and print the new blueprints and instructions for your friends, which takes a lot of time. This would be called \"porting\" the blueprint, it's tedious and you need to do it once per blueprint you want to play with. Hopefully, at the end of the day, you can throw the old Lego blueprint away and everyone can use the new K'nex blueprint to this helicopter without needing the Lego. However, when I said there was no simple way, I lied. What you could also do instead is to figure out how to *build Lego bricks out of K'nex*. Think about it, if you came up with a K'nex blueprint for all of the basic Lego bricks, then you'd be able to build *any* Lego blueprint without needing to port it. Genius! You just need to build the bricks you need from K'nex and then fit them together according to the Lego blueprint directly. However, there's a huge drawback, you need a *lot* more K'nex than you needed lego and therefore it takes a *lot* longer to build. The same would also be true if you were to try the process in reverse: converting K'nex blueprints to Lego by building K'nex pieces out of Lego bricks. This is an unavoidable problem with the method: emulating one \"architecture\" in another by simulating the smallest parts is a very easy way to accurately cover all blueprints, but it is also very inefficient. You may be able to take shortcuts that let you use a lot fewer pieces, sacrificing the ability to accurately build some models, but it's still not anywhere near as fast. For the sake of this analogy though, you need to assume that kids are now thousands of times faster at building stuff than they were before but that the process of porting blueprints manually is *very* difficult. Glossary: * Kids with their K'nex/Lego: gamers with computers. * Blueprints: games. * Building a blueprint: running a game. * K'nex/Lego: architecture. * Blueprints for Lego blocks in K'nex: emulator.",
"Also extremely simply put, N64 for example was speaking japanese, your current intel PC is speaking american english, AMD is speaking british english, most android phone chips are speaking scottish, apple chips are speaking a specific dialect of irish, etc. To run a program that was built for the N64 on an intel PC, you need something (emulator) to interpret from japanese to american english on the fly. It is not very efficient, but it can be done. Same if you make a phone app that you want to run on a PC. You need something to emulate a phone environment for the app to be able to run. There are also other factors. For example the N64 was like an old japanese man, speaking slowly, and the games were based on that speed. New PCs are speaking like super fast on crack english, and they can translate japanese to english very fast, but the game isn't built to be read and show that fast, so it basically slows things down on the emulator in order to time things as they were on the N64. And with that, it also slows down the translation. You can in theory translate the game and then show it on the time it needs to, but it makes emulators much harder and difficult to make, so they are rarely being made like that.",
"There are two levels of architecture: The Set of instructions that a processor can understand, and the micro-architecture (the implementation of those instructions, how the circuit is wired) The set of instructions, for a 32 bit processor, would be a list of binary numbers with 32 digits. Using the RISC-V as an example: The first 7 bits select the format of operation, and depending of the format, the other bits will select an operation (e.g. add, subtract, jump, branch, shift, etc), the memory address where are stored the operands, and where the result should be stored, etc. (That's what is machine code) The micro-architecture is how everything is wired so that if you send that if you input the instructions of a certain architecture, the output will be correct (think of it like a calculator. If you type in any calculator \"2 + 2 = \", the output will be 4, but how the calculator is wired changes between calculators. So, when people say that a computer runs on a different architecture, it generally means the machine code that a processor A understands is different from processor B. But in the case of the N64 emulation the rabbit hole goes furher. The issue isn't with the instruction set (actually, the MIPS is quite light to emulate), but with the separate chip that deals with graphics and audio (RSP). Some games had a microcode that changed the configuration of that chip, to optimize the graphic rendering (and those are the games that people have more headache to emulate). Also, for a long time, the development of n64 emulation was really messy.",
"A lot of good responses on what people mean by architecture on a general level. But a more specific level, why N64 emulation is so hard is down to simple hardware. The N64 had a special GPU, the \"[Reality Coprocessor]( URL_0 )\" which was like a dual core processor for graphics. No one makes a dual core GPU, it's not necessary for anything other than the N64 specific architecture. It being basically a two core meant that it could do 2 tasks at once and send the results of both at the same time for the console to display it in game, whereas a single core GPU like in a Retropie or your PC can only do one task at a time, sure it can do each task 10 times faster, but it still can not spit out the two tasks simultaneously, which means there's a delay in the result. That's why emulated N64 games come out all choppy.",
"Think of it like this... The engine drives your car, but each manufacturer has their own engine design. So you can take a Dodge Viper engine and put it in a PT Cruiser because they're the same manufacturer: URL_0 While it's technically possible to put a Ford engine in a Chevrolet, it's a lot harder and requires re-routing and re-engineering. So computer code designed to run on a particular kind of chip may require extensive re-working to work on a different class of chip. This is why PS4 games can run on the PS5, they have chips of a similar class, but PS3 games cannot, the Cell processor is too different from the later machines."
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lo5t0q | Is PGP still perfect encryption? And is it still used? | I just finished reading Simon Singh's The Code Book, and I got the impression that PGP was basically uncrackable, and more or less always will be. However, the book was written 20 years ago, so, is this still true? | Technology | explainlikeimfive | {
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"I don't think there are any known serious attacks on PGP it self, but PGP is more \"a practical way of using asymmetric encryption\". It has to use some form of asymmetric encryption (e.g. RSA) to share secret keys - and the security of PGP can therefor never be stronger than the encryption used here. Usually when someone says \"perfect security\" it means that even with infinite computing power, you could never decrypt the message. Which is not the case for something like RSA - but we still believe it to be infeasible to break in practice for now.",
"The encryption itself is solid. But PGP is so hard to use correctly that almost nobody uses it nowadays (at least not for e-mail), and if they do, there's a good chance that they're making mistakes that mean they're not really as protected as they think they are. Nowadays, people tend to use e.g. Signal, which is secure *and* easy to use (and easy to use *correctly*). PGP (or rather the open source version, GPG) is still used in some places, especially for signatures, but the original use case (e-mail) ist almost dead.",
"When we design crypto systems like PGP and SSL we do so assuming that computers will get faster and vulnerabilities will get found. So we make them modular so that we can upgrade the modules one by one and still retain backwards compatibility. So the PGP version used 20 years ago is no longer considered uncrackable, although it does hold up very well. However the modern versions are using encryption algorithms that were not even invented back then and typically use key sizes that were unheard of back then. They still use the same principles and message formats but that is where the comparison ends.",
"PGP was never perfect encryption, it was never meant to be. PGP even stands for \"Pretty Good Privacy\" and is wayyyy better than unencrypted emails but nothing except a properly used One Time Pad is \"uncrackable\" PGP relies on the same stuff as HTTPS/SSL by using public/private key pairs. These key pairs are longggg so they're hard to crack, hard enough to ensure no casual script kiddy can do it. Modern systems are using 2048 bit or 4096 bit long keys which would take years even with the NSA or similar working on it, but 1024 bit and below keys are definitely crackable by any nation state, and 512 bit keys could be done on AWS in an afternoon which is why we use extra long keys now"
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lo9h1s | Why do download bars show 100% for more than 0 seconds? | Technology | explainlikeimfive | {
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"Progress bars are never an exact science. There's no way to accurately calculate exactly how long something will take. Say you want to copy 100 files from one folder to another. You could go okay 100 files and each folder is 1% but obviously not all files are the same size. You could calculate the totally data size to transfer but disk read and write rates fluctuate sightly and there's also overhead to create a new file. There's always things like flushing file write caches etc. Basically it's just not an exact science",
"Could be a few reasons depending on the program. Maybe rounding up from 99.5%. Maybe after it’s downloaded it takes a bit to shut down or switch from download to installation mode. Maybe it does the entire installation during the 100%.",
"In addition to what others have mentioned about general inaccuracy in progress meters, once the file has been 100% received, your system kicks off a few processes to check if the file is safe. First, it will compute a signature (hash) of the file and send it to one or more public servers run by Google, Microsoft, etc. which check to see if the hash is a common one (a frequently downloaded file is more likely to be safe), or if it matches any known malware downloads. On desktop operating systems, your anti-virus software will also activate to analyze the file to look for any suspicious markers that could indicate malware. During these processes, the download is progress is locked at \"100% downloaded (but still not finished)\" so you can't accidentally run any malware before it has passed all the tests.",
"Usually the percentage is calculated based on the trending history, so if it pauses towards the end it could just be that the DL slowed down. Also at the very end it can pause because your virus scanner is checking the now complete file before the program signals that it's completed. If you have a slow disk, it can also be flushing part of the file from memory to the hard drive.",
"Once it's downloaded the app needs to do something with it and nobody thought it was worth the bother to add a \"_Doing something with what just downloaded_\" alert."
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lod0ws | What do phone manufacturers mean when they talk about pixel binning and why do some some phones that uses just 16mp better than phone cameras that uses 108mp? | Technology | explainlikeimfive | {
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"text": [
"Megapixel is measuring only resolution, more is better, but after 8 or so MP, it really makes no more difference, it’s useful because you can zoom and crop in more, but it won’t look any better Lens, sensor quality, sensor size, software used for processing the image have much better impact, in fact a 2 MP DSLR could look way better than a 100 MP phone because the phone can’t have the lens or size for as good a picture",
"The camera in your phone has a sensor that has tons of tiny little sensing elements on it. When light of the right color hits the sensing element(blue light to blue sensor) then it charges up a bit and gets read out when the \"shutter\" is closed (aka the time is up) A 108 MP camera in a phone is going to have a sensor that's roughly the same dimensions as the 16 MP one, you can't easily fit one that's 2.5x longer in each direction, so that means that each of the sensing elements is smaller. This is good because it gives you more pixels per mm^2, but bad because smaller sensors are more sensitive to noise like temperature variations, this isn't a huge problem in bright sunny conditions but becomes a big problem for low light operations when you don't have as many pixels hitting the sensors so having heat count as 1 hit could be a significant change if it only got 100 total hits. Low light photos with high density sensors are often not good because the noise overwhelms the actual image. Pixel binning takes the tiny sensor elements are pools them together to deal with the noise and simulate a lower MP sensor with bigger elements on it. Say you take 2x2 pixel squares, now you've got a 27 MP sensor, and since you're combining the results of those pixels the noise tends to cancel out (noise is a mix of ups and downs) so you can end up with a reasonably high pixel count image and a lower noise image when you need it, and an ultra high resolution image on bright sunny days when you don't need to bin"
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lofc8f | - Photo Image Fingerprint Effect | Why does [this effect]( URL_0 ) happen, especially when a photo is taken directly off a screen? In this case, when I save the same image file as a screenshot and by clicking into the file, the file quality changes significantly. I’d expect the screenshot to be the one with worse quality that is not the case. | Technology | explainlikeimfive | {
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"go5kjdm",
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"text": [
"This is called a moire pattern. It comes from the screen using tiny boxes to draw the photo and from the camera sensor also using tiny boxes. They don’t line up and create a weird effect. Funfact, this predates computers as you’ll sometimes see it if you photocopy a newspaper photo",
"[Moire pattern]( URL_1 ). It gets asked very regularly, but I guess not everybody knows the name. [Here's a previous discussion]( URL_0 )"
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"https://www.reddit.com/r/explainlikeimfive/comments/gkxuzn/eli5_why_does_taking_a_photo_of_a_screen_cause/",
"https://en.wikipedia.org/wiki/Moir%C3%A9_pattern"
]
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lou3yp | How do modern websites display real time database results as you are typing? | Technology | explainlikeimfive | {
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"text": [
"The webpage listens to every key you type in the search box and send a request each time. You can see it for yourself - go to Google, press F12 or Ctrl+Shift+I to open developer tools and open the Network tab. You'll see that with every key you type, a new request is sent. > Doesn't this cause a big strain on their system? Sure, far more than without it. But they have big servers farms with lots of servers that can handle this volume of data. > Is this a new technology? Not that new. Google introduced it in 2010. It existed in offline applications long before that.",
"Based on the type of database, the search (called \"query\") can be pretty fast. So I would assume that those websites are just updating the query everytime there is a change in the search box. You should be able to notice that by the fact that the results does not update in real time when you type really fast.",
"The other answers aren't wrong, but there's another layer to it: caching. When someone types something in the search box, the website looks through it's database and returns the results. *And* it saves the results. Now when someone else comes and types the same thing, the website doesn't have to go through the database. It just grabs the results from before. But eventually the saved results are too old and out of date or no one types the exact same thing for awhile. So the saved results are thrown out. This temporary saving is called caching, and basically every website uses it to prevent overloading the servers."
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louh92 | How does the QR code manages to not be the same with other QR code that has already been generated? | I was reading online and saw an option when I right clicked an image to create a QR Code. I know QR Codes are unique but how do they manage to avoid having the same pattern with the other QR Codes? Does it have a database where all QR codes are stored? I tried searching through this but can't find any similar queries aside from QR codes are unique. | Technology | explainlikeimfive | {
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"text": [
"If you generate two QR codes for the same piece of text or link, you'll get two identical QR codes. They're not randomised or generated out of thin air and then matched with a site or link or something. Rather the QR code itself encodes the information onto it. So as long as whatever you're encoding is unique, the QR code is unique to it. The wikipedia page (section 'encoding') actually shows you how it functions.",
"> I was reading online and saw an option when I right clicked an image to create a QR Code. I know QR Codes are unique but how do they manage to avoid having the same pattern with the other QR Codes? Does it have a database where all QR codes are stored? I tried searching through this but can't find any similar queries aside from QR codes are unique. A QR code is only unique in the sense that the word \"house\" is unique. It's simply a different writing system - there is no database.",
"QR code is just a way to encode text as a series of black and white dots. The QR code isn't for the image itself, it's for the image's URL.",
"a QR code isn't just a random image that then gets associated with a link or some text. It's like a secret code. There's a key that translates a letter to a specific pattern of pixels in a specific location in the square. When you scan the code, you use the key in the reverse to translate it back into text. A barcode is basically a simpler version of a QR code. For each digit 0-9, there's a specific pattern of black and white stripes. Smash a bunch of them together and you get a barcode that can be translated into a number."
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louhuj | What is NFTs and DeFi? | Technology | explainlikeimfive | {
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"text": [
"DeFi means decentralized finance, which means that there isn't one entity controlling the finance operation. The centralized model is that there is a bank or something similar and when you want to do something with money, like exchange it to another currency, you need to go to the bank and they exchange it for you. The idea of DeFi is to cut out the bank. Instead you have a secure way to either exchange the money with someone else directly or with a blockchain. This is different inthat way, that the blockchain can't influence the exchange outside of the known rules, because it is basically just a simple program. Your account can't get frozen, you can't get rejected, you are anonymous and all of that while still being secure.",
"Fungible means something is interchangeable. Bitcoin for example, in the crypto world. 1 Bitcoin = 1 Bitcoin, it doesn't matter \"which\" bitcoin you own out of the millions in circulation it is identical in property and value to any other Bitcoin. Non-fungible is simply the opposite. Each token is unique and it can't be replaced by another token. DeFi means Decentralised Finance. Its a general term used to describe financial systems which don't require something like a traditional bank and instead run on a smart contract blockchain. Ethereum is the biggest example."
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loxj0n | What is the difference between virtualization and grid computing | Technology | explainlikeimfive | {
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"text": [
"That's kind of a strange question since they don't really have anything to do with each other. Virtualization is basically simulating a computer on another. Grid computing is using a bunch of computers to compute something big."
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loycuz | Why do we need really big and small speakers to properly reproduce 20hz-20khz at high volumes, but headphones can do it just fine? | Technology | explainlikeimfive | {
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"The larger the speaker, the harder it is to yank it back and forth 20 thousand times each second. But it can move more air than a small one, too.",
"Two points. 1) just fine isn't enough for some people ( audiophiles). 2) to make speakers louder, they need more power, the more power you need, the better quality components you need, which are generally heavier. Trying to move a 5 lbs speaker cone 20000 times a second just won't work. So they divide the work between multiple speaker elements.low frequency to the big cones, and high frequency to the smaller tweeters",
"Headphones aren’t high volume. Speakers generally have a hard time vibrating slowly for lows and quickly for highs at the same time, so by separating them you make both speakers sound better than the original.",
"It's all about the size of the space you want to fill with sound. If you want to fill a small space, say the inside of a headphone muff, then it takes a small amount of sound. Want to fill the tiny space between an earbud and the eardrum, even a super tiny speaker can do the job. Alas, many rooms are much larger, large enough to walk around in. That takes much, much more sound energy. You could do this with many, many tiny speakers. It would be good because tiny speakers can move very quickly and reproduce a broad spectrum of sound efficiently. Alas, an array of 1M earbud speakers would cost far too much money. Instead large rooms use fewer speakers and sophisticated audio equipment that measures the room's acoustic properties and applies large amounts of power to a few larger speakers to make the right sound profile. When it comes to higher frequencies, smaller speakers can be more efficient, so the overall speakers mechanism can be made be made a little smaller by a mix of large speakers for low frequencies, medium sized speakers for middle frequencies and small speakers for high frequencies.",
"Bigger speakers are louder but are harder to move fast enough to produce high frequencies, which is why bookshelf speakers tend to separate out the frequencies using different sizes of speakers. In headphones the speaker diaphragm doesn't need to move all that much since they are pretty quiet relatively speaking. This means that the smaller diaphragm can be used to produce more frequencies since it doesn't move all that much anyways"
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lp1k8i | What happens once curiosity or Perseverance die out? | Like do they just stay in Mars? Do they self destruct? What about voyager 1 or 2 | Technology | explainlikeimfive | {
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"text": [
"> Like do they just stay in Mars? They don’t really have any other options do they? When they stop working they aren’t going to suddenly decide to teleport to Earth or something. Their behavior will become the same as other inanimate objects. > Do they self destruct? There was no reason to include a system to turn a rover into small pieces of rover spread all over the place, and several good reasons not to. A self-destruct doesn’t make something just vanish. > What about voyager 1 or 2 They too will do what inanimate objects do, namely nothing. The Voyager probes will keep on going until they hit something.",
"They get left there. We generally continue to listen for them in case they turn back on somehow. We might go looking for them once we get humans on Mars."
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lp1zxl | Why does touching certain electronics cause a hum in bluetooth headphones? | Technology | explainlikeimfive | {
"a_id": [
"go95x45"
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"text": [
"A deep low pitch hum sounds like a ground loop. That’s when two components are supposed to share a common ground, but due to some problem, there is an electrical potential difference between the two grounds. (Sorry, but electrical theory really can’t be explained at a “Like I’m Five” level) when you touch the power supply, you are grounded to the same circuits as the computer thus eliminating the ground loop."
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lp9dg3 | How do closed captions work? | Does someone physically type everything in? If so, why do the words sometimes not match what was said, or even whole sentences? I'm watching a show & the line was about insurmountable odds but, the caption said unassailable. | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Traditionally used to be typed by a person on prerecorded programmes. Now it tends to be done by a computer program much like how Siri or Google assistant can listen to your voice then transcribe it to text. Just like Siri etc sometimes someone has an accent that slurs certain sounds and the software doesn't quite interprete it correctly.",
"It depends, sometimes for live TV channels there's someone who types it. You can tell because sometimes they backspace and correct the captions. For things like movies, it's usually part of the broadcast. Since the script is known beforehand. Differences here could be that the script the caption is using is somehow different from the what is being said. For things like YouTube, they are experimenting with voice recognition. The same stuff that Alexa and similar use."
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lpanqm | How do spacecrafts send images from millions of kilometers away to the Earth? | Technology | explainlikeimfive | {
"a_id": [
"goab4my",
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"text": [
"Radio signals. Just like the Internet, the image is collected digitally, in an image sensor (= camera). Then it's broken into packets and sent over a digital radio network.",
"We use something called the *Deep Space Network* which consists of large antennas at three facilities spread around the Earth. When the Earth rotates, the signal is passed from one facility to the next. There are also a few antennas in orbit to fill in some gaps."
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lpbubh | More and more people are buying electric vehicles. Presumably, these will be charged at home in the evenings. Will this overload the electric system due to higher demand? | Technology | explainlikeimfive | {
"a_id": [
"goaj42t"
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"text": [
"It is unlikely, since the buying of electric vehicles is not a sudden event. Consumption will ramp up slowly, and since power companies are already ramping up production to keep up with increasing consumption in other areas it's really no different."
],
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lpcrj6 | Why do remotes starting working again once you hit them? | Technology | explainlikeimfive | {
"a_id": [
"goapqh5"
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"text": [
"One working theory is that oxidation forms on the battery contacts which causes a poor connection. By hitting the remote it causes the batteries to change position slightly and causes the contacts to rub against the batteries like sandpaper, cleaning the contacts. This is the same reason blowing into the classic Nintendo cartridge causes it to work. It actually has nothing to do with the blowing, it's merely the fact that removing and re-inserting the cartridge cleans off the oxidization layer on the contacts."
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lpferc | how do noise canceling earphones work | How does it work and how are they able to cancel out noise better than regular headphones? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"To elaborate on clyde's answer for active noise cancelling: Sound waves can interfere with each other, just like any other wave. When one sound wave is telling a material to compress, and another sound wave is telling the same part of the same material to expand, the material just does nothing. It's like adding a positive number to a negative number. The more similar in size the numbers are, the closer their sum is to zero. Active noise cancelling headphones have microphones on the outside of them, and they record the ambient noise of your environment. This never gets stored anywhere - it goes right into a circuit which reverses the sound, like multiplying it by -1. Then that sound is played alongside your music through your headphone's speakers. Just to be clear, the sound doesn't get reversed in terms of time - what you actually need to do is shift the sound so that when the actual ambient sound outside has a wave that's going up, the 'reverse' sound has a wave that's going down. Whatever one wave tells your eardrums to do, the other wave will try to tell your eardrums to do the oppsite thing. This way all the ambient noise gets cancelled out, and your music is all that you hear.",
"I assume you're referring to active noise cancelling. Passive noise cancelling is just making sure the headphones/earphones are sealed up so noise doesn't get through. Active noise cancelling playes certain frequencies that help mitigate outside noise."
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lpn64w | how come we can use telescopes to take long exposure images when the world spins? | Technology | explainlikeimfive | {
"a_id": [
"goc2rsj"
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"text": [
"Modern telescopes are computer controlled so you can track an object across the sky easily enough. The Earth isn't rotating that fast so it's not really a big issue. Or you can just let it blur and get cool images like [this]( URL_0 )"
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"https://apod.nasa.gov/apod/image/0609/startrails11h_hambsch_c90.jpg"
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lps9tu | Why is it that when a new cellular network comes out (4G/5G) the previous version seems to be completely obsolete? | Technology | explainlikeimfive | {
"a_id": [
"god3l3e"
],
"text": [
"Something is not right here since the previous generation should be largely unaffected for some time and there are plenty of 4G/LTE phones (most of them in fact) in service without trouble. (AT & T's 3G network is still online until next year actually.) I can't tell you for sure but troubleshooting that issue is likely beyond this subreddit and will be device/carrier/location specific."
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lpy68d | Why does our power outlets have three different holes (live, neutral and ground)? Why can't there be just one? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Electricity has to run through something to work. Like a river through a waterwheel. Live is where the electricity is coming from. The high point of the water. The neutral is where the electricity is going after it flows through your device. The low point of the water. Ground is a special place so that if the electricity escapes to somewhere it shouldn't, the power goes into the ground instead of more important things.",
"You always need two connections to make a circuit, otherwise electricity doesn't flow. The difference between live and neutral is that neutral is... neutral and live is... live. There are a few ways you can make a circuit with two connections, but the way we do it for wall power means that live is the one that pumps the electrons through, and neutral is a return path that doesn't really do anything by itself. Touching live will shock you, and touching neutral shouldn't, but it could if there's a wiring mistake so don't try it anyway. The third one - ground - is for everything that's **not** supposed to be part of a circuit, like the outside of a toaster, to stop it accidentally becoming part of a circuit, as a safety measure. If live touches ground the circuit breaker should shut off; it also prevents static electricity buildup.",
"You probably already know that electricity is conveyed by electrons. However electrons aren't *consumed* by the device like some kind of fuel, they are just methods of conveying a force. Imagine it sort of like if you were using hydraulics. You push fluid into one end of a pipe and since it cannot compress very well it is pushed out the other side with similar force. There doesn't need to be a high speed of flow within the pipe in order to get the push out the other side very quickly. Similarly electrons within the conductors move much slower than the electrical force is conveyed. Now imagine what the problem would be if you only had the one input wire. You push some electrons down the wire from the generator end, but without an outlet the charge of the wire and device at the end just increases. There is no significant **flow** which is where you are getting the force. The generator also has a problem in that it is losing electrons with no way to replace them; when the generator has a lack of electrons they will want to flow backwards to fill the void, moving the flow in the wrong direction! So you need both an input for the generator's electrons and an output for the device, something which is logical to link in the form of a neutral conductor. Now the system is like a chain drive on a bike, reusing the same chain (electrons) to convey a force. The ground comes in more like a safety outlet. The physical ground we stand on is potentially a massive sink for excess electrons, or even a source of needed electrons. It isn't infinite of course but the planet is huge enough that it is for all intents and purposes endless. Having a ground plug allows something like connecting a metal housing of a device to ground, so if a live wire comes into contact it doesn't conduct through a human touching it and instead will prefer to short to ground."
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lpyzni | Why does computers have to work in binary? | Instead of only 1 and 0, what if there's an inbetween? So that 1 bit can have 3 possible state instead of just 2? Is binary the only way a computer could work or is binary the most efficient way of doing things? Basically my question is, if there is an alien race out there with advanced supercomputer, would they still use binary or is there other way of doing things that our current understanding in technology simply haven't reached yet? | Technology | explainlikeimfive | {
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"They don't have to, it's just the easiest way to do it. We do know how to make a computer that uses base3 or higher, but it's just needlessly complicated for not much gain. \"No voltage\" and \"Yes voltage\" is very easy to distinguish, once you introduce in-between levels there is much more need for precision in order to not get confused. Heck, *before* we had digital (binary) computers, there were analog computers! And analog = infinitely many different levels.",
"It's much easier to design circuits that are either hard on or hard off. Circuits that work smoothly over a range of voltages have to be carefully tuned and need fine tolerances. The small gain is not worth the huge increase in complexity. The exception is flash memory which have cells that use 8, 16, or even 32 different voltage levels. They require analog electronics between the cells and the components (ADCs and DACs) that convert to and from binary. No calculations are done with the many-level signals, only storage and retrieval.",
"You know how ships used to communicate using lights? They'd have a big light with shutters in front of it and they would open and close the shutters, using Morse code to talk to each other. They only had two states to work with: open and closed, or 'on' and 'off'. If they had added a third 'half-open' state, they could have used a more efficient encoding system than Morse, and they could have transmitted the same number of words using fewer signals. So why didn't they add a third 'half-open' state? It's very easy to distinguish between 'on' and 'off', even in bad conditions (bad weather, long distance). Either there's light or there isn't. If you add a third half-open or half brightness state, that becomes a lot trickier and you may get it wrong sometimes when you're trying to read the signals from another ship. There are going to be cases where you're not exactly sure whether the light was at full brightness or half brightness. Computers using a third state would have similar problems, especially at very high speeds. Keep in mind that we increase the working speed of computers to the point where they juuust about work. If you use signals that are less distinct than just on or off, you'd have to give them more time to properly read it. On/off are easy to distinguish, even if the signal isn't 100% clean. There's also the fact that on/off signals are easier to produce with the electronics that we have developed. If you were tasked with operating the shutters of one of those signal lamps on ships and you only had to do either on or off, you could operate them very quickly. If sometimes you had to stop midway to do 'half-open', you'd have to go slower and be more careful in order not to open them too far. Electronics are sort of similar, in that switching something hard off or hard on is easier to do than nailing an in-between state without under- or overshooting.",
"Computers don't really think in 1 and 0. They think in on and off. We just use 1 and 0 to represent them and do higher level math about them, but really it's on and off. The brain of a computer has a few basic logic operations. AND, OR, XOR, and NOT (then also NAND, NOR, and XNOR as NOT'ed versions of the first 3 that don't require an extra step). That is *all* a computer does. They take 1 or 2 true/false inputs, and create a single true/false output. Do this several billion times a second in the right structure and you can make a computer. So no, there isn't really an in between, because those basic operations don't have in betweens.",
"Every once and a while, a ternary computer comes up, though we haven't really seen one in production since the Russians in the 1980s. Instead of 0 and 1, they had -1, 0, and 1. The Intel x87 math co-processor actually had 4 states in its memory. The x87 instruction set is baked into your modern Intel processor, though, there are more modern math instructions available to modern software. In the end, these computers are all Turing Complete, and equivalent to each other. There's nothing any one of these machines can do that the other can't. Some of these architectures make certain problems easier, but also some harder. The performance gap between them have long since closed. Instead, what you're seeing is a resurgence in analog computing. You can multiply or divide, for example, a lot faster in analog than in digital logic. Precision suffers, but it's cheaper to get an approximate answer to start, and then march that approximation toward the desired level of precision with a Monte Carlo simulation than it is to compute the desired level of precision from scratch. EDIT: We also commonly see multi-state data in wire signaling and modulation, such as PSK, which is used in WiFi and RFID."
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lq0tjv | How does a CRT fire electrons at a screen with such accuracy? | So, I've been reading up on how a TV works - specifically, the older style ones. I've learned that they have a gun that fires electrons at the screen which 'lights up' the pixels because they are made of special materials. The thing that amazes me is how the electron gun can fire the electrons with such precision. The pixels are so close together. Does the gun physically move or is it done with magnets or something and if it is done with magnets how do they control the current precisely enough to fire each electron at the exact right place? | Technology | explainlikeimfive | {
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"CRT TV electron sources are stationary. The electron beam is deflected horizontally and vertically by specially-shaped electromagnet coils, controlled by a main circuit. That's why wide CRT screens were very deep and needed a deep shelf. The intensity of the electron beam at each part of the screen is based on the received analog picture signal. In the case of color CRT screens, there are 3 separate amplified signals, to control 3 separate electron beams, for red green and blue. These 3 color signals are generated in real-time, inside the TV's circuitry, based on clever analog processing of the (one) incoming received signal. The secret sauce is a precision manufactured grid screen with tiny holes. This grid sits between the electron source and the colored phosphor pixels that're on the backside of the glass TV screen. Given the manufactured angles and positions, each hole in the precision grid allows one of the 3 electron beams to pass to illuminate only the red phosphors, one electron beam to only illuminate the green phosphors, and one for only blue phosphors. Very accurate angles and positions of the screen, means the electron beam intensity does *not* need to change improbably fast, precisely, or be super focused. That allowed home VCRs to record TV broadcasts, albeit with fuzzier horizontal picture resolution and worse color resolution. Still, analog data allowed quite a lot of information, so it took decades for digital computer technology to become fast enough to \"catch up\" to allow comparable frame rates and image resolution."
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lq5ww7 | Kubernetes | Please explain like I am 5. | Technology | explainlikeimfive | {
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"text": [
"Have you looked at The illustrated Children’s Guide to Kubernetes?"
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lqbtb3 | The Xbox Series X has its CPU and GPU on a single chip, but the CPU runs at 3.8 GHz and the GPU runs at only 1.8 GHz. Why can't the GPU run at 3.8 GHz too? | This also applies to the PS5, why can't the GPU run as fast as the CPU? | Technology | explainlikeimfive | {
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"I don't know if you are in the US but in high school in the US we have a thing called the PACER test for physical education. You have to run a small distance to get to a \"check point\" in under a few seconds, and you have to keep running back and forth between two checkpoints for faster and faster times until you just fail and can't run in time for the checkpoint. This is kind of how cycle times work in computer chips. The limiting factor in CPU clock speeds is whether the electricity can make it to the \"checkpoint\" in time. So clock speed is related to cycle time, 3.8 billion cycles per second also means that each cycle takes about 0.2 nanoseconds. Within these 0.2 nanoseconds, everything in the CPU has to \"settle.\" Chips contain devices known as transistors, electricity flows through them to do computations. Chips are designed to do a small amount of computation every cycle they run by the transistors choosing how electricity flows through the CPU. Within these 0.2 nanoseconds, electricity has to travel through a bunch of transistors and make it to a \"checkpoint\" which saves what it just computed. If there are too many transistors, 0.2 nanoseconds isn't enough, and the computation isn't done in time before the next computation step starts and things just go bad from here. So our goal with clock speed is to reduce the cycle time enough such that we can get it as small as possible but that all circuits on the CPU running at this clock can make it in time for their \"checkpoint.\" There are a few conclusions from this. 1. Faster clock speed doesn't necessarily mean faster compute speed when comparing different chips. One chip might have a slower clock speed but does more in a single cycle. For the same chip though, if you can increase the clock speed without bad effects, it will increase performance. 2. You want all of your circuits in your chip to take about the \"same amount of time\" to hit the checkpoint. If one circuit takes too long to checkpoint, it will be dragging down the speed of all the others because this circuit becomes the limiting factor as to how fast you can cycle. This is what CPU engineers painstakingly optimize. The big problem though is that for different inputs into each circuit, it takes different amounts of time, to get things to work properly we have to checkpoint the slowest time. 1 is the bigger reason for why the xbox's graphics chip can run slower, it just does more in one cycle. You can design a faster clocking GPU by decreasing the amount done in one cycle, but graphics tasks don't benefit as much from it so why bother.",
"A GPU runs very specific tasks, and those tasks are \"harder\" than the more \"general\" tasks a CPU performs. Because the GPU runs \"harder\" tasks, it takes longer to complete them, and the GPU has to put more effort in. This in turn results in more heat being generated (modern GPU's run significantly hotter than CPU's)",
"The CPU is like a fast sports car. If you're trying to get a vial of anti-venom from the lab to the hospital as quickly as possible, you want the car to be able to go as quickly as possible. The GPU is like a big truck. If you're trying to get a huge shipment of anti-venom from LA to NY, a truck is going to be far more practical. It has much more cargo space and it can go many more hours without needing a refill, even though it doesn't travel as fast. The CPU and GPU are good for different things. They work together. The CPU needs to be as fast as possible. The GPU needs to have high throughput, not raw speed."
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lqcplo | Are blank rounds harmless? What do they do? | Technology | explainlikeimfive | {
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"text": [
"They are not harmless. They still create pressure in the chamber to simulate a live round. But because they create pressure, any debris in the barrel of the gun will be blown out at high velocity. People have died from being shot by guns not properly cleaned and using blanks. But they are mainly for training purposes or movies.",
"They're pretty much just the powder charge, so there's no actual projectile being fired. They're not entirely harmless, though. The gun will still discharge a jet of fire and burning powder at very close range.",
"Generally speaking (because there are so many different kinds of ammunition), a blank cartridge is identical to a cartridge intended for live fire, with one **crucial** difference- live cartridges have a bullet affixed to the front or cap of the case, which- when acted upon by the ignited propellant in the case, will be pushed through and out the firearm barrel towards the target. Since blank cartridges have no such bullet, there is no projectile with which you could endanger a target at ordinary firearm engagement distances. For this purpose (and at these ranges), blanks can be practically considered harmless. However, when firing a blank, you still create a controlled explosion in the gun that must be capable of creating the impact to cycle the cartridge (ejecting the spent cartridge and loading the next one), producing heat, rapidly expanding gas, blisteringly loud noise, and other such theatrical elements leaned on in military exercises. You'll note that any of these things are dangerous if you get too close; I still have a bit of tinnitus from my service days. The *real* danger of a blank, though, is that since there is no bullet pushed through the barrel to remove the primer and propellant left from the firing of a previous blank, the inner barrel gets obscenely dirty over the course of a blank-fire exercise, necessitating hours of rifle disassembly and cleaning between training operations. Boo. Source: trained and instructed as an ammunition specialist in the Armed Forces for several years."
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lqe136 | How does a digital camera turn light from a lens into a series of 0s and 1s? | Technology | explainlikeimfive | {
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"The sensor in a camera is made up of millions of tiny capacitors that can hold an electrical charge. Light from the lens is turned into a charge in the capacitor, with more charge building up the more intense the light is. Circuitry in the camera then is responsible for shifting that charge off of the array, where it converts into a voltage. Those voltages are then sampled and stored as a sequence of 0s and 1s for later display.",
"Essentially, using some variant of the [photoelectric effect]( URL_0 ). The incoming light hits specially designed materials, essentially 'knocking' electrons out of the atoms and causing them to be able to move freely. Because of the way the circuit is designed, those freed electrons prefer moving in one direction rather than another, so the light hitting the sensors directly translates to a difference in charge between one end of the sensor and the other. This difference in charge can be detected and amplified into a voltage, which can then be chopped up into a series of fixed levels by comparing it against reference voltages. Those fixed levels can then be expressed mathematically as a series of 1s and 0s and saved/transmitted digitally.",
"Imagine a grid of squares, if light falls on one you colour it black “1”, if no light falls on it you colour it white “0”. If you have a large number of small squares in a grid and zoom out, you’d have a black and white image. If you want more distinction than black or white, you could have a scale from eg 1 to 8 for no light to lots of light, and you’d represent each number in binary (ie 1s and 0s) on the grid. For more detail you could increase the size of the scale from 1 to 8 to 1 to 16, or make the squares smaller so you could fit more in. Colour would work the same expect you’d essentially have three grids, one for each colour.",
"There's a pretty good diagram and explanation here. Basically you put red, green, and blue color filters in front of photosensitive material (the sort of elements that allow electricity to flow when light shines on them, like in a nightlight) and when they're arranged in a grid pattern you can start to assemble a 2D image from them. Fun fact you can also do this with a single photodiode by scanning left, right, up and down. Fax machines and scanning electron microscopes essentially work like this, and old CRT TVs work in oppositely (a single electron beam that scans left to right, row by row, not to sense light but to project it onto a phosphorescent screen.) It just takes more time so if you can pack a bunch of photosensors into a tiny grid it's better. Even still, a grid of digital sensors usually gets turned into a single steam of data, row by row, for simplicity and cost savings. URL_0"
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lqf0cz | how does the laser thermometer measure how hot/cold something is, by just shining on it with a few rays of laserlight? | Technology | explainlikeimfive | {
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"It has nothing to do with the laser, that is just an indicator to see where it is pointed. Instead the temperature is measured by gauging the frequency of infrared light the object emits, as that directly relates to the temperature of the object. If it gets hot enough the frequency actually raises into the visible spectrum which is why very hot things will start to glow."
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lqfrxu | What’s the difference between analog and digital? | I’m pretty sure that that analog signals is just a continuous stream of input versus digital which provides signals at discrete time steps. Why have we shifted from analog to digital for so many things? Wouldn’t a steady stream of information be of better use? | Technology | explainlikeimfive | {
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"Really, the answer is 'computers'. Digital processing of information is much, much, much easier to do in a consistent, reliable, reproducible, controlled, fault-tolerant, noise-resistant manner. If we could build analog computers as good as digital computers, you may have a point.",
"For an ELI5, analog is like writing an essay, digital is like multiple choice. Essays can give a much richer and deeper exploration into a single subject. But it is hard to switch context or explore multiple subjects in one essay. Multiple choice is easy to context switch and is easier to mark. So with multiple short questions, one can switch subjects or areas within a subject easily. Same with electronics - analog has to be fine tuned to that application. It can be done but once tuned, it isn't very flexible. Analog systems are hard to build if they have to accept a wide variety of signals. Digital is usually based on binary logic. Logic is easily chained, \"stacked\" or layered. So very complex structures and functionality can be built that can deal with many sources of input and be fairly easily upgraded and changed.",
"Your summary understanding is pretty good. The big fundamental reason behind the shift is noise/error. If you have an analog signal, and it gets distorted with noise, you don't know what it was beforehand, the noise is carried all the way to the end. If each step, each wire, each filter introduces a tiny bit of error, you are both limited in the number of steps before noise overwhelms the signal, and need perfect, great quality components to process it with as little noise introduced as possible. If you have a digital signal, where 0 is 0 volt, and 1 is +5 volt, if you get 1.1v of noise on the line, you still know upon arrival which one was 0, and which one meant 1, run that through a buffer / schmitt trigger (a special circuit that takes such \"dirty\" digital input, say, +0.8v and +4.4v, and scrubs it, producing clean 0v or +5v on output). This way your only point where you lose quality is when you convert from analog to digital, once - afterwards your data remains unchanged and undamaged, no matter how many processing steps it undergoes, because every time it has a chance to go a little \"dirty\" it can be cleaned up. And if given step risks introducing noise so bad the data can't be \"cleaned\", you just send more data, so that whatever was lost can be reconstructed from redundant extras. That means cheap, tiny components, because you don't care about a bit of noise. That means arbitrary media, because in analog converting between electric current, light intensity, magnetic field, magnetization of recording tape and so on was always tricky, as they never converted completely 1:1. What your tape recorder got through the microphone and wrote to tape was never identical to what it read and replayed; similar, yes, but if silence was still silence and max volume was still max volume, the bass was a little more warbling, the really quiet parts were completely gone, and so on. With digital, a \"1\" is always a \"1\" and \"0\" is always a \"0\"; in particular \"0.98\" is still a \"1\" and \"0.2\" is still a \"0\", you know the inaccuracies are an error, and you can reconstruct the original just as it was digitized, simply by discarding the error."
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lqfu0c | Why does a phone's volume need to be increased to ear-hurting levels for a person to be able to hear a podcast over washing dishes when hearing another person speak live over the same sound is fine? | Technology | explainlikeimfive | {
"a_id": [
"goh0iaq"
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"text": [
"Sound is a signal via the movement of air. Look at the amount of air that the speaker in you phone can move as opposed to the amount of air a human's lungs would move to the same sound. The larger amount of air would help override the noise from the washing."
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lqhgl8 | How do fax machines work? | Technology | explainlikeimfive | {
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"text": [
"Imagine taking a black and white picture. Divide the paper up in to lots of small squares. Then, through the image line by line and write down a 1 if a square is mostly black or a 0 if it is mostly white. Now you have a long list of 1s and 0s. Now you call up your friend. He has a sheet of paper with a similar grid on it. You go through the list of 1s and 0s, and he colours in a square if you say 1 or leaves it blank if you say 0. At the end, he has a picture similar to yours. This is basically what fax machines do. One machine scans a piece of paper, works out where the light and dark bits are, phones up another machine, and that one prints out a copy of the image.",
"It's like an all-in-one scanner-email-printer machine. On the sender side, it scans a piece of paper, then sends the data (as if you send it by email). On the receiver side, it receives the data (like an email), and prints it."
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lqxjki | In open world games like GTA 5, what happens to NPCs when no one is around? Do they still “move,” drive, etc? | Technology | explainlikeimfive | {
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"text": [
"Videogames typically use a technique called \"Culling\", which basically means, when an object or a part of the map is not in view, or not in the area of the player, it is typically removed from the scene, to save memory/processing power. Once the player/camera is in view of a new area or in view of some NPCs and Cars they quickly get put back into the scene. This is why you can sometimes see Objects and cars loading in if you look at them zoomed-in from far away. So to answer your question, when no one is around, the NPCs are simply removed from the scene.",
"It depends on the games. Cyberpunk makes NPC spawn in when you look but disappear when you turn away. Fallout keeps your area loaded but disappears it when you leave. Not sure about GTA but I’d imagine it’s the same as fallout. You can have all things spawned in at all times but it would take so much ram and be so hard to play since you have to account for all things!",
"Most games As soon as you step out a certain range the npc will simply not exist anymore"
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lr1uq4 | Why are photographs rectangular, and not circular, like the shape of the lens? | Technology | explainlikeimfive | {
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"text": [
"The lens does not relate to the shape of the image. A rectangular lens will still produce a circular image. However, the thing that captures the image is a sensor within the camera, and this is most easily produced as a rectangle (as it is a grid).",
"Because it's easier to manufacture and feed through a camera film that is rectangular than circular"
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lr21ld | How do those LED light therapy face masks work? | What are the benefits, and how does it get to the skin? | Technology | explainlikeimfive | {
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"gojm05o"
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"text": [
"URL_0 There really isn't any strong evidence that they work at all. If they do work, it's by stimulating specific structures in the skin that have rejuvenating effects. Each color of light has a specific wavelength; red has the longest and violet the shortest. These wavelengths determine exactly what structures they can interact with, kind of like a lock and key. Shorter wavelengths can also penetrate barriers (like your skin) deeper than longer wavelengths."
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lrd5e1 | Why do some links declare that they are redirecting you to a webpage, but others don't? | Technology | explainlikeimfive | {
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"text": [
"It's set up as a courtesy within the website hosting the link as a warning in case you accidentally clicked it. This gives you time to cancel if you didn't intend to go there, or you identify that link as something you don't want to see or potentially unsafe.",
"There are some websites that people put a lot of trust into. If there was a link on one of those sites, especially if it's a link in user-provided content like a forum post, they want to make sure that the user is aware that they are going to leave the site. This ensures that people don't link to another site that makes itself look like the original site to try and use that trust the user has. This is something that the website does on a technological level. The code they used to build the website automatically changes links to some external site into a link to a redirector page that will then take you to the external site. It is not something that is free to do, so many websites won't take the time or effort to do it."
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lrirco | What is usenet? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"It is an old protocol leftover from the early internet, like http or ftp. It is essentally a bulliten board format and it pretty much was the internet before web pages caught on. You could access it through almost anything, usually your email program. There were/are thousands of newsgroups covering every subject you can think of, like alt.lemurs, or news.austrailia or alt.lemurs.i.hate.them or alt.share.corvette.pictures. it is completely decentralized and I think you can set up your own nodes. And noone really pays attention to it anymore. Or at least that's what it was the last time I used it like a decade ago. And the first rule of usenet is you don't talk about usenet. Now get off my lawn ya whippersnappers. :)",
"In a way it was a bit like Reddit. There were different subs or newsgroups you could subscribe to (there was no concept of \"default\" subs or anything, you had to opt-in to every single one), but once subscribed to a particular newsgroup (alt.binaries.babylon5.episodes) then your newsreader (like an email client) would start to receive posts from that newsgroup from its nearest newsgroup server. There were newsgroups for everything: tv shows, bands... sharing of software, porn, you name it. But essentially under the hood it was very similar to email - all text based. There was a practical message/post size so larger posts could be broken up into chunks or parts of a message. And, like email, there were ways of encoding binary data as ascii text... although back in the early days of binary file sharing via newsgroups, a picture would get chunked up across maybe 5/6 posts. Pretty soon newsreader apps could automatically collect all the parts of such a msg and rebuild the binary attachment automatically. There was a practical limit to how far \"back\" in a newsgroup archives you could go - it depended on how much drive storage your ISP's newsgroup server was allocated. Once we started sharing big pictures, game cracks in zip/rar form and digitized videos (tripping_the_riftS01E01 Part 1/567), most news group servers only had a few days posts in their cache, so if you wanted a particular post you'd have to post yourself asking for someone to repost what you're looking for. But just like Reddit, anyone could sub to a newsgroup and post whatever, and there weren't admins (that I recall) or anyway to moderate content. So some groups were really great because everyone contributed and behaved and others really went to shit. edit: why did they go away? web/CGI script based bulletin boards like Digg, 4chan, Slashdot sprouted up once the \"web\" really got started in the late 90s and THOSE platforms had the missing features like content filtering and moderation etc. Plus, there was no single/master newsgroup server, the server had to be put up (and paid for) by someone, usually your ISP... and as newsgroup traffic (or rather data usage) skyrocketed with binary posts, alot of ISPs would either cut out the binary groups (boring!) or lost the newsgroup server entirely. I mean why download a big binary file from 8852 chunks (what if you missed piece 487? you were screwed) when you could download it a lot faster direct from the content maker's website? It would have been like each ISP hosting their own Reddit but having to prune unpopular or too active subs because they couldn't handle the traffic/storage."
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lrksud | What’s the deal about Roko’s basilisk? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"It's a thought experiment: * Let's say that, at some point in the future, a super-powerful AI will be created. * Once it comes into existence, it will punish everyone who *didn't* help bring it into existence. * One way it could punish them is by creating a perfect simulation of those people and then torturing those simulations forever. Those simulations wouldn't know that they were simulations - they'd believe that they're real people, living in a real world, and they'd feel the torture as if it were real. * Therefore, you must start working right now to help bring that AI into existence, to prevent the future eternal torture of those simulations. If you think that that's a dumb idea for numerous reasons, then...yeah, I'm with you.",
"So, an argument happened once on a message board for particularly smart, obsessive, and neurotic nerds. People were arguing about different ways to think about making decisions, and different ways of thinking about what \"you\" even are. A few of them came up with some ideas, one of which was that if a computer could perfectly simulate all the parts that make up \"you\", it would literally *be* you, and you would \"wake up\" inside that computer. If the original you wasn't dead, it would also still be \"out here\" - which implies that the moment the computer simulation of you was \"turned on\", you'd have like a 50/50 chance of experiencing your next moment \"outside\" or \"inside\". This led to a bunch of crazy conversations about Pascal's wager - the idea that you should pay attention to really horrible ideas that are unlikely to be true, but would be absolutely awful if they WERE true, because \"there's always a chance\". So someone named Roko came up with \"the basilisk\", which is an idea of a God that only exists if enough people create him (as an AI, obviously), and that immediately begins torturing everyone who DIDNT create him, by spawning so many different simulations of each person being tortured, that the chance that you wind up being the experience of \"out here\" is almost zero. Its basically a really stupid probability trick, and was meant to show how taking certain ideas about probability seriously would make you act crazy. So of course people started taking it seriously. Because *of course they did*.",
"Roko's Basilisk is part meme, part thought experiment. It asks the reader to assume that in the future there will be a super-intelligent, vengeful AI capable of travelling backwards in time. This AI decides to punish everyone both in the present and the past who did not directly or indirectly help make it. It's a rather ridiculous proposition so it's rarely taken seriously as that, but there is a modified version of Roko's Basilisk that's much more interesting - the idea of a basilisk that only punishes those who *knew* they could be doing more to help the basilisk. In this modified situation, anyone who never knew about the problem of Roko's Basilisk is never punished. The only people punished are those who learn about Roko's Basilisk and subsequently don't choose to help the basilisk be made. This would then make simply knowing about Roko's Basilisk a dangerous thing, and brings into question the morality of telling someone about Roko's Basilisk."
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lrwe4u | What is the difference between Saas(Software as a Service), PaaS (Platform as a Service), and IaaS (Infrastructure as a Service)? | I tried looking up the most simplest of explanations to these services but it just bamboozles the crap out of me. * SaaS, if am understanding the definition correctly, is what you can use on some centralized cloud platform that doesn't require you to install that software it on your system, e.g: Office suite, zendesk, dropbox. * I don't get the different from SaaS with PaaS. * IaaS is like gaining access to the full system, from your own system, and doing with it as you please? I know I'm like out of the ballpark with these terms, can you someone please dumbify it for me. | Technology | explainlikeimfive | {
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"SaaS - a company has software that it created that you can use on a subscription basis. You are paying just to use their program. They host it and you access it in most cases. PaaS - a company has a virtual machine network for you to use to create and test your software. You can interact with the system indirectly, using set commands. The company maintains the OS of the virtual machines and often maintains run environments and other utilities. This allows you to focus just on app development and not worry about the VM hierarchy. IaaS - a company has hardware capable of running virtual machine networks. They let you use it and set up your own virtual machine network with your own hierarchy, OS, utilities, etc. You have a lot of freedom to do things how you want, but you may not get much support from the company if it isn't working right. PaaS and IaaS are similar, and there are some cases where it's not clear where the exact line between them is. But the general idea is that with PaaS there is a lot being maintained and done for you by the provider, while with IaaS you are more in your own with more freedom but less support.",
"Computer services run in several \"layers\" built on top of each other. At the bottom is hardware, and on the top is a user-facing application like Reddit or Netflix. Rather than managing the entire stack top-to-bottom, you can go to a Cloud Provider company and rent from them the \"lower\" layers, and you only need to interact on the \"upper\" layers. The difference between IaaS, PaaS, and SaaS is *how many layers* are managed by the Cloud Provider company. Classic software, not as a service: You get your own computer, and install software on it. It's your computer, you're responsible for it. At scale, you might rent rack space in a datacenter or operate your own datacenter. But the physical computers are yours. Infrastructure as as service: Someone else (like Google or Amazon) manages the physical computers. You rent access to a computer. You cannot physically access the computer, but you can remotely manage the computer. The computer starts as a basic Windows or Unix box, and you install your own software on it. Nowadays the computers you rent are actually virtual machines, not physical machines. The provider will have one beeftank server acting like a hundred regular-size machines, rented out to different clients. Software as a Service: The Cloud Provider is not renting out access to a computer. They are renting out access to *a program* running on their computer. The program is not installed on your machine, it's installed on theirs, and they manage the configuration and installation and update stuff. There are a lot of programs that are SaaS-only, like Reddit and Netflix and GMail. There are also programs that can be classic or SaaS, depending on which you want. This is more common for business software, like Atlassian (JIRA, Confluence) or Tableau. The best consumer example is probably the Microsoft Office suite: you can have Excel running on your computer, or you can use an Office365 account and access the SaaS version of Excel through the browser. Platform-as-a-Service is basically a SaaS product for creating SaaS products. Google App Engine is an example of PaaS. You can create SaaS software using Google App Engine. While you rent VMs from Google, you don't generally remote into them and manage them like you would a regular computer. You write software, but you don't deploy it onto something that looks like Windows or Unix. You hand it to Google, and it makes calls out to Google services that are part of App Engine, which handles all the lower-layer stuff for you."
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ls2hi6 | - Why are some LEDs unsuitable for use with dimmers? | When I build a simple circuit with an LED in series with some kind of variable resistor, then, as expected, changing the resistance varies the brightness of the LED, and I can't notice any flickering or anything like that. So why do LED light bulbs need to be specifically designed to work correctly with a dimmer switch? What happens if I put a "non-dimmable" bulb on a dimmer? | Technology | explainlikeimfive | {
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"Dimmer switches don't work by changing resistance. They essentially work by PWM, chopping the voltage on and off. And the PWM frequency is quite low because it's synced to the mains frequency st 60Hz which makes the electronics super cheap to make. The thing with LED lights is that they respond very quickly to changes in voltage. AC power runs at 60Hz so in order to not have a 60Hz blinking LED the voltage needs smoothed out. Generally one does this with a rectifier (turns ac to dc) and a capacitor filter. Unfortunately this also tends to render dimmer switches useless for a basic LED light. Dimmable LED lights have some smarts built in that look at the incoming voltage, determine if it's being dimmed, then adjust the brightness of the LED output. Using a non dimmable led bulb can have any number of results from flickering, just staying off, to being damaged.",
"LEDs in household lights don't just have a resistor in series because that wouldn't work very well with a higher power light that uses AC power. Instead they have a more complex electronic driver circuit that turns the incoming AC into lower voltage DC, while keeping the output current constant. These driver circuits contain relatively complex chips that need a certain voltage to function, and that often need a small fraction of a second to start working properly. If you just put one of those lights on a dimmer, the driver chip can't do its job properly. At higher dimmer settings like 90% or 80%, the chip will usually just ignore the dimmer and still keep the LEDs at a constant brightness. At lower settings the driver chip will still attempt to do that, run out of power and turn off until there's enough voltage to start working again, resulting in a LED that flashes on and off. To make an LED light dimmable you need a smarter driver chip that basically looks at power coming in, recognizes that someone is trying to dim the light and then instead of trying to keep the output to the LED constant, adjusts its output to match the dimmed input. So you're not dimming the driver directly, but the driver is taking the dimmed input as a clue to figure out what it should do with the LED.",
"Dimmers that are intended for mains voltage AC is not based on a simple variable resistor as this resistor would quickly burn out if you apply the full current of a lamp through it. Even LED lamps that use resistors due to the lower currents spread them around a bit to prevent any hot spots. Instead a regular dimmer circuit will reduce the current through it with other means, for example by reducing the cycle length of the AC cycle. But this assumes the load is a simple resistive load which is not the case for LED lights. The effect is that depending on the circuit used to power the LED and what power curve the dimmer outputs you either get full power all the time or the LED light will flicker with the cycles of the AC current. There are a few ways around this but it requires that you find a dimmer and an LED driver which are compatible with each other. For example a dimmer based on a capacitive dropper is more expensive but will be able to reduce the current to a lot of simple LED drivers. You also have LED drivers with active circuitry to monitor the input to detect the precense of a dimmer and then regulate the output to emulate the dimmer settings. And if you were to design a completely new system from the grounds up without any existing wireing or compatability issues then you would put the dimmer on the output of the LED driver or as a controll for the LED driver directly."
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ls7ljt | Why can multiple apps use a mic at a time, yet only one app can use a webcam at once? | Technology | explainlikeimfive | {
"a_id": [
"gopsryw"
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"text": [
"The biggest reason is that different programs encode the camera feed using different softwares behind the scenes. Generally speaking, making a computer translate a single feed into multiple simultaneous computer languages and output to different video-chat softwares is too taxing to be useful. There are some 3rd party softwares that do it though, you just need some computer savviness. Audio feeds are A. easier from a computational power standpoint, and B. were standardized in computing languages so the inter-operability is less of a issue at the start. EDIT - some platforms will allow multiple camera use simultaneously, for example a cell phone using the front and rear cameras at the same time. I also neglected to point out the privacy and security implications of allowing overly liberal access to your devices camera feed."
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lscb54 | Why is liquid metal like NaK used instead of water for cooling computers when water has > 4 times the heat capacitance? | Maybe it's not NaK, maybe another alloy; but anything short of liquid helium is nothing compared to water, deuterated or not, right? So why use NaK? | Technology | explainlikeimfive | {
"a_id": [
"goqah05",
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"Water has too low a boiling point. When it boils, the pressure increases significantly, making the required walls of the container much thicker, making the heat transfer less effective.",
"It would appear that NaK is used as a coolant in situations where it must remain liquid at a large temperature range and where it must absorb minimal neutrons. So, nuclear fast reactors. Some reasons to use non-water coolants despite the difference in specific heat capacity is that water is corrosive, boils at 100 c, is relatively viscous, and evaporates a lot.",
"Cooling isn't just about how much heat your coolant can hold but rather how quickly it transfers that heat. You want it to be able to absorb the heat off your device as quickly as possible, then expel that heat somewhere else just as quickly. The rate at which heat is transferred is called thermal conductivity. Imagine emptying a tub full of water by scooping out one cup at a time. A bigger cup can empty the tub in fewer trips but each of those trips is going to take some time. A smaller cup will need more trips but if it can complete those trips fast enough, it can potentially remove more water per minute than the larger cup. In this example, heat capacity is the size of the cup and thermal conductivity is the duration of the trips. NaK has a higher thermal conductivity relative to its heat capacity than water does, which means NaK can remove more heat in the same amount of time.",
"NaK have a higher thermal conductivity which means that you do not get as much issue with parts of the liquid being hot and part of it being cold. Its freezing point is also much lower then that of water so you can run it in freezing environments."
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lsdqv7 | Ultra Fast Charging in Smartphones, what is it and why does it took so long for us to achieve this? | Smartphones has been around for a decade now. The performance of today's chipsets has improved by maybe hundreds-thousands times compared to the first android phone. However, 65 Watt charging was less then 1-2 year ago (0-100% 4000mAh in 30 minute). . The public clearly demanded better battery life and charging, so the fact that it doesn't improved significantly was because it was either impossible or not profitable enough for manufacturers. So the question is, why/how? Why are we not able to charge things safely in minutes many years ago? | Technology | explainlikeimfive | {
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"It's a limitation of Li-ion batteries. The full chemistry is pretty complicated and not my field, but in general, all lithium batteries like to be charged at a slow pace or they start to degrade (they degrade with charge cycles anyway, but a faster charge worsens this). Even still, 30min charging *does* reduce the lifespan of your battery, but since the tech has vastly improved over the years, it's now at an acceptably low level. Plus the manufacturers figured out that if your phone only holds half the charge after 2 years and you can't easily get a new battery, you'll probably just buy a new phone. So that's also a plus. Edit: forgot to mention, charging isn't 100% efficient, so it produces heat which needs to be dissipated or it, again, degrades the battery. Faster charging means this heat is produced faster and doesn't have as much time to dissipate."
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lsi2jb | Why Should We Not Wash A Cast Iron Skillet With Soap? | Technology | explainlikeimfive | {
"a_id": [
"gorcrn6",
"gorjp47"
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"text": [
"That's fake news, or at least outdated. This dates back to when soap was basically lye and wound destroy everything in its path, including the seasoning on a cast iron pan. Cast iron pans have nonstick properties because over time polymerised grease builds up on the surface due to the high cooking temperatures, and it fills in the pores making the surface really smooth and nonstick. This buildup of polymer layers from grease is called the seasoning and its extremely durable, although it can chip because its so hard so don't go hitting your cast iron with a hammer. Old soap used to be strong enough to destroy the seasoning, but modern dish soap is all good to use on a cast iron skillet. Just remember to dry it carefully so it doesn't rust Edit: More specific that the grease polymerises into a plastic sort of hard layer, instead of being vaguely \"hardened grease\"",
"Modern is soap is fine to use on cast iron. Just don’t scrub the living shit out of it with a Brillo pad."
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lsj1oo | What happens when servers ‘go down’, for example Xbox servers right now, and what do they do to fix them? | Technology | explainlikeimfive | {
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"Take your laptop for instance , if there are too many things open you hear the fan to start working. Keep opening applications and your computer will freeze up and you can't do anything because your ram is full and it can't complete the processes. Well this is likely what is happening. Their \"servers\" (you can think of them as computers) are locking up and they can't scale up fast enough to share the amount of processes that are taking place. Therefore no new process can be taken on. This or they need to fix a bug across their systems and they haven't gotten a good strategy in place. Either way they need to stop these requests from coming in so that they can fix the problem or else it will just keep happening at an exponential rate."
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lsj97f | What are you doing to a game when you port it, besides changing the button mapping? | Technology | explainlikeimfive | {
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"gork3qk"
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"text": [
"Some of the programming gets changed. Because each port is going to be running on different hardware/operating systems, some of the programming has to get tweaked/altered to make the game run just as well on the new platform."
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lsmcu3 | What are NTFs and how do people earn money from them? | Technology | explainlikeimfive | {
"a_id": [
"gowje4e"
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"text": [
"I think you're talking about Non Fungible Tokens in Cryptocurrencies. A fungible item is an item that is replaceable, we could swap two dollars and it wouldn't make any difference. In terms of Cryptocurrencies, each Bitcoin is the same as every other Bitcoin. These could be called a fungible tokens. People have been creating tokens with cryptocurrency that represent non fungible assets, such as artwork. A painting is non fungible as it will be unique and different to all other paintings. This means that an artist can create a token that represents a unique piece of art. So that people can trade/sell direct ownership of the art. They trade/sell them on sites such as [Rarible - create and sell digital collectibles secured with blockchain]( URL_0 ) If you're thinking about getting into it then don't do it right now on rarible, or any other Ethereum based site. Ethereum gas fees are very high and you could be paying around $100 just to get your art on the site. Wait for alternative NFT marketplaces on other blockchains in the near future."
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lsoctr | Why is film grain generally considered good, but digital noise is considered ugly? | Technology | explainlikeimfive | {
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"text": [
"I'm not sure what you're talking about film grain being \"good\". Film grain (in modern context) is used a visual effect to portray it as an older-style film in which film grains were unfortunately more common. They were never good, people would love to have never had film grains in there ever. Its used a nostalgic effect in modern cinema representing another age and time of filmmaking. Digital noise can actually be used in the same manner to make it appear as an \"incomplete\" or damaged video missing parts. But both film grain and noise were never something people want in their film, its an unfortunate effect that exists in their medium that they cannot always control"
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lssyuk | How does code even work? | Technology | explainlikeimfive | {
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"text": [
"You write human readable code. The compiler or interpreter translates this into machine code. Machine commands are usually less powerful than those of higher languages, so a single function in your code might call many machine code instructions. These instructions are just binary numbers your CPU knows. So 00000001 is basically \"run instruction 1\" wich could be the adder for a specific CPU design. The ones and zeroes open and close switches, and with a cascade of switches called Multiplexer you can then open a channel to the correct calculation circuit (wich then adds numbers, compares numbers, jumps to a specific line in your code etc.)",
"First you write the code in whatever language you choose. Different languages have different syntax (grammar) and different features (strong type systems, function currying etc.). To run code there are basically 3 ways: 1. Compile it all the way down to machine code 2. Use an interpreter to execute it without compilation 3. Use something called just in time (JIT) compilation to execute it instantly but also compile it as you're going so its fast 1. Compilation is a very complicated process to do optimally, and an active field of research, but basically you make a program that scans the code you've written, and produces machine code that is \"correct\" in the sense that it produces exactly the same output as the program you wrote. Then you can execute the machine code, known as a binary, because the machine code instructions are known by your processor by design 2. Interpreting is when you don't compile the code but instead you have another program that reads the code, and does what the code says, in real time. Basically the interpreter itself is a machine code binary that has the possibility to perform any function the input code could say. Interpreting code is slower than executing binaries, but on the other hand you don't have to wait for compilation to happen, so it feels nice when your program executes just like that after changing the code. 3. JIT compilation is a bit newer, but its like a hybrid between the two. Basically here the compiler compiles your code as the execution goes along, only compiling the parts of it that are immediately needed, such that the execution can carry on smoothly. JIT compilers are pretty complicated and cutting edge, but this is very nice because it offers the instant feel of interpreting, while also having some of the speed of compiling"
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lsuair | How can you "steal" source code of a program? If the program is already on your device, don't you already have access to it's code? | Thought about it when I've read news on how source code of the cyberpunk got stolen from CDPR. | Technology | explainlikeimfive | {
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"gotatu8",
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"text": [
"How can you steal the recipe for a cake ? If I already bought the cake, don't I have access to its recipe ? Basically the same thing. Sure, you can guess parts of the recipe of a cake (like whether it uses chocolate, stuff like that), but you can't find the exact recipe just from the cake itself, because ingredients are too mixed up, and you can't really know the process (like order in which you put the ingredients together), etc... The source code has be \"compiled\" into an executable, the same way ingredients and recipe are \"cooked\" into a cake. You can't just reverse it.",
"Source code is what allow a human to write instructions for a computer. But, these instructions cannot be understood by the computer directly, as a computer only understand 1 and 0 (binary). So, for a computer to be able to understand code, it needs to be translated into 1 and 0. This stage is called \"compilation\". Compilated code is what you have on your computer, and in most case (if well done) it cannot be reverted to source code, so you never have direct access to source code, only to the Compilated version",
"Your computer doesn't read code directly as it's written in a language like C++. It is compiled into machine code that your processor can understand. C++ Code (stolen from [here]( URL_0 )): #include < string > #include < iostream > using namespace std; int main() { string name; cin > > name; string message(\"hi\"); cout < < name < < message; return 0; } Compiled Machine Code would be this madness: .LC0: .string \"hi\" main: push rbp mov rbp, rsp push rbx sub rsp, 88 lea rax, [rbp-64] mov rdi, rax call std::__cxx11::basic_string < char, std::char_traits < char > , std::allocator < char > > ::basic_string() [complete object constructor] lea rax, [rbp-64] mov rsi, rax mov edi, OFFSET FLAT:_ZSt3cin call std::basic_istream < char, std::char_traits < char > > & std::operator > > < char, std::char_traits < char > , std::allocator < char > > (std::basic_istream < char, std::char_traits < char > > & , std::__cxx11::basic_string < char, std::char_traits < char > , std::allocator < char > > & ) lea rax, [rbp-17] mov rdi, rax call std::allocator < char > ::allocator() [complete object constructor] lea rdx, [rbp-17] lea rax, [rbp-96] mov esi, OFFSET FLAT:.LC0 mov rdi, rax call std::__cxx11::basic_string < char, std::char_traits < char > , std::allocator < char > > ::basic_string(char const*, std::allocator < char > const & ) lea rax, [rbp-17] mov rdi, rax call std::allocator < char > ::~allocator() [complete object destructor] lea rax, [rbp-64] mov rsi, rax mov edi, OFFSET FLAT:_ZSt4cout call std::basic_ostream < char, std::char_traits < char > > & std::operator < < < char, std::char_traits < char > , std::allocator < char > > (std::basic_ostream < char, std::char_traits < char > > & , std::__cxx11::basic_string < char, std::char_traits < char > , std::allocator < char > > const & ) mov rdx, rax lea rax, [rbp-96] mov rsi, rax mov rdi, rdx call std::basic_ostream < char, std::char_traits < char > > & std::operator < < < char, std::char_traits < char > , std::allocator < char > > (std::basic_ostream < char, std::char_traits < char > > & , std::__cxx11::basic_string < char, std::char_traits < char > , std::allocator < char > > const & ) mov ebx, 0 lea rax, [rbp-96] mov rdi, rax call std::__cxx11::basic_string < char, std::char_traits < char > , std::allocator < char > > ::~basic_string() [complete object destructor] lea rax, [rbp-64] mov rdi, rax call std::__cxx11::basic_string < char, std::char_traits < char > , std::allocator < char > > ::~basic_string() [complete object destructor] mov eax, ebx jmp .L9 mov rbx, rax lea rax, [rbp-17] mov rdi, rax call std::allocator < char > ::~allocator() [complete object destructor] jmp .L4 mov rbx, rax lea rax, [rbp-96] mov rdi, rax call std::__cxx11::basic_string < char, std::char_traits < char > , std::allocator < char > > ::~basic_string() [complete object destructor] jmp .L4 mov rbx, rax .L4: lea rax, [rbp-64] mov rdi, rax call std::__cxx11::basic_string < char, std::char_traits < char > , std::allocator < char > > ::~basic_string() [complete object destructor] mov rax, rbx mov rdi, rax call _Unwind_Resume .L9: mov rbx, QWORD PTR [rbp-8] leave ret __static_initialization_and_destruction_0(int, int): push rbp mov rbp, rsp sub rsp, 16 mov DWORD PTR [rbp-4], edi mov DWORD PTR [rbp-8], esi cmp DWORD PTR [rbp-4], 1 jne .L12 cmp DWORD PTR [rbp-8], 65535 jne .L12 mov edi, OFFSET FLAT:_ZStL8__ioinit call std::ios_base::Init::Init() [complete object constructor] mov edx, OFFSET FLAT:__dso_handle mov esi, OFFSET FLAT:_ZStL8__ioinit mov edi, OFFSET FLAT:_ZNSt8ios_base4InitD1Ev call __cxa_atexit .L12: nop leave ret _GLOBAL__sub_I_main: push rbp mov rbp, rsp mov esi, 65535 mov edi, 1 call __static_initialization_and_destruction_0(int, int) pop rbp ret Programming such a huge game like Cyberpunk would be basically impossible if it was done entirely in machine code. That's why a programming language is used. The machine code is what the processor actually executes. The executable file that runs the game on your computer is machine code, not source code. The source code that is compiled into machine code is kept secret by CDPR, well, at least it has been."
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lt30f3 | an ozone generator? How? Why? | We are temporarily staying with friends after our home burned down. We stay in a small, removed...hut? Shack?... behind the house. The house is old, railway origins, and has some reoccurring mold (not black, yet) in the bathroom. Friend comes to warn us that they set up an ozone generator overnight, they’re not sleeping there, just make sure we turn it off in the morning and let it air out for a while before using the facilities. So the mold part I get (sort of). Anyway. I’m using said facilities currently after fearfully airing out ozone which sounds like some sus villain-in-a-lair shit. | Technology | explainlikeimfive | {
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"Ozone is an oxygen molecule made up of 3 oxygen atoms instead of 2. It's naturally created by lightning strikes and UV radiation high in the atmosphere. It's kinda poisonous in large amounts because it oxidizes (rusts) shit *real* hard - harder than normal O2 molecules. Including living things. This also means it kills stuff like germs and mold in an enclosed space, so you can use it like that instead of chemical spraying."
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lt3fcm | how do docking stations work? | Technology | explainlikeimfive | {
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"text": [
"Older docks have a connection on the bottom with a couple dozen wires. These are literally the same to the machine as if it had all the ports a dock has. The dock just connects the ports to these wires. Newer docks are a piece of hardware with all the chips and wiring for the ports with a thunderbolt connection feeding that all to the laptop. Thunderbolt 3 has enough capacity to handle all of that data with ease."
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lt3pev | Why do motion sensor nightlights sometimes turn on even when nothing is there to trigger it? | Technology | explainlikeimfive | {
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"Wind, dust in the air, bits of leaf debris, small wildlife, bug on the sensor, if the sensor is particularly sensitive it could well pick any of these up.",
"Ive always thought static electricity? There are various opinions regarding the phenomenon.",
"Motion sensors are looking at the room in infrared. One of the most common reasons they would turn on is that the furnace kicks on and the room gets a blast of much warmer air coming in.",
"Motion sensors are usually \"PIR\", passive infrared. They look at heat, not an actual picture like a camera would take. If the sensor detects a sudden rise/drop in the voltage being made, it assumes that to be the motion of a warm object, and triggers the light. Dog, human, car, doesn't really matter. But, the obvious issue is that something like hot air from your dryer, exhaust from a car, or breeze over a hot asphalt driveway, will also cause a change in temperature, causing the light to trigger. So, when it goes on for no apparent reason, it's probably just a bit of hot air floating by."
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lt4htj | Why can't cell phone manufacturers use carbon fibre to build phone body instead of plastic, ceramic, glass, etc. ? | Technology | explainlikeimfive | {
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"They totally could. Why would they? Carbon fiber scratches fairly easily and can shatter. It's biggest advantage is being lightweight, which isn't super necessary for a tiny phone anyway. Plastic's way cheaper and plenty durable. Glass is scratch resistant. Aluminum is strong.",
"Carbon fiber is very strong and stiff, but it is also very brittle. It fails catastrophically as soon as you pass its breaking point. It's especially bad when a lot of stress is put on one small point of it, because then you're only stressing a small number of the fibers. The strength is also directional with the direction of the fibers. This is great for a mountain bike with known stress angles, but not great when you don't know exactly how a phone will drop. Plastic and metal can give a little bit before they break, and their strength is in all directions.",
"[Well at least one manufacturer is attempting to make a device out of carbon fibre ]( URL_0 ) I know this thread is a bit old but figured it was worth posting this.",
"They can. It's just not a a great material to build a cell phone case from. Cell phones need \\*extremely\\* tight tolerances for all the parts to fit properly (like single digit thousandths of an inch). The only way to get that from carbon composite is to mold it, which means you need to use chopped fiber, which doesn't have that cool \"carbon fiber weave\" look, which sort of defeats the point. If you do the woven carbon so you get the look, you need to post machine it to get the tolerances you need. That's not impossible, it's just an extra step that adds cost. Blackberry used to have a carbon back panel, and Dell uses carbon palmrests on their XPS laptops (I think Lenovo does too). And in order to be strong enough, it's needs to be thicker than you usually want for a cell phone case. And the plastic resin is relatively soft so it scratches easily...so to make a premium phone with the \"carbon look\", you need to make it thicker, then overcoat with something scratch resistant (glass or ceramic)...the end result isn't very premium anymore."
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lt517d | What would happen if i plug my headphones into an outlet? | Technology | explainlikeimfive | {
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"I'm assuming you're talking about connecting a USB headphone into a USB charger. If everything is built strictly to protocol specifications, nothing. If not, then anything from fried headphones to electric shock.",
"Nothing. The lines that carry data in USB are not the same lines that carry power. Your headphones would be powered up, but you would hear nothing since nothing would be connected to those data lines.",
"Nothing. Here's why. Theres 6 wires in USB. The outer two - one in each side Are a little longer than the others. These two are for power. Your charger only connects those two as it doesn't carry data. Just power. So if you have say an USB headset it is basically a sound card in itself. So it's powered. But nothing on the input pins. Thus no sound. Because there's not any data."
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lt85s3 | What Edward Snowden did? | Technology | explainlikeimfive | {
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"He told the world that the American government was breaking its own laws by spying on everyone without any sort of legal process.",
"So Edward Snowden worked at the NSA. Which means he was computer spy. While working there he saw the NSA was spying on the American public. All of them. All the time. He believed this was wrong because if the police or security services want to spy on a person, they must prove to a judge that they have a reasonable suspicion the person is committed a crime. The NSA was spying on everyone, just in case they might be planning a crime. Edward Snowden believed the public should have the right to decide whether they agreed with this or not. He told his boss how he felt and his concerns were ignored. So he started to collect as many documents as he could and devised a plan to leak them to the public. He contacted several journalist secretly, who he believed were trustworthy enough to decide which documents the public should know about and which should stay secret. Then he flew to Hong Kong and arranged to meet them. He didn't tell his girlfriend or his family. As he didn't want them to be guilty of breaking the law. He met the journalists and passed them all the documents and explained what they were. They quickly began writing articles about some of the programs. The world started to put two and two together and Edward Snowden went into hiding fearing he might be arrested by Chinese security services or possibly worse by US spies. About this time wikileaks' Julian Assange and a small team started trying help Snowden. They sent one of their most trusted legal advisors to meet him and began booking multiple airline tickets for him all to different places in order to confuse the security services as to when he would be travelling and which flight he would be boarding. He boarded a flight to somewhere in South America, however he had to stop in Russia to board a connecting flight. By the time he landed in Russia the US state department had revoked his passport. Consequently he was unable to enter Russia, and unable to board any flight out. He was stuck in the transit area of the airport for 39 days while he applied for asylum in dozens of countries. The US government was pretty annoyed at this point as many of the stories journalists were releasing made them look very bad. So they started calling every country they thought he might apply for asylum in and told them they had damn sure better not grant him asylum. Which they agreed to, as you don't want to piss off the US government.... Unless you are Vladimir Putin. He loves to piss off the US government. Consequently Edward Snowden was granted asylum in Russia. Sadly what then happened was that the public he risked so much for, pretty much didn't a fuck. The programs he told journalists about were ruled to be illegal, and useless. They hadn't prevented any major terror attacks and the release of them hadn't cost any American lives. But people started to believe that \"if I've done nothing wrong I have nothing to hide.\" and none of the NSA senior staff or Government officials even resigned, let alone got charged for the hugely illegal surveillance programs they were secretly running and deliberately hiding. In fact a couple of them got promoted. So what did Snowden do wrong. Nothing in my opinion."
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lt9may | Why do pilots always say we’ll be able to “make up time in the air”? | Whenever a plane is a little late taking off, the pilot will say that we will be able to make up time in the air. What does that mean, and if we’re able to make the plane go faster to make up time, why can’t they make the flight shorter to begin with? | Technology | explainlikeimfive | {
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"Its less fuel efficient to fly faster. If everything is going ok they will fly at a more efficient speed to save money. However if the plane is late to take off it may be worth it to go a little faster so that the next flight isn't also late.",
"As others have said, flying faster (either with a tailwind or burning extra fuel to keep the schedule), but there is also some flexibility with the Air Traffic Control (ATC). A pilot can request a direct take-off to potentially jump ahead of other flights that are closer to their on-time departure. ATC can provide a slightly faster overall route (especially if weather or other traffic conditions permit). And, on the other end, the flight might be able to land directly, land on a runway nearer to the terminal in a direction that is more favorable to get to the gate faster. (An airplane landing has to slow down and pull off the runway to a taxiway, then taxi to the terminal. The direction the airplane lands can allow the plane to be able to spend less time taxiing if it can leave the runway closer to the gate the flight is headed to. Also, large airports have multiple runways, and one will always be closer, meaning less time taxiing. Plus, a runway further away will probably have to cross another runway, which can add another minute of delay if the flight has to wait for another plane to take off/land from the other runway.) And, finally, many flight schedules have extra time added due to the possibility of weather, traffic conditions, or other factors that can cause delays. Airlines want to have fewer \"regularly running late\" flights, so they will work to build in extra time where needed to reduce the change that any of those factors will cause enough of a delay to make them look bad. (It is more complicated than that, but this is a simple explanation.) So, a flight from Colorado Springs to Denver (total distance of 65 miles, \\~35 minutes flight time) may be scheduled for a full hour, since snow at either airport or traffic in Denver might add an average of another 20 minutes. In fact, if you book that flight, you will notice that flight times vary depending on time of day, and the flight into Denver (the busier airport) is given an extra 10+ minutes, and the return flight is listed as shorter, due to airport and route conditions."
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ltdok3 | How do companies decide which fonts to use for their software? | Do they base it off of popularity polls or something like simplicity? You never see elaborate fonts used which makes sense because consumers likely have difficulty reading them (if they're used for generic text as opposed to headers or something of the like). | Technology | explainlikeimfive | {
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"A combination of \"the skill and expertise of their designer\", and \"arbitrarily, based on an executive's whim\"."
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ltfl8c | Modern filming techniques vs 90s (?) | This question requires some set up...Im not a film nerd in any sense So im not sure what the proper terminology is for all these things...Iv recently come across the 24 hour version of Pharrell Williams's - Happy and the type of filming it used felt oddly nostalgic I tried googling some stuff but never got any good results. So the closest thing I can use to describe it was it feels like the camera is equally on the environment and the person being filmed it seems like whatever this is it was used in a lot 90s movies/tv too.Its as opposed to modern movies which seem to focus on the person in the frame rather then the entire area like its more zoomed in. | Technology | explainlikeimfive | {
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"I am going to believe you are describing one aspect of a production shot on film versus modern digital recording. Film cameras were the shit, still great, but like wine corks versus screw tops eventually practicality and cost and availability and ease-of-use wins out and digital and screw tops become the norm. But for a while shot on film was the thing and with it came certain conventional uses, wide frame shots to show how clear and focused and true to life the scene could be and cameras at eye level for most shots with conversations or thinking etc. Digital becoming accepted then the norm freed up productions from large expensive studio cameras and all the conventional use cases. But they also couldn’t replicate the ‘big’ feel of film, so they pivoted to more tight shots, close-ups, etc to play to the strengths of the new equipment. Very soon it led to a decidedly different type of production with more cameras available, hand held, easily mountable, many different configurations and all sorts of practical effects available that more than made up for the limitations of the newer medium."
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ltja6n | Why can my laptop play realistic games like Hitman 3 smoothly, but lags like hell with Minecraft shaders? | I use a lenovo legion 5 | Technology | explainlikeimfive | {
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"Quality of code can differ from a shaffer made by a fan and a professionnal game studio. Also minecraft is in java so it slow from start.",
"Realistic games don't look realistic because somebody just went and made the shaders simulate reality as realistically as possible. They look realistic because somebody has spent hundreds of thousands of dollars hiring programmers to make the game *look* as good as possible on limited hardware. Generally, this translates to a lot of effects that look more impressive than they are expensive to compute, aesthetic trade-offs, compensating for engine limitations with creative design, and so on. The studios doing this have years and years of experience in figuring out what *looks* good to humans. The goal isn't to *be* realistic, it's to *seem* realistic. Somebody working on a Minecraft shader in their spare time is not going to be able to devote those amounts of resources. Most likely their shader will do something conceptually simple and do it without much fuss or optimization. The ones that look impressive are probably impressive because they're actually computing impressive amounts of data, rather than doing something less impressive and trying to make it *seem* more impressive, which is what well-optimized video games do.",
"The problem with minecraft is that it was never meant to be as big as it is today. It was some swedish dude's pet project that just exploded in popularity, so the core isn't really made with efficiency in mind. Shaders are also an add-on and something that's just added to the completed project always suffers from inefficiencies compared to an integrated solution.",
"Minecraft's engine is more cobbled (lol pun) together than Bethesda's Skyrim/Fallout engine. It's less \"functional\" and more \"held together with duct tape and chewing gum\"."
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ltjv9g | How does a radio receiver discriminate between different signals? | If there are lots of different radio signals with the same or very similar wavelengths, how is it possible for a radio to pick up just one signal? | Technology | explainlikeimfive | {
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"In general, it can't. If two signals over lap, both will be received and will, generally, garble the message. While frequency - the number of oscillations of the carrier signal - is important, bandwidth - the \"width\" of the information in hertz - is important, too. For example, a radio station on 101.3 FM actually extends from 101.2 to 101.4. This spacing prevents signals from \"clipping\" into one another when adjacent channels are co-located. 101.1 doesn't go past 101.2. With two stations at the same frequency, they're usually spaced far enough apart that the power of one broadcast is significantly weak within the area of reception of the other station, thus interference is avoided. Propagation phenomena changes with different frequencies, though. AM broadcasts can travel farther at night, and some stations are required to reduce power at these times to reduce interference. Additionally, it's possible to encode transmissions to be dug out later. This is not uncommon in things like radars, where a code is embedded in the phase of the transmission and returns can be discriminated from interference despite being at the same frequency."
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ltnhtc | How hard is it to hotwire a car? | Like when you turn the key in a car, it completes a circuit right? How hard is it to just take the wire connected to the switch and touch them together? | Technology | explainlikeimfive | {
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"Newer cars are basically impossible . Older cars such as a 1996 Honda Accord for example you can hop in and have it going in 45 seconds .",
"Older cars are as easy as you describe. You just need to provide power to the ignition circuit and then the starter circuit. In order to do this fast though you need some knowledge of the car so that you know which wires to short circuit. Some cars do somewhat protect the wiring loom from the ignition key making it harder to find the correct wires as well. However to combat this people started to install anti-theft systems in their cars. First it was third party systems but then these became incorporated in the cars design and are now pretty much standard. In addition to a normal key there is now electronics in the key which communicate with the car over radio to identify itself. So the electronics of the car will not allow you to start the car without the correct key in place and may even sound an alarm if you try. So it is no longer enough to just short circuit a few wires together but you need to trick the computer into thinking you have the correct key. This is still fairly easy but it means that car thiefs have to learn some basic electronics skills and some programming in order to make the tools required to hotwire modern cars. And it is expected that car manufacturers will soon start to incorporate some actual security measures like electronic signatures in these keys making it much harder to fool the computers.",
"As stated, old cars it was relatively easy. Gain access to the wiring off the ignition cylinder and complete the circuit, easy-peazy. New cars run near field authentication protocols or imbedded chips in the keys that need to match encryption in the ECU. So unless you can overcome that… there’s no hot wiring in that cars future.",
"It was pretty easy long ago or in older vehicles. Connect the ignition circuit, the one that completes the circuit for the coil/battery/alternator, and then connect the starter circuit that feeds power to the starter motor that initiates the system to those wires and it would start and run. [Three wires]( URL_0 ). Today's vehicles are much more complex and hot wiring one involves bypassing and/or feeding power to a lot more systems, some that are computer controlled and need an electronic signal from a computer chip in the circuit to work. Starting these involves completing a lot more than just the 'run' and 'start' circuits. Extremely difficult in most cases."
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ltt1mr | How does geothermal energy work? | and how does it compare to carbon emissions? | Technology | explainlikeimfive | {
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"Power plants all use the same principal, generate heat to produce steam to spin a turbine. Geothermal uses heat from in the Earth as that source of heat, instead of burning coal/gas. You run some pipes into the ground where there is natural geothermal activity, the water in the pipes pick up the heat and bring it to the surface where the steam is used to turn turbines and generate electricity."
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ltvnco | Is there any strategical or functional advantage to the shape of the B-2 stealth bomber? Why is it so geometrical? | Technology | explainlikeimfive | {
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"text": [
"I know this is slightly left of topic, but I'm a bas-relief sculptor, working mostly for coins. Once, I had to sculpt a stealth fighter for a coin series about planes. Bas relief relies on light and shadow to create the illusion of form where there isn't any. Modeling the stealth fighter was almost impossible because the angles didn't bounce light and shadow at all. The whole thing looked flat, no matter how deeply I sculpted it. It was the same principle as being invisible to radar, just in a visible light spectrum.",
"The shape is designed to be invisible to radar. Radar detectors send radio waves off and then listen for an echo. Your typical aluminum cylinder-shaped aircraft with a big tail fin bounces a lot of radar signals back and shows up clearly. The B2 has this unique shape to minimize that signal reflection. The geometric design bounces radar signals off at odd angles instead of back towards any detector. It’s also coated in a secret and fabulously expensive radar absorbing paint to further dampen any signal."
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ltw34a | If a gigabyte is 10^9 bytes, then why do common technologies use numbers like 32, 64, 128, 256 gigabytes instead of something like 100, 200, 500 to easily file into 10s? | What is the purpose of these seemingly arbitrary multiples of 2 | Technology | explainlikeimfive | {
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"text": [
"It's important not to mix up gibibytes and gigabytes. Colloquially we use the word \"gigabytes\" for gibibytes but one is base 10 and the other is base 2. 2^30 vs 10^9",
"In low level, computers don’t work in base 10, only in base 2 (binary, only ones and zeros). Because of that, storage also have to be designed and organized in blocks of multiples of 2, when you see something advertised as a gigabyte (10^9), it’s actual size is a gibibyte (2^30). It’s just called a gigabyte because modern humans think in base 10 and it’s easier to estimate what 10^9 is than 2^30. Some websites actually have disclaimers to clarify things when they sell you a product (I think there are such disclaimers on Apple’s website).",
"Okay, first there's a terminology difference. Traditionally in the computer fields people used the following definitions: - Kilobyte: 2^10 or 1,024 bytes - Megabyte: 2^20 or 1,048,576 bytes - Gigabyte: 2^30 or 1,073,741,824 bytes Once computers started to get really popular, in the late 1990's this made some people start to get grumpy about the situation. Those grumpy folks said basically \"Okay guys, the whole rest of science uses kilo to mean 1,000, mega to mean 1,000,000, and giga to mean 1,000,000,000. If you insist on working with numbers like 1,024, 1,048,576 or 1,073,741,824, you can't call them kilo, mega, and giga. You have to call them something else, how about kibi, mebi and gibi?\" So there are now two camps of computer folks. One camp agrees with the grumpy pedants and use \"gigabyte\" to mean 1,000,000,000. Your question says \"a gigabyte is 10^9 bytes.\" So you would be in this camp. But there's another camp. There are a lot of people in the field who prefer the older traditional usage, and will use the word \"gigabyte\" to refer to 1,073,741,824. The kibi / mibi / gibi prefixes sound a little silly, and they never took off in terms of marketing or advertising of computers and related products. For example, effectively all RAM actually has power-of-2 sizes, but I doubt you'll be able to find any RAM for sale anywhere that's advertised or labeled using \"gibibytes\". As to why they pick powers of 2, it comes from the number of possible patterns in some number of wires carrying digital binary signals. If you have say three wires, there are eight possible signals: 000, 001, 010, 011, 100, 101, 110, 111. If you want to represent eight possible values, it works great. However if you want to represent ten possible values, three wires is too few, but if you add a fourth wire and start counting combinations: 0000, 0001, 0010, 0011, 0100, 0101, 0110, 0111, 1000, 1001 -- that's ten -- but there are still some combinations left, 1010 1011 1100 1101 1110 1111. You'd need to then have an extra circuit to detect these \"extra\" combinations and have the chip do something else. That extra circuit has actual costs in terms of size, power usage, speed and money (not to mention extras design / testing). So designers instead try to match the sizes of things to the number of combinations available on particular wires, in particular powers of 2. If you think in binary, it makes a lot of sense. One billion only looks like a round number to us because we use a decimal (base-10) number system. To a computer scientist who thinks in binary (base-2) number system, one billion is `111011100110101100101000000000`. Which is very not-round, at least when you compare it to 1,073,741,824, whose binary representation is `1000000000000000000000000000000`."
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ltwyjo | Why does computer memory and storage capacities always double? ie 16gb, 32gb, 64gb, 128gb.... etc | Technology | explainlikeimfive | {
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"This is actually a question fairly like another question asked here just a couple of minutes ago. [ URL_1 ]( URL_0 ) I think the comments on that thread can answer your question as well ;) & #x200B; OK short edit. In addition to it being easy for computers to calculate memory addresses in amounts of 2\\^x, it's also simply easy to double it. Have 1 GB of RAM? Put in one extra and you have 2. Double the amount of chips per unit of RAM, and you go to 4, etc, etc.",
"Every time you add memory storage you add the ability to store an extra 1 or 0, that means you double the possible combinations that could exist before. With 1 slot: 0 1 With 2: 00 01 10 11 With 3 000 001 010 011 100 101 110 111 And so on"
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lu6t69 | How does a manual credit card machine work? | What the titles says. I mean I can imagine it creates a copy of the card with a paper but how is the money actually taken out? | Technology | explainlikeimfive | {
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"text": [
"Way back when, those credit card charge slips were sent to credit card companies. Some bookkeeper would go through those slips, and remove the funds from their user's cards. Then, the credit card companies would deduct their merchant fees and cut checks to pay the various merchants. It could take some time.",
"The imprint acts as evidence the card was physically present even if the transaction itself wasn't submitted for authorization when it happened. The merchant would record the card imprint and accept the risk the cardholder didn't have funds to pay for the transaction, and then later contact their card processor and give them the information from the card."
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lu9m7j | What exactly is the "Great Filter" theory, and how does it work? | Technology | explainlikeimfive | {
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"To explain the idea behind the Great Filter, I first have to tell you about the Fermi paradox. The idea was first brought up by Enrico Fermi, one of the scientist behind the creation of atomic bomb. Fermi pointed out that the universe was very, very big both in terms of size and age. There a re billions of stars in out galaxy alone and even if only a small fraction of them ever ended up developing intelligent life, there should be some intelligent civilization that had been around for a very long time and had enough time to visits every star in the galaxy. There are however no easily noticeable aliens around here. That means that something weird is going. Another physicist called Drake came up with a a way to quantify the problem. He basically summed up all the fractions involved. If only 1% of all stars in the galaxy have rocky planet and only 1% of those can support life and only 1% of those will develop life and only 1% of those will develop intelligent life and so on. Obviously we don't actually know the percentages but we can make guesses. If you multiply all those fractions and then multiply the tiny fraction that results with the number of stars in our galaxy that tells you if there should be spacefaring civilization out there. We are starting to get an idea of some of the numbers. We for example have found out in recent years that planets seem to be very common at least. One way to look at the whole problem is to imagine that to go from a star to an interstellar empire, the potential alien civilization needs to pass though a number of filters that take out some of them and allow others to pass. For example we might imagine that life is incredibly common but that the jump to intelligent life is really, really rare. So developing life would be a small filter that only diverts a small faction of candidates but developing intelligent life is a big one that stops most of them. Since there are no signs of an alien civilizations out there and from what we know about physics, it would be hard to hide evidence of one, we can imagine that at some point all potential alien civilizations pass though a number of filters that filter most of them out. It could either be a number of small filters that add up or a really big filter that catches almost all of them or a combination of those. We humans are already most of the way there to colonizing the galaxies. So it would be nice to assume that there was a great filter at some point in out past that we passed though successfully. It is a bit scary to imagine that a great filter is still ahead of us. The idea that plenty of alien civilizations make it to where we are now and almost all are killed of before they can reach Star Trek level of advancement is really scary. Since this whole thing first came up during the cold war, one of the popular filters proposed was that many advanced civilization kill themselves of with nuclear war or an equivalent. It seemed natural at that time to consider that a possibility. Currently people are eyeing some future tech that might go catastrophically wrong, like AI going skynet on us or nanobots going out of control or some bio engineered plague taking us all out. Those seem less likely scenarios. Especially the robot takeover suffers from the problem that if that was a common fate of civilizations we would expect to see interstellar robot empire out there in equal numbers to the biological ones they replaced. It only shifts the problem. There might be something ahead that we can't even think of yet that will kill us all. That is a really scary thought. Sci-fi writers have embraced this idea in various forms. A common theme is that one civilization came first didn't want any competition and thus periodically wipes out any civilization that reaches a certain point of advancement. It makes for good sci-fi but seems overly complicated to explain real life. (Why not wipe out all planets with life on them?) In any case as far as we know great filters are real. We don't know if we passed them all a long time when life first began on our planet and that life is extremely rare or when we first developed intelligence or when we avoided destroying ourselves with out technology (so far) or if there is something still waiting ahead that has a 99.9% chance of killing us all. Doing things like searching for extra-solar planets to see how common they are (apparently very), searching for signs of life on Mars and Venus (maybe) and looking at the history of life on our own planet and the intelligence of other animals gives us some clue to which numbers we should use for the stuff that may have filtered us out in the past. If everything we know of our past doesn't add up to a 1 in 100 billion chance, we may have to worry a bit more for our future.",
"The universe is huge. The observable universe, less so, but still quite huge. It's been around for quite some time. It is speculated that life probably existed before us. Why, then, have we not seen evidence of such life? We would expect to see evidence of any radio-using spacefaring life - especially a Kardashev-2 or -3 civilization. However, we don't see any. Why not? What barrier stands between primordial life and kardashev-2 civilization, which has prevented any alien race before us from reaching it? This barrier is 'the great filter'. It is possible that 'the great filter' is math, or language, or abstract thought, and we humans have already been lucky enough to pass it. It is possible that the great filter is nuclear weaponry, and we are still teetering on the edge of oblivion. It is possible that the great filter is something we have not yet discovered."
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lud9ho | How is it that software run ON operating system but not software and operating system are 2 independent programs running on the same resources? | Both software and the operating system use the same resources like RAM, hard disk, processor etc. Shouldn't they be 2 different programs that run on the same resources? How is it that software run on top of operating system when they are running on the same resources side by side? | Technology | explainlikeimfive | {
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"The whole notion of \"programs\" is something operating systems create. Without an operating system there's no such thing as \"2 different programs\". The CPU is just hardcoded to load some code from a fixed location on boot, and start running it. Back before modern operating systems, you had unlimited access to the machine. There was nothing above your code, so you could do whatever random thing you wanted with the hardware, sometimes up to doing physical damage to it by commanding it to do something it couldn't tolerate.",
"They are not running on the same resources. An application is running on a the subset of resources that the operating system have assigned to it while the operating system itself can run on all the resources. This is why we say that the application runs on the operating system."
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luklxw | If it gets leaked so often, why do game developers put files in a game before they release them? | Like when they put data files in a game, then data miners find the information and leak it. Can't they just copy the files onto a separate server that the public can't access and then move them over so the files don't have to be planted there first? Is this out of convenience or is it something technical I don't understand? | Technology | explainlikeimfive | {
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"Less data to have to transfer at launch. If you literally just had 100% digital downloads for everything with no pre-downloaded files, that's a lot more data that needs to be uploaded to thousands/tens of thousands/hundreds of thousands of people at the same time. And bandwidth costs money. And at the end of the day, the leaks rarely are of a nature that are negative - if anything they'll drum up even more interest in the game.",
"There are a variety of reasons you might do this. Bandwidth issues have already been talked about. Some others are: - Your company or the platform you're on has some kind of limitation to how you can do patches that mean you *have* to release the content early. You can see this in Genshin Impact - almost 4 weeks ago they released patch 1.3, a big content patch that was going to contain 3 2-week long premium gacha banners. They only announced two of them, because I guess they wanted to keep the third a secret or something, but because the company has a 6 week patch cycle, they had no choice but to add the third character to the game files in the original 1.3 patch, cos that banner is going to be the 5th and 6th weeks of patch 1.3. - You actually want dataminers to find the stuff to generate hype about new content so you put in a few little hints like emotes or sprays or something but not the full content. - The game files are built in such a way that would make removing the content really difficult and not worth the hassle. Skyrim is an example of this - the game files include loads of content that was cut from the final release, but instead of being deleted were just hidden. Fallout 76 probably has the same thing, since it's made on the same platform, and that would be an example of a game still receiving patches but that also has dataminable content."
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luqp0n | If an electric car plugs into an outlet that takes its power from coal or gas, isn’t that just trading one pollution for another? | Technology | explainlikeimfive | {
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"Yes, but that's not a bad thing. Even in an old coal-fired plant the conversion is much more efficient than in an automobile engine, all the pollution is in a fixed place where it can be treated, the least efficient plants are closed every year, and eventually it might be replaced by more renewable sources. All these are better than their gasoline engine alternatives.",
"1. The total amount of pollution is less, because even if the electricity is 100% non-renewable (see pt 3 below), huge power plants are much more efficient at getting energy from fossil fuels than a combustion engine can possibly be. A gasoline engine turns less than 30% of the fuel's energy into usable work. With electric cars you get more miles per fossil fuel burned. 2. That smaller amount of fossil fuels is being burned at power plants. Power plants generally have better scrubbing/emissions control than cars, have tall stacks so the pollution is never at ground level, and are releasing the pollution in remote places rather than where cars (and people) are. Downtown/freeway smog avoided. 3. In reality the electric power is very rarely 100% non-renewable. So it's already better, and will automatically improve even more as renewable sources become more widely used. Source: My MSc thesis on hydrogen fuel cell vehicles. The hydrogen for these is made from methane (natural gas). A LOT of people have OPs question, and it's a good one.",
"Yes, but it's easier to shift the grid to renewables and reduce power plant emissions than it is to do the same with 270 million separate internal combustion engines.",
"It is. But there are some aspects that still make them \"better\" than ICE cars in terms of pollution. 1. you take the source of the pollution away from the cities (where people live) to more remote locations, therefore fewer people are exposed to high levels of pollutants 2. As electricity production becomes more sustainable, the cars will automatically mirror this improvement if they're electric.",
"Even if the *entire power grid* was driven off of gasoline, which it obviously is not, industrial engines are easily twice as efficient as your corolla. This means that the same energy requires half the pollution. Combine that with regenerative braking and no engine idling, and you can see why electrics make for efficient vehicles *even in heavily fossil-fueled grids*.",
"Yes, but a good portion of electricity is renewable these days and becoming more so every day. And even if there is pollution, it’s not spewing out of the back of a cars directly into populated areas.",
"We could talk about how much more efficient an electric motor is vs an internal combustion engine but others have already gone there. Instead, remember that a gas car will burn the same amount of fuel per mile for as many years as it lasts. Not only does an electric car start as the greenest option, in all but the most extreme cases, an electric car actually gets cleaner over time as the grid is cleaned up.",
"In the UK you can chose the company that supplies your energy. Some of these companies only use renewable sources.",
"But COAL isn’t the only thing that Gives your Electricity. HYDRO/SOLAR/WIND are Green energy. In the Eastern part of the world , Hydropower is the Main source of electricity to houses. So Cars can go Green again. But buring coal for Electricity too can be greener because even though the Burn’t pollution is Treated at once the emission starts. Also Cars that use petrol have Sulphur/lead/CFCs/Greenhousegases too. So ElectricCars are the Future",
"Yes, but it's doing it in a more efficient (and less polluting way). Coal and gas plants are highly regulated and burn cleaner (per mile driven) than your tiny car's engine. And it's cleaner to move electricity through wires to your car's battery than to haul gasoline from refineries to gas stations. EVs are not ZERO pollution. But they're a whole lot less than combustion engine cars on a mile per mile basis.",
"Gasoline powered cars will always remain as gasoline powered cars for their whole life. Electric cars will use whatever fossil/renewable power mix is supplying their local grid. Electric cars are able to move from a 100% fossil fuel grid, and then as that grid upgrades to become renewable, then eventually that same car can leverage its local 100% renewable power grid. Even if an electric car is only ever powered by coal power plants for its whole life, it still ends up using less fossil fuel over it's operational life due to the super high efficiency of coal power generators, as compared to gasoline powered car engines, but that has been said elsewhere in the comments."
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luyss9 | what is the advantage of being in a location with a few wireless access points over one where you have a lot? | Technology | explainlikeimfive | {
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"Wireless networking uses radio waves within a fairly narrow band, and the range of channels is such that there are only about three that don’t overlap at all, and 11 total with some amount of overlap with their neighbors. The problem this causes is that someone trying to talk to one access point on the same or nearby channel as another can interfere and be interfered with by people talking to that other access point. It is like trying to hold a conversation in a crowded room; because it is crowded you are necessarily wedged closer to other conversations and start talking over each other. Having a bunch of talking in the same space actually interferes with communication overall."
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lv0rdb | How do touch-less thermometers work? | I feel like they aren’t nearly as accurate as you would think? At my work one day I was read 94.7 and I know that’s not true. | Technology | explainlikeimfive | {
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"Every object in the universe that isn't at absolute zero glows. This is called black-body radiation. Something has to get quite hot, about 1,000 F, to glow in the visible spectrum of light. But, things that are about 100 F will glow in the infrared range. The thermometer is detecting the infrared radiation that your skin is putting out and uses that to determine what temperature you are.",
"It’s just an IR thermometer. The accuracy is likely fine, it’s just that your forehead may run cooler than your mouth, arm pit, ear, or butthole. That said, it needs to be used properly, when taking the reading it needs to be perpendicular to your forehead. It’s likely your reading was user error.",
"Just to touch in the accuracy part of your inquiry, it's measuring your skin so if you just came out of the cold and weren't wearing a hat your foreheads temp will be lower. This isn't to say it won't tell you if you have a fever since fevers will still radiate stronger through your skin but in reality screening stations should wait 5 minutes at least before testing you. These types of thermometers also require calibration over time so it is possible it's off. The one I own was off by 2.75 degrees. Basically you take your temp with an oral and with the contactless and you can adjust the contactless by however many degrees it's off."
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lv6bti | - When tv shows replay footage from several years ago, it looks grainy and incredibly old. But when watching it those years ago, I didn't notice this. Is there a reason by why this is the case? | Additional info, I was watching something on TV today which replayed some live footage from 2006. But the clarity of the footage seemed like it was recording 10 years before that point. | Technology | explainlikeimfive | {
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"Yes. Old TVs don't show defects in the image as clearly as modern ones. Also, analog signals lose quality when recorded.",
"Couple of reasons Back then the quality of the footage was the best it could be, you didn't have anything to compare it to Older CRT TVs blurred the image a bit so that the low resolution and colour compression didn't looks so bad Most modern TVs do a very rough job of upscaling old tv to match their native resolution, which tends to highlight all the problems old CRTs were trying to hide Finally, old tv footage would have been archived to tape, and will have lost some quality during the transfer, and possibly more while sitting in storage for years"
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lv92k4 | What is threat modeling and how does it work for cyber security companies? | Technology | explainlikeimfive | {
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"Threat modeling is making a model of your security measures so that you can identify how various different threats might attack you. If you compare it to a physical scenario it is like going around looking for how different people might possibly get through your fences and doors. If you find out that some people might have an easy time gaining access to one area you have to find out what potential harm they can do there and if they can get access to other places where they can do more harm. So you do the same thing but in a digital sphere. So you find who can access which areas on your computer system and what is preventing them from getting further access. The objective here is to both find flaws in your system which people might exploit so that you can fix those flaws but also to better react whenever you do discover an attack."
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lvf0aw | How does a computer generate sound and music that then transfers it into headphones that then play it to our ears? | Technology | explainlikeimfive | {
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"Sound is vibrations in the air. The faster the vibrations, the higher the pitch. A computer is sending a very complicated digital signal to the little speaker in the headphone. That signal tells an electromagnet when to turn off and turn on, which causes the headphone to vibrate, which makes the air around the headphone vibrate, thus producing a sound that you hear in your ear. So the short answer is, it's all 1's and 0's. Lots and lots of them. Millions of them for every second of music.",
"Audio is analog, or in other words it has infinite values between 0 and 20k Hz, Hz is a measurement of how many times something happens in a second, so a sound at 20k Hz \"pulses\" 20 thousand times in one second. Computers are binary, which means they deal exclusively with on and off values. With enough binary bits played in one second you can create the illusion of an analog signal for sound. At some point those bits need to go through a DAC, or Digital to Analog Converter, so the computer signal can actually become an analog signal to be used on speakers."
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lvgp7l | Why Aren't There Many Bluetooth Mobile Games? | It isn't a new technology and was used in Nintendo DS to play multiplayer offline. What is the reason behind not making more mobile games or apps that have this technology so you can do more when you aren't connected? | Technology | explainlikeimfive | {
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"Much lower bandwidth, lower range and ability to propagate between walls, potentially more security concerns with having two devices paired together via bluetooth, less stable, and more cumbersome to start the connection as compared to wifi. The only benefits that Bluetooth has over wifi are that it's much lower power, and the protocol has built in transfer protocols for things like audio that can make very specific use cases more efficient and easy to implement."
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lvnttm | Why can't you just program a robot to click the "I'm not a robot" sign? | Sorry for my bad english, i hope y'all can understand it. Have a nice day! | Technology | explainlikeimfive | {
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"they totally can, i found a video on youtube where some robot did exactly this the part that is supposed to catch them is the capcha that follows",
"You can. And you'll be getting whether or not your not programming is better than Google's bot detection programming. My money is on Google heh",
"You can sure, but the button is looking for signed the thing doing the clicking is a predictable robot rather than an unpredictable person.",
"Usually there are 2 parts to the \"I am not a robot,\" button. The first part is the checkbox. This is a little more than just a checkbox. From the second the page loads, it's capturing mouse movement data along with some other metrics. When you actually click it it analyzes this data to see if you're mouse moved more like a robot or like a human. If you pass, then that's usually it. If you fail this (clicked too fast to capture meaningful data, you're IP address is sketchy for some reason like a VPN, you actually are a robot, etc.) then it will send you to the \"click all the stoplights,\" to validate you actually area human.",
"Because it does more than just detect whether you clicked the box. It measures how you move your mouse, the time it takes you to click, all kinds of things that are hard to fake since humans have so much more random movements than anything less than the most sophisticated bot.",
"I’m a designer, not a programmer, so I include captchas in my programs but I’m not qualified to discuss how this all works in great detail. In theory, it can be done, but robots as we have them now rely on being “taught” the algorithm required and while a robot could learn the necessary algorithms to beat one specific captcha then a thousand and then a million captchas and eventually beat specific captchas, anti robot captchas like choosing specific objects from visually noisy captchas are working hard to beat the bots so their technology is always being updated and refined. This is why generally across the web captchas seem to be getting harder and more frustrating for humans to solve.",
"You can. Then the people making the capcha will come up with something that defeats whatever you did. Then you can try to work around whatever they do. Then they can try to beat your workaround.",
"When you click the ReCaptcha button and you're not prompted to complete an image captcha, it's actually because the browser (and by extension the website) has *already* determined that you aren't a robot. When you first get a new computer (or you clear your cookies) you often will get a ReCaptcha test. Nowadays, technology running in the background allows your browser to store the fact that you completed a Captcha before. It then sends this information to websites that ask for it. Check out [this great Tom Scott video]( URL_0 )."
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