q_id
stringlengths 6
6
| title
stringlengths 4
294
| selftext
stringlengths 0
2.48k
| category
stringclasses 1
value | subreddit
stringclasses 1
value | answers
dict | title_urls
sequencelengths 1
1
| selftext_urls
sequencelengths 1
1
|
|---|---|---|---|---|---|---|---|
hzc206 | Computer RAM | Quick Question: I am getting a PC built and i ordered two sticks of 16 GB of Ram (Total of 32). The sticks were backordered, so we switched to 4 sticks of 8 GB of RAM. I was told RAM is like a highway and the more sticks you have, the more "lanes", better performance. Can someone tell me if this is true? What are pros and cons of each. I will share specs of my build if you would like. Thank you. \-Tony | Technology | explainlikeimfive | {
"a_id": [
"fzi04un"
],
"text": [
"In short, yes it's true. This is about channels, which is how many simultaneous access points your cpu has to your ram. This all depends on the ram sticks and the motherboard to all be compatible with each other. Read your product manuals. Putting a 4 stick kit into a dual channel rated motherboard will probably become dual channel. You still get all the memory, but not all the speed. Mind you this speed increase isn't really the speed of one channel times the number of channels. It's a much less dramatic increase, but that's not to say it's not noticeable. In terms of pros and cons, con is your motherboard might not be able to handle four channels and pro is the speed boost."
],
"score": [
7
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
hzdhke | Why does Laptop/Smartphone battery get worse overtime? | Technology | explainlikeimfive | {
"a_id": [
"fzi7ii1",
"fzi962u"
],
"text": [
"Smart/Laptop batteries are currently Lithium Ion (Li-Ion) or Lithium Polymer (Li-Po). Now to give an ELI5, There is something analogous to needles inside the batteries that change direction when you provide a voltage difference (basically when you connect them to a power source or when you are using them). The 'needles' go from end A to B while charging and ends B to A when discharging. They are very flexible at first but with more and more charging cycles, they lose their flexibility and they can't go to the extreme ends anymore. Since the extend of their 'bending' signifies how much charge they can store, the less they can bend in the future, the less charge they can store. Also, the 'flexibility' degrades faster the more extreme the 'bending'. That's why it's recommend to not charge modern batteries beyond 80% and not to let it drop below 20-30%. Your battery will last longer with multiple shallow discharges instead of lesser deep charges like 5-100%.",
"There are two sides in a battery, (+) and (-) Using a battery grows tiny crystals inside of the battery on one side. As the distance between the crystals and the other side grows shorter, there is less and less potential energy between the two sides. When the crystals get long enough, the battery shorts, and dies. Edit: there are LOTS of types of batteries, this doesnt apply to all of them."
],
"score": [
13,
5
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
hzg59f | How do rovers sent to planets or outer space able to send data to Earth with such ease ? | Technology | explainlikeimfive | {
"a_id": [
"fzio0b5",
"fzipjyo"
],
"text": [
"Same principles as RF (radio frequency) transmission in your car's radio and your cell phone. Just at higher wattages and in chunks of spectrum well suited for long distance transmission. We also have a series of relays/orbiters that can pass along signals and the [DSN]( URL_0 ) (Deep Space Network).",
"It's not with ease, they have giant freaking dish antennas pointed at the planet with giant freaking amplifiers delivering several microwave ovens worth of power straight at the planet. (You might think that's not a lot of power, but it's a crazy amount of power for what is effectively a Wi-Fi signal) And the spacecraft receives less signal than the amount of noise caused by the heat in the atmosphere, so the transmitter has to send the same bit several times and the receiver has to average them out to cancel out the noise. In the other direction, the spacecraft sends out such a weak signal that the same giant antennas are needed just to be able to receive enough of it. And they only have a certain number of giant antennas so they can't even control all the spacecraft all the time. By the way, most Mars missions are relayed through a satellite on Mars called the Mars Climate Orbiter. So the rovers themselves don't need as much fancy radio gear."
],
"score": [
7,
3
],
"text_urls": [
[
"https://en.wikipedia.org/wiki/NASA_Deep_Space_Network"
],
[]
]
} | [
"url"
] | [
"url"
] |
|
hzgwtf | Who is the owner of internet? | Technology | explainlikeimfive | {
"a_id": [
"fzit8jg",
"fzitrv9",
"fziswg0"
],
"text": [
"No one. The internet is just a web of connected computers that provide content to one another. When you visit URL_0 , your computer connects the server farm that hosts the URL_0 content - Reddit owns the content, and leases space from whomever owns the servers that content lives on. Same is true for any website. ISPs will own the physical connections. They lay the copper or fiber optics that connect hubs together, and the hubs will own the copper or fiber optics that connect to server farms or end users. Now, that said, there are corporations that _steward_ the internet. ICANN controls how TLDs are allocated (the url that you type in) and IANA controls the IP address allocations and DNS servers that allow IP addresses to be linked to URLs. They don't _own_ the content and they don't own the connections themselves, but they set the standards on how everything talks to each other.",
"That's like asking \"Who owns New York?\" Lots of people own lots of things and the combination of those things is labeled \"New York\". The label doesn't really connect those things in any way they weren't already connected. You own your house, and your computer stuff. If that stuff is on the Internet, that part of the Internet is owned by you. OK, that's a small part of the Internet, but your house in only a small part of New York (if you live there).",
"No one individual or group \"owns\" the internet. You might as well ask who owns the international power grid."
],
"score": [
28,
22,
5
],
"text_urls": [
[
"reddit.com"
],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
hzlpyc | Why does turning something 'off and on again' fix it? | Technology | explainlikeimfive | {
"a_id": [
"fzjtzch",
"fzjparm",
"fzjpc0d"
],
"text": [
"I think it was on reddit that I read an explanation comparing a PC (or other device) to an orchestra, here’s my slightly sleep deprived version: When then device is running smoothly the orchestra is in time, playing a symphony. Over time some parts of the orchestra slip out of sync with the conductor, so the music falters. If you ask the conductor to get that area of the orchestra to re sync then you risk losing other areas and everything gets discordant and messy and slow / it completely falls apart. By turning it off and on again you allow everyone to re-sync with the conductor and everything works together again nicely.",
"Turning things off turns off all processes going on. When something problematic is happening, or perhaps a glitch it will get rid of it, until you repeat what causes that error in the first place. Turning things on also allows for any updates a software installed to finalize. This can prevent issues and cause the device to run smoother.",
"Honestly it's because software has bugs and sometimes it's easier to just start over than to try to locate the very specific problem and fix that"
],
"score": [
13,
6,
5
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
hzscua | How do radio stations transmit text to your car? (Example: the song and artist name showing up on your car’s screen.) | Technology | explainlikeimfive | {
"a_id": [
"fzl1la0"
],
"text": [
"The signal broadcasted for an FM transmission is actually pretty complicated. Not only do they transmit the audio for a left/right signal, they also send a mono signal, an RBDS signal (Radio Broadcast Data Signal), traffic data etc etc etc. The picture at URL_0 shows all the different data being transmitted. The song data and station is broadcasted in in the RBDS signal of the FM transmission."
],
"score": [
6
],
"text_urls": [
[
"https://en.wikipedia.org/wiki/FM_broadcasting#Other_subcarrier_services"
]
]
} | [
"url"
] | [
"url"
] |
|
hzwptc | Why are well-known pirating sites not taken down? | Why are websites like MyFlixer and Soap2Day not taken down, despite it being well known they stream movies illegally? | Technology | explainlikeimfive | {
"a_id": [
"fzlpq17",
"fzlqvna",
"fzn4hw7"
],
"text": [
"Probably becuase their servers are spread over several countries. International police cooperation isn't a common thing. Imagine Sony finding out that an illegal stream is offered by a site having their servers in Canada, Mexico, The Netherlands and Russia. They'd need to file law suits in all of these coutries. At the time when they have filed them and the local governments took action against the operator of these servers, the site has been renamed, moved to another location or just deleted that very certain thing Sony was sueing about, causing charges to be dropped in maybe one or two countries. Afterwards they will re-upload it at another URL or make it available under some different name.",
"Or like pirate bay (atleast how I understand) They dont physically have the pirated software, music, games etc. They only keep links to a torrent. If the torrent disappears or the torrent host site is taken down. That link will be removed from the database. Again this is how I think it works",
"Copyright is a law that applies within a specific nation. There is no internationally agreed to standard for copyright law, no is their a central organization responsible for enforcement. Most Pirate websites are located in countries that don't have copyright laws, or at least laws that aren't enforced. International police cooperation is difficult at best. Some countries like the US + Canada have treaties in place that define how this works, but the US can't enforce it's own copyright laws on countries like Grand Cayman, Russia, China, Taiwan, etc. So the US can send all the take down notices it wants to the webhosting providers in those countries and they can just ignore them or tell the US to pound sand. The other problem is that Pirate websites are like plague rats. You take down one, and 10 more pop up with 48 hours to take it's place. The US spent tons of resources to take down the Pirate Bay. It took years of legal work and political pressure to get the operators prosecuted, and the site just changed hands and is still up today. So the US has kindof given up in a lot of ways because it just isn't worth the hassle. Another option is to block access to the sites at the border. Essentially filtering what content users can access on the internet. Some forces in the US government and industry would like nothing more than to set the Great Firewall of the USA but political pressure prevents this kind of filtering from being implemented because of concerns over censorship. The industry (streaming, movies, etc) has finally started to wake up to the idea that the reason a lot of people pirate has nothing to do with theft, it's purely a matter of convenience. As they offer more and more reasonably priced streaming services with on-demand content piracy decreases. Or you can do what the music industry has done and lobby to put in a legal framework that allows them to prey on Youtube content creators and steal their ad revenue without any recourse..."
],
"score": [
27,
8,
4
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
hzxh4s | what is inside a cpu, and how does it perform thousands of calculations a second? | Technology | explainlikeimfive | {
"a_id": [
"fzlsx0g",
"fzlx4bk",
"fzm0595",
"fzm4xr0",
"fzm98pv",
"fzo0z0b"
],
"text": [
"Transistors, basically just lots and lots of transistors. A transistor switches electrical output. So it can switch from on to off or a 1 to a 0. These then make up logic gates. They have multiple in puts and one output. So if both inputs are 1 the out put 1. You get various types AND, OR, NAND and NOR. These are put together to give various outputs depending on the input. Like a calculator. So then you get CPU commands which translates what you want to do say maybe Add 2 numbers, and it then translate this in to 1's and 0's for the cpu to work with. It really basic on the lowest level but as you add more complexity to it can get real confusing petty quick. Basically it's magic.",
"Try millions. If you're seriously interested you could try watching Ben Eaters series on Youtube. [ URL_0 ]( URL_0 ) Its extremely well thought out and programmed although long.",
"Inside a CPU there are billions of transistors, generally configured into NAND gates. Transistors are Hyper-Faster-faster-super switches that are a few hundreds atoms wide and can commute billions of times a second. But the internal clockwork of even a basic 1950 CPU is complicated to understand even to the ones that have experience in computer hardware. You can try to think of a CPU like a player piano or automatic piano with a crankThe roll of paper contains the code to be executed.When you spin the crank half a revolution, one beat of the score is played, and when you complete a revolution another beat is played (this is the clock of the CPU)Now you start to spin the crank at a fucking 4.2 billions revolutions per second and you are playing a lot of notes all of a sudden. The piano will get really hot from all that movement and friction so you better be pointing a large fan on it. If you want to spin the crank faster, you should consider buying a large water hoose and drench that piano in water at least while you are spinning the crank.",
"I'll answer the first part. Although, transistors are the correct answer, it's probably not the answer to satisfy your curiosity. CPU chip basically consists of glass (~~silicone~~ silicon), that has been pumped with specific impurities in just the right places to give it desirable electrical characteristics. As a result - in some places silicone can conduct electricity, in others not, and in some places only conduct electricity under specific circumstances. Besides that this glass is also etched so that conductive metal like copper can be poured into it which gives the chip an electrical wire structure. Using these and other methods more complex structures such as transistors and many other necessary electrical components are created in the chip.",
"Electricity can be tough to ELI5. Sometimes it's easier to think of water flowing through pipes. Imagine a water pipe hanging horizontally, like on a wall or from the ceiling. This pipe has dozens of pipes sticking out the bottom of it, which can be opened or closed by valves. These flow down into other pipes, and they can crisscross and flow into little pools or tanks, or larger pipes or smaller pipes, all the way down to the floor. It looks like a mess, right? But you know that water flows from the top pipe into the other pipes, and by turning certain valves, you can get the water to flow to different places. That much should make sense, even if you can't follow the flow through the entangled mess. If you open/close certain combinations of values, water can fill certain tanks or pools along the way. Some of these could be attached to a water wheel or some other object that reacts to water flowing. This is how electric circuits work: electrons \"flow\" through conductive wire, like copper, and certain special materials can sense and control this flow, maybe able to turn on a light. In a CPU, this is happening billions of times over minutes or seconds with tiny \"electrical valves\" called transistors. You don't need to understand how a transistor works, but it's like a water valve, like a faucet at your sink, for electricity. On a computer chip, you have power from the wall, which comes from a power plant. This is the top pipe in the water pipe picture above. Without the \"power,\" the CPU has no electricity to calculate with or measure. Computer software performs calculations. It translates instructions from code or from your interactions with the computer into very basic building blocks. Essentially, it turns language into a series of \"yes\" or \"no\" questions for the computer. To ask the CPU these \"yes\" or \"no\" questions, it turns a series of these valves open or closed, and \"water\" (electricity) begins to flow. Once it flows, the \"water\" flowing through those \"pipes\" will have flowed to a particular pipe or a particular tank, and the computer software reads it, then translates it back to your monitor so you know what happened. Of course to create the level of complexity we see with a full modern computer this machinery would have to be extraordinarily complex, and it is. You need billions of these \"water pipes and valves\" to represent the information you expect the computer to do, like addition and subtraction, and displaying letters and numbers and colors on the monitor. It has to do all of that by electricity flowing through little circuits and measuring where that electricity goes, and sometimes how much of it goes there.",
"Before we had CPUs, we had devices we called \"electromechanical\". Ever seen an old jukebox, the kind that has records inside? Those are very complicated machines but don't have a computer inside of them! Even before we had electricity, we had devices that did computer-like work. For example, in the 1800s Ada Lovelace and Charles Babbage worked on a fancy calculator. Today's CPUs are just REALLY tiny versions of the work that started there. So how it works gets sort of complex, but it all comes back to switches. Just like light switches. Turn the switch on, and electricity flows through it. Turn the switch off, and electricity doesn't flow through it. Non-electric machines didn't use electrcity, they used gears and shafts that moved when you flipped a switch. Hundreds of switches were carefully connected so if you flipped one switch, it interacted with all the others in predictable ways. Electromechanic machines (like the jukebox) are just like that. When you push buttons, electricity makes motors move that turn gears. Those gears flip switches, and that makes other motors turn, and so on. It's very complicated, but fun to watch! CPUs and other kinds of computer circult use transistors, which are ultimately microscopic switches. Over decades, we played with this concept of switches and found a lot of neat ways to arrange them. We gave them silly names like \"latches\" or \"flip-flops\". We figured out we can use those arrangements to make more useful things, like an \"Arithmetic Logic Unit\" or ALU. For that to work, we have to say, \"flipping the switches this way is how we represent numbers\", and \"flipping the switches that way is how we tell it whether to add or subtract\". There are some switches called \"outputs\" that will turn on or off after we set number switches and whether to add or subtract. But the point of an ALU is you give it two numbers and it will do math and give you the result as a number. Neat! If we wire up a lot of light switches and light bulbs the same way as those \"circuits\", we can operate a very slow \"computer\" by turning switches on and off in patterns. That's what's happening inside your CPU at a very small scale. There are literally billions of tiny switches inside of it, carefully arranged to do exactly the right thing if you flip them in the right order. The CPU has \"input\" switches that tell it what it should do next, and the result shows up in the \"output\" switches the rest of the computer is connected to. There are millions of steps to go from \"here is a picture file\" to \"the picture is on my monitor\", so forgive me if I don't walk you through an example! How's a CPU go so fast? Well, that's a little hard to answer but I'll try. One of the switches the CPU listens to is attached to a crystal. Some crystals vibrate when we charge them with electricity. The neat thing is they always vibrate at exactly the same speed. So we figured out how to make a device we call a \"clock\". It has a crystal, the crystal gets electricity, and there's some fancy wiring that turns the switch on and off every time the crystal vibrates. If the switch is off, the CPU isn't \"listening\" to its other switches. That's when all the things inside the computer set up all the switches just how they want. When the clock turns on, The CPU lets electricity in through switches, and the patterns of the ones that turn on make it do things. The end result is a bunch of other switches on the other side turn on or off. That's the \"output\". Clocks are very fast. Most computers today \"tick\" more than 2 billion times per second. The only reason they can't go faster has to do with some weird science. All that electricity makes heat, and it takes more electricity to stop the CPU from melting itself. At some point, the CPU makes so much heat we couldn't possibly cool it. We used to be able to deal with this by making the little wires connecting all the switches smaller. But they are so small now, even weirder science happens. Think about a wire like a \"lane\" that electricity goes down. If the lane gets too small, it's hard for the electricity to stay in its lane. If we make the lanes much smaller than we make them right now, that happens a lot. Since everything depends on the switches being wired together perfectly, having electricty go in the wrong lane breaks the entire system. So we're currently a little stuck in terms of making them very much faster. We're working on it, though. We usually find a way."
],
"score": [
125,
22,
22,
7,
6,
3
],
"text_urls": [
[],
[
"https://www.youtube.com/playlist?list=PLowKtXNTBypGqImE405J2565dvjafglHU"
],
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
hzxx11 | Why does high frame rates look fine in video games but tend to feel “weird” in normal videos (movies for example) | Technology | explainlikeimfive | {
"a_id": [
"fzlvny1",
"fzm0i49"
],
"text": [
"It’s a subjective thing to say it feels weird in television. If I had to say why, I would think because in games, a high refresh rate allows you interact more effectively/quickly than with lower frames. With tv, there is no interaction so image quality is of higher importance. It isn’t normal for tv shows or movies to be higher than 24 or 30 frames per second, so 60fps or 144fps might look “weird” or unconventional.",
"Probably the same reason soap operas look cheap and phony, even though their lighting is a lot closer to real light than movies'. You are just not used to it."
],
"score": [
8,
5
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
hzxylh | Trains seem like no-brainers for total automation, so why is all the focus on Cars and trucks instead when they seem so much more complicated, and what's preventing the train from being 100% automated? | Technology | explainlikeimfive | {
"a_id": [
"fzlvh3w",
"fzlv5v5",
"fzm0z2l",
"fzlvsrn",
"fzm05tc",
"fzm9g64",
"fzm8uk4",
"fzm5jph",
"fzm8spu",
"fzm5pah",
"fzm9rc6",
"fzm11uw"
],
"text": [
"The simplest answer is: trains have already been hugely automated, with not much noise and publicity. They still have humans for oversight, since you can only have a fully automatic train on a track that never intersects with other roads, is inaccessible to pedestrians, and where all the trains are on the same automated system. (Such as airport shuttle trains and some subways.) Not all traffic can be changed from cars and trucks to trains, though. That's the next step.",
"You only need one operator (or one small team) for a huge train carrying tons of people or cargo. And unlike a car, a human is pretty capable of operating it safely except in very rare situations. In contrast humans crash cars and trucks all the time. The cost of *not* automating trains is low, and the benefits of automating are low. There are also big risks to developing the automation and laws requiring human operators, these are the same challenges as trucks, but due to how few humans you need to operate a train it’s just not as worthwhile to fight against these obstacles. Like cars and airplanes, there is modern tech that helps humans drive trains safely though like electronic warnings and communication.",
"Since a single train can carry hundreds of passengers, automation doesn't bring as much improvement in efficiency. Trains are efficient by nature, and cars are inefficient by nature.A train with 100 passengers has already reduced the cost of driving by 99% compared to a car with one passenger.",
"Trains are already automated as much as can be expected. When hauling hundreds of tons of cargo or people you really want a person present to handle anything unexpected. Compared to the revenue generated by the train the cost of the train driver is not big enough that it makes sense to automate his job further then it already is. It is a similar issue with airplanes where autopilots is now capable of doing everything a pilot is normally doing but you still need pilots on hand just in case. However for truck and cars the cost of a driver is quite a big part of the overall expenses because they carry so little cargo. It is also much harder to make autopilots for road going vehicles then for trains and aiplanes so this is just something that have been started being possible now. But even if we are able to automate trucks and cars it is very unlikely that we can automate all the tasks. But it might be possible to reduce the number of drivers needed to run a fleet of trucks or taxis.",
"Trains cannot go door to door. If all trains magically changed into being fully automated tomorrow (from which we aren't too far off, anyway), they wouldn't be able to do anything new in comparison to what we already have today. We still need the trucks.",
"Because its really hard to mark up trains for ridiculous profit and sell them on high interest payment plans to teenagers. When you build a train there's usually a whole process of legislation, committees, boards, and people invested in getting the best value out of the transaction. You have to invest in a lot of infrastructure for trains, which means you have to deal with local governments and all kinds of stuff. Our transportation system wasn't designed around efficiency. It was designed around profit. Automated cars are an extension of that system. It way easier to make a shitload of money selling you a fleet of automated cars than a train because the cars use public infrastructure you don't have to invest in. If you're a business, you're thinking about how to maximize profit, and the profit potential for a system you can sell at both the enterprise and consumer level is way more than a system you can only sell at the enterprise level.",
"The [Vancouver Skytrain]( URL_0 ) is one of longest driverless train systems in the world. It’s been driverless since it’s opening in 1985. Why there aren’t more completely driverless systems is a bit of an open question.",
"What’s stopping trains being 100% automated? [Rumsfeld’s Unknown Unknowns]( URL_0 ) There are things we know might happen, and we can plan the automated response. There are also things that we don’t yet know but we can plan an automated response all the same. A little bit of logic and the automation can make a measured response. But the real world is always ready to surprise us, and something entirely unknown can happen, and at this point the automation needs to refer back to a human to make a new decision. Trains on tracks, especially if fenced from the real world run a very fixed and predictable path, so automation rules are relatively simple. You control much of the environment, so limit the unknowns. Roads have so many more variables that need rules and so the number of unknown unknowns is significantly higher.",
"A lack of incentive is a big reason. The conductor is a very small part of the expense of operating a train. Making a fully automated train would be expensive with minimal upside.",
"There are many trains already that are totally automated, and cost of drivers relative to load carried is lower.",
"Look up the US auto and oil industries lobbying against mass public transport in the early development of western metro areas like Los Angeles. The city planners had envisioned mass public transit but they lost out to big money from industry.",
"I mean if you look at the DLR in London, you could argue that its part of a transport system that is popular increasing in popularity (though this may be scuppered with Covid-19), is mostly automated and is a train, so they exist. I think the problem is it was developed to put life into the area. Where a lot of cities would need significant disruption to have an effective system to put in place. However these systems do exist and I imagine will increase in popularity as time goes on."
],
"score": [
1404,
216,
60,
20,
10,
9,
7,
7,
4,
3,
3,
3
],
"text_urls": [
[],
[],
[],
[],
[],
[],
[
"https://en.m.wikipedia.org/wiki/SkyTrain_(Vancouver)"
],
[
"https://en.m.wikipedia.org/wiki/There_are_known_knowns"
],
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
hzyjwp | How are humans so much more energy efficient than robots? | A human can eat two 1000 calorie meals (around 2 KWh) and then move around all day and run its brain and all other systems. A robot needs a lot more energy to perform the same tasks even if it's plugged in and doesn't need to carry a battery. There are sophisticated robots now that are as agile as humans if not more (like Boston Dynamics' Spot) but they need 2 KW every hour just to do what a human can do with 2 KW in 16 hours or more. Why do robots need to eat so much? Edit: Correction, Spot has a 605 Wh battery which is good for 90 minutes of active operation. | Technology | explainlikeimfive | {
"a_id": [
"fzm0cn1",
"fzm17of",
"fzm0w8o",
"fzm066g",
"fzmhee0"
],
"text": [
"Human body efficiency is usually quoted at around 20%, meaning 80% of energy input will be lost to waste heat, while 20% will be converted to useful work, as defined by the task. A brushless DC electric motor will usually end up between 70% and 95% efficiency - let's go with 80%. A human could convert 2KWh of meals into 0.4KWh of work. A purpose-built robot for a task solvable by electric motors could convert 2KWh of electrical energy into 1.6 KWh of work. Consider the possibility that some of the numbers or assumptions in your question might be faulty.",
"4 million years of evolution vs 100 years of automation technology. Give it another 100 years for our technology to catch up with evolution.",
"> just to do what a human can do This is where you are way, way off. A machine using 2 kW of electricity can do far more than a human could ever do.",
"Look at it this way: On the one hand, you have animals, incredibly complex biological machines that are the culmination of hundreds of millions of years of evolution and natural selection. All of these machines evolved with the primary goal of survival and propagation of their respective species, and to that end, the more energy efficient of those animals survived to pass on their genetics. On the other hand, you have robotics, man-made machines that are the culmination of a couple hundred years of technological development. We are still a long way off from making energy generators and storage as effective as what the animals use. In addition, since robots don't occur in nature, we don't have the advantage of random mutation and natural selection to do the hard work for us. Granted, because humans are actively researching it, robots are probably becoming energy efficient much faster than modern animals did, but it's still a relatively young field.",
"Humans doing heavy exercise need more like 5000 calories a day, which is more like 6kWh. 2000 calories a day is for \"normal\" activity, which is not 16 hours of activity. Robots are much more efficient if they use wheels, but the robots which use legs like the BD spot are quite new and not yet that efficient. It's likely their efficiency will improve drastically over time. An electric motorbike with 6kWh of battery can go for 143km [zero-s]( URL_0 ). A human walking for 16 hours can go ~4*16=64km. The motorbike is much more efficient than the person!"
],
"score": [
31,
12,
8,
6,
4
],
"text_urls": [
[],
[],
[],
[],
[
"https://www.zeromotorcycles.com/en-gb/model/zero-s"
]
]
} | [
"url"
] | [
"url"
] |
i016gj | How does the codes from authenticator apps like (Google Authenticator) works even offline ? | Technology | explainlikeimfive | {
"a_id": [
"fzmehde",
"fzmkm8a",
"fzmizon"
],
"text": [
"The codes are generated based on an algorithm that has two key data inputs: - Your unique code (which was included in the QR code you scanned) - The current time Since both the app and the site requesting the code know both of those pieces of information, the app can generate a code the site will accept. If the app goes offline, the current time should still be the same, so it is still capable of generating a code the site will accept.",
"You take some secret that is pre-shared. You do math on that secret using the current time (up to the latest minute, typically) to produce a result. One minute difference results in a very different result. Both sides can do the math on the same secret and know what the answer should be.",
"They don't communicate with the server to generate codes. When the 2 factor authentication scheme is set up, a \"password\" is shared between the host and your device, typically by a QR code or typing in a very long string of text. When codes are generated, that password is used, along with the current time, to generate a temporary code. Since the current time is known by both ends, along with the initial password shared during setup, each end knows what codes will be valid at that time"
],
"score": [
8,
3,
3
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i050nf | On a racing circuit, is the purpose of the rumble strips to slow down the car? | I understand they are used to denote entry and exit points as well as give the driver and car extra width to take corners faster. | Technology | explainlikeimfive | {
"a_id": [
"fzn6pau",
"fzn4md4"
],
"text": [
"The rumble strips are used to define the outside of the corners. Taking a wide line into a corner is often the fastest way to take that corner (called the racing line). The rumble strips both help the driver identify when they are on the limit (leaving the track is a penalty) but it also is a deterrent because the strips are uncomfortable to go over and can damage the car. Going onto the strips might be uncomfortable but that extra foot of space can be worth a few tenths a lap so the driver will take the risk.",
"It does slow down the car in two ways. Firstly whenever a wheel hits a curb it is forced backwards and upwards and therefore slows down the car. The forward kinetic energy in the car is now transferred to upwards kinetic energy in the wheel and suspension. And secondly hitting a curb at high speed is not only uncomfortable for the driver but also damages the car. So drivers is forced to slow down a bit the next time around the circuit so that the car will last the entire race."
],
"score": [
6,
4
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
i06dp2 | Why have we settled on 16:9 as the standard aspect ratio? | Technology | explainlikeimfive | {
"a_id": [
"fznfegh",
"fzq45v9"
],
"text": [
"16:9 is the aspect ratio that can most easily handle all of the other historical aspect ratios (like 4:3 for broadcast TV, 2.2:1 for Panavision (movies), 2.39:1 for Cinemascope) with a minimum of picture loss and a maximum of the screen used. When they were developing the HD standard and needed to come up with an aspect ratio, a committee member actually cut out rectangles of equal area in the various historical and candidate aspect ratios. when they were laid over one another with the centerpoints matching, the smallest rectangle that would contain all of the other rectangles had a ratio that was very close to 16:9.",
"Laptops are getting 16:10 ratio screens on smaller laptops to utilize the depth that the keyboard and track-pad use anyway. This provides a better format for productivity, where word documents can be fully viewed at 100%. Alternatively, 1440p 16:9 screens accomplish the same, but with smaller text for the same monitor width. The reason it was chosen has already been answered. I have a 21:9 monitor for gaming. It's got it's benefits, and watching 21:9 movies on it is great."
],
"score": [
439,
5
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i0a8lm | Why has the progress and development of human society sped up so much in the last 150 years or so? | Technology | explainlikeimfive | {
"a_id": [
"fzo7gci",
"fzownc1",
"fzo4i39",
"fzof8a3",
"fzp0bim",
"fzobp0j",
"fzofvkz",
"fzoeb0h",
"fzodwox",
"fzoovsb",
"fzohwm2",
"fzomblm",
"fzokii6",
"fzoncv0",
"fzoqyot",
"fzolm0d",
"fzoub0o",
"fzobvvx",
"fzonne5",
"fzonmn9"
],
"text": [
"We are standing on the shoulders of giants. As we create new technologies (or other advances in society), we are able to use those technologies to then create other newer technologies and so on. We built crappy computers that helped us build faster computers that helped us build even faster computers and so on. Ever heard of The Singularity? It's basically the implied \"endpoint\" of the rapidly accelerating nature of technology you are asking about. One interpretation is that when we create AI it's going to be able to create a better AI and so on and so forth until the speed at which it evolves at becomes so fast that one day it will basically become advanced way beyond us (and evolving almost near instantly from our PoV) and society/humanity will change almost immediately as a result. URL_0 > The first use of the concept of a \"singularity\" in the technological context was John von Neumann.[4] Stanislaw Ulam reports a discussion with von Neumann \"centered on the accelerating progress of technology and changes in the mode of human life, which gives the appearance of approaching some essential singularity in the history of the race beyond which human affairs, as we know them, could not continue\".[5] Subsequent authors have echoed this viewpoint.[3][6] Edit: RIP inbox. Loving all the discussion! FTR I'm not claiming this is definitely gonna happen, it's just a ton of fun to think about.",
"The harnessing of energy in the form of steam power, electricity, and combustion engines unlocked massive potential for technological development that was simply impossible before, when society largely relied on human and animal muscle-power to power everything. And not only that, but this harnessing of energy also freed up massive amounts of human *labor*. In a society where 90% of the population's labor is required to till the land and produce food, there's not much labor available for anything else. But once we can mechanize agriculture and increase the food-production of the land, then the population's labor can instead be directed at other pursuits, building railroads and skyscrapers and great big machines. And these people can be *educated*, taught to read and write and do math and understand how the world works. Unlocking even more potential for progress and development. Next is medicine and sanitation. It can't be understated how catastrophic child mortality used to be. In most societies, nearly *half* of all babies born would die before the age of 5. In many places, the solid majority of people who ever lived would not survive to adulthood. And even people who made it through the gauntlet and survived to adulthood, they were still just *decimated* constantly by disease. Basically any major wound was likely to be fatal, because it would be infected and eventually kill you. Surgery of any kind was nearly impossible. There were basically no effective medicines beyond a couple of folk remedies that slightly improved symptoms but otherwise didn't do much. No antibiotics whatsoever, all infections had to simply be *endured*. No sexual protection of any kind besides abstinence. And people lived in absolute filth. Only in part because they didn't understand germs. But even when they did understand cleanliness, they still didn't possess the kind of technology necessary to build sewers to carry their sewage away. And they couldn't banish livestock (constantly shitting in the street) from the city streets, because animals were their only energy source for hauling weights, so epidemics spread through cities constantly, killing huge fractions of the population. Think of how hard it would be for society to function and prosper if top leaders and top scholars were just constantly being randomly wiped out by disease. EDIT: Really not sure why so many people feel the need to remind me I left out X-important-technology. I never gave the impression this was like a comprehensive and exhaustive explanation.",
"Well, in ancient times, if you wanted to, say, invent a car... you needed to invent every single piece of equipment on a car. Eventually, written language was introduced, so now in order to invent something new, you just had to create the \"last\" piece that is necessary to make the product... you could start with what everybody has done before you. Now, written language has been around for millenia, but the number of people who have access to it has exploded exponentially, as well as our ability to share it. A few hundred years ago, if you wanted to be an inventor, you *had* to be born to a wealthy family to have time to tinker. If you wanted to go to college you were elite. Now, almost any person has access to a tremendous amount of information. So we have significantly more people, and they're just moving forward on what people before them have done.",
"Positive feedback loop: One technology/invention helps with the development of a second, and with each new technology it becomes easier to develop more in different fields that aren’t even directly related to that first or second technology, and things get better at a rate that gets faster and faster.",
"The answers you've received are great, but not hitting on what I think is the crux of what you're asking about (that I've read, anyway). 150 odd years ago came the industrial revolution. What's important to realise is that living prior to this demanded a pretty high output of energy to keep warm, fed, and safe. Once you are able to outsource energy requirements to something, even as inefficient as coal, you get a lot more free time. Free time can be used by smart, resourceful people to increase free time by improving the main driver of the industrial revolution: the steam engine. From there, you essentially have a feedback loop of more time means more learning/ingenuity that may have been sidelined before and so on.",
"Almost certainly the invention of the Printing Press. This allowed vast amounts of information to be disseminated rapidly.",
"From what I've seen from all of the answers I'd say this: Over the course of the past one or two hundred years, the spread of information, technology, and ideas has allowed for the rapid expansion and development of technology. These technological inventions compound eachother so once we got past the \"information sharing barrier\", everything exploded. When you also factor in capitalism and the desire to be the first in order to make money on a new technology you can see *why* everyone has the desire to grow.",
"The availability of unlimited amount of energy to power all the machines we design. 200 years ago we had coal as our main source of power but just 100 years afterwards we were in the middle of industrialisation. The more power we can access the more powerful machines we can build which in turn help us build even better machines.",
"Far more people alive then ever before. More chances for Einsteins to be born. Far larger % of the population is educated then ever before. Einstein born to a couple of peasant farmers in the dark ages has almost no chance of accomplishing anything, since his intellect wont come into play when he never learned to read and farms all day. Far larger % of people not farming. Every new innovation has a compounding effect on the ammount of people who can pursue new innovations, instead of just surviving. Storage of knowledge and ease of it's access. Much of what brilliant people did 1000 years ago was rediscover what other brilliant people 1000 years before that already discovered. Now instead of wasting time inventing the wheel for the 437th time in history people can learn about the wheel quickly then instead spend their effort inventing new brake pads or ABS systems.",
"It's crazy that so many of the answers here are not talking about the **Industrial Revolution**. Of course everything throughout history has had a cause and effect chain with many high points like the printing press and the Enlightenment, but really the exponential advancement in human society over the past couple centuries comes directly from the major changes that began in the late 18th and early 19th century. Here's the Crash Course episode on this topic: URL_0 Quick summary: The discovery of coal as a plentiful and concentrated heat source led to steam power and electricity, mass manufacturing (as opposed to hand-made *everything*), and the migration of people from farm life to city life. Yes, the printing press was important. Yes, advancements in chemistry and metallurgy were important. Yes, political changes from monarchy toward some form of democracy were important. Yes, the enlightenment principles of science and invention were *crucial*. (It might even be tempting to say the enlightenment was the \"cause\" of all this, but it wasn't until *industry* changed in a series of interdependent advancements that *society* really changed on a large scale.) All of these things (and more) came together in a series of *massive* innovations we now call The Industrial Revolution. The advancements made during this time created a **Positive Feedback Loop** that meant advancements in one sector created benefits for all sectors that relied on it, which might come back around to the same sector. For example, steam engines ran on coal power, and then steam engines were used to drain coal mines of water seepage, which meant coal was easier to get, which meant steam engines were cheaper to run. *Everything* about a typical person's life (in the so-called \"western\" countries that benefited the most from these changes) was altered by changes that are mostly traceable to this central historical period of massive social change.",
"It’s mostly the industrial revolution that accelerated the growth rate. I wrote a brief article here[How Did Inequality Begin in Societies?]( URL_0 ) on a similar topic and I’d love some feedback",
"Lots of answers getting at parts, but the key thing that put lots of them together was the rise of economic liberalism (i.e., market economies), which implies greater freedom to pursue an idea, get the resources needed to do so, and profit from success all while the legal structure protects your enterprise from disruption. The result is that people are driven to pursue new and better ideas, turning them into meaningful change accessible to an increasingly large number of people. Greater and more widespread wealth not only then make more resources available to feed the process, they also gradually remove human beings from older material conditions, which then encourages social change alongside economic change. That doesn't mean the system doesn't have its (many) problems, but there's a reason economic and social development closely correspond to the liberalism of its economic institutions (for better and for worse).",
"As a side note, I saw a cool documentary in the year 2000, talking about this kind of change. They talked to several historians, sociologists, etc. and the group agreed that the generation alive from 1900 to 1950 probably witnessed more technological advancement than any previous generation. A person from 1850 transported to 1900 would find the world mostly the same, except for some (not inconsequential) things like electrical lighting, telephones, etc. A person from 1950 transported to 2000 would recognize most things- they were just more advanced or miniaturized. But a person from 1900 to 1950 would have gone from the world of the horse and buggy to rocketships and atomic bombs, from not even radio or movies (yes, kinetoscopes were a novelty) to television, etc.",
"Largely due to the industrial revolution. With the advent of the industrial revolution discoveries were made which rapidly accelerated the progress of technological advancement. These enabled even more discoveries which sped it up further. Technology has increased rapidly due to that cycle.",
"HEY, OP SAID EX-PL-AIN LI-KE I'M FI-VVVV-E. For real, though what yall are talking about sounds cool as . I have no clue wtf y'all are talking about. So please, for this southern boy, like I'm 5.",
"ELI5: we have gotten much better at recording and sharing information that helps us get better at doing things. Lots of people got really good at doing things but weren't able to share how they did it. Now almost anyone can share that info.",
"Compounding advancements. Each advancement made it possible for the next one. So electricity really kicked stuff off That and more people are more educated",
"Because of industrialization we got extremely efficient this came hand in hand with taylorism and fordism which caused the production capacity to skyrocket. After that goods like cars etc became something for everybody because the prices dropped. Logical if you follow the ask-demand charts. After that the same tendencies followed around the world and globalization became a real thing.",
"Global communications, basically. That discovery alone means that scientists in Osaka and New York can work together daily. Discoveries are discovered and recorded instantly, meaning everyone can build on each other's work and nothing is 'lost'. Engineers can order new materials from the other side of the world instead being forced to use inferior materials. Countries can specialize so that parts of a whole product can be made by getting the best parts from various countries. Basically, the ability to cooperate on a global scale means everything we could do before, we can do faster now.",
"A huge part of what allows the complexity of our society is the small proportion of society that is required to sustain the rest of it. For example, in an ancient civilization, the overwhelming majority of the population was probably subsistence farmers, meaning the people are growing food to provide for themselves and their families. But if each farmer is able to provide a little extra, eventually that means there's one less person that could effectively survive off the collective output of the rest of the people. Often these were people like kings and religious leaders. But those people could still help the society develop: religious leaders often studied the stars and could help farmers know when to plant their crops, for example. Over time, incremental developments allowed more and more people to not have to provide food for themselves, which led to significant progress. A dedicated blacksmith making metal tools for the entire society can make farming much easier, which means farmers can plant more crops and harvest more food. The Industrial Revolution began in part due to development in the UK of the Norfolk Four-Course Rotation, a method of crop rotation that allowed farmers to get away with not letting some of their land go fallow every year. Widespread acceptance of the four-course resulted in (IIRC) only about 60% of the working population of the UK needing to feed the entire country. That meant more and more people could specialize in skills that a less complex society could not sustain. Over time these specialists helped improve agriculture further, either directly or indirectly, creating a positive feedback loop. Today, the population of a developed country only needs about 5% of its people to provide its sustenance. All those other people can do other things without having to worry about starving to death, things that benefit all of society. Which isn't to say that people in agriculture don't benefit society, quite the contrary: without farmers, society simply could not exist."
],
"score": [
4697,
3599,
1266,
348,
280,
217,
147,
106,
69,
51,
28,
26,
11,
7,
6,
6,
3,
3,
3,
3
],
"text_urls": [
[
"https://en.wikipedia.org/wiki/Technological_singularity"
],
[],
[],
[],
[],
[],
[],
[],
[],
[
"https://www.youtube.com/watch?v=zhL5DCizj5c"
],
[
"https://link.medium.com/fD9KuNMRw8"
],
[],
[],
[],
[],
[],
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i0bezv | Why are some phishing scams so obviously phishing scams? | Technology | explainlikeimfive | {
"a_id": [
"fzobdwi",
"fzolv8t",
"fzog5l2",
"fzoi3pc",
"fzonx1s",
"fzopkaq"
],
"text": [
"Because they are trying to find the dumbest people possible. If they fall for the obviously fake scam they will probably be stupid enough to actually send money.",
"Theory 1: select out the dumbest people on a first pass filter. Theory 2: between language barriers, low cost of entry and the type of person running these scams, they are going to come across as idiots. Theory 3: it's a volume game. They may seem obvious to you, but they may hit another person at just the right time to seem more believable. (Calling Grandmas saying they are their grandson who needs bail money might with really well if they have a grandson with legal issues) Theory 4: the con is on getting the emails out. They aren't trying to get you to respond, just verify the email or phone number is valid. Theory 5: the obvious ones are the ones you know about. You may have fallen for ones and not even known it.",
"What may seem obvious to you may be realistic to some. In high school around 2009 I got a Facebook message, someone asking for help. I knew nothing about scams at the time but story did not make sense to me. Out of curiosity I entertained them until they realized I was toying with them. Last year a friend of mine was in a similar situation. I told him what was going on, he did not believe me saying I was jealous if him finding love online, I let him be but asked him not to send money if they ask. Two weeks later he came to me and apologized for not listening to me. I was 14 when it happened to me, he was 25, Same tactics.",
"Ignorance and bad luck combined with desperation can put people in positions that in their right mind, they wouldn't think to pursue. There's enough people in bad situations to allow for scammers to take advantage of them and make sustainable money. It's pretty sad.",
"As other people have said, it's because they want to select for people of low intelligence. To go a little deeper into why that is, it's because low intelligence people offer them the best time spent/money earned ratio. Sending out the fake e-mails is cheap and easy. Sifting through each person who responds is costly from a time perspective. It is in their best interest that they only spend time reading e-mails from and responding to people with a high probability of falling for the scam. Maybe there are smarter people who with some time and effort have a small chance of falling for the scam, but time is money. Every effort they spend on people who don't end up falling for it is time wasted. They want only the dumbest because those are the most likely to reward their efforts.",
"Scams don't target young, mentally able people. Those people generally don't have much money and aren't going to fall for the scam regardless. The people that they target are old, senile people. Those people do have lots of money, or the ability to get money, and also have a significant impairment to their judgement due to age related brain degeneration. These people quite literally aren't able to comprehend that someone is trying to scam them, even if they otherwise seem mentally capable of living on their own. A scam email doesn't need to be elaborate or convincing to get these people - it just has to be read or listened to. This means that there is no incentive for the scammer to invest any effort in making the scam convincing. What the scammers are incentivized to do is to automate the process. IE, by coding an AI that scrapes email addresses or steals your account if you log in with their link. But again, the incentive is to minimize the amount of time that they, personally, have to spend on scamming you. Also keep in mind that these scammers are operating out of the third world - North Korea, China, India, and Russia are pretty common sources of origin for them. The people running these scams are not native English speakers and in many cases are using something like Google Translate to produce English language text. But again, there is absolutely no incentive for them to learn better English. The senile 80 year old man that they're targeting just has to be able to identify that the email contains a clickable link. At that point he's going to click the link, it doesn't matter that he can't read the rest of the email."
],
"score": [
52,
17,
8,
7,
4,
3
],
"text_urls": [
[],
[],
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i0bpt5 | What does it mean that Ada Lovelace wrote the first computer program if computers didn't exist yet? | Technology | explainlikeimfive | {
"a_id": [
"fzodqzb",
"fzodshj"
],
"text": [
"Basically, she did a lot of theoretical work about what would a computer be able to do, and what sort of math problems could you give a computer and get results from. She did a lot of brainstorming about how computers would work, based on the work of Charles Babbage, and realized that if that computer idea he came up with was made, that it could end up doing more than just math problems. So while computers didn't exist yet, the work she did was very important to the early computer programmers who could use the research she did as the start of their own work.",
"There were mechanical computers before electrical ones. Before that computer was the job title of someone who computes. Ada Lovelace wrote the first algorithms for a mechanical computer to save time for the user."
],
"score": [
7,
5
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i0ewra | What prevents an internet provider from offering higher speeds? | I moved and the only provider available offers one plan. 3mbps for $49.99 a month. I feel like that should be illegal. | Technology | explainlikeimfive | {
"a_id": [
"fzozxk2",
"fzp9ey7",
"fzozx10"
],
"text": [
"Absolutely no science behind my opinion but my first thought is greed. We pay for it but don’t receive it.",
"There are two different questions in your question. One is about technological limitations, the other is about business model. The technology side of it is that your provider gets their own connection from an upstream provider. Overly simplifying, they get a big pipe to the internet and sell smaller pipes to your area. The maximum speed they can sell is the speed of their big pipe divided by the number of small pipes that they sell. Because nobody uses the internet at exactly the same time and exactly the same way, they can get away with a little bit of overbooking, just like an airline. Airlines tend to sell a few more seats in every flight because they know that a couple of people are going to cancel or be late. When everybody does show up, somebody will get bumped to the next flight. In the case of internet providers, when everybody actually does use their connection at the same time and to the fullest, instead of bumping someone off the network, everybody's speed is lowered by some amount. Now for the business plan part. Like any business in a capitalist society, your provider will sell their product at the highest price their consumers will pay, and they will produce their product at the lowest possible cost they can get away with. In a monopoly situation, which is what you describe, the price will go to the absolute maximum people are willing to pay to have internet. In your case, that's about $50/month. The quality of the product, on the other hand, will go as low as people can tolerate. In your case, that's 3mbps. Consider also that your provider is also doing as much overbooking (called oversubscribing) as they can get away with, so your actual speed will likely be slower than the advertised 3mbps. For a counter example, I just contracted Internet service for the place I'm moving to, in Paris. I got the cheapest possible option, which is 300mbps for 14€/month. It is a fiber connection and includes some TV channels and a land line as well. The most expensive I could have bought would be 30€/month for 2Gbps, 160 channels of TV and a land line with unlimited calling to Europe and North America. This is all great, and it happens because there are 5 or 6 providers in the area, and there is legislation and enforcement that forces them to actually compete. TL;DR: it sucks to be a customer in a monopoly market.",
"The physical infrastructure to your house might be an issue. If the only available options for providing service are an older DSL service with a station not very close to your house, that might be the fastest speeds physically possible with the existing infrastructure."
],
"score": [
6,
5,
4
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
i0hk48 | Why do coins have “heads” and “tails”? | By that I mean, why do coins have different engravings on either side? Why can’t there just be the same picture on both sides of the coin? | Technology | explainlikeimfive | {
"a_id": [
"fzpgu0y",
"fzq356n"
],
"text": [
"It’s kind of unclear but British coins (namely the 10 pence piece) have the Queen’s head on one side and a lion with a raised tail on the other. The Romans used to call the game ‘navia aut caput’ (Ship and head) because one side depicted a ship while the other depicted the Emperor’s head",
"This stems back to the question of \"how do you make a coin\" Where the answer is, take a bit of metal (usually softer) and smash it between two other pieces of something harder than the metal you want to be your coin. the hard pieces we now call dies. When you do this, whatever is on the harder pieces; a bump, scrape, scratch or engraved picture; ends up on the coin in reverse of what's on the die. For the longest time dies were hand engraved, and thus each one took roughly the same amount of time to make, whether you made the same image, or a completely different one (given the complexity is similar) You quickly realize that it takes time/energy to engrave the die with the image you want on your coin, and you can double your \"ad space\" by making a different image on each die without increasing or decreasing costs. It doesn't mean you CAN'T have two dies with the same engraving (or similar enough to make no difference) and therefore a coin with both sides the same, but it doesn't make sense to \"waste\" that energy and only get the same image on each side."
],
"score": [
4,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
i0hnr5 | Why some websites crash when suddenly large number of people try to access at same time and apps like whatsapp , youtube instagram dont crash even if millions of people are using it same time? | Technology | explainlikeimfive | {
"a_id": [
"fzphbmw",
"fzpqkki",
"fzphe5p",
"fzq0e91"
],
"text": [
"Big websites and services like YouTube, WhatsApp, Facebook etc are specifically set up to handle huge volumes of traffic. When someone posts a link to a tiny website on Reddit and millions of people hit it, it's more than the site has been set up to handle.",
"The way websites work is that your computer sends a request to a server (just a different computer). The server then generates the content for you and returns it to your computer to show to you. The server only has the processing resources to handle a certain number of requests per second. If too many requests arrive at the same time, then the server can't keep up and requests will start timing out or simply be rejected. In order to serve more requests and keep up with demand you have two primary options. Either you scale vertically, which means adding more resources to your one server. (Faster CPU, more RAM, etc.) Or you scale horizontally, which means adding more individual servers. Vertical scaling is by far the simplest but has a hard limit on how much you can improve. Horizontal scaling has potentially limitless scalability but brings a whole new set of challenges like keeping data synchronized.",
"Because they are built to withstand that kind of traffic. For example, instead of just one server, they have multiple servers behind a [load balancer]( URL_0 ), which is a server that can redirect clients to different backend servers, thus reducing the load on each server.",
"Not saying anything someone else in this thread hasn't said already, but just with a metaphor: Picture the number of people visiting a concession stand at a crowded sports event. The lines might be longish, sure, but the number of people they're able to serve is remarkable in such a short amount of time. They have enough workers to service all the customer requests, and furthermore, their entire infrastructure/business model is built around serving a bunch of people all at once. Now picture the same number of people showing up at your house for dinner. Maybe you're a great cook, maybe you can serve people relatively quickly, but there's just no way you're going to be able to serve them all in a reasonable amount of time. No fault of your own, you're just not set up or trained for that. A site \"crashing\" is basically like this -- in this analogy, either having a nervous breakdown and telling everyone to leave (the site is down), or people leaving of their own accord because it's taking way too long and they're hungry (site is not \"down\", but throughput is so bad it might as well be)."
],
"score": [
15,
9,
5,
4
],
"text_urls": [
[],
[],
[
"https://en.wikipedia.org/wiki/Load_balancing_(computing\\)"
],
[]
]
} | [
"url"
] | [
"url"
] |
|
i0iyvz | Why are revolver cylinders still used? | I would have thought that using a magazine for a feeding system would have more advantages over using a revolver cylinder, such as higher capacity and maybe faster fire rate. Does the cylinder affect bullet velocity or power in any way? | Technology | explainlikeimfive | {
"a_id": [
"fzpotza",
"fzpr5rp",
"fzppfhg"
],
"text": [
"Revolvers are a simpler mechanism, so usually must more reliable, magazine fed automatics, being more complex, are more prone to jam. The advantages of more rounds available, without reloading, are not that relevant to most gun owners.",
"It has its ups: - less moving parts, therefore more reliable / less likely to jam. Also easier to maintain. - Cheaper to produce. - Can fire directly from the cylinder without having to push the round into the barrel first. - Safer to handle, since most revolvers need a lot more pressure on the trigger to fire. Also can be used single-handedly, as with a strong enough index finger, you can roll the cylinders, cock and fire the gun in one action, which comes in handy for money trasporters who always have one hand on the money box. And its downs: - less ammo. - longer reloading times. - no indicator whether the top chamber is loaded or not. - harder recoil becuase of stiff barrel and chamber mechanism.",
"I had a retired police officer as an instructor at a firing range and he told me that a good revolver is far more accurate and reliable than a magazine fed gun. Magazine fed guns are far more popular than revolvers due to the capacity issue that you already mentioned, but if the goal is to put a limited number of bullets on target a revolver in the hands of someone who is well trained can do that more accurately than a magazine fed gun."
],
"score": [
30,
6,
4
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
i0jmmw | Why did Zoom get more popular than Skype? | Technology | explainlikeimfive | {
"a_id": [
"fzpugxv",
"fzptzg3",
"fzptz11"
],
"text": [
"I started using zoom several years ago in my startup because it was more reliable for quality, and it was more user-friendly. Skype was acquired by Microsoft, but they never made the tool easier to use. It still feels like a clunky 90’s tool.",
"I moved over to using Zoom to run group lessons during the lockdown, rather than trying to use my existing Skype account. My motivation was mainly that Zoom looked nicer and was a bit friendlier to use, the interface was nicer and easier, the quality of calls and video was better, and it offered a lot of functionality that Skype didn't have. I have been using Skype for years and it doesn't really seem to have improved much since I first started using it. It still looks and feels like what I started using a decade or so ago. Zoom seems much more sleek, modern, and effective. A big black mark against Zoom was all of the issues with security and privacy, but they pledged to work hard to improve these issues. For my purposes, since I wasn't sharing anything sensitive, I was happy enough with the steps they were taking to address the problems.",
"Mainly because of all the tools within the app. Zoom provides many more tools (like separating participants in groups, silent reactions for when your mic isn't open, slide share is more easy to work with etc), while Skype and many others mainly connect you with other people and let you share your screen and, at max, mute everyone (but only the person can unmute her/himself, you can't do that, but in Zoom you can)."
],
"score": [
13,
11,
7
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i0kj04 | How did some otherwise-advanced ancient civilizations, like the Maya, never develop the wheel? | The wheel was known to many/most ancient civilizations, yet some, like the Maya, never developed it. Why not? | Technology | explainlikeimfive | {
"a_id": [
"fzpxo4y",
"fzpxvec",
"fzq1lh4",
"fzpzzye",
"fzq8hfe"
],
"text": [
"You need to have some reason for inventing it, for the wheel to be a practical solution to transport you need flat open areas that can be turned into a form of road and also preferably need some draft animal like a horse or oxen to pull carts or wagons. Most of the area was unsuitable for wheeled transport and humans carrying packs on their backs were a more efficient method of transport. The other factor is that there was a substantial amount of water transport which is far more efficient than wheeled transport, so you could say the invention of the boat/barge blocked the need for the wheel.",
"The Mayans did have the concept of wheels, but did not implement them in the form of vehicles. Historians believe that this is due to the lack of draft animals, and it was more efficient to travel by boat in those areas. It is as they say, necessity is the first cousin of invention. The circumstances and environment they lived in did not benefit them enough to develop wheeled vehicles.",
"The geography of the area the Mayan, inca and Aztec civilizations covered features: 1. Steep mountains 2. Swamp 3. Extremely dense tropical jungle You may notice all 3 of these are terrains that are very diffcult to drive a car, much less haul a wagon through. They had a HUGE empire-spanning trade system... that was run entirely on foot or pack animals, because they have a much easier time with the terrain. They had wheels as toys, but took one look at the terrain and went \"...I can just go get a Llama and save my back the trouble.\" and while they might not have had the wheel, they DID invent the suspension bridge way before anyone else, on account of having lots of narrow mountain canyons to cross. you could drag a wagon up and down that rocky hellscape OR you could build a suspension bridge and hike your llama across it and arrive at your destination two weeks earlier TL;DR: They had wheels, but the local terrain wasn't suited for wheels to be used as a transit tool when they had more readily available options.",
"The key thing is that the wheel in itself is made useful by context. The Mayans did have the concept of a circular construction that is allowed to spin freely in one direction, but which can't go in others. They could make it because that kind of thing showed up in toys. But the wheel as a tool for transportation and grinding of things is most useful in flat terrain with access to start animals to actually pull it along. Without either of those things, it looses a lot of its potential value.",
"This reminds me of an article I once read about how Europeans and Chinese independently developed the wheelbarrow. Both were useful due to extensive road-building programs... The European style is cheap to make. One wheel on the front, with two poles passing under a box with the poles acting as a frame plus the handles. They had peasant labor, and in spite of wanting good production, they saw no need to improve it. The Chinese used a lot of compelled labor, but they also cared about good design improving production. Their common wheelbarrow was a scaled-down version of a one-axle ox-cart. The mass of weight was carried by the axle, and the ox only had to pull it. The two outer wheels were very large in diameter. This made the wheels expensive, but also allowed them to travel faster over rough unimproved roads. If you take the standard ox-cart configuration, scale it down for a human to use, and allow it to be pulled or flipped around and pushed...you have a very effective wheelbarrow that can hold a lot of weight. The Europen style with one wheel out front requires the operator at the back to lift half the weight of the cargo. This severely limits the weight that one man can carry. The Chinese even had some single-wheel carts with a large-diameter wheel in the center, and two cargo section with one on each side. There were outrigger on the back and either side to keep it from tipping over, but a judicious arrangement of cargo would result in the axle bearing 98% of the load."
],
"score": [
78,
29,
24,
3,
3
],
"text_urls": [
[],
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
i0mjys | why is 3D printing such a big deal? | Technology | explainlikeimfive | {
"a_id": [
"fzqaejb",
"fzqb7hf",
"fzqaolo"
],
"text": [
"Because it makes it easier to prototype, you can print models to see how they are without having to make molds for injection molding. You can design or download useful objects like replacement parts for yourself without having to pay a lot or go to the store and lots of other applications for example for artists",
"It entirely circumvents the manufacturing process and the assembly process, without having to have specialized machines for each individual part, at a fraction of the usual time and price. We're out here literally 3D printing buildings in 24 hours, reducing the cost of labor, requiring fewer laborers, reducing the cost of materials, fewer machines, less noise, at a fraction of the time. We can 3D print **your home** for around $3,000 a room. We can print new tools, repair kits, plates, all sorts of things in places like the ISS; meaning if something breaks, they have all they need to fix it. This reduces the time it takes to make repairs dramatically because we don't have to send things to these faraway places. And you don't have to be a skilled technician or manufacturer to make it work, you just have to be able to press \"download\" and \"start\" on a machine. 3D printing is a **massive** deal.",
"Data to make a part is much, much easier to move from place to place and share than actual low-cost plastic parts. That means more design flexibility, less up-front tool and die cost, less inventory investment and management, and quicker response time to get a replacement part."
],
"score": [
12,
10,
3
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i0smcy | Why do different parts of The world use different types of electrical outlets? | Technology | explainlikeimfive | {
"a_id": [
"fzrnx39",
"fzs4mg9",
"fzrr2ze",
"fzsq033"
],
"text": [
"Different countries developed the electrical networks/cabling/standards at different times and independently of each other. There was no particular reason to conform to a single standard because international travel was not as widespread as it is now (as well as portable consumer electronics not being popular). Nowadays, there isn’t enough incentive to redo all the wiring to switch to one standard, so everything stays as is.",
"To add on, back when electricity started becoming more commonplace, there wasn't even a national standard. There were multiple different types of outlets and plugs even within a single country, depending on which electric company supplied your area.",
"The electric grid was developed and deployed independently throughout the world with each company responsible defining their own standards. There was no international effort or desire to develop a global standard for electricity at the time. The name of the game was owning the patents, so it was to your companies interest to develop your own standard. Neighboring countries like Mainland Europe and Canada+US adopted the same systems because it made sense. It allowed them to share power and buy the same appliances. Which was important because they were only manufactured by a handful of companies at the time. Today redefining a standard for outlets and the electrical grid would be far too much of an undertaking. The cost would be so enormous that it just wouldn't be worth it.",
"In Britain alone there were over forty different companies supplying public electricity. Each had their own voltage and frequency. Since plugging into the wrong voltage can be dangerous, each had their own plug. We didn't get a standard electricity supply till the 1930s. Even then there were lots of manufacturer's each trying to get their style of plug to be the new standard. One of the houses I grew up in had at least five different types of sockets. As a child I can remember having all sorts of adapters to be able to plug one type of plug into a different type of socket. It wasn't until the 70s when Britain standardized on one type of plug. That's just one country, can you imagine how hard it would be to get the world to standardize."
],
"score": [
14,
3,
3,
3
],
"text_urls": [
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i0trk6 | how does RAW option work on a camera? | Technology | explainlikeimfive | {
"a_id": [
"fzs7v6b",
"fzsfdfo",
"fzs8oy7"
],
"text": [
"RAW is data from the sensor, as-is. JPEG is automatically processed data, after things like color correction, sharpening and white balance. Plus it's got less bit depth and has lossy compression. RAW is good if you want to do your own processing, because JPEG already contains changes to the image that can't be reversed, and loses some of the information the camera got from the sensor. For instance if your image is underexposed, RAW will often make that recoverable, while with JPEG doesn't really work for that. Using RAW means you have to go through a post-processing step after downloading the images from the camera. Natural RAWs tend to look very flat out by default, because they don't have all the color enhancement and sharpness filters that are usually automatically applied to JPEGs.",
"Adding to what has already been said: * a RAW file contains the raw (pun intended) output of the sensor, so you don't have to worry about white balance while taking the picture – you'll do it anyway in post-processing; * JPEG compression works on 8x8 pixels blocks, you not only lose details from the lossy compression but also get blocky artifacts which are very difficult to cure afterwards.",
"For most photo modes, the images are saved as JPEG files. The camera’s onboard image processor (depending on settings) applies a certain amount of processing (color correction, red eye removal, etc.) and compress the image data into said JPEG. This process is largely irreversible and results in less data that can be manipulated later. The upside is that file sizes are smaller and compatibility isn’t an issue. RAW files preserve every bit of image data picked up by the sensor, and the camera doesn’t do any processing when it saves the file. That makes the image files much larger, but all that extra data makes manipulation/processing much easier and yields better final products."
],
"score": [
10,
5,
3
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i0uts5 | In thermae of ancient Rome, how were they able to cool water and keep it cold? | Technology | explainlikeimfive | {
"a_id": [
"fzslcg0"
],
"text": [
"How cold did they need it to be? Water from pipes underground will generally be 60°F (15°C) or less, and that's plenty cold for a cold bath."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
i0xfdz | how do websites get redirected to spam pages, and why does it happen more often on mobile pages | I’m talking about pages like NYTimes being redirected to ‘you’re the 5 millionth visitor’ websites, how does this happen? | Technology | explainlikeimfive | {
"a_id": [
"fztgpp5",
"fzts0cv",
"fzt7dr5",
"fztt2cv",
"fzuf3pi"
],
"text": [
"1) You web browser or operating system could be compromised. 2) Many, many, many sites out there are WordPress or similar. These sites tend to be run by people will low or no technical skills. It's people that simply want a website or require one for their business. These are mainly the kind of sites that will get infected with redirects and other nastiness. The reason that it's worse on mobile is because these low or no skill website maintainers either aren't aware of their site's mobile view and/or never check it. The people infecting these sites know this. They can keep the site infected for longer if the rest of the website is functioning. Malware writers also like to hide fake logins for banks and PayPal deep in a websites path, again leaving the main site operational. Update your WordPress plugins people. Seriously. Edit: I wrote that whole thing thinking I was in /r/webhosting",
"Make sure you're using the ACTUAL website. Scam artists will take similar domain names and make them into scam hubs, I cant think of any off the top of my head but lets say [ URL_2 ]( URL_0 ) is real and [ URL_3 ]( URL_1 ) isnt. You might make a typing error or your autofill might, or they might have boosted their similar looking but fake site to the top or near the top of the page. As for why its more common on mobile, probably because its harder to discern when your fingers are in the way. I am not a software engineer, this is just something I picked up on.",
"Most likely your phone has a little virus. Otherwise it could be possible that the NYtimes site developers allow some code to run in paid ads and they were not careful enough in what they allow which then gave the creators of those ads a means to redirect site visitors.",
"Mobile redirects is a huge problem in display advertising. Some bad decisions were made early on and now the internet is paying the price.",
"I had a similar problem a few years ago, and it turned out, a virus had hijacked my router DNS settings. If this is the case, then pop-ups will only appear when using the affected wifi, on any device connected to it. If instead it happens regardless of how you are connected (4g/wifi) and on any network, ignore this post, because the problem is most likely your phone/browser/OS. In scenario 1, to fix: 1) Connect to your router. Usually you need to type [192.168.1.1]( URL_0 ) in the address bar (refer to your router instruction manual for differences) 2) Login. The source of the problem is, most likely, that you left the default login/password, in which case try admin/admin (also see manual for differences) 3) Look for a DNS Server (or similar) option (again, manual) :) It's usually below several options named \"Address\" and \"Subnet mask\" 4) Delete it entirely and save the changes 5) Also change the password! This is crucial not to get the same virus again The popups should now be gone & #x200B; Less ELI5 explanation of what happened to me: The DNS showed me regular pages for almost every site, except one: the jQuery Javascript file hosted at Google. Instead it served a malicious version that opened annoying ads. It took me days to figure out :("
],
"score": [
39,
15,
5,
4,
4
],
"text_urls": [
[],
[
"https://youtube.com",
"https://yootube.com",
"youtube.com",
"yootube.com"
],
[],
[],
[
"https://192.168.1.1"
]
]
} | [
"url"
] | [
"url"
] |
i0zqw5 | Why are there three and four letter alt-codes for foreign letter characters? What is the difference aside from the output? | Whenever I look for alt codes for special characters online, I see sites that show ones with 4 characters to be entered while holding alt, and sites with 3 characters to be entered. One place to see this is [here]( URL_0 ). Why is that? | Technology | explainlikeimfive | {
"a_id": [
"fzu4ph5"
],
"text": [
"The three-digit alt-codes where the original ones. From when computers where 8-bit, and there was no more than 255 characters available to choose from. The four-digit alt-codes, that still all start with a 0 if you look careful, are the newer ones that has popped up since Unicode is starting to become a standard."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
i100x7 | Why do power outlets all have three holes? Would they still work with more/less holes? | Technology | explainlikeimfive | {
"a_id": [
"fztov6h",
"fztr1gx"
],
"text": [
"In most of the world, you have one hot lead, one return lead and one ground lead. The ground is mainly for safety. In Japan where I am currently, they don't use the ground, so only have two terminals. For safety, the devices are double insulated.",
"As others already said, usually you have two to create a full circuit through whatever you want to have electricity, and the third is the ground, which is there for safety. To your second question, they would still work without the ground, but not with less. And, there are also plugs/outlets that have more than 2/3 connection points. Those usually are used in places where you have higher voltages."
],
"score": [
8,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i104ij | Why do countries have different shaped electrical outlets ? | Technology | explainlikeimfive | {
"a_id": [
"fztqnnq"
],
"text": [
"Its been many years since the foundations of electrical grids have been laid. Many grids were established without some big single vision of what standards were needed. As these grids grew independently, they created their own standards. They had their own voltage, their own amperage, and in case of AC, their own frequency. Each plug is designed for the specifics of its grid. Later safety measures and improvements would later be added. But due to the current cost of conversion in order to change all the grids to a single trait we won't have universal power plugs anytime soon."
],
"score": [
4
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
i14fnf | What is a DDoS? | Technology | explainlikeimfive | {
"a_id": [
"fzui5yw",
"fzugolv",
"fzuhlma"
],
"text": [
"Imagine you are stood at your front door with a box to one side of you and a trash can to the other side. Your purpose is to wait for a piece of mail to come through the letter box and land on the floor. You will pick up the envelope, open it, throw the envelope in the trash, then read the enclosed letter and place it in the box. Lets say it takes 10 seconds to bend down, pick the letter up and open it. Throwing the envelope away takes 2 seconds and reading the letter takes 30, putting it in the box takes 3. So our process takes 45 seconds. Ok, so lets say a letter arrives every minute - you complete the process easily and even have 15 seconds idle time in every minute. If 4 letters arrive in 3 minutes you can handle this but your idle time has been eaten up. If 2 letters arrived per minute you can keep working, but you'll be behind - there will always be at least one letter on the floor, waiting to be processed. If 60 letters arrive per minute you're in trouble, the floor is awash with unopened letters, eventually there are so many they obstruct the trash bin and your box, you can't process anything because you can't get to the box and bin. You have to stop working. Eventually the letters reach the level of the letter box and no more letters can even pass through it. This is a manual DDOS if you like. You are the web server and the letters arriving are the requests being made. If the volume of requests is so high that the web server is inundated it just can't cope and stops working. The first D is distributed, that means that the requests come from many different places. The reason for that is its fairly easy to put protection on the web server that says \"if you get (say) 100,000 requests from one source, block that source\". It is much harder to block 100,000 requests coming from 100,000 different sources. (note: numbers are just examples).",
"It's when a large amount of computers or electronic devices all try talking to a single server or other computer resource at the same time. The target gets overwhelmed trying to handle the massive increase in attempts to communicate or requests for service that it stops functioning or is unable to properly service legitimate requests. The attackers continue doing this over as long of time as possible so that the server/resource is prevented from being useful to anyone else and may even damage the target.",
"The server is like a government department where you give them a form asking for a webpage and they give you back a webpage. The DDoS is like when a group of bored students get all their friends together and they just keep handing in forms when they don't actually want to see the web page and waste the clerk's time. There are different kinds. A layer 3 DDoS is where everyone just stands in the waiting room so the people who actually want the service can't fit easily. A layer 4 DDoS is where they take all the numbers from the machine until it runs out of numbers. A layer 7 DDoS is where they hand in forms over and over."
],
"score": [
60,
10,
5
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i15919 | How does the weighing scale measures our weight? | Technology | explainlikeimfive | {
"a_id": [
"fzum61w",
"fzumi09"
],
"text": [
"Your weight is a Force (in Newton) caused by earth gravity pulling you down proportionally to your mass. When you step on a scale, this force is exerted on a spring that deforms proportionally to your weight. This deformation is translated into a number that corresponds to your mass ( in kg) .",
"There's an electrical component inside the scale that, when compressed, will increase it's resistance. That resistor is part of a circuit, and it's reading the voltage drop across it. The higher the resistance the higher the voltage drop. Id think the type of component is selected so it behaves in a predictable way. You know that when uncompressed, the voltage drop is x, and with a 100 lb weight the voltage drop is y, so then it could be as easy as a linear equation. Took a class in medical instruments, and it seems like many of the ones you're used to are just clever ways to change the resistance in a circuit."
],
"score": [
27,
5
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i16fiu | How does a phone know what time it is? | Technology | explainlikeimfive | {
"a_id": [
"fzurm86",
"fzury51"
],
"text": [
"Your phone is never completely turned off, there are always (even if small) parts turned on, which include the counter for time.",
"Many devices with any computation ability will have time-keeping circuits in them. Even if your phone is turned off for an extended period of time and without signal, it still has an internal clock it'll check when first turning back on. It only verifies the time against the network when available."
],
"score": [
6,
5
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i17ezt | What makes a Compact Disk (CD) so shiny? | Technology | explainlikeimfive | {
"a_id": [
"fzuy7j6"
],
"text": [
"Aluminum. A thin layer of shiny aluminum is sandwiched between two clear plastic layers. The data is recorded by burning tiny pits in this shiny surface."
],
"score": [
4
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
i1adpn | How does switching the rotation of a ceiling fan decide whether the fan gives cool air or warm air? | Technology | explainlikeimfive | {
"a_id": [
"fzvpae9"
],
"text": [
"It doesn't. Rotation decides whether the fan is sucking the cold air up or pushing the hot air down."
],
"score": [
16
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
i1eyh3 | How are games like Kerbal Space Program, Space engineers optimized? | Kerbal space program and Space engineers allows player to build space ships with a large number of parts. The more parts you have, the worse the performace tends to be. How do games normally handle many moving parts, are there ways to get around this? | Technology | explainlikeimfive | {
"a_id": [
"fzwso7g",
"fzx9ox4",
"fzwtw9s",
"fzwwg7p",
"fzx63df",
"fzxb1hs"
],
"text": [
"The majority of games tend to simply not allow many moving parts, to avoid this exact issue, and prevent players from making things that could cause this sort of issue. The more \"things\" you add to a game world, the worse the game will perform, simple as that! If you add a new physics object, it can potentially interact with every other already existing physics object, and they all have to \"talk\" to each other to see if they're colliding. So to optimise this sort of game, you make that \"talking\" as simple as possible, and make each \"part\" as simple as possible in terms of data",
"Professional software engineer here, working in games. Performance costs increase when you have more objects in the scene that need to perform complex interactions with other objects, such as applying physics or occlusion culling. For rendering in games with user generated content like KSP and Space Engineers, you don't have the luxury of telling a designer how to optimise the scene for better performance. In this case, you rely heavily on things like occlusion culling, LODs, and GPU instancing. Occlusion culling is the name given to any way of telling what 3D objects will not be visible on screen. Objects that aren't visible get ignored by the game, reducing how much time the game spends running calculations for them. LOD stands for \"level of detail\", and is used to show a less detailed version of 3D objects as they get further away from your camera, with the goal of being unnoticeably different. GPU instancing is useful if your scene has many of the same 3D object in it. It's a way of reducing how much information your game needs to send to the GPU, by identifying objects as having the same 3D form and / or the same surface materials. If you have a spaceship with 300 identical thrusters, the game could send full information about all 300 thrusters to your GPU... Or it could send information about just one thruster, and then say \"by the way, this same object appears in these 300 places\". It's a massive time save! There's a ton more optimisation that goes on for improving the performance of 3D rendering, but these are some of the bigger ones. For physics with user generated content, you have a whole host of challenges. The biggest runtime costs you'll run into with physics is when moving objects through a complex scene - ie one with lots of objects very close to each other. This cost occurs with or without having simulation (ie the ability to be shoved around) enabled for the objects, and is purely due to the physics engine keeping track of the overlaps between different objects. Another big cost can occur when needing to simulate many objects, when they're all hitting each other in close proximity. The first big optimisation is often to have designers create simplified invisible 3D versions of the visible 3D objects, using spheres, capsules, boxes, and (more often) convex meshes. These simplified objects perform much better in physics engines than the visible 3D geometry would, because the engine can make a number of assumptions about their shape to speed up calculations. Another big optimisation is setting up your objects so the physics engine knows only specific objects can ever interact with other specific objects. For example, most games approximate the player with a vertical capsule shape, and this capsule represents where the player can physically move in the world. If the capsule doesn't fit, the player won't be able to go through. But at the same time, the player would expect, say, the character's body to interact with the scene, for example letting their foot kick a cardboard box out of the way while running. In this case, the cardboard box interacts in no way whatsoever with the player's capsule, so designers can set the two objects up so the physics engine knows this. It will then never run into the cost of checking if the cardboard box and player capsule are overlapping. This is done *a lot* in videogames, and players are often none the wiser. For another example, think of shields in Overwatch. Players can pass through them, but explosive projectiles and bullets can't. Finally, another optimisation can come from carefully attaching solid objects to each other, so that moving one object will pull the rest after it, as though they're made of one piece of solid, inflexible material. This tells the physics engine that these objects can be treated as one big object instead of many small ones, which saves many calculations. Once the object gets hit by something with enough force, the game can be designed so the object breaks, giving the player the illusion that it was made up of many smaller, individual parts all along.",
"Moving parts are difficult to handle efficiently. Some programs do some levels of optimization by utilizing things like bounding boxes to at least provide a quick and simple check to see if any two things need have even a remote possibility of colliding. If the bounding boxes would overlap in the next frame, then more detailed calculations may be made to see if the things actually intersect. Another improvement along similar lines clusters items that are geographically close to each other. That way you only need to check collisions within your cluster since anything outside would be too far to have a chance to intersect. Now, both of these optimizations break down if you have a lot of small, moving parts all close to each other (such as with a modular spaceship). It becomes harder to find quick and easy checks when in any given frame, things might start to intersect and collide.",
"So in general, those games weren’t optimized for the longest time. They focused on adding features and I still can’t play Space Engineers on a machine I played the entirety of Death Stranding and Resident Evil 7 with max settings in 4K HDR on at 60fps, without severe lag and crashes. There are a ton of tricks though, some old some new. The most common optimization is greatly reducing poly counts in place of normal and bump mapping. Following that, you can use what I believe is called a proxy object. These are objects that are just flat images or severely simplified objects that at the distance they’re drawn at look almost exactly the same as they would at full detail at that distance. If an object is so small that it would only take up a 10x10 space on the screen then you can use a 10x10 image of that object instead, or one consisting of 10 polys instead of 10,000. Last, you can use tricks like Gears of War did which would render the same creature objects in multiple places on the scene - which effectively greatly reduces the scene poly count (think of it as using the same brush to make multiple strokes on a painting instead of a brush for every stroke simultaneously - it does mean more renders per pass though). This is becoming especially more common as graphics cards are increasing their pipelines which allows those objects to be rendered simultaneously from the same chunk of memory.",
"BTW, these games not only optimize for performance, but also for precision. Game engines use floats to save position of objects. Problem is, they get less precise the larger they are. Everything is fine for the most part, but anything over 10km gets janky really fast and the whole game just melts. Thats why in KSP the dont move the player, but everything else. Some other games just teleport everything back when you get too far. This way everything stays close to 0 where everything is precise. I think this is also really cool.",
"There are several conceptually simple methods to optimize physics performance. One method is to create multiple layers of physics simulations sorted by accuracy, and the further something is away from being important, the less horsepower you devote to making an accurate calculation. In essence, the less you *care* about an accurate calculation, the less time you need to devote to getting it right. So in KSP, if you're working your ship through takeoff, it's important to simulate your ship components as accurately as possible. But when you crank that sucker up to 4x speed, the engine is cutting corners and best-guessing a lot of these calculations. That's why your ship sometimes tears itself apart under 4x speed, but does fine under normal speeds. In this example, your ship is normally getting updated 60 times per in-game second, which takes the full horsepower of your rig. When you go to 4x speed, you now have to use 60 updates to calculate 4 in-game seconds. So obviously, you have to cut some corners. The time delta between updates is 4 times larger, and you lose accuracy by cutting out those middle steps. Most optimizations are generally variations on this theme. The important design decisions go into know which parts of your simulation don't require perfect accuracy, and which parts do. The parts that do require accuracy are updated as many times as possible, while the parts that don't require accuracy are updated as few times as possible. Optmization is tweaking these levers until you like your results."
],
"score": [
73,
25,
7,
4,
3,
3
],
"text_urls": [
[],
[],
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
i1h2tu | How are undersea fiber optic cables powered? | I know that undersea fiber optic cables are active and boost the signal every 80 mi or so. I know that the cables carry electricity for that purpose. But can you really have an electric line running thousands of miles from the source and maintaining a charge? Doesn't electric charge attenuate with distance too, especially with power consumption along the way? | Technology | explainlikeimfive | {
"a_id": [
"fzxeesr"
],
"text": [
"High voltages are necessary meaning that each signal booster will include its own power supply to convert the voltage to something it can actually. I mean, we already have power lines going many miles at a time. That's how you do it - send it at high voltage. It's the current (amps) that drain power over a long cable turning it into heat. \"Power consumption along the way\" doesn't mean anything. You wouldn't want each repeater's power supply chained up to the next one. You'd do it how your home electricity is wired: each outlet is a split off a single master feed. The voltage will drop slowly over the long distance but power supplies are designed with tolerances, and can be made with very large tolerances if need be. Most of your home electrical stuff already supports anything from 100 to 240 volts."
],
"score": [
8
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
i1j7ox | how do satellites work? | Technology | explainlikeimfive | {
"a_id": [
"fzxt8y0"
],
"text": [
"Technically the definition of satellite is anything orbiting a planet. This would include our moon. Assuming you mean the science ones, a big rocket put it in orbit. They generally use solar power for electricity, and can communicate to earth using radio waves. If you are more specific on your question I can explain more."
],
"score": [
4
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
i1jphh | Why wont Automakers bring back replicas of popular classic cars but with upgraded safety features? | Technology | explainlikeimfive | {
"a_id": [
"fzxwnvl",
"fzxwzd1"
],
"text": [
"> I think Automakers would make a killing if they brought back some of the most popular models they ever made but with upgraded safety features I think you might be surprised. Car makers have done this repeatedly and they are frequently of questionable success. For example the Ford Thunderbird was one of the huge successes of the company and lasted from the 50s to the 90s. It was brought back in the 2000s and it was a dismal failure.",
"First, the market for such a vehicle is probably not as large as you think. Most people just want a cheap car that gets them from point A to point B cheaply. Most modern cars do that already. The only people who would be really interested in such a vehicle are the ones who already have the money and desire to seek out *actual* vintage vehicles. Second, part of the reason vintage cars have charm is *because* they are vintage. We can easily make a reproduction whatever, but it will always only be that: a reproduction. It doesn't have the same allure. This part goes hand-in-hand with the first: the people who appreciate those cars won't be as interested in a reproduction, and the people who aren't interested in a reproduction won't want a weird-looking car. Third, part of the reason older cars were simpler to work on was because the technology used to manufacture them wasn't as sophisticated as it is now. A lot of the modern safety features and fuel economy we enjoy today is because of sophisticated electronics and complicated mechanical devices. Making a car \"easy to work on\" necessarily means stripping out a lot of the features we take for granted. Modern safety requirements, fuel economy, and amenities *necessitate* a minimum threshold of complexity and cost. Returning to that level of nostalgia would mean giving up a lot of the benefits we've picked up along the way."
],
"score": [
3,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i1k0ae | How does Wifi actually work? | Is it literally like radio in that you have an antennae connected to input and output pins to send and receive? | Technology | explainlikeimfive | {
"a_id": [
"fzy1xr5",
"fzy1l1y"
],
"text": [
"So like, you know how you turn a flashlight on, and it shines around corners? And even if you used one in your kitchen in a pitch black house, you could probably see it a few rooms away? It's almost exactly like that. Your router spits out invisible light in a ~~lower spectrum~~ ~~shorter wavelength~~ different wavelength than you can see, and it literally bounces around your house like a high powered flashlight, and also goes through a bunch of surfaces visible light doesnt,albeit not as well as through open air. It eventually bounces off your wifi antenna and you do the same back to it. Picture your wifi and your laptop as two ships at sea flashing lights as eachother to communicate, but they're really good at it. And instead of huge lights with shutters, its antenna. Edit: also, if you could see in radio waves, your room would be bright as hell. Someone correct me if this is wrong or off a bit.",
"Kind of, yes. WiFi (or tv, or cellphones, or walkie talkies) are only wireless between what is listening and talking. In wifi, you have a receiver and a transmitter on both sides (your modem/router and your device) which uses a special language to \"code\" the binary bits (1s and 0s) to communicate data (if you're curious it's IEEE 802.11 protocol). WiFi is interesting though, because unlike your cell phone (FCC licensed frequencies in the USA) or your radio or tv (one way signal), WiFi is unlicensed. It means anyone can use that frequency up to a certain power. How can that be possible? Well, there are different channels. Think like on your TV. And your router is smart enough to \"listen before talking\" to make sure it's not trying to speak over someone else trying to talk. That is why you can see your neighbors wifi signal but still use yours! You are both using the same frequency, buy a different channel most likely."
],
"score": [
73,
12
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
i1k5sc | "Bouncing" audio tracks? | I was just tweaking an audio file in GarageBand, and when I went to export it I got the message "Bouncing..." When I Googled this, it said it's a feature for when you're trying to save space on tapes. The way it apparently used to be done was you would record all but one track, mix them together, and move them to the last track. I don't really understand what's happening there or how it saved space, could someone please explain this to me? | Technology | explainlikeimfive | {
"a_id": [
"fzy0moo",
"fzy5gvw"
],
"text": [
"You hit the nail on the head with your description. Bouncing, or ping-ponging, was a way to record more instruments / vocals back in the day when you were limited by the amount of tracks you could record on tape. On an 8 track recorder, you could record on the first 7 tracks, mix and EQ everything, and then dump it down to track #8. Now you've got 7 more tracks you can work with so you've turned a 7 track recording into a 14 track recording. Always nice for when you have to add more cowbell.",
"> But today, bouncing usually means writing the final mix of your song to a stereo audio file. It can also mean printing stems of all the instruments in your mix or exporting individual tracks for collaborative projects as well. URL_0"
],
"score": [
9,
4
],
"text_urls": [
[],
[
"https://blog.landr.com/export-tracks-daw/"
]
]
} | [
"url"
] | [
"url"
] |
i1lx41 | How do they keep your vital systems all intact when you are in a medically induced coma? | It is probably quite a simple answer but i have actually never heard the way they do it. | Technology | explainlikeimfive | {
"a_id": [
"fzych2n",
"fzyxcd6"
],
"text": [
"You're fed through a tube and piss through a tube, body does pretty much everything else on its own as normal. Your heart rate, breathing, blood pressure, etc. are all tracked and someone comes to intervene if something goes wrong. In the end you're just asleep even if it is artificially induced",
"If your level of consciousness is really low, you would stop \"protecting your airway\" - like think of a tube collapsing. You also stop breathing as often or at all. So, in a deep coma, you are on a breathing machine. Side note: there are different levels of a coma. Health care professionals measure the level of a coma on a scale looking at what is needed to cause movement, eye opening, and speech/awareness (and the kind of movement and sounds are caused by the stimulation). An awake alert, responsive person would be 15. No movement, eye opening, and sounds would be a 3."
],
"score": [
3,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
i1t2ao | Why can't game servers differentiate between people who get disconnected and those who choose to leave a match? | Technology | explainlikeimfive | {
"a_id": [
"fzzj5rw",
"fzzkg41",
"fzzj3e9"
],
"text": [
"The game can only differentiate if they use a game function to quit the match, like pulling up a menu and choosing the \"quit game/quit match\" option. Otherwise, the game only knows it has stopped receiving data from that player, there's no way for it to tell why it has stopped receiving data. Computer crashing, network going down, killing the client: They all look the same, the player just became a data black hole. Even if they look back in a minute later, it could be because their network came back, their machine restarted, or they restarted the client.",
"You can definitely tell if someone used the game menus to leave, since that will send a signal to the system. If someones internet legitimately cuts out or they've sabotaged it you can't really tell. However, you still kind of want to punish people similarly, but compound the punishment for repeat offenders. If someone keeps disconnecting, they either are sabotaging their connection, or they have such a bad connection that is is unreliable. In either case, it is unfair for the other people on their team. They either get paired with someone who is leaving the game intentionally, or they get paired with someone who has an unreliable connection and may not stay with the game.",
"If you would differentiate and introduce some kind of penalty for leaving, people would just pull the plug to avoid the heavier penalty. EDIT: they can and they do, however you can’t take actions on it"
],
"score": [
14,
8,
3
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i1ucmf | Why did intel 𝘳𝘦𝘥𝘶𝘤𝘦 the contacts on their CPUs? | Technology | explainlikeimfive | {
"a_id": [
"fzzue1i"
],
"text": [
"The different number of contacts is mainly to make the parts physically incompatible so you can't put them in a slot they weren't made for. There are probably a dozen or so reserved but unused pins in each socket layout, and a hundred or so ground/VCC pins that they could easily gain or lose a few without issue. Even when they added 50 pins, it wasn't because they needed 25 more communication pairs, it just means that motherboards can more effectively restrict the chips they support electrically, physically, and software wise"
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
i1uy40 | Why do smartphones/laptops get slower and develop issues over time? | Technology | explainlikeimfive | {
"a_id": [
"fzzx83y",
"g000l18"
],
"text": [
"Batteries degrade over time. That's just how they work. They're based on chemical reactions that don't work ideally, and various waste products and inefficiencies build up with each recharge. As far as speed, it doesn't really change in the hardware. Apple specifically would throttle down CPU speeds on phones with worn batteries to preserve function and battery life. Old batteries are weaker, and a CPU demanding a lot more power could lead it to asking for more than the old battery can provide, and lead to the phone just powering off suddenly. These days there's a menu option for that. Besides that, lots of phones were low on RAM historically, which means that as newer, bigger software comes out, they'd struggle with it. If you have a modern, fancy phone with 8GB or 12GB RAM it should have plenty headroom for a long time, but a 2 GB phone would have a hard time. For things like laptops there's also that installed applications can add load on the system. Some things either run in the background, or constantly like an antivirus, and the more such things you install, the more it taxes the system. Reformatting the system can get rid of all of that and help a lot, but of course it only lasts until you fill it up with stuff again. A computer used for only a few applications will usually keep on performing well.",
"Why aren't these devices made with replaceable batteries?"
],
"score": [
9,
4
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i24kxf | Why are video games region-locked? | What's the difference between NTSC and PAL? Are PC games region-locked? If I move to another country (region), will my PC games be affected in any way? I hope I'm using the right flair. Edit: thank you, everyone!! I think I got the necessary information to begin and dig deeper into this rabbit hole. Thank you kindly!! | Technology | explainlikeimfive | {
"a_id": [
"g01qijx",
"g01vubp",
"g01ywlw"
],
"text": [
"no PC games are not region locked. but depending on where you are, you may or may not be able to connect to that game's servers for online play. & #x200B; NTSC and PAL are different formats for displaying video output.",
"At this point it's nearly all legacy. PAL and NTSC TVs required different outputs, so the actual games - on consoles - were marginally different. It used to also be far more common for games to only come out in one region, and then only get a \"foreign\" release if they did well or if a publisher in a different region approached the developer (a small Spanish publisher might have no way of getting a game into the shelves of North American Electronic Boutiques, for example). This lead to situations where a single game might have many different publishers in different regions, each with exclusive rights to sell the game in a given region. A lot of the relationships have been maintained, and different legal entities exist in different regions already set up to sell there, so they continue to.",
"On Steam PC games are region-locked in an interesting way. If you are from Russia/CIS, you cannot buy games from other countries (by changing your location) and vice versa. Steam actively bans users who try to use VPN to region hop. That's because prices in Russia are typically lower than in, say, US. When Russian currency (rouble) plummeted back in 2015, all prices, which are connected to dollars (video games too), suddenly rose. To counter that, and to allow large Russian gamer community to keep playing, Steam somehow managed to lower the prices somewhat. And Steam doesn't like to make lesser profits either. For example, if I buy a game (I live in Russia), I can't gift it to my friend from the US. Some games explicitly state, that they cannot be played in certain regions, but that's mostly because of censorship. Of course, you can change your location on Steam, once per 14 days, provided, that you didn't make any purchases in several days."
],
"score": [
8,
4,
3
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
i25tz1 | Whats the difference between AM and FM Radio? | Technology | explainlikeimfive | {
"a_id": [
"g01zigb"
],
"text": [
"Imagine you had a stick in a still pond. You start whapping the water at a continuous frequency. The is your base frequency. You want to encode information in your whaps. Here are two options: you can either change how hard you whap the water (AM) or how often you whap the water (FM)"
],
"score": [
9
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
i264w0 | How do laptop companies install the Operating System into their laptops? | Technology | explainlikeimfive | {
"a_id": [
"g021hsv",
"g02n0c4"
],
"text": [
"TLDR: Imaging/hard drive cloning on an industrial scale We use similar techniques in Industry to prepare laptops and desktops for businesses. You install the Operating System on an example machine, install the drivers and any software that you want to package with the device. Once the machine is in a state that's ready for deployment you prepare it for imaging. You run a tool call 'SYSPREP' which puts into what Microsoft calls OOBE (Out of Box Experience) which means that on the very next boot the machine randomizes certain variables to make it a unique instance of Windows (think serial number) and goes through all the various menus to do an initial setup of the machine. This is how you get a machine into the state of First Boot asking for setup, passwords etc, while still having pre-packaged programs like a demo of MS Office, and antivirus pre-installed. (aka OEM software or crapware) This machine is then imaged. Software is used to clone this prepared computers hard drive to a file. This imaging software (Norton Ghost for example) can then be used to deploy this image to any number of machines with identical hardware. So a company like HP or Dell for example makes thousands of machines and images them all using this technique. An imaging rig could be easily built to handle uploading this image to hundreds of computers simultaneously taking about 10-20 minutes per machine. In industry we typically use a Windows PE disk to run the imaging software (booting off USB of PXE ie network) but at big manufacturers they probably plug the hard drives into an imaging rig directly and then install them into computers on the factory floor and ship them out.",
"If you are interested, I did a 25,000 unit laptop roll-out for a massive Resources company. They had 1200 applications that needed to be available for the end-user to select from, all of which had to be tested on the new version of Windows, as well as with each other, on the new hardware. We rented a building in Singapore, filled it with servers, hired a bunch of testing experts, and ran every possible combination of OS and apps... up-to and including someone running all 1200 apps on the same machine at the same time. All up it took nearly a year."
],
"score": [
37,
4
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i266f6 | Military jet trails. What causes the streak in the sky, and why does it linger so long? | Technology | explainlikeimfive | {
"a_id": [
"g023q34",
"g02zn8w"
],
"text": [
"You're probably thinking about the trails left by the military jets at air shows. For those shows, there a machine that sprays oil into the exhaust. The exhaust heats up the oil making smoke. Sometimes that oil is even colored. It stays up because it's not much more denser than air, and much hotter. I think the majority of the oil is what amounts to be liquid wax (paraffin-based smoke oil), but I'm not 100% sure. When fighting a war, military jets really don't want smoke trails. It shows up really really well on radar and everyone can see it. But in an airshow in peace time, you want everyone to see you, and look at how cool your moves are. So they put them in. That being said, there are ways to unintentionally make a smoke trail. The differences in air pressure caused by the engines and wings sometimes causes the water vapor to condense around stuff in the air. Often around the stuff left over from when they burnt jet fuel. So that makes clouds. You see this quite often in air liners, but it sometimes happens to military jets. In war time this makes the pilot very very nervous.",
"Jet trails aren't just military jets. There are 2 types of trails behind jets - the ones that are made on purpose - like you see at air shows and it's the same thing sky writers use - they just push smoke out of the back of their plane. But most of what you see in the sky is contrails - contrails exist for the same reason you can sometimes see your breath. The hot, humid exhaust from jet engines mixes with the atmosphere, which at high altitude is of much lower vapor pressure and temperature than the exhaust gas."
],
"score": [
6,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i266j2 | How do they program computers to understand programming? | I understand computers run on programs, but how do they program the computer to do said programs? | Technology | explainlikeimfive | {
"a_id": [
"g024nbu"
],
"text": [
"The chipset (CPU, etc.) has a set of very simple instructions, like \"copy the value from this spot in memory to that spot\" and \"add 5 to this\". They're very low-level, simple instructions, but when you combine them, you can build compilers/translators so that higher level languages can translate down into that low level language. So you can say \"x = 5 + y\" instead of \"move the value at memory location y into register Q, then add 5, then move the result which is in register R into the memory location pointed to by x\". Same thing, but you don't have to specify every step in detail. Layers upon layers of that translation and simplification make modern software development possible. Ultimately, it all gets translated to the most basic of instructions - \"copy whatever's here to there, then jump to this other place\". Those few basic instructions (copy, jump, add, etc.) are baked into the hardware. All software, no matter how complex, ultimately has to express itself in terms of those few simple operations. It can do so because those few hardware supported instructions are infinitely combinable into turing-complete software - software that can do anything that the hardware is capable of. So modern software is built upon layers upon layers of translation, but at the end, after all that translation, it's just a bunch of really simple operations like go here, do this, then go here. And those few simple operations are built into the hardware."
],
"score": [
7
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
i2ds3i | how smart scales can give you all kinds of information about your body just by standing on it | Technology | explainlikeimfive | {
"a_id": [
"g03yp4g",
"g04b8u6"
],
"text": [
"Those types of scales generally run a very tiny current from one foot to the other. Depending on how well the current runs, it estimates your body-fat. If it knows how tall you are, it can convert that into BMI. It’s not particularly accurate, but it does give a decently good rough estimate.",
"One of the things they do is to run a very low electrical current from one foot to the other - which is why you generally have to stand on them bare foot. The scale measures the time the current takes to travel through your body and return to the other foot. The idea is that the human body is around 60% water, and electricity travels easily through water. However, body fat produces a certain amount of resistance to the electrical current, essentially slowing it down. And so, the scale is able to measure the electrical resistance of your body and from that calculate an *approximate* body fat percentage. I say \"approximate\" because it cannot be totally accurate. A simple factor of how hydrated you are can significantly affect this measurement. Therefore, it's usually not advisable to use electrical impedance body fat measurement (such as in smart scales) as an 'absolute' measurement. It's fine if you're consistent in your measurements - ie, approximately the same time of day each time, and with a similar level of hydration - and want to track a general trend. Additionally, as electric currents will always travel through the path of least resistance, the current will generally travel no higher than your waist, and so these scales generally do not accurately measure upper body fat. So, if you were pretty lean in your upper body, but naturally held fat around your thighs and butt, then you could get a skewed reading. Some scales can calculate body composition - ie, the amount of muscle, water, bone and body fat you have. However, this is really just an additional calculation the scale makes once it's measured your weight and body fat, making some assumptions about the average percentage of overall body weight that bone makes up based on average bone density. Some smart scales can calculate your Body Mass Index (BMI). Usually, you have to tell the scale your height and then it's a simple matter of the scale measuring your weight and making a simple calculation using that weight and your height to determine your BMI. Some can also measure heart rate - again, this is done through electrical impedance."
],
"score": [
22,
7
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i2g08e | How are scenes like Platform 9 3/4 filmed? | They run into a solid object but looks like they’re going through. | Technology | explainlikeimfive | {
"a_id": [
"g04mitb"
],
"text": [
"It looks like it's probably a green screen. They have the actors run through a certain point on the green screen set and then record the station footage separately. If you notice, the shot of them running into the wall is static; the camera never really moves once they start running toward the wall (it quavers a bit when Fred/George are running but that wouldn't ruin the effect). They can then use video editing software to track the actor, place them into the full shot, and then use a feather mask to essentially blend each part of their body out as they move through the wall. If you want to see a bit more in depth, [here's a tutorial on how to do a simpler version of that in After Effects.]( URL_0 ) The difference is that the running shot in the movie would be done against a green screen in order to allow the actor to keep moving through the object."
],
"score": [
6
],
"text_urls": [
[
"https://www.youtube.com/watch?v=OpEqCjD_pqY"
]
]
} | [
"url"
] | [
"url"
] |
i2gcwo | How do Youtube view counts work? Like, if I exit a video before it's completely done, does it count as a view? | Technology | explainlikeimfive | {
"a_id": [
"g04kyg0"
],
"text": [
"I’m not an expert on YouTube’s algorithms but I think if you watch at least 30 seconds of the video, then it counts it as a view. That’s what I’ve heard anyway"
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
i2iozm | Why does the volume on my television have a 0-100 scale, yet any setting above a 10/100 is unusably loud? | Technology | explainlikeimfive | {
"a_id": [
"g051fce"
],
"text": [
"The size of the room it is in may factor in also. Bigger tvs generally may have bigger rooms in mind. Having them in a smaller space could make those low volumes perfectly acceptable, whereas you may need to get I to the bigger numbers if you had it in a much larger room."
],
"score": [
5
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
i2k7f6 | Why when downloading or installing something the amount of time remaining is always wildly inaccurate? | As an example, I’m downloading an update for my Mac currently and and I only have .27 GB left to download and it says I still have 5 hours remaining. | Technology | explainlikeimfive | {
"a_id": [
"g05b212",
"g0585z1"
],
"text": [
"I have also heard on good authority that some loading bars and time remaining counters are basically aesthetic with no actual connection to the process",
"Time remaining is amount of data left to download divided by your current network speed. If the network speed is not stable, the estimation will vary wildly, usually the numbers are averaged over time, to give a more constant value but you cannot do that too much or you'll not have reliable information either (the system could tell you : in 10mn I'm done, decrease the timer 1s every second, but after 10mn you're still not done)"
],
"score": [
3,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
i2muru | why do we still use signatures if they're so easy to forge? | Signatures are really easy to forge, right? If somebody saw a signature, couldn't they copy it? | Technology | explainlikeimfive | {
"a_id": [
"g05pb2s",
"g05t8y8"
],
"text": [
"Signatures aren’t actually used much anymore; I use a PIN with my plastic cards, signing deeds and contracts is usually done digitally these days. That said, it’s really hard to accurately forge a signature. The ink flow is dependent on angle and speed, and the shapes need to be accurate.",
"It's much more about acknowledgement of payment or an agreement than prevention of forgery, especially nowadays. When you sign something you are making an agreement, even if you just draw a squiggle or write an x for your signature."
],
"score": [
6,
5
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
i2niwm | How does "I'm not a robot" verification actually work? Couldn't bots also check for the button and press it? | Technology | explainlikeimfive | {
"a_id": [
"g05vmwq",
"g05z30y",
"g0617mx",
"g060j6o",
"g05vgey"
],
"text": [
"Yes, but that would take time and computer processing. The button is there to stop bots from making thousands of request every second. The button might drop it to merely dozens per second. One of those \"type the letters\" might drop it to single digits per second. Also the button often looks for human like variation in where its clicked and how long it takes to click it. You can fake that too, but again, more time and computer power.",
"I do automation and hate captcha, hah. Those check boxes are deceptive because your “human score” has already been calculated by google. We don’t know exactly what google checks for, but it’s things like natural noise movement, and other things I don’t know. Once you click the checkbox, you submit your score and google decides if they want to challenge you with the old style “click the pictures with traffic lights” captcha.",
"You're training AI. \"Click on all the busses\" You're training self driving cars when you do that.",
"It's not hard at all for a robot to tick that box...but that's **not what the website is checking**. It's actually checking how you move the cursor as you go to check that box - the box itself is pretty meaningless. If your cursor makes a perfectly straight line directly to the box, and it happens within an instant of the website loading? Then it assumes you're a robot. If it takes you a moment to react, and you move the cursor in a straight-ish - but not perfectly straight - line? Then it assumes you're a human. \"But,\" you cry, \"can't the bot just do those things too? Make itself take a moment to react and make a not-perfectly-straight line?\" Well, sure...and then that means that whoever is making the \"I'm not a robot\" check needs to come up with clever solutions to whatever the bot is doing. Then whoever is making the bot needs to come up with a sneaky way around those changes. Then whoever is making the check needs to fix those holes. Around and around...the security arms-race never ends. But that's *generally* how it works: the box itself is a distraction; the real work is happening behind the scenes.",
"Once checked it reviews your recent browser history and looking at that it can tell that you are human."
],
"score": [
22,
12,
5,
5,
3
],
"text_urls": [
[],
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i2ovfp | Why is "turning it off and back on again" such a good fix for electronics? | Technology | explainlikeimfive | {
"a_id": [
"g062fj9",
"g062so4",
"g062lbj"
],
"text": [
"It gives the operating system a chance to \"start over.\" If there is a process that has stopped for some reason, you can shut down the computer, and then when you boot it back up it will be started along with the rest of the operating system. Also, it refreshes the internal list of hardware it's working with, which is why you sometimes have to restart when you make certain system changes. It's a lot like how when you have a bad day you can go to bed and have a good day tomorrow.",
"When you turn it off, the iterations happening must stop and maybe the one who is causing the problem is stopped that way. To initiate properly many starting programs also do a checklist and find the problem before it became alive again, so turning off and on helps with that.",
"Electronics often fail by getting into a bad state. That is, a program reaches some state that either continues forever by not moving into another state, or enters a loop that cycles between a few states forever. As an example, consider the following short snippet of code: x = random(0, 2) // randomly sets x to 0 or 1 while (x == 0): // run this part until x isn't equal to 0 do_nothing() // repeats forever because x stays equal to 0 continue_to_some_other_state() Of course, no one would deliberately write such a program, but the value of x - which is set in the first line and then never changed - turns out to have a big impact on the function of the program. Resetting the program and rerunning it might have x set to 1 instead, avoiding the infinite loop and continuing with other parts of its execution. Many problems in real-world programs basically boil down to logic like the above, where rather than x being totally random, it depends in some complex way on the other history of the program's execution. A reset breaks the loop."
],
"score": [
4,
3,
3
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i2ssfd | what makes a 5th gen fighter plane so superior to 4/4.5th gen? Why havent many countries been able to develop 5th gen fighters? | Technology | explainlikeimfive | {
"a_id": [
"g06rtgq"
],
"text": [
"Some properties of 5th Gen Fighter aircraft, like: 1. Supercruise: ability to fly faster than and sustain speed of sound, in level flight, without using afterburner / reheat. The engine technology and materials required to achieve this, are simply not available in the piblic commercial domain. 2. Stealth: ability to reduce apparent radar cross section in reflected radar waves, so that a large plane appears no bigger than a small bird. The technology to achieve this using fuselage shapes and / or using material coatings (RAM, like the F-22, F-117) are closely guarded secrets by the US. It is also very difficult to maintain these coatings, since even one scratch may cause RAM to flake off and increase radar visibility. --Are just not so viable to invest large amounts of cash in, for R & D. Russian designers believe that a faster, highly manoeuvrable aircraft, with superior armament, can beat a stealth aircraft. This has been one of the reasons why there are not many Russian stealth fighter aircraft, though their fighters are relatively cheap to own and operate. US designers believe that a fast, undetectable fighter aircraft, with superior armament stands a better chance in combat. This comes at the price of higher operational and purchase cost, but means that these aircraft have a higher chance of surviving combat, under many circumstances."
],
"score": [
8
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
i2tnqx | Why are circuit boards often green of color? | Technology | explainlikeimfive | {
"a_id": [
"g06y65f"
],
"text": [
"It’s a coating added to the board so the solder only sticks where they have to add components, making it easier to solder. Nowadays we can use different materials, but green was first Early circuit boards didn’t have this coating, making them look white with silver colored traces because solder sticked to the whole track"
],
"score": [
5
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
i2uxfl | What is a nuclear reactor and what does it do | Not sure if physics is the right flair but I was bored researching Chernobyl and I realized I don’t exactly know what a nuclear reactor even is or what it does? | Technology | explainlikeimfive | {
"a_id": [
"g0759t7"
],
"text": [
"(God I hate the \"it just boils water\" explanation of a nuclear reactor. That's like saying an electric car works by friction, because its wheels touch the road. It's using the most mundane aspect of it to avoid talking about the part that actually is what makes it important and interesting.) A nuclear reactor is a type of machine that produces a controlled nuclear fission chain reaction. Nuclear fission is \"splitting atoms.\" A nuclear fission chain reaction is when the splitting of one atom can produce particles that lead to the splitting of more atoms, which can lead to the splitting of more atoms, and so on. A reactor is the kind of machine that makes the conditions right for a lot of splitting to occur. But ideally it also lets you control that reaction, so that the splitting only happens when you want it to, and stops when you want it to. There are a lot of different ways to design a nuclear reactor. That splitting generates heat and that heat can be converted into electricity, if you want to. That's the water-boiling part. Not every reactor makes electricity. At Chernobyl, what happened is that because of an experiment they were running, and because of conditions in the reactor, and because of the specific type of reactor it was, the reactor got out of control. They tried to shut it down but instead the amount of fissioning went WAY up, creating a spike of heat that caused a steam explosion, which blew the top off of the reactor. That let out a lot of the remains of those atoms that had been split, which are very radioactive and dangerous, and they contaminated a wide area. There are of course a lot more details of exactly went wrong and why, but that is the gist of it. It is of note that the Chernobyl reactor was a kind only used in the Soviet Union, and which had certain design flaws that made it inherently vulnerable to this specific kind of accident."
],
"score": [
12
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
i2vfch | How does automatic Hover Mode in Helicopters detect wether you are flying or standing still relative to the ground beneath you? | Technology | explainlikeimfive | {
"a_id": [
"g07zkz8",
"g093m2x"
],
"text": [
"The Tello has vertical computer-vision sensors; it remembers what it looked like 'before' and if the image is offset it knows how to move it back into alignment. It works best when there is some high-contrast item within view -- if it is over a flat matte surface it doesn't work well. & #x200B; Which as I say that sounds quite a bit like the homing sensors of a missile; my how technology has advanced.",
"I'm not exactly sure if you are speaking of full sized helicopters or drones and radio controlled helicopters. Let's start with the basics. A full sized helicopter will hover on a cushion of air near the ground. It is very similar to what happens in air hockey games or hovercraft. It's a inbuilt feature just by being near the ground and is in fact called ground effect. This also affects airplanes. You can see that happen when a airplane appears to hesitate before it lands. Since helicopters make good use of this phenomena, it will just sort of hover over a spot and slowly drift around. The pilot can prevent this with minimal movement. It's one of the first things a helicopter pilot learns. Note a helicopter can hover outside of ground effect but that's much harder. Now many helicopters don't use any special methods to keep it stable other than the actual stuff that makes a helicopter works, and the pilot. There are no gyros, no accelerometers, Zippo. It's just kind of stable on its own, at least in hover. However newer helicopters will make use of digital gyros and accelerometers. These are very much like what is in your phone. They can help keep a helicopter in hover even in a wind and do much much more. One instrument important to all flying helicopters is what is called a Air Data Sensor. The one in the front looks like a pointy tube sticking out of the helicopter. Usually called a Pitot tube. Airplanes have em too, even the most expensive aircraft have them. there can also be more hidden air sensors facing in every direction. This is how a helicopter can measure airspeed, sink rate and climb rate. This happens by measuring the wind speed, in any direction and by measuring barometric pressure. One thing you often see is the airport tower telling the barometric pressure. This is so you can calibrate your own instruments. Usually this is just to tell you what direction you are going in, up or down. Autopilot with hover mode will use all these to help keep a helicopter flying over one spot. The tower may also give you compass settings as you'll need to recalibrate that too. But mostly, especially in basic trainer helicopters, its YOU and your instruments. No helpers. Just your throttle, collective, cyclic and tail rotor pedals. Although many helicopters have switches to control rotor speed. Some of these instruments are in modern helicopters, drones are different however. Especially multimotor drones. They will have a whole list of sensors that go far beyond what most helicopters use. Because they are hindered by not having a pilot on board. 1. Accelerometers are in almost all multimotor drone. They couple with a flight computer to keep the motors tuned to keep it stable. It's the first basic sensor. They can also be in real airplanes and helicopters. Usually for instruments. This can also be very useful for indicating true ground speed. Real aircraft often use radar for this. 2. Rate gyros sense direction changes like tilts and turns. This also couples to the flight control computer to keep you stable and level by adjust motor speeds. Also used on radio controlled airplanes to help you from crashing. This is also seen in real aircraft for instruments. In fact a gyroscope has been common in aircraft for many decades. Newer gyroscopes can be hooked up to a computer for autopilot. 3. Barometer. This is useful to help keep you hovering at the right altitude. Even small altitude changes can be detected. It also is fed into the flight control computer. Barometer has problems with changes in weather. 4. A compass. Believe it or not, a simple compass fan still be very useful. It's basic for all aircraft and a digital compass can be hooked up to a computer. The computer can then be used to help autopilot. These four sensors are in the vast majority of toy multicolored drones. Without them, the drone is almost impossible to fly. However, more expensive drones carry even more sensors. They are also built into newer full sized aircraft and are usually meant to help the pilot via instruments. 5. GPS sensor will measure gross changes in direction including altitude. Within the error of any GPS unit. They are used in conjunction with the sensors listed above. This is most useful for full autopilot modes lover long distances but also great for hovering especially in a wind. 6. Optical Flow Sensor. Works pretty much like your mouse. It can sense movement over ground just by comparing pictures stored temporarily. Your mouse does this too. A lot of industrial machines that need alignment do this. 7. Visual 3d mapping. This is a new one and only a few drones have it. Very few real aircraft use it for navigation as they use radar. High resolution cameras, much different than the optical Flow cameras, are combined into a special computer and ate processed to create a 3d image that the computer and thus the aircraft, can navigate through. That part is beyond me to talk about. 8. Radio Direction Finding. Less used today but still in active service, mostly for navigation. These are calibrated radio signals given at fixed locations. This is not useful for hovering but is very useful for navigation and for many decades was the only viable long range na citation, even better than a compass. I listed it here for completion. Not used in drones at all (except GPS). One of the hardest things to learn in general aviation and has accounted for many lost aircraft. (Edited)"
],
"score": [
5,
4
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i2vmcy | if 4G has better range than 3G, how come if I'm in the middle of nowhere, far from any antenna, my phone switches to 3G? Shouldn't it be a case in which only 4G has enough range to reach me? | Technology | explainlikeimfive | {
"a_id": [
"g07669b",
"g0769hm",
"g076gva",
"g076alm"
],
"text": [
"I'm not sure that 4g has better range because the higher the radio frequency the shortest it can travel.",
"It depends on a number of factors, but a big one could be carrier upgrades. If you're in the middle of nowhere, the cell tower might be older and less of a priority for upgrades. So maybe the nearest tower only supports 3G. Rather a surprise at this point in time but technically possible. Second, just because it has better range doesn't mean it has better signal strength. 4G uses signalling tricks that help deal with obstacles better than 3G, but if that's a non-issue and you can see the cell tower from where you are standing, then raw signal power tends to rule the day for reliability.",
"Since 4G is newer there might not be a 4G antenna in range, 3G being older usually has higher overall coverage due to more antennas installed.",
"It’s the other way around, 3G is stronger than 4G. Basically the higher the ‘G’ rating the higher the frequency of radio waves it uses. The lower the frequency the stronger it is but carries information slower"
],
"score": [
14,
7,
3,
3
],
"text_urls": [
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i2wp2t | if sound is, in simple terms, air vibrating in your ear, how are electronic devices able to produce sound from videos/ recordings? | Technology | explainlikeimfive | {
"a_id": [
"g07c687",
"g07c89w",
"g07cdj1",
"g07d54v",
"g07fq24",
"g07cerp"
],
"text": [
"The use electricity to move magnets in speakers which physically move an object to create a sound wave.",
"we use magnets to move a membrane back and forth really fast. If you do it 440 times a second you have a A 440 note playing.",
"The electronics vibrate air of course. The usual method of doing this is taking a flexible cone and moving it back and forth with an electromagnet which will cause the air near it to vibrate. This is called a speaker.",
"The electronic device controls the speaker and makes it wobble, the wobble of the speaker creates air pressure, the air pressure wobbles on over to your ears, your eardrums wobble and your brain decodes this so you experience sound.",
"To make the sound into electrical signals you have a diaphragm that is connected to a coil of wire with a magnet inside it(or out) when the vibration in the air hits the diaphragm it vibrates and that makes an electrical signal that you can now store (there is more that one way to store it). to play it back you reverse it so that a electric signal flows to the coil and that vibrates the diaphragm.",
"The audio information basically is an instruction for the phone/pc/whatever how to move the speaker membrane to move the air."
],
"score": [
95,
34,
10,
4,
4,
3
],
"text_urls": [
[],
[],
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i2wso8 | Why is it a problem that "they" are farming our data? | Technology | explainlikeimfive | {
"a_id": [
"g07cz67"
],
"text": [
"For most people it isn't a problem, it all depends on who is using it and why. So assume someone is waiting for a cancer test and has been searching online for cancer a lot just to be prepared, if that person then tries to get medical insurance the data about their searches may be used by the insurance company to increase their insurance or decline it entirely."
],
"score": [
7
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
i2xhn8 | All this new technology and we still cant take a $10 out the ATM. | Technology | explainlikeimfive | {
"a_id": [
"g07hlj0",
"g07hvid"
],
"text": [
"It's just much easier to only stock an ATM with one type of bill. It only contains $20 bills, therefore it can only give you money in multiples of $20. If you did, say, half $10 and half $20, for the same number of bills it would contain on 75% as many dollars, and so need to be refilled more often. And realistically how often are you in a situation where you can't take out the extra $10?",
"The $20 bill is most often used for spending, and represents about 23% of the total US currency in circulation. People are most likely to spend a $20, so the machines are only stocked with $20's."
],
"score": [
5,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i2yp84 | how come scientists/developers cant make phones that capture and send odors,scents,smells? | Technology | explainlikeimfive | {
"a_id": [
"g07r405",
"g07s4xx"
],
"text": [
"Smells are actually **particulate matter** that our olfactory nerves inside are noses bind to and send signals to our brains to tell us that that particle is a \" < fill-in-the-blank > \" smell. For phones to do that, then those devices would have to be able to create molecules and release them for our noses to pick up.",
"Light is photons, you can make photos with quantum mechanics out of nothing using electrons shifting between atomic orbitals. Smells are chemical compounds, they are matter. We do not have a technology to make matter out of nothing."
],
"score": [
9,
4
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i2yz0l | Why is a passphrase important for keeping your Home network secured? | Two questions I'm curious about: 1. Why should we change the preset passphrase on a router 2. Why should we create a guest passphrase for vistors. | Technology | explainlikeimfive | {
"a_id": [
"g07t21a",
"g07u2jz"
],
"text": [
"Do you want everybody in your neighborhood to see what you are doing on your computer? If not, you need a strong passphrase. You you want everyone who drops buy to visit to see what you are doing on your computer? If not, then you need a separate guess passphrase.",
"I assume you are talking about Wifi and not the actual router setup web page, which has its own password. Also change that password if you haven't.. For WiFi passwords what matters is that the password cannot be guessed. Some routers these days have a random password that's printed on the label on the bottom of the router or such. This password is safe, if difficult to remember and type into your cellphone. Changing it for convenience is fine, as long as it's still hard to guess. Keep in mind that knowing the password is basically the same thing as physically plugging into one of the LAN ports. This puts a bad guy a position to access your computers, surf the internet on your bill, and all that stuff from the convenience of your neighbour's driveway. You don't want that. Put a good password on it to keep them out. Guest WiFi usually limits access to just internet rather than all devices in your home, which is less dangerous but still not good. If you have a no-password Guest Wifi network I can connect, go download something illegal like child porn, and drive away. You'll never know it happened, but it's your door the police will knock on."
],
"score": [
6,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
i30i09 | How are the high quality photos of microscopic creatures taken and why do they look fake? | Not sure whether to put this in biology or technology lol. Talking about things like [this,]( URL_0 ) [this,]( URL_2 ) and [this.]( URL_1 ) They're always described as photographs but they look as if they're 3D models made by computers. I don't doubt they're photos but they look so different from anything we're used to seeing with our naked eyes and I've always wondered why they look Like That. | Technology | explainlikeimfive | {
"a_id": [
"g087j10",
"g087sw4"
],
"text": [
"They are not photos, at least not in any sense of the way most people understand photos. These are taken by a scanning electron microscope, then processed out into an image that we can recognize. So in a sense, yes they are computer generated 3D models, but they are based off of the exact measurements and readings of a massively powerful microscope.",
"The pictures appear to have been taken with an electron microscope. As the name suggests, these use electrons instead of light to capture the image. As the wavelength is much smaller than that of visible light it can capture very small objects in great detail. They look fake partly because of just how weird and unfamiliar the world is at that scale, but also because the colour **is** fake. Electron microscopes only capture greyscale images, so the colour is added in post-processing. (In recent years electron microscopes that capture colour have been developed, but from what I've seen they are not near this level yet)."
],
"score": [
12,
5
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
i38zgi | Why do you have to wait 30 seconds after unplugging something before plugging it back in? | Technology | explainlikeimfive | {
"a_id": [
"g0ak5bs",
"g0aqk8b",
"g0a2sha",
"g0adzyb",
"g0ajijq",
"g0b8yvh",
"g0alkjm",
"g0ajtd5",
"g0amqq2",
"g0apumi",
"g0awzp1",
"g0ak9dl",
"g0avm23",
"g0b4cq3",
"g0aqxz6",
"g0auav8"
],
"text": [
"Listen, I'm gonna be honest with you. You only need to unplug things for about 10 seconds, before you plug them back in. You can often speed things up by pressing the power button and holding it for 1-2 seconds (this closes the circuits to things like fans and power LEDs, allowing any energy in the capacitors to bleed off faster). But when some mouth breather calls tech support complaining about their computer being frozen and the poor schmuck on the other end has already had a half-dozen arguments that day with callers who insist upon pulling the plug out half a millimeter and then slamming it back in as if the flow of electricity through the overworked circuits of their device was directly responsible for each sluggish, strained beat of their plaque-encrusted heart, all because the plug is \"too hard to get to\" after they shoved it under their desk behind a box of antique porn magazines... Well, 30 seconds begins to sound like a nice, round number. Just long enough to keep them honest, but not long enough to encourage them to regale you with their political opinions or anecdotes about their various medical conditions while they wait. Edit: fixed a word.",
"I’ve worked in IT for 28 years and have never waited longer than a couple seconds after a power down to restart a server or workstation and it’s been fine. So I call bullshit on the 30 seconds rule. I’m guessing this was just to give IT support some breathing room when talking to some not so technical user on the phone.",
"If an electronic device starts behaving strangely then it is often to do with the built in software that is stored in the devices memory. So if you switch the device off, that software will automatically clear and when you switch it on again, the software will be reloaded fresh from an internal store and hopefully the reloaded version will not have the problem. Great. That old faulty software should clear the moment you switch off the power but sometimes, remaining charge in the system (stored in capacitors) will keep it hanging around for a few seconds. If you switch on before it has fully cleared, there may still be parts of the old software left when the new one tries to reload - this is not what you want. So giving it about 20 seconds to make sure it is really clear before restarting is a good idea.",
"This is a mild secret in the IT community. We tell you to do that, or to do some other exotic timing ritual, so that you actually unplug the thing and plug it back it. Overwhelmingly, leaving it unplugged for 5s is just as good as 30s, but some people just won't do it again. Long fancy words like \"reseat the power cable\" or emphasizing thing like \"unplug the power at the device, NOT from the wall\" is equally unnecessary, but when you're walking someone through something over the phone, it increases the likelihood that they'll actually do the thing. Edit: if we are deeply interested in the status lights on your machine, that means we don't think you actually unplugged it. If you tell us the wrong sequence of lights, we will know you're not unplugging it.",
"Short answer: you actually have to wait less than 1 second. Long answer: the reason for it is because capacitors have to drain inside the device. Capacitors are little things in the circuitry that are basically rechargeable batteries. However, the small capacitors that are in devices like computers discharge in well under a second.",
"ELI5: wtf is everyone talking about?? You have to wait before plugging something back in???",
"It's like when u cut a chicken's head off, the nerves and blood are still pumping for a bit, so if you plug it right back up, then those nerves that were misfiring will keep on misfiring",
"This has been answered in other comments, but here it is with a slightly more ELI5 answer Most electronics have capacitors in them - capacitors are like batteries and store electricity in them. If you don't leave it unplugged long enough, the capacitors might still have some charge in them, so the electronic item may still have power running through it and might not have completely run out, so the other bits and pieces still hold memory of what it was doing before it was unplugged. Unplugging an item is done to get all the bits and pieces in a device to forget its memory - once you plug it back in (if its drained all its capacitors), it'll reset to its default settings.",
"Everyones going nuts about capacitors, but thats maybe 20% of the actual reason. The more common reason is that other devices need to recognize it is no longer there. You want to reestablish any active connections. This is why its very important for modems, cable boxes, etc. Anything where another device needs to recognize its 'gone'.",
"You pour apple juice in a glass and now want milk in the same glass, you need to empty the glass before pouring milk. It takes some time for electronics to empty the glass. Otherwise you might get a nasty combination of milk and apple juice. PS: Glass is capacitor, Milk and apple juice are different pluggable devices.",
"Back in the olden days, the harddrive of a computer had to spin out before booting up again. It took about 30 seconds to do so. It somehow stayed as a ‘just to be sure’ thing to do.",
"Capacitors....... A baby battery that keeps power for 10 seconds or so. Gotta let it die before plugging in again. Microwaves have a Capacitor that could be a month from being plugged in but the electricity it holds can still kill you.",
"Imagine a river. Deeper in the autumn and summer, shallower in the winter. Imagine you put a waterwheel on the river, but the river is regularly either too high or too low - so you build a dam. The dam then controls the exact water height, and ensures the wheel is always spinning. But, if you redirect all the inflows, the dam is still full of water - so the waterwheel will keep spinning until the dam is empty. To stop the wheel, we need the dam empty. In your case, replace \"dam\" with \"capacitor\", and \"waterwheel\" with \"electronic device\".",
"The computers memory works by using electricity to hold a certain charge which relates to data. Computers also have tiny little batteries called capacitors inside them so every bit gets the power it needs when it needs it. If the capacitors are still charged, the memory will still be powered. This can cause problems because the computer will remember things it shouldn't. Luckily the capacitors are so small they'll lose charge quickly, thus the 30 seconds. Then the computer will boot up as a \"blank slate\" again. Sometimes, if you turn something off, then unplug it, then turn it on again, the LEDs will flicker on and then die. That's the capacitors using the last of their charge.",
"I worked with electronics for a long time. It's to do with capacitors but the time is arbitrary. Most the time its the instruction we give to a customer because no matter how fool proof you write instructions there is always a bigger fool. Some people read unplug the device and they barely pull the power out long enjoy for it to cycle down. In some cases they don't even unplug because they don't think it's important. If you add an arbitrary time value to it they think the instruction is important all of a sudden and they'll actually unplug the device. Yes capacitors hold charge but on 99% of devices it won't take more than a second to reset. I say 99% because in my years servicing electronic equipment I never found a device that couldn't be plugged back in within seconds and it still reset. I'm sure there may be some devices with failsafes that will try to maintain state for 10-15 seconds but I never met them.",
"You don't. Depending on what the \"something\" is it may not lose power completely as soon as it is unplugged. For some \"somethings\" this can be like not turning them off but seldom is it true that a device needs 30 seconds to make any difference to it's operation. If we are talking about an electric heating device it's pretty easy to see that the item will not instantly cool down but that doesn't mean you can't safely plug it back in before it has cooled down. Just because all the energy hasn't been lost from it doesn't mean returning energy supply to it is a problem. Some somethings may have a capacitor keeping some sort of powered on \"memory\" active, those somethings may require enough time for that power to drain and that memory to clear to have a full reset when unplugged and then plugged back in. \"Capacitors\" isn't really an answer to this question. Capacitors can be removed from and returned to power supply safely. It really all depends on the device and why it is you want to remove it from power that will determine whether there is any need to leave it unplugged for any length of time or what that time should be."
],
"score": [
2476,
243,
132,
94,
40,
26,
18,
14,
13,
4,
3,
3,
3,
3,
3,
3
],
"text_urls": [
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i3944w | Why do digital displays have input lag? | As a gamer and collector, I love my retro and classic consoles. I always hear people talking about how CRT displays are better for playing with old systems due to having "zero input lag". But what isn't well explained is why digital displays (LCD, LED, Plasma, etc.) do suffer from input lag. So, explain it like I'm five: Why do digital displays have input lag? | Technology | explainlikeimfive | {
"a_id": [
"g09yrd0"
],
"text": [
"By sheer virtue of being digital. Analog/CRT displays process image data in real time. It gets the signal, it uses it at the same time it gets it, 1:1. The instant it receives the input, it is using it to make the image. A digital display has to process data to figure out how to display the image. It has to get a frame worth of data, work out how to display it, display it, repeat. It’s lightning fast to us, but in comparison to a crt it’s very noticeable."
],
"score": [
8
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
i3bb3p | Why do FAT32 Drives can only have upper case letters on its name? | Technology | explainlikeimfive | {
"a_id": [
"g0agnfn"
],
"text": [
"The really short answer is backwards compatibility. The longer answer is that the file names are not case sensitive, but the file system is case-insensitive. This means that a file named “file” and one named “File” are the same as far as the file system is concerned. Trying to save both of those files in the same directory would result in the second over-writing the first. If you’re wondering why commands like “dir” show everything in uppercase, it’s that backwards compatibility. However “file” was saved, it will be displayed as “FILE” for ease and consistency. In savvier programs, you should see the last case of the file as saved."
],
"score": [
5
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
i3c0rk | how do the tube tv’s work | You know the tv’s that are super fat and have the tube thing in the back I never understood how they worked | Technology | explainlikeimfive | {
"a_id": [
"g0aii3v"
],
"text": [
"They have three meshes at the front (screens) with red, green and blue phosphor on them. Then at the back is an electron gun — a cathode with a vacuum between it and the anodes, which are the screens. Electricity is run to the cathode, and then arcs across the vacuum to ground on the screen. To control where this beam hits, the voltage is controlled, and electromagnets bend the beam so that it draws lines across the screen, left to right, top to bottom. When it finishes the last line, it goes back to the top. At each point along the line, the output voltage controls how bright the phosphor glows. To make things easier, only every second line was drawn on each pass (interlacing) so on one pass lines 1,3,5,etc were drawn and on the next pass lines 2,4,6,etc."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
i3cxft | on a physical level what happens when data is written, read or deleted on a solid-state storage device? | i know that when data is read or written on a cd or dvd it is making physical changes on the dvd to store that data in the form of ridges ups and downs , on a hard disk there are platters and a reader that does a similar sort of thing what happens in a ssd or say a memory card that it is able to hold the data in it without any moving parts , also is there any life span of the data in such storage | Technology | explainlikeimfive | {
"a_id": [
"g0apef4"
],
"text": [
"So basically a normal mosfet transistor turns on and off when you add or remove electrons from the gate. The gate is made of conductive metal so that electrons can pile in and out freely. The electric field from the buildup of electrons affects nearby silicon and allows current to flow or not flow. A transistor used in flash has an insulated gate. To turn the transistor on permanently voltage is applied that shoves electrons through the insulator leaving the electrons trapped on the gate. This is how programmable memory worked. Early versions of eraseable memory actually used UV light to erase them. Basically the UV would ionize the insulator making it conductive and allowed the trapped electrons to leak out. With modern flash memory better material and more precise manufacturing make it so that applying a different voltage can basically suck the electrons out of the gate with an electrostatic field. This erasing is usually not precise so large sections (called pages) of transistors are cleared at once. As for lifetime, yes there are limits. Electrons leak out slowly so a typical flash drive can expect to hold data for about 15-20 years before it starts loosing bits. Also shoving electrons through the insulator degrades the insulator. A cheap flash memory might only last through 10k erases. These are generally only used in programmable chips, but are usually designed to hold data longer. A normal USB drive can be expected to last 100k cycles, while high endurance industrial flash memory can be expected to last 1 Million cycles. Most flash memory now uses wear leveling. That is it will cycle automatically through the least used memory areas when erasing and rewriting in order to extend memory life. This can make the memory last longer if they aren't being used to full capacity."
],
"score": [
4
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
i3d71k | In many video games, why do character models have transparent parts you can see through? | This can be a question for game devs who are part of this subreddit. Sometimes, when you look hard enough, you'll see a character model has a gap. For example, if you look up a character's bracer, you'll find that the character doesn't have a forearm underneath the bracer; instead, you only see a floating disembodied hand. You may even see through one area of an object, but it's rendered normally on the other side. Another example would be if you look up a character's coat or something, you'll find that the legs are only modeled up to the knee, and anything else above is invisible, except maybe for the character's hair and disembodied eyes and SOME of the clothing. I'm planning to take on game development in the future, I was just wondering what's the purpose of those since they look really odd and easy to spot if you know where to look. Is this by choice or is it a bug? If so, any tips on how to model and make sure those doesn't happen? Forgive me if I sound like an idiot. | Technology | explainlikeimfive | {
"a_id": [
"g0apmvq",
"g0axjru"
],
"text": [
"It is intentional. Things which are not supposed to ever be visible don't have textures or geometry because they soak up memory and graphics processing power for no benefit. Every graphic in a game has a performance impact and spending resources on things nobody can see is pointless. Now errors where this becomes visible to the player are not intended. Ideally it would be seamless and invisible, but a character model that changes its shape dynamically is difficult to get perfect at all times.",
"Another thing that could lead to this is face culling. Almost everything you see on screen is made up of tiny little triangles. These triangles have two sides, one is considered the front and the other one is the back. Any triangle that has its back side facing the camera is (most of the time) not drawn on screen like it's not even there. So if you can move the camera Ina weird angle that makes the back sides of the triangles that make up the character model face towards it they simply never get drawn on screen making gaps in the model."
],
"score": [
8,
4
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
i3dfyw | Can anyone explain how Activision adding a 36 GB update to COD MW will decrease the games overall size ? | Technology | explainlikeimfive | {
"a_id": [
"g0artv1",
"g0arxcf",
"g0arud9"
],
"text": [
"Well, optimizing the code overall might bring a reduction of individual file size of the game. Is like you are copying a file with the same name but smaller and selecting overwrite",
"Let's say you have a very awkward house that has too much hallway and weird sides and corners. The house is listed with a lot of area but much of it is unusable. You decide to renovate the house to have better use of space. This still requires buying new lumber and materials because you can't just recycle the old stuff (new data in update). The renovated home could be made smaller than the original home.",
"I am not familiar with COD MW specifically, so this is all general; Depending on how it's structured, it could remove unused assets, code or other bits of debris leftover from development. It could also optimize code structure, such as merging 2 very similar functions, although this would result in minimal gains. The update may change the compression of the original code, greatly reducing the space required on disk, or it could update the save format so saves games utilize less space. It could do any or all of these things."
],
"score": [
7,
4,
3
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i3eqvr | Why are solid state hard drives so much faster than regular hard drives? | Technology | explainlikeimfive | {
"a_id": [
"g0az2yj",
"g0az4pj",
"g0azbgd",
"g0b0z2v"
],
"text": [
"SSDs use NAND Flash memory, much like what's found in a USB stick. It's much closer to computer RAM then an HDD. This means it is as fast as the SATA connection will allow. (In reality, it's actually much faster than advertised, but SATA bottlenecks SSD ) An HDD, on the other-hand, is closer to optical media (CD, DVD, Blu-Ray). Inside the HDD are rotating platters, and the HDD has to physically move an arm to read the data on a platter. (Exactly like Optical Media) Because of all the moving parts, HDDs are limited by how much data is in order on the disc (Defragmented), and how fast the arm can move and the disc can spin.",
"They do not contain any moving parts, unlike conventional HDDs. HDDs work somehow like a VHS Tape. There is a head and it writes data on different parts of several disks inside the HDD, using electromagnetic energy. This does not happen in SSDs.",
"A hard drive works by changing magnetic charge in of one or multiple spinning disks, there is a time that the disk needs to get to the read/write head. SSDs on the other hand have no spinning or otherwise mechanical parts so the speed of accessing and manipulating data is not that restricted. It's sort of like ram but it won't lose data when the power cuts off.",
"Hard disk stores data on a disk (which is also hard, hence the name) To read the data they have to rotate the disk until the data is underneath a reading part. And also they have to move the reading part to where the data is. All this is done very fast and very efficiently to reduce the amount of moving and waiting; but it still takes time. An SSD doesn't have anything moving. It has some electrical switches it flips to find your data. So there's no waiting for stuff to move around."
],
"score": [
9,
7,
5,
3
],
"text_urls": [
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i3f03l | Why do street lights turn off when people walk by them so often? | Technology | explainlikeimfive | {
"a_id": [
"g0b0fr9"
],
"text": [
"They don’t. This is confirmation bias (you only notice it when it happens so it feels like it happens really often). Street lights (In the uk anyway) have a sensor on the top, which causes the light to turn on and off at the appropriate light levels. For further details you could lookup the potential divider."
],
"score": [
8
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
i3paae | Why do graphics cards have fans on the bottom and heat plates on the top, even though hot air rises? Wouldn't it be more beneficial to flip that design over and push hot air up? | Technology | explainlikeimfive | {
"a_id": [
"g0czqmr",
"g0d9uzf",
"g0d0anc"
],
"text": [
"The fans on graphics cards are intakes, not exhausts. GPUs actually exhaust through the back of the case, meaning that if you pointed the fans upward, they'd be sucking in warmer air, for exactly the reason that hot air rises. Not only that, but motherboards and cases are designed with GPUs in mind; flipping the design would require redesigning motherboards and cases to conform, which would be a pain.",
"Hot air rises, because its less dense and therefore is buoyant compared to the surrounding air. At gpu temperatures this effect isn't that strong. A fan overcomes this effect by orders of magnitude, and it doesn't really matter.",
"The standard for PC expansion cards say that they need to have the PCB on top and the components on the bottom. It leaves very little room on top for any fans and even if there were room the components that needs cooling would be on the other side of the PCB. In fact most graphics cards violate the standard by adding the heat plate to the back and would therefore not fit in tight chassis that are designed around the standard. The plate is also not so much a heat plate but rather a backing plate to help support the heavy heat sinks and fans on the front, it have a minimal impact on thermal dissipation."
],
"score": [
8,
3,
3
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i3q9j6 | How do online multiplayer games work so well despite so many differences in the systems behind each user (processing power, internet speed, display refresh rates)? | Technology | explainlikeimfive | {
"a_id": [
"g0d8ijv",
"g0da4sd"
],
"text": [
"They avoid dealing with those issues at all tbh. What you send them isn’t what’s on your screen you send your inputs. Then your inputs get sent and the game reacts to them on your screen and the server. Lag is actually a result of this process being interrupted. To restate for clarity everyone just puts inputs in and the server sends that info to everyone playing whose computer then interprets them.",
"They work so well because there is, usually, a server behind them that streamlines the differences in players' specs. Display refresh rate doesn't play any significant role usually. Frame rate on the other hand, sometimes can. Some games can, for instance, say a skill animation is 10 frames with the effect being applied at the last skill. For a player, whose device runs at 30fps, the whole thing takes 0.3s. one with 120fps - 0.085ish seconds. This can play a huge advantage in more competitive games. It's usually the server's job to gather all the information, process it and send it back to all the players in a meaningful way. Internet speed isn't a massive bottleneck as the data the players' device is sending is usually rather small, network ping is. That's the time it takes for a packet of data, as in, 'I'm moving here, casting this, using that item, and so on, to reach the server, or for the server data, again 'player X cast this, enemy has Y health, etc, to reach the players. Internet issues are by far the bigger hurdle in online games. You've definitely seen/experienced rubber-banding, lag, etc. Those are due to either the server not receiving the information at all or receiving it too late. Tldr: there is a server on the other side that keeps track of everything and makes sure it's a streamlined experience for all."
],
"score": [
29,
5
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i3sie7 | how do network cables transmit data from thousands of people without interference? Like a phone cable for 5 houses not mixing up calls? | Technology | explainlikeimfive | {
"a_id": [
"g0dpk23",
"g0drgo6"
],
"text": [
"Long story short, each device has an unique number assigned to it and each communication is made using those numbers. Think of it as a a mailman, he has the exact address and gets you your mail. That s how packets work. For the not mixing part, the switch router theoretically is a small computer as it has it s own memory processing power. Each router stores your exact address :) or a way to get to your address. Hope this helps",
"The word you are looking for is \"multiplexing\". There are many ways: In packet networks you are sending small pieces of data called packets (up to some thousands of bytes), each of them has a header that says where it is coming from and where it is going. The devices at the end of the cable have a queue for packets that should go down that cable. You can get clever about how much of the total bandwidth each of the flows is allowed to use and even more clever about whether other flows can get the bandwidth a flow is allowed to use, but does not. With sufficient cleverness you can make it so you can guarantee someone's packets will be delivered within a given time if they do not send more than a given amount. You can assign _time slots_ to flows. Split time into some intervals (called frames, I think), split frames into slots, assign each slot to a flow. If that flow does not use it, no one does. That gives you lower efficiency, but very deterministic timing (this is what we used for phone calls before compression was clever, when we knew exactly how much bandwidth any flow would use). You can take an optical cable and assign different wavelengths (colours) of light to different flows, then use a prism to split them again. I think you can get about 160 different colours into a single cable. When you really need lots of bandwidth, you would combine these --- send 8 (or 160) different colours down a piece of fiber and on each of them use packet multiplexing."
],
"score": [
3,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i3t15u | How come induction stove is more energy-friendly than gas stove (with gas cylinder), while induction stove is using electricity and gas stove is not ? | Technology | explainlikeimfive | {
"a_id": [
"g0dsf3m"
],
"text": [
"Induction is far more efficient. A gas stove burns fuel for energy. Energy is lost as light from the flame, heat escaping around the sides of the pot, heating up the stovetop itself, as unburnt gases escaping, etc. An induction stove works by utilizing a magnetic field to excite the material of the pan itself. No pan present to get heated, very little energy is used. Can’t have heat escape around the pan because the pan itself is what is getting hot, not the stovetop. Every watt of power that it takes in, aside from a tiny amount for control boards, is converted into heat that is used for cooking."
],
"score": [
7
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
i3ul0e | Why do some phone batteries have more capacity than laptop batteries? | Technology | explainlikeimfive | {
"a_id": [
"g0e7esp",
"g0e32d2"
],
"text": [
"They haven't. I'm pretty sure you are basing this on the amp-hours rating of the batteries. Let's take Apple for a second, and I chose that only because they sell both. iPhone 11 is a 3110 mAh (milliamp-hour) battery. MacBook Air is 4379 mAh. So those are close, right? Nope, not at all. Why? Because amp-hours is a rather stupid and misleading rating without more knowledge. I have no clue why it's used. Basically the amp-hours is how much electrical charge the battery stores, *but it does not say with how much energy that charge is held.* That would be the voltage. To compare batteries you need to multiply the amp-hours by the voltage to get the watt hours. Then you can compare. Watt hours being how much power it can supply and for how long, aka the energy. 1 Wh can last 1 hour with 1 Watt of power. Or 2 hours at half a watt, or 1/2 hour at 2 W. Amp-hours only works for comparison if the voltage happens to be the same. In the case of phones (3.7V) and laptops (12V), it does not work. iPhone 11 is 3.83 V, so gives 11.92 Wh. MacBook Air is 11.4 V, so 49.9 Wh. They aren't close, the MacBook Air, a really small and weak laptop, is over 4x a phone battery size.",
"TLDR: Phones use considerably less power to operate than a laptop. The electronics and processors in a Phone are optimized for power consumption in a manner that isn't practical for laptops. The ARM CPUs in most phones are comparatively stripped down to a Laptop CPU. This means they aren't as good at doing a variety of tasks, but more than good enough for what your phone is doing and at a fraction of the power consumption. If you should take anything out of the recent Apple announcement about changing from Intel to ARM CPUs in their laptop range its that mobile ARM CPU's have come a long way in the past decade. Smaller screens, and not having to power fans and external devices helps a lot as well."
],
"score": [
7,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i3ve5g | How do online video games connect multiple players together in a session | How do developers make it possible to render the same map and real-time events to people using different devices and living a thousand miles away? | Technology | explainlikeimfive | {
"a_id": [
"g0e9gqu"
],
"text": [
"Simply networking. There is a server that holds every player on. Each player connected to the server is a client. The server has to 'allow' actions from each client if each player wants to see what happens. For example, in a shooter game, A client (player) will press the 'fire' button. On their screen, it will show them firing but they are asking the server 'can you tell everyone on the server that player 3 has fired his gun? Also, tell them that out of 30 bullets, he now has 29. If the server shuts down, the clients inside will be kicked out of the world. regardless if they have good computers or not. You should also note: sometimes actions made by another player might take time registering to the server. The lower the ping, the more accurate the player. Now as for map loading, if it is a fixed size such as say... team deathmatch... the map is the same size for everyone. it will be loaded in. But if it is a HUGE map, then the client will only load in specific chunks they can see. (they will be lower quality from far away, but as they get closer, the details show (or if they use a scope)) I'm currently into game design and Ive dabbled with networking. I still have some things to learn."
],
"score": [
6
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
i3w393 | How does the Google Authenticator app work? | Technology | explainlikeimfive | {
"a_id": [
"g0ee9m9",
"g0ftzq8"
],
"text": [
"It uses your phone's GPS clock and public encryption key(s). Every 30-60 seconds it encrypts the time using this key and displays the result on your phone screen. The servers that use it have a matching private key. They decrypt what you type and if it is the correct time, they let you in.",
"Your phone and the application pre-share a secret, typically via QR code scanner. Both your phone and the application can take that secret, do some math with it and the current time, and create a new time-sensitive secret. If you enter the right code at the right time, the app knows you must have the original secret. If you enter the same code a few minutes later, it doesn't trust that you have the original secret. One important thing is that the way the math is done, you can't find out the original secret, even if you have millions of codes."
],
"score": [
4,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i46aml | Why can’t you email “large” files? | You can send 10 minute videos through text but when you try to email, it can’t even handle a less than one minute video clip. Why? What is holding it back from sending through? It doesn’t make sense to me | Technology | explainlikeimfive | {
"a_id": [
"g0g6u9e",
"g0g80qq",
"g0g4zy6",
"g0g560o",
"g0g60nb",
"g0gfqah",
"g0g7qug"
],
"text": [
"Email was invented in 1971. It is almost 50 years old. It far predates digital audio or video. MMS was invented in 2002. It is less than 20 years old. It was specifically designed to deal with multi-media (hence the name) content that the original SMS spec did not. As others have said, some/most email systems will prohibit sending or receiving large files because it uses up storage space and can clog networks. However, this isn't inherently true of ALL e-mail systems.",
"TLDR: Email as a protocol is very old and was never meant to do that Because Email is not a file transfer protocol Email was invented in the late 70's and it's verifiably ancient by computer standards. By comparison Websites weren't invented until the 90s. In all honesty it's kind of astonishing that we still use it because as a protocol it's pretty awful, and inherently un-secure. It was only ever designed for text transfer and is not well suited for transmitting files. Email doesn't do compression (shrinking files for transmission) and being able to attach things like pictures was tacked onto the protocol long after the fact. What's actually stopping you from sending a large file is a hard limit set on the email server you are sending to. As a server admin I actually set how big an attachment to allow into my email server, and I try to keep it as small as possible (say 20mb or less) because any larger fills up the email database and clogs the system. If we allowed unlimited file size it is possible that a hacker could discover this and send large files to us non-stop and cause the server to crash and the database to fill up very rapidly.",
"Because that is not what email is designed for. There is no technical limitation to it, it just is not supported by most email providers.",
"The devs who built your email client are stopping you intentionally. Google doesn't want to spend the money send massive data attachments on free email accounts, its not profitable. Instead you sell things like Google Drive accounts. Oh, and cell phones compress video files when sending via text. Thats why the quality goes to hell",
"When you send a video through text, it usually compresses and downscales the video to make the file size much smaller. Email is designed to send files as-is, so if you don't downscale them first, they will be very big files.",
"Others have spoken thoroughly about the e-mail situation, but your understanding about MMS (the system used when you text a video) is a bit off. E-mail generally supports files of 10-20MB depending on the service you are using. MMS is limited to 1-3.5MB depending on your carrier. Your phone automatically resizes and compresses the video to make it fit in that limit. E-mail will not do that, but you could do that on your own and send a much higher quality video than what MMS allows. You may be thinking of something like iMessage which is used for iPhones. This is not a text message but is a different system completely. It's more like WhatsApp or other chat services. iMessage has larger file size limits because it's *only compatible with itself*. For e-mail, everyone agreed 10MB was a good limit for file sizes. For text, 3.5MB was agreed as the maximum between all the carriers. For iMessage, Apple is in full control and does not need to negotiate with anyone else to agree on a file size limit.",
"Mostly because it would be really slow and inefficient since that's not what email's really intended for and most email software isn't designed for it. The email could take forever to even show up in the recipient's inbox because the entire attachment needs to be sent before the recipient's server can process the email as a whole & add it to their account. If the transfer fails once for some reason, you gotta start over, etc. If the recipient server is on a bad connection this could take hours or even days. Sometimes emails have to pass through multiple servers and filters before getting to the recipient server: in that case, each of these servers has to receive, process (and maybe filter for viruses), then forward. For an email of a few gb this becomes impractical very quickly. Also because even if you set up your email server and client to handle 10gb files, if most other email servers in the world don't also support it, then you won't be able to send such a large file anyways, and it's so much work to change that that it's not really worthwhile. Also, it'd be easily abused: find a company's email server you want to take down, then just start sending giant emails to bog down their resources."
],
"score": [
64,
43,
11,
4,
3,
3,
3
],
"text_urls": [
[],
[],
[],
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
i4a0yg | Why adding @, & , *, #,%,etc makes your password stronger? | Technology | explainlikeimfive | {
"a_id": [
"g0gwk9c",
"g0h9m9d",
"g0hsq5w",
"g0huapq",
"g0hh948",
"g0hu2z0",
"g0ia8tk",
"g0hwl33",
"g0hnzst",
"g0hu6kb",
"g0i60sc",
"g0he6wo",
"g0i2cem",
"g0hw9sq",
"g0iav42",
"g0ho5de",
"g0ipeaw"
],
"text": [
"It makes for more different possibilities of what each character could be, and it makes it so your password won't be found in a dictionary. So eg: if your password was only numbers (0-9) and lowercase letters (a-z) then each character has 36 possibilities, right? so a 5 character password would have 36\\*36\\*36\\*36\\*36 possibilities. Now say you add uppercase letters and 15 different special characters. Now there are 77 possibilities per character, so 77\\*77\\*77\\*77\\*77 possibilities for what your password could be. Edit: I understand there's more to it and the latest suggestions have changed to using a longer password/password managers instead, this was just trying to explain the basic premise of OP's question.",
"The short answer is that it means someone trying to guess your password using brute force they have to use a wider range of characters to test at each character greatly increasing the amount of time to find the password. The long answer is that the industry is veeery sllllowwwly moving away from those kinds of complexity rules. Why? Most passwords are not stolen this way anymore, they are stolen by sending phishing messages and having the user hand their password over willingly. [NIST]( URL_0 ) now suggests not to create strict password rules anymore. Focus on \"strength meters\", suggesting (but not forcing) longer passwords, and testing proposed passwords against lists of [compromised passwords]( URL_1 ) (and trivial changes) and only demanding password changes after a suspected or known breach.",
"this may be controversial, but it's security theater, and it really doesn't. expanding the **potential** set to full ASCII from the basic alphanumeric does increase entropy per bit. but because of how combinatorial math works adding more characters will always give you better security than expanding the set of possibilities for a character. also, so long as **some** people use \"special characters\" (edit for the advanced students **or include them in your pssible salts**) then any attempt to crack the password will have to account for them. it might matter a little bit if they steal an entire database of all user passwords, if the password database is designed **so badly** that a single weak password anywhere in it can be used to break the encryption of all passwords in the user database (see below for more on that) in general it would be infinitely safer to allow alphanumeric but set a minimum of 16 or even 24 characters rather than allow 8-character passwords but make you pick passes that look like the quadratic formula threw up. also, those super complex rules just make people write them down someplace or store them in often insecure ways. TL:DR-- it's mostly useless old thinking, \"ThisIsTheAdministratorPassForFallOf2019ForActiveDirectory\" has tons more entropy than \"aHs$@1k5p!S\" more on what I meant about cracking a stolen DB-- there may be a **little** utility against a precomputed hash attack against a stolen password database which was designed very badly, because without nonces or with a single shared salt, a single weak password anywhere in the database can break the encryption.",
"As others have said, it increases the total amount of characters that the password could contain. The equation for the total amount of passwords is the number of characters the password could contain (lets say *n*), to the power of the number of characters in the password (lets say *x*). Or, ***n******^(x)***. This equation tells you how many **bits of entropy** are in the password. And the higher a passwords entropy is, the harder it will be to brute force. So if we had just letters and numbers, we would have 52 (26 \\* 2, because capital letters and lowercase), + 10 (0 through 9), giving us an *n* of 62. If you had an 8 character password, the equation would be: ***62******^(8 =)*** **218,340,110,000,000** A strong botnet could generate roughly a billion guesses per second, leaving the the maximum crack time for this password at 55 hours. (I'm glossing over some technical hurdles here, but that's irrelevant for this discussion.) **However**. It may have occurred to you that simply having the *option* to use additional characters increases **n** and therefor increases crack time. This is partially true, but a brute-force attack is likely to be sequential, trying all lowercase combinations of letters first, then all alphabetical combinations, then all alphanumeric combinations, etc... (up to a certain character length). **Still, the necessity of special characters is overblown in computer security.** Increasing the base of the that equation, the **n**, does increase the total bits of entropy in the password, and thus the crack time. But increasing the **x** is actually more important. Take 10^(5) = 100,000 for example. If I change that 10 to an 11, the result is 161,051. But, if I change that 5 to a 6, the result is 1,000,000. The point here is that people end up using complex passwords for all these special characters, which end up being hard to remember. Alternatively, they use common substitution patterns like P4$$W0RD or H3110. This isn't helpful what so ever. Length is the most important property of a password. Memorability is the second most. Writing a password down negates its security. **Want to know what a real secure password looks like?** *Thisisaverysecurepasswordbecauseitissuperlongandthatmeansithasacrazyamountofentropy* It's just a sentence, with no special characters, and yet to crack it would take this many attempts: **26808809068614883 with a 126 zeroes after it.** Or, **2.6808809068614883e142.** Brute forcing it would be impossible (except maybe with a quantum computer? But thats a story for another time.) However, a dictionary attack could actually reduce that crack time to realistic scales. A dictionary attack uses combinations of *words* instead of characters. **The solution?** Mix them. Allow for white space and special characters and all that jazz. Then, you can have passwords like this: *This password is just too good to be forgotten! In 100 years I'll still remember it! #secure! Best password ever, don't @ me!* You want stuff in there that will throw off a dictionary attack, and you want it long enough to negate a brute force attack. And as I said earlier, you want it to be easily remembered. Use pass-phrases or pass-sentences, not pass-words. Now of course, a good password manager like Keepass bypasses all of this by generating super long and super complex passwords that'll you'll never have to remember. You only need to remember the master password (which should be something like what I wrote above.)",
"It doesn’t... It’s just that a password brute-forcing algorithm is likely to guess the passwords with just letters and numbers first, because those are the most commonly used. Most websites which have passwords with requirements like “add a number and a symbol and a capital letter and no english words” have the wrong idea. These restrictions make passwords slightly stronger but also make them much harder for a human to remember. The best way to create a strong password is to make it LONG. Something like “Eucalyptus Paraguay Dorian Petrified Hindenberg” is very easy for a human to remember. However, it would take a computer ages to guess, even if it only guessed passwords composed of 5 English words separated by spaces and with each first letter capitalized. In any case, if you don’t think your password is secure enough, you can just add another word. Then, take your password’s security and multiply it by the number of words in the english language and that’s how secure the new password is.",
"The XKCD comic explains why the complexity rules are stupid. Words are easy to type and easy to remember, therefore easy to make long. Nonsensical random strings of lower and upper case numbers are hard to remember, hard to type... and likely to end up written down on a post-it note that’s stuck to the back of the monitor. Least secure password there is.",
"Answer: **It DOESN'T!** Password complexity requirements were an *attempt* to stop people from picking easily-guessed passwords, but they don't actually work, as explained by the latest NIST Digital Identity Guidelines. > Research has shown, however, that users respond in very predictable ways to the requirements imposed by composition rules [Policies]. For example, a user that might have chosen “password” as their password would be relatively likely to choose “Password1” if required to include an uppercase letter and a number, or “Password1!” if a symbol is also required. URL_0",
"It doesnt. If you want to make your password stronger, make it longer. [XKCD explains it very concisely.]( URL_0 )",
"They don't, there is a lot of research on strict requirements, and the NIST standards have updated to reflect this. The ability for the system you are accessing to accept a wide variety of characters is important, but length above all else, has proven to be the most useful thing.",
"I was told by a IT security guy that works for the Airforce that special characters are not needed. He said to make you password is 16 digits or longer and you should be safe. I dunno I'm not a security guy in the Airforce though.",
"Because if someone has one arm they can’t press the shift button to do a special character therefore they can’t hack your account!",
"123123Abc is as secure as & $@123Abc IF the attacker doesn’t know what set of characters you used. If the password requires different sets of characters, the characterspace for a bruteforce is much larger and harder to guess. Common passwords like sequencial ones as I used for example are weak for different reasons. Their hash is common and are testes first A password salt improves security in this case",
"The guy who wrote the guide on this has changed his mind on a lot of it, though... [link]( URL_0 ) He now recommends long, easy to remember phrases. It’s length that makes it difficult, not the kind of symbols you use.",
"Spoiler alert, while technically it does, it really doesn't. Use longer passwords or as is becoming industry standard, Pass Phrases.",
"Makes you less susceptible to dictionary or rainbow table attacks. Those being more sophisticated forms of brute force that uses popular passwords. If the site forces you to use a special character it drastically increases the amount of time it will take to brute force a single password. In all honesty you're more likely to get hit by a database leak anyway. Just have different passwords on every site and you're safer than most.",
"Imagine I have a secret code that you don't know and have to guess, but you know that it can't be very long, and you know that it only consists of the number 1 and the number 2. There's only so many things to guess right, so it's pretty easy. There's only so many combinations, right? But if I use all the numbers, then it's a lot harder And if I add all the letters too then it's even harder And if I make them case sensitive that adds more combinations as well. And if I start adding symbols on top of it, then there are even more combinations to try. If you want numbers to go along with this to help show how many more combinations there are with symbols included I'd be happy to go figure it out.",
"Imagine you have 2 pebbles: one with a cross painted on it (+) and one with a star painted on it (\\*). If I ask you to order them in a random way, you really only have two choices: (+)(\\*) and (\\*)(+) & #x200B; If we play a game where you order them without me seeing, I guess the order I think they are and you have to tell me if I am correct or not, then it'd take me at most 2 tries to guess. What happens if I give you one more pebble, with an arrow (\\^) on it and ask you to pick any 2 pebbles and order them in any way you want? There are more options for you, so it might take me more time to guess. You could do: (+)(\\*) (+)(\\^) (\\*)(+) (\\*)(\\^) (\\^)(+) (\\^)(\\*) Phew. Now it may take me, at most, 6 tries to figure your order out! Now, let's say I give you 34 more pebbles (the same amount of letters a-z and number 0-9 that we have), all different, and I ask you to pick 2 random pebbles and order them in any way you like. You have a lot of choices, and it'd take me significantly more time to try and guess. This is what hackers do with your password. They are trying to guess. When you add a symbol (something different than letters a-z and numbers 0-9), you are basically getting a lot more pebbles to your pool of possibilities and making it harder to guess. Thing is, computers are really fast at giving guesses, so for a strong password, having more pebbles is not enough. You also need to have more \"slots\" to place them. So instead of asking you to pick 2 pebbles, I might ask you to pick 8, or 10, or 15. I may give you an infinite amount of pebbles so you can repeat as many as you like in any order you please. Heck, I may even give you freedom of length. You can create a queue of pebbles as long as you want, with any pebbles your heart desire. This game is unfair and I don't want to play anymore. \\*\\*SERIOUS\\*\\*: For good password hygiene, length is more important than the characters you use. A good idea is to use a passphrase instead of a password. So instead of choosing \"@pple0198726\\_ & \", you could try \"i like the apple trees in my ranch\". These kinds of passwords are stronger and easier to remember, though a bit more susceptible to dictionary attacks (instead of using single characters as pebbles, they use words). If you combine both strategies, you are golden. To give you an example, I use \"Peter Piper picked a peck of pickled peppers\" as my actual password on one of my accounts (different passwords all the time, guys!). However, there is an uppercase, 2 symbols, 2 numbers and a purposely missed space somewhere in between. I may or may not use a different language as well. This makes it pretty much impossible to crack my password by brute force, but it's still pretty easy to remember to me."
],
"score": [
8552,
1576,
367,
54,
52,
28,
24,
18,
13,
12,
6,
6,
5,
3,
3,
3,
3
],
"text_urls": [
[],
[
"https://pages.nist.gov/800-63-3/sp800-63b.html",
"https://haveibeenpwned.com/Passwords"
],
[],
[],
[],
[],
[
"https://pages.nist.gov/800-63-3/sp800-63b.html"
],
[
"https://xkcd.com/936/"
],
[],
[],
[],
[],
[
"https://www.wsj.com/articles/the-man-who-wrote-those-password-rules-has-a-new-tip-n3v-r-m1-d-1502124118"
],
[],
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i4a89t | Why do sites that work perfectly well in web browsers also have apps? | It seems like more and more sites are getting aggressive about trying to get people to install their apps. This includes things that work fine in web browsers, and don't have any obvious need for an app. Wouldn't it be easier for the company to just focusing on making their site work well, instead of having a site AND an app to worry about? What's the benefit? | Technology | explainlikeimfive | {
"a_id": [
"g0gx615",
"g0gyad1",
"g0h3b2y"
],
"text": [
"1. Once you install an app you are less likely to use another service as it forms habits. 2. With an app they can get know more about you.. your location, device and so on, making it easier to market to you.",
"It depends on what the purpose of that website is. For example - for a bank, having an app, which is sandboxed, solves a lot of issues from security perspective. For a shop with an app - you can do lots of things that on web are crap, but on mobile are useful - like the use of camera for example, or ability to really step up the loyalty experiences for their customers - waving your loyalty QR code on the app is much easier than going through the pain on having actual vouchers or codes printed and sent via post. An app can keep you logged in when you use the same device over and over again... For some businesses it's cheaper to have an app than a mobile-optimised website. So they will focus their dev resource on updates to two streams - mobile and pure web (maybe with small mobile modifications if devs feel like it, but wouldn't be as smooth as m version). These are some of the reasons why the apps are being pushed so much. Do you have any examples of what annoys you specifically?",
"An app can do push notifications to your phone to get your attention when there's new content they want you to know about. The website version of that is where they try to get you to sign up for an email list and hope you're not just routing them straight to your spam folder."
],
"score": [
12,
7,
6
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
i4ekb8 | What is BIOS? | Technology | explainlikeimfive | {
"a_id": [
"g0hrb80",
"g0hqw45"
],
"text": [
"The Basic Input and Output System. Put very simply, it's a mini computer that performs all the tasks necessary to start your actual computer. Like the electric starter motor in a car.",
"BIOS is ~~Built-In Operating System~~ Basic Input/Output System and is used at a system level to tell the CPU how to function at boot, and where all of the hardware is, before software-level instructions are executed (OS like Windows, Mac OS, Linux). These are built into a ROM chip."
],
"score": [
8,
4
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i4f9ig | What is used to determine how much power a power strip will provide? | Technology | explainlikeimfive | {
"a_id": [
"g0hvobw"
],
"text": [
"The first one is talking about the power available on the USB ports(5 volts DC). The second one is talking about the power available on the mains voltage plugs(120v AC)."
],
"score": [
5
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
i4h310 | Why does the most powerful supercomputer in the world use ARM processors if x86 is faster? | Technology | explainlikeimfive | {
"a_id": [
"g0ia4fx",
"g0i72vx"
],
"text": [
"Imagine that you build a computer chip that adds numbers together very quickly. If you use it correctly, you can use that same chip to multiply numbers. For example, 5\\*5 is just 5+5+5+5+5. Even though the chip can't multiply numbers, you can still use it to multiply numbers. But if you want to multiple large numbers it gets slower and slower because you need to add more times. So you build another chip that can both add and multiply. Now it multiplies much faster than before, even on large numbers. But adding that functionality to the chip makes the chip bigger and more complex. Unfortunately, that causes addition to slow down a little bit. It's still fast, just not as fast as before. If you need to multiply a lot of numbers, the chip that can multiply will be fastest for you. If you only need a little multiplication, but mostly just use addition, the first chip will be faster. --- This is a big simplification and both ARM and x86 natively support multiplication. But the general idea is that ARM natively supports fewer operations but is faster at the ones it supports. So what's faster for you depends on what you're trying to do.",
"“Powerful” doesn’t necessarily equate to “fastest”, rather “able to do more in a specific amount of time with an array of processors”."
],
"score": [
8,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i4ihhv | Why are Windows BSOD messages so vague and unhelpful? | Technology | explainlikeimfive | {
"a_id": [
"g0ighwf",
"g0igrix"
],
"text": [
"A BSOD means something failed at the operating system level, which is usually many layers of abstraction below the programs you're actually running on your computer. The reason this usually displays some sort of memory address is that when something goes wrong, a program often notices because a part of it is trying to interact with memory it shouldn't, or trying to interpret memory in ways that make no sense. In a lot of cases, this memory fault - and not whatever the root hardware or software causes is - is that Windows sees when it fails.",
"To be perfectly honest, the simplest way I can explain this, is by saying it's this vague, because it's not the actual thing that caused the BSoD that generates the message, it's windows trying its best to tell you what it was doing when it went BSoD. System service exception is a mainly software critical issue where Windows was expecting a specific behavior from one of its base services, and that behavior just was way out of whack, and Windows had no idea how to handle it. If the problem persisted through a formatting, it is likely that a software you are installing post-formatting messes up with one of those services."
],
"score": [
4,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i4jy0a | what exactly is "about:blank"? i see it a lot in loading webpages.. | Technology | explainlikeimfive | {
"a_id": [
"g0ir4zo",
"g0j1iz6",
"g0ir1wn"
],
"text": [
"Browsers have \"about\" commands. They don't require internet connection, they just do things. about:blank is the way to show a blank page. about:credits is another one if you want to see who made the pieces of the browser (it should work in all browsers). I don't currently have Firefox on this computer, but about:robots is something you can type in for something ominous. In Chrome, about:about will give you a list of browser utilities.",
"Here's a simplified partial breakdown of a URL: ` < protocol > :// < authority > < command > ` ` < protocol > :` comes first, it's basically telling your browser how you want it to do something. `// < authority > ` is more or less which computer has the resource you're after. It's optional, but some protocols are never seen without it. ` < command > ` is what you want your protocol to do. So we can look at, for example: ` URL_0 ` `https:` tells your browser you want to find a web page with secure HTTP. `// URL_1 ` tells it that the resource you want is at some computer out there named \" URL_1 \" `/r/explainlikeimfive` tells the browser that, once it finds \" URL_1 \", to ask it for the file at that path. There's about a dozen formally defined protocols in the URL standard. `http:` and `https:` should be familiar. You may have seen `ftp:` or `mailto:`. The rest are pretty obscure. So, what browsers eventually did at some point was they added their own extensions to the URL standard by creating their own protocols. Two you may have seen are `about:`, which allows you to send commands to the browser itself, and `file:`, which opens a file on your hard drive. So we can break down `about:blank` like so: `about:` tells the browser you want to use one of its native commands. An authority doesn't really make sense in this context, so we don't specify one. `blank` is the command to show a blank page. Similarly, `about:config` issues a command to open up your browser's configuration settings.",
"about:blank is exactly that, a blank page It's used to display nothing, because that's the quickest thing for your browser to load. I use it as my homepage just to make my browser load faster."
],
"score": [
13,
9,
5
],
"text_urls": [
[],
[
"https://reddit.com/r/explainlikeimfive",
"reddit.com"
],
[]
]
} | [
"url"
] | [
"url"
] |
|
i4k12x | How do you build your own PC? | Technology | explainlikeimfive | {
"a_id": [
"g0iqvm8"
],
"text": [
"You pick up a list of compatible parts then put them in a box. URL_0 is super helpful"
],
"score": [
4
],
"text_urls": [
[
"Pcpartpicker.com"
]
]
} | [
"url"
] | [
"url"
] |
|
i4kzv0 | Why does it take ages to encrypt and decrypt a hard drive, but you can access the data instantly by simply giving it the password? | Technology | explainlikeimfive | {
"a_id": [
"g0iybqk"
],
"text": [
"When you enable encryption, the computer has to read every byte of data on the drive, encrypt it, delete the old data, then write the new encrypted data back to the drive. This requires a read, a write, a delete, and some computation for EVERY piece of data. This is a massive amount of work to get done. Writing is especially slow. (Deletion is just fancy writing.) When you disable encryption, the same process is required in reverse, which is about as slow. However when you request a specific file or folder structure from a drive that is already encrypted, the computer only has to read and decrypt *that* data. There is no slow deletion and writing involved (until you save your file) and only the files you request are decrypted. This is a much much smaller task, so it can be accomplished much sooner."
],
"score": [
6
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
|
i4l4po | What is a virtual server and where it is used as opposed to physical servers? | Answers would be highly appreciated. | Technology | explainlikeimfive | {
"a_id": [
"g0izuxh",
"g0izayx",
"g0izc9p"
],
"text": [
"Here's a quick metaphor that I found helpful when I learned about virtual machines. Imagine we have a building, this is our server. In its current state, we house a family in this building (a computer program)... but that's it. It's a big building but right now it's only good for one family. So we get creative. We put up walls, we divide the building up and what was 1 building is now 10 apartments. Instead of 1 family we can now house 10 families! They are still using the same building, but it is now acting as 10 buildings not one. That's the basic idea of virtual servers. A single physical server pretending to be many servers using software. All of the virtual servers share the resources of the physical server (they are allocated by software or physical devices) but are effectively separate entities.",
"Virtual servers (aka virtual machines) are software that are used to emulate a physical device. There are many types of virtual machines out there. Think of it this way: when buying a virtual machine, you have full access to the OS. You are able to use the supplier’s panel to upgrade your machine seamlessly, in 2-3 minutes. Compared to buying an actual server, you have to set it up, and when you want to upgrade your setup you need to buy more ram sticks, etc. and take time to replace it. If you’re looking to host your average Joe app, a VPS will do. But for enterprise applications, you might consider bare metal. Examples of Bare metal are ZAP Hosting’s Rootserver plan, among others. Examples of VPS are Linode, DigitalOcean, and AWS ECS",
"On a physical server. Virtual servers are \"fake\" machines made by splitting up the resources of a more powerful physical server using a software called a hypervisor, so the same machine acts like multiple separate computers."
],
"score": [
6,
4,
3
],
"text_urls": [
[],
[],
[]
]
} | [
"url"
] | [
"url"
] |
i4mmsd | How come a battery that's full weighs the same as a battery that's empty | Technology | explainlikeimfive | {
"a_id": [
"g0j91qu",
"g0jiatq"
],
"text": [
"Because the only thing lost in most cases is the energy equivalent mass, ( e= m c^2) C is very large, so the change in mass is very small. There are some batteries that get heavier, like zinc air batteries. A battery is just a chemical reaction that spits electrons out from one place and sucks them back in somewhere else. An analogy would be a closed bottle of hot water. You can get heat energy out of it, but the water is still in the bottle, so it still weighs basically the same.",
"essentially it is because the charged particles that make up the battery's charge are in a different position within the battery. hardly any of them actually leave the battery itself."
],
"score": [
9,
5
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
|
i4n5bn | If you change the file extension of a non-text file (like a video or a picture) to .txt and then try to open it in notepad, a bunch of gibberish appears. Why does this happen? | Eg: A .jpg renamed to .txt \[žð°@UQ5´ëÞPém”€móïûýûñ’\`„Ž›C|Éå:8 > ©ß(h¥¬(‹\_}6?OëÄAæ T.Ëß –¤6 ¾OßåÀ‰Ÿ2¾ñâNŒUæ=-Î ²Ú A$k{oïø‡·þÝ9EåÄ%}Aøïq\*=É \~ïÄÃã!W:'Øk{|É·¥T¾ï@5\^§úŒ\]B{,6÷ > ‡óàR | Technology | explainlikeimfive | {
"a_id": [
"g0jaux9",
"g0jbhju"
],
"text": [
"It's because notepad will interpret the data as if it is text. Data is represented by bytes. No matter the type of data, it's still bytes. A byte is a number. If you want text, you might expect an A to be represented by the number 1. But if you have a jpeg, you would need, say, 3 numbers to represent the colors of a single pixel. But cause it's all numbers, each application has to interpret them based on what it thinks they represent. If you open a jpg file in notepad, you are telling it \"interpret these numbers as text\", whereas if you opened a text file in paint, you would say \"interpret these numbers as a jpeg\".",
"2 things are really at okay here: 1. Everything on a modern computer is just bytes, from your word documents to your family photos, even your games. Bytes are 8 bit numbers, so they range between 0 and 255. What the bytes in a given file mean is interpreted by every application individually. Notepad, for example, will interpret them as characters. Resulting in seemingly random gibberish, since the Latin alphabet is only 2x26 out of the total 255 (in the case of simple 8bit ASCII text). Most often utf-8 is used as text deciding, having 1,112,064 different characters represented by 1 to 4 bytes. 2. Since every file on your computer is really just a bunch of bytes the extensions really don't mean anything. I mean, the can tell you system what kind of file something is supposed to be, but they can (as you now yourself) easily be changed or chosen at random."
],
"score": [
36,
3
],
"text_urls": [
[],
[]
]
} | [
"url"
] | [
"url"
] |
i4n6f5 | What are inserts in a Digital Audio Workstation used for? What can I do with them? | Technology | explainlikeimfive | {
"a_id": [
"g0jxa0z"
],
"text": [
"They are a place to put an FX plug in. The plug in is **inserted** into the signal path, hence the name. Insert FX are used when you want to change the original signal. Examples include EQ, compression, distortion etc. The alternative is **send** FX. These send some of the original signal to the FX and allow the original unchanged signal to flow as well. These are used for things like reverb and delay. The benefit is that many tracks can use the same plug in. So it's a lower cpu load and convenient to, say, add the same reverb to multiple tracks. With inserts, you can use process the sound to alter it to your liking."
],
"score": [
5
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.