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cfb6bj | Biology | Why does our blood pressure stay lower for a good while after a hot bath? I understand why hot water would reduce our blood pressure, but why wouldn't it immediately go back to normal once we get out of the bath? Especially if we rest sitting/lying down afterwards..! | Hot water causes vasodilatation which feed into two systems while in hot water - it helps to disappate heat but also, water warms up the blood in our body, raising core body temperature. After you get out of the hot water your body is not giving away all the heat you have accumulated at once, but body is disappating it at normal rate via physiological mechanisms, thus lower blood pressure after the bath for a bit of time. | 1 |
f2pa9n | Biology | SERIOUSLY, what are hiccups??? | It's just your diaphragm going into spasm. Normally the diaphragm works rhythmically unconsciously, but with conscious control you can stop it or use it to expel air so you can talk etc. When it goes into spasm it jerks suddenly causing that horrible sensation we call hiccups. All the old wives tales such as holding your breath and drinking from the wrong side of a cup of water are ways of exerting control over it in the hope that it stops that infernal spasm. So they work, but I'd imagine there was very little science or understanding behind their origins. I find they're usually a lot less painful if you just relax and go with it, rather than trying to stifle them. That ends up making it worse. | 3 |
n8o4p6 | Earth Science | Do female animals menstruate? | Yes. But it is much less involved. Human females spend a lot of resources to get ready for a short pregnancy, which requires developing the brain very fast. So they have much more blood by comparison. | 4 |
aj4a17 | Biology | If the Great Lakes were formed by melted glaciers from the Ice Age then how did they develop a fish population? | Birds. Sometimes when the wading birds are flying around, they will have mud on their webbed feet and there will be some fish eggs on it. My mother had a pond on her farm, isolated from everyone and everything except the wildlife. One day she showed me this odd long fish, like a gar, in it. Now, that pond had been dried down right to caked dirt during a drought, so I knew no one had restocked it. No fisherman would ever catch a gar and put it in a pond - I am not certain anyone even eats gars. But there it was. I asked her how, and she pointed out that the cranes and ducks would come by during their migrations. She thought maybe some of them had fish in their beaks too. I just don't know how it all goes down, but birds can be a big factor (and vector). | 16 |
6stn42 | Culture | How Did Sikhs Come to Be, And What Do They Believe In? | Sikhism is based on the spiritual teachings of Guru Nanak, the first Guru, who started the religion around 1520. The first 10 Gurus wrote the Guru Granth Sahib, the religion sacred text. Three Pillars of Sikhism are: 1) Meditation on God and reciting and chanting of God’s Name—Waheguru. 2) Life as householders and honestly earn, with hard work, by one's physical and mental effort, while accepting God's gifts and blessing. 3) Sharing their wealth within the community. | 1 |
jwnayi | Biology | Why is one nostril blocked while the other is unblocked when breathing through your nose? | It's all about maintenance. Temperature regulation and immune response. Your lungs need to keep to a good temperature, and the nose can get quite cold. So to keep things regular, one side blocks up to gain temperature, and the other cools down. This is why it is worse in colder environments. | 7 |
boef62 | Other | In the movie Intersetllar they said how one hour on the water planet was a year on Earth, so how does that actually work? I have never been able to figure it out. | Time moves more slowly around immensely massive objects. If I remember correctly, the water planet was orbiting a huge star or something. | 3 |
bzin6b | Technology | What's the difference from installing and downloading? | You order delivery food. The guy delivers the food. That’s downloading. You “unpack” the food to eat. That’s installing. You eat the food. That’s using the program. | 3 |
6mggrz | Engineering | Why didn't old massive sailboats flip over, and why didn't their masts break being so far from CoM? I'm guessing they had massive heavy fins at their bottoms for the first question, but idk for the second one. | They did not have massive fins but they had lots of weights at the bottom of the hull to counteract the leaning caused by the wind pushing into the sails above. As for the mast breaking, wood is pretty strong and bends before it breaks, the sails further up on the mast were smaller to reduce the load and in strong wind some might need to be taken down to prevent the mast from snapping. | 4 |
m6q7rw | Technology | Why do videos from 10+ years ago have such potato quality these days when they looked fine back then? Unless I'm misremembering, but I feel like I didn't struggle to make out details in some videos back then the way I do these days, because the quality seems so degraded. | It’s a combination of having your expectations elevated by modern resolutions and the fact that screen sizes are generally just much bigger now. You used to watch low resolution content on tiny screens and that was all you knew. Now you watch super high resolution content on very large, high resolution screens. The older content is no longer standing on its own, but being contrasted with these better images, especially when displayed on screens that play to the better quality content’s strength while highlighting the poor quality of the older content. | 3 |
jmlp46 | Other | why does having a long story before a recipe help websites get better search engine results? | SEO. Search Engine Optimization. Google (or any search engine you're using) has a crawler that goes out and gathers information about all the content they can find on the Internet. The crawlers bring all those 1s and 0s back to the search engine to build an index. That index is then fed through an algorithm that tries to match all that data with your query. Pages with more words AKA "content" end up ranked higher in the search results, so they are seen more frequently by people like you who are looking for said thing. Because the page has a story before the recipe, it has more keywords that the algorithm likes, so it thinks that page is a better fit for what you're searching for, and thus shows you that page at the top of the search results. | 11 |
76jxgh | Culture | I keep reading that Greeks didn’t have a word for blue and humans couldn’t see it until modern times. How is it possible that our ancestors didn’t see the color blue? What did the sky look like to them? The ocean? | Why do we have separate words for blue and indigo? They're essentially the same thing, only darker and lighter. What we refer to as 'blue' is a colour that was always there, there just culturally wasn't a seperate name for it. In the same way that we Brits talk about rain in terms of drizzle, sleet, spitting, raining cats and dogs, mizzling, pelting down etc. It's not that other countries haven't seen these kinds of rain before, they just haven't chosen to differentiate in that level of detail. | 5 |
6eeofa | Mathematics | Why every number n^0 is equal to 1? | One small catch: n^0 is *not (necessarily)* equal to 1 when n = 0. Usually when n=0 you will have to do some limit analysis to see if you can assign a value, depending on the actual function you are using. Otherwise it is simply undefined. | 5 |
crwdiu | Engineering | How do people build things like oilrigs and bridges over water? | Oil rigs are weighted floating pontoons (heavier on the bottom than on top to prevent capsizing) that are anchored to sea floor - the pontoons are built closer to shore then towed to postion before being anchored - then the rest of of the rig is built on top of the pontoon by cranes taking construction materials delivered to the rig by ships | 2 |
frpe7r | Chemistry | Why does NaCl solution conduct electricity while solid NaCl doesn't? | When you dissolve an ionic substance (like NaCl) you actually no longer have NaCl what you have are Na+ and Cl- floating around in the water. Since these pieces carry a charge, they can arrange to conduct electricity. & #x200B; EDIT: Since people keep asking why salt water tastes salty: Your salty receptors detect the sodium cation (Na +). In fact if you have salt in your mouth, it's at least partially dissolved so it would be a more interesting experiment to try eat a block of salt with no saliva and see if you taste it( not that that's actually possible) | 9 |
il4doq | Biology | how is the passage of time consistent between people/animals? The brain is made up of chemical reactions happening all the time but do we experience it the same? i.e. your 5 seconds is the same as my 5 seconds | The brains of all people work in a similar way so they perceive time at a mostly same scale. Even if some differences occur, nobody can notice them because the language we use synchronizes us: we tell a child "this timeframe is called five seconds" and the child remembers what a second means. Even if his perception of "this" is different from mine, we are talking about the same object. | 2 |
em8k0l | Biology | what actually is the noise our belly makes when we are hungry? | What about that sensation in the throat? Peristalsis? | 13 |
7vapgd | Physics | Why is centrifugal force an “imaginary force”? | Imaginary, or fictitious, forces are poorly named. The name doesn't really mean they don't exist. Rather, they are "non-inertial." I think this is a better name for them, because it gets away from the whole "You're imagining it" hullaballoo. They exist. They just exist in non-inertial frames of reference. They're caused by an object having inertia, and entering into a non-inertial reference frame. An example of this is a rotating one. So imagine you are on one of those spinny things at the fair. It spins rapidly, and you are pushed against the wall and kind of float there. You wouldn't float if it was sitting still, right? You'd fall to the floor. Rather, you are held to the wall by the rotation of the amusement ride. Your body wants to fly outward in a straight line, because it has been 'sped up' by the ride, but the wall is in the way, so you smush against the wall. The force is 'fictitious' in that it is a force which arises from the acceleration of the frame itself. | 2 |
6hcxad | Chemistry | How come when you take a pain killer (Morphine, Percocet, Etc.) while in pain, you don't experience the same euphoria while taking the drug without pain? | When you take an analgesic (painkiller) while in pain, the pharmacological effect is that it blocks the pain receptors in your brain from receiving their signals. This may or may not correspond with the production of pleasure-causing chemicals such as dopamine, depending on the active ingredient(s) in question. This is why drugs that people 'get high off of' produce 'different' highs, as some simply block pain (which corresponds to blocking ALL pain, even the minor, imperceptible everyday itches, scratches, and aches you have on a daily basis without even realizing it, and thus leave you feeling just generically 'floaty' because you are experiencing less stimuli); while some explicitly cause pleasure. | 2 |
l7ckr5 | Economics | Stock Market Megathread There's a lot going on in the stock market this week and both ELI5 and Reddit in general are inundated with questions about it. This is an opportunity to ask for explanations for concepts related to the stock market. All other questions related to the stock market will be removed and users directed here. How does buying and selling stocks work? What is short selling? What is a short squeeze? What is stock manipulation? [What is a hedge fund?]( URL_0 ) What other questions about the stock market do you have? In this thread, top-level comments (direct replies to this topic) are allowed to be questions related to these topics as well as explanations. Remember to follow all other rules, and discussions unrelated to these topics will be removed. **Please refrain as much as possible from speculating on recent and current events.** By all means, talk about what has happened, but this is not the place to talk about what will happen next, speculate about whether stocks will rise or fall, whether someone broke any particular law, and what the legal ramifications will be. Explanations should be restricted to an objective look at the mechanics behind the stock market. EDIT: It should go without saying (but we'll say it anyway) that any trading you do in stocks is at your own risk. **ELI5 is not the appropriate place to ask for or provide advice on stock buy, selling, or trading.** | Did I miss the chance to make tons of money? And how/where exactly do the people who invested in game stop get more money? | 489 |
hbrdzc | Physics | How can the sun create so much energy if photons are massless? | A quick note, before I begin. The first law of thermodynamics/conservation of energy states that energy can neither be created nor destroyed, but merely transmuted from one form to another, like kinetic to potential, chemical potential to thermal, etc. At higher levels of physics you realise that *all* energy is really just either kinetic (thermal energy is just particles vibrating/moving very quickly), or potential (by virtue of being present in some conservative force field). As you may well know (or possibly not), the Sun is a giant nuclear fusion reactor, fusing four hydrogen nuclei (really just naked protons) into a helium nucleus by the [proton-proton chain reaction]( URL_1 ). Now, protons are positively charged, and it is *incredibly* hard (at least, on Earth, which is why we haven't gotten fusion reactor power stations yet) to force them sufficiently close enough that they stick, by means of the [strong interaction]( URL_0 ), which is what keeps protons and neutrons clumped together in the nucleus of an atom without the whole thing exploding apart. So how *can* we force them together? Well, that's what happens in the core of the Sun: pressures are something like a billion to tens of billions of times as much as normal Earth atmospheric pressure, and temperatures are around 15 million degrees C. At this stage, when protons get sufficiently close tpo each other, the strong interaction (which peters out very quickly) takes over the electric repulsion, and the strong nuclear force is established between the protons which releases a lot of energy, in the form of photons, electrons (beta particles), as well as the kinetic energies of the daughter nuclei (which are the products). Now, photons are massless, but they most certainly carry energy. In fact, it's why solar panels work, and it's *also* why going into the Chernobyl core will kill a person, because gamma photons are *too* energetic, and rip through the human body on a molecular scale. The exact equation for the energy of a photon is actually given by the formula, *E* = *hf*, where *h* is the [Planck constant]( URL_2 ), and *f* is the *frequency* of the photon. Note that the two protons which have stuck together (technically a helium-2 nucleus) are less massive than the sum of the masses of the two protons separately. This is likewise for the normal helium-4 nucleus (2 protons, 2 neutrons): it is slightly less massive than four protons, separately. This tiny difference in mass gives rise to the absolutely *massive* amount of energy produced, by Einstein's famous mass-energy equivalence equation: *E* = *mc*^(2). The *c*^2 term is the square of the speed of light, which is a *huge* number: it is 8.98755179 × 10^(16), or a 9 followed by 16 zeroes. This is the fundamental idea behind nuclear fusion: several nuclides of lower mass each, with *less* binding energy, under sufficiently high pressures and temperatures, fuse to form nuclides of higher mass, with higher binding energy. | 2 |
auv5u8 | Biology | Why can't we drink salt water? | Salt was used in ancient times as a preservative, as it draws out moisture (water) from things. Normally when we drink water, our organs absorb that water and it is used in the cells of our body for various things. When we drink salt water, however, there then becomes a higher amount of salt than water in our body, so our organs release water to try and balance out the salt level. This leads to severe dehydration-and in some cases: death. | 2 |
cnrin8 | Biology | What are genetic haplogroups and haplotypes and how do they work? | The human genome contains around 20,000 genes and plenty of other sections of DNA that are involved in controlling them. You may have learned before about Gregor Mendel's [law of independent assortment]( URL_1 ), which is the idea that different traits are inherited separately from one another. In reality though, this isn't always true. Genes that are physically close to each other (i.e., in the same section of the same chromosome) are described as "linked", meaning that they are often inherited as a single unit. This is because the process that mixes up the two sets of chromosomes you have ([recombination]( URL_4 )) doesn't really mix them very thoroughly. Though the number varies from species to species, in humans there are on average [between 1 and 2 crossover events]( URL_6 ) per chromosome. So, if two genes on the same chromosome are close together, then the chance that one of these [crossovers will happen in between them]( URL_0 ) is quite low. Of course, genes come in different versions (alleles), and not everyone has the same ones. Fundamentally, **a haplotype is just a set of closely linked alleles that are often inherited together**. For example, imagine three genes that are all right next to each other on the same stretch of DNA, which I'll just call genes 1, 2, and 3. They each have two possible alleles: A and a for gene 1, B and b for gene 2, C and c for gene 3. Additionally, for each of these three genes both alleles are equally common (i.e., at 50% frequency). If these genes were physically separated on different chromosomes, then you would expect roughly equal numbers of all eight possible combinations of these alleles. But, since they are in fact *not* separated, this isn't what we actually see. It turns out that everybody either has the AbC alleles *or* the aBc alleles, because crossover events that would be required to generate other combinations (such as ABc or abc) almost never happen in the right places. So, for genes 1, 2, and 3 in this imaginary population, there are two existing haplotypes (AbC and aBc). In reality, we don't have to look at actual genes to find haplotypes, and they're often just based on groups of individual DNA letters. For example, looking at [this figure]( URL_2 ), most of the letters in that sequence are the same in all people, but two are variable. However, they are do not vary independently and so form a (very simple) haplotype; if someone has an A at the first variable site, they always have a G at the second one, and similarly with G and T. AT and GG people don't exist, even though these combinations would probably work just fine. A haplogroup is basically the same thing, but at a slightly larger scale incorporating more DNA sequences. As you have probably heard, the most famous kinds of haplogroups people usually talk about are those based on human Y chromosomes or mitochondrial DNA. Because neither Y chromosomes nor mitochondrial DNA *ever* experience crossing over, they are always inherited as a single giant piece of DNA; in the case of Y chromosomes (if you have one), it comes from your father, and mitochondrial DNA comes from your mother. This means that any mutations that happen in these DNA sequences will be passed down in an unbroken chain from parent to offspring, while other kinds of DNA can be shuffled around and disappear over time. To put it another way, your mitochondrial DNA is the same as your mother's, and your maternal grandmother's, and your maternal great-grandmother's, (etc.), but there is no guarantee that you will share a gene for eye colour with your great-grandmother, for example, since the one you got from your mother could have come from any of her four grandparents. So, since Y chromosome and mitochondrial DNA are inherited directly like this, they can be used to trace back one specific line in your family tree very far. The various mutations that have happened in these pieces of DNA have been well studied, so that we have a good idea of how different Y chromosome and [mitochondrial haplogroups relate to each other]( URL_3 ), and can see that certain haplogroups are associated with certain parts of the world ([Y chromosome]( URL_7 ) and [mitochondria]( URL_5 ) respectively). However, since people sometimes get a little caught up in this sort of thing, it's important to note that this tells you very little about your actual ancestry. Both the Y chromosome and mitochondrial DNA make up a tiny percentage of your overall genome, and these haplogroups can only tell you about a single lineage out of the many that make up your family history. | 1 |
859lx5 | Technology | Why are satellites more powerful than wifi? To my admittedly little knowledge, our satellites are like 50+ years old in outer space but my wifi antenna is brand new and in my house. I can't get my wifi in my drive way YET I can get satellite signal for my GPS anywhere in the United States like immediately. Why? | GPS satellites broadcast a much stronger signal than your home wifi can. They broadcast on reserved frequencies that nobody else uses while wifi needs to be shared with everyone and everything. They also don't need to receive any data from your phone. It's a one-way system. | 3 |
9v5s37 | Other | What is the Silurian Hypothesis? My professor talked about it today in class and it just made me more confused. | Basically, it is the idea that an advanced civilization might have existed on earth at some point in its past and then was annihilated and went extinct, and since fossilization is rare enough for it to be possible that none of that species would happen to be found fossilized and any other remnants of civilization could have degraded entirely by this point in this time. | 1 |
g2uypd | Technology | Why does movie volume vary so drastically from scene to scene? | It's a thing that became more prevalent in the last 10 years or so. If I recall correctly, sound grading in movies usually just sucks these days. I don't remember if I made this up in a dream, or saw a video about it a few years back... Something about not remastering for broadcast vs in theater, or something? Might not be the case, but in any event, I've noticed it too | 1 |
5p3rhj | Other | Some entries on Wikipedia have bizarre spellings that appear to be how to pronounce the word, but are confusing. What do the weird letters mean? For example, this is apparently how 'Ireland' is pronounced: aɪərlənd | > this is apparently how 'Ireland' is pronounced: aɪərlənd In fact /ˈaɪərlənd/. This is the International Phonetic Alphabet, used by linguists (and in at least some countries most people with an academic education, especially those who have learned foreign languages) to exactly describe the pronunciation of the word. The IPA contains enough symbols for all the sounds in all of the world's languages. Going through /ˈaɪərlənd/ bit by bit: * The slashes indicate that this is a *phonemic*, not a *phonetic*, transcription. Basically, a phonetic transcription is a description of exactly how one speaker is pronouncing something; while a phonemic transcription is a rough description of how it should be pronounced, although individual speakers may pronounce it slightly differently depending on their accent. * The little sign that looks like a kind of apostrophe indicates that the next syllable has the primary stress -- that is, it's emphasized. * aɪ is the first syllable, and it's a diphthong -- two vowels smushed together. It begins like a short "a", but ends like a short "i" -- this is the pronunciation of the word "eye". * ə is a sound called "schwa": it's the indistinct "uh" sound, like the "a" in "about". * All the other symbols are pretty much self-explanatory. The point is that you have a universal system for describing pronunciations. Instead of saying, for example, "It's like the 'a' in 'hat'" (because how you pronounce "hat" will vary depending on where you're from), you can say, "It's pronounced /æ/." If you go to that Wikipedia page and hover the mouse pointer over the transcription, you should see a tool-tip pop up with a more understandable pronunciation guide (assuming your native language is standard American English, that is). ---------- Non-ELI5 section: The difference between a phonemic transcription and a phonetic transcription is a little tricky to explain. But in the IPA transcription for "Ireland", you can see the symbol /r/. But it you look it up on the IPA chart, it will tell you this represents a sound called an "alveolar trill", which you might better know as the "rolled R". Not many people actually use that sound: we just use it here, in the phonemic transcription, because it's the most convenient symbol to use. But if I want to write a *phonetic* transcription, I would need to know the exact sound being pronounced. To indicate a phonetic transcription, I would use square brackets instead of slashes. In other words, the different ways of pronouncing /r/ in English are: * [r] = alveolar trill, the "rolled R", most often used in Scotland * [ɹ̠] = postalveolar approximant, the usual American pronunciation * [ɻ] = retroflex approximant, like the postalveolar approximant above, but with the tip of the tongue curled more * [ʋ] = labiodental approximant, pronounced by bringing the lips close together but not actually touching; it sounds almost like a "w" * [ɾ] = alveolar flap, pronounced by rapping the tip of the tongue once against the roof of the mouth just behind the teeth * [ʁ] = the very rare voiced uvular fricative, once used in some dialects of English but now dying out: it's a weird raspy noise pronounced by pushing the back of the tongue against the uvula, that fleshy thing that hangs down at the back of your mouth. | 2 |
dc0jva | Technology | How exactly do magnetic waves become encoded/decoded (ie. on tapes) I'm fascinated by this article URL_0 Disney used magnetic tape to play commands for animatronics while rocket scientists used magnetic tape to guide nuclear missiles. All the explanations have said that a tape head is able to "read" these magnetic waves on plastic tape but do not go into the actual science/physics of it. Any help? | A tape head is a type of transducer. It can convert electric signals to magnetic fluctuations, and vice versa. Basically you have a coil of wire with a gap in it, and the gap is filled with a diamagnetic material, like gold. If you apply a variable magnetic field at the gap, it'll induce an electric current in the coil. If you run current through the coil, it'll create a magnetic field at the gap. When you record, you run a magnetic tape past the tape head. The electric signal comes from your microphones (or your other instruments.) As the tape runs past the head, a magnetic field is "imprinted" on the tape, which happens to be the same as the electric signal that came into the tape head. When you play, there's no current in the tape head. As the tape runs past the head, its magnetic field induces a current in the coil that corresponds to the one imprinted on the tape. The coil is connected to an amplifier, and what you hear out of your speakers is the same as what was recorded on the tape. | 2 |
iveilw | Other | Why do some stars, planets, and galaxies have really cool and unique names while others are just numbers? | Because the cooler named ones were discovered first. At some point there were just too many so they started giving them only scientific names. | 1 |
auqkg9 | Biology | How does a body generate heat from the food we eat? I get that our organs break it down into smaller and smaller bits, and the bits mix with oxygen or something, but I clearly need it ELI5. | Any energy transfer will result in the loss of energy as heat (think about how friction makes things hot). Your body uses various different molecules from the food you eat and strips the electrons from the them, passing them off to a series of carriers. Eventually, the electrons are pushed through a special cellular machine that uses their energy to create molecules of ATP, which is the energy "currency" of a cell. If this is done efficiently it generates little heat, but it can generate a lot of eat if it is done inefficiently. Certain types of tissue in your body, called brown fat, are very inefficient and generate a lot of heat. Babies have a lot more of this tissue than adults. You can also generate more heat by cranking up your metabolic rate, akin to revving the gas to heat your car up quicker in the winter. This is regulated through the thyroid gland. People with thyroid issues usually have weight problems (either burning too many calories or not enough) and have heat regulation problems (too hot or too cold). | 2 |
avizdj | Physics | How can you stick your entire hand into an open flame[camp fire, lighter] for a few seconds with minimal damage, but touching a hot metal [stove] burns instantly? | Uhh, wait, if you stick your hand in a fire for a few seconds, you will get burned. & #x200B; You can move it in and out very quickly(less than a second or so), but a few seconds will earn you a third degree burn. | 4 |
7gih9w | Biology | why canned food last much longer than other packed food? Why does storing food by canning it make it last so much longer than any other method? | So there is bacteria everywhere right? This bacteria causes food to spoil. Once you put food in a can and create a hermetic seal (fancy term for saying nothing gets in or out, not even air), you have to cook the can. It is cooked in a giant pressure cooker with steam until all of the dangerous bacteria is killed off. The food will last as long as the seal. For a canned good, the seam is made of 5 layers of metal. When stored at room temperature, if the coating on the can is good, canned goods should last indefinitely, however there will be a small drop in quality after 2 to 3 years. Highly acidic products can eat through the can coating after a while, and have shorter shelf life as a result. | 14 |
nc2u0z | Other | Why do we get angry and frustrated when we’re in pain? Is this some sort of thing the brain does to help cope with pain? | Psychologist here! We do something called emotional regulation, which is a cognitive process. Our brains can only process a certain amount of input every second, so it needs to filter out a lot of the things our senses perceive at any given moment. Pain is high priority, so it is hard to filter out. Compare it to a person shouting over a conversation. Pain makes the brain busy, so regulating emotions become a second priority. It also triggers the body's stress system, which activates chemicals that make you more emotional and aggressive. It's complex to say the least. | 1 |
6vgn3u | Biology | How did the world develop STIs if you can only get it via sexual contact with the infected? Basically how did the patient 0 for gonorrhea and herpes contract them. HIV was apparently because of some guy and a monkey? | HIV was not because of sex with some guy and a monkey. That is a myth. Most sexual STIs started off as different kinds of infections that found living in/on the genitals to be more advantageous, and once there were transmitted via sex. Over time they mutated to primarily be transmitted by sex. | 1 |
iyne3w | Other | How Would A Non-Peaceful Transfer Of Presidential Power Work? | That's sort of like asking how trash pickup will work on Mars. The US has never experienced one and we don't have any data points on what would happen. That being said - The Constitution/Law do spell out some clear points. 1) The President's terms ends on Jan 20. There are NO exceptions to this. So on January 20th if a President did not win reelection they are no longer the President. 2) The Vice President is under the same terms as the President 3) If there is no President, and No Vice President, then the Speaker of the House becomes the new President. This assumes that the election is only disputed at the Presidential Level, if the House elections are disputed as well then the Senator Pro-Tempore selects the next President. 4a) The Secret Service protects *The President of the United States*. They are not personally loyal to the current President. Former Presidents of the US are afforded Secret Service protection as well, but that is a separate provision under the law. 4b) Based on 4a we can make the projection that on Jan 20th if a President refuses to leave office, they (The Secret Service) will politely but firmly remove them from the White House. If that involves opening the door with their head, they won't feel great about it but they will. 5) The US Elections are actually fairly devoid of fraud. Unless the votes in particular states are REALLY close, we can expect a clear victory verified and announced. So any disputed election would either be an extremely close one or someone refusing to accept the result that is SUPER OBVIOUS to everyone else. | 1 |
60m47b | Technology | Why are my old smartphones (2013) so slow today doing simple stuff like photos and internet browsing when it could run Playstation 3 graphics games with ease? | Planned Obsolescence. URL_0 Basically, if you make the perfect product, then people would not need to replace or buy a new version. However, if you ensure that your product degrades over time, then you'll force your customers to make repeat purchases. | 1 |
bi3fm0 | Physics | Why does the moon look huge in the distance when poping over a mountain but small on a picture or a video? | Forced perspective. When it's next to the mountain, your mind has a frame of reference. In a picture, or even just higher in the sky, you don't have that same reference. | 10 |
a4m87s | Other | the difference between a legal and an illegal war. Yes, I know there are numerous treaties and conventions governing conduct in war but is war itself legal and is there a distinction between a legal and illegal war? | War is illegal, with 3 exceptions, as stated in the Chapter VII of the UN Charter. You can declare war if you are going to get attacked imminently, war can be allowed by the UN Security Council, and you can engage your troops in a country that requested assistance and has accepted your intervention. | 6 |
ai4fw4 | Physics | Why are we able to see more with a telescope if we're not shortening the distance between us and the "target"? It's stupid, I know, but holy cow I can't understand how we can se more with a telescope. It seems that we're closer to the object without moving closer. Amazing, really. It seems that we're shortening the distance that the light needs to travel to our eyes from the object we're looking. | For the same reason you can see things larger with a magnifying glass. Think of a telescope as a series of small magnifying glasses arranged in such a way that the small speck of light in the night sky appears larger and more detailed. Its all due to the type of lenses used. | 5 |
76zsns | Physics | What is local realism? (Quantum Physics) I watched an interesting [MinutePhysics video]( URL_0 ) on Bell's Theorem and how local realism may not exist. I'm not a mathematician, so some of it went over my head. But as far as I can tell, they never explain what local realism is. So what is it and what implications would its non-existence have for us? EDIT: sprlling | Here's the version I give high school students who have no idea about literally anything: In quantum physics we can prove experimentally that particles vast distances apart seem to communicate with each other instantaneously. This seems to violate at least one conventional metaphysical "truth" about the universe. The solutions to this problem that Bell came up with are: 1. Distant objects are actually not distant. Our sense of locality is flawed somehow. Perhaps at higher dimensions, spatial distance doesn't exist in the same way? And these supposedly distant particles can communicate instantly because, at some level, they're not distant. 2. Everything is absolutely determined. No free will exists. The universe knows exactly what will happen at every moment, so "faster than light communication" appears to be possible simply because everything is accounted for in advance. 3. The universe is a simulation, like a video game that doesn't bother loading information you're not currently interacting with. Particles appear to communicate at impossible speeds because they don't even really exist at all outside of our perception. This is the zen approach :) if a tree falls in the forest, and no one is around to hear, does it make a sound? No. It doesn't. Again this is at a typical 9th grade American level so I'm aware it's a bit simplistic, but hopefully helps you understand. | 2 |
adqfyk | Biology | Why do our eyes change focus when looking at a screen vs reflections on that screen, even though it's the same surface? | Go to a bathroom mirror and stick a small dot of stickynote or damp paper or tissue on its surface to make a "model" of a reflecting screen. Then back away from that mirror a bit, say, three feet, and line that dot up with your nose. Focus on the dot for a second. Then focus on the reflection of your mouth instead, and you'll see the transition. They look like they're different distances. The reason is because the dot on the mirror's surface is three feet away from your eyes... but the reflection of your mouth is *two times* three feet away from your eyes. The light that you're seeing that comes from your mouth hits the mirror three feet away, and bounces back to your eyes which are another three feet away, making six feet in total that it's traveled. To properly process that light that's traveled that six feet, your eyes have to adjust and focus as if your lips actually are six feet away from you. But the light coming from the dot of paper is only three feet away from you. The images your phone, tablet or computer screen makes are generated very near to its surface, so they're just like that bit of paper. But any images your screen reflects if you have, say a black background or you turn it off are the same as an image seen in a mirror, so that distance-doubling applies and you have to refocus to see it properly. If you leave that mirror and then set up two objects that are three feet away and six feet away from your eyes - say, a pen you're holding at arm's length and a nearby chair - you'll get the exact same effect when you switch focus between them. The only difference is the light in the mirror's and screen reflection's case goes through one "bounce". | 1 |
crue9h | Technology | How can nuclear launches be detected and identified? If Russia launches at The US, how does the US know that it was Russia? | There's a few arrays of satellites in orbit watching for bright or hot spots on the ground. A rocket launch is this intensely bright and hot spot for about a minute, far far brighter than anything around which makes it easy to spot. All rocket launches and missile tests are publicized in advance because they'll trip this warning system These same satellites can also detect a nuclear detonation on the surface. They work in conjunction with the seismographs around the world which are used to detect earthquakes but were initially installed to detect underground nuclear tests. | 3 |
76xnq6 | Engineering | - Are speed bumps designed to damage your car if you go over them too fast? | Some are, yes. We have the normal speed bumps but there is a whole road nearby that uses ~~his~~ these rubber things bolted down and even if you are going really slowly the jolt they give you is enormous. | 7 |
n1d6tu | Technology | How does ray tracing work? | Former game developer here, So you have 3D points, 3 points make a triangle (polygon) in 3D space - the smallest primitive object you can make. Everything can break down into terms of triangles. The surface of that triangle also so happens to describe a 2D plane that goes on to infinity in that 3D space. The surface of the triangle, that plane, faces a direction - we call that a "normal vector". You can think of it as an arrow, pointing from the surface of the triangle, and for the sake of argument, just presume it's at a right angle to the surface, it points straight out. (It doesn't always, we can tweak it for different effects.) The points of a triangle can all have their own normals, too, and can have more than one normal if that one point is shared with multiple adjacent triangle. Then you have matrices. These are numbers, very complicated numbers with multiple parts. Remember complex numbers, from high school algebra hell? a + b*i*? Shit like that? That's not an equation you *solve for*, notice there isn't an equal sign anywhere. That mathy thing is a way of representing a kind of number. Matrices are also a kind of number, and they come in different sizes. For 3D games, most matrices have either 9 or 16 terms. We can write them in a handy notation of rows and columns, in tabular form. So you'll see 3x3 or 4x4 grids of numbers, those are matrices. A 3x3 matrix represents, mathematically, 3D space. Literally the whole universe. You can rotate it, scale it, or transform it - maybe your space has a slant to it... A 4x4 matrix has X, Y, Z, and W. W is interesting, it's a translation. What it is, is a 3D matrix with a position. We're talking ONE UNIVERSE relative to ANOTHER UNIVERSE. This is very useful, because if your torso is represented by one matrix, then your arm can be represented by another matrix. Now you can describe how your arm is positioned relative to your torso. And when you rotate your arm matrix, the whole arm universe rotates with it, along with your arm in it. The torso remains unaffected. When you rotate the torso matrix, it moves the arm with it, because the arm is relative to the torso. We build whole hierarchies of matrices, one relative to another, and build up a whole universe. You can draw the relationship like a tree. When a character is standing there and their head is moving around, their head matrix is changing, and then you can multiply the matrix against all the points that make up the triangles of the head, and now you know where in the universe the head polygons go, and their orientation, and everything. And matrices multiply against each other, too. You have one matrix at the top, typically your camera, and that's the center of the universe. And then you start multiplying from the top of the hierarchy down. So all the map geometry, all the model geometry, all the items, you multiply them from the top of the hierarchy down to the bottom, that's how everything gets placed in the universe. Something moves, and everything relative to it moves too, requiring some recomputation. To render your 3D space, the camera is a matrix that skews the universe, things further away are smaller, because the universe is actually geometrically smaller the further away it is! Then the matrix also collapses the Z axis, making this skewed projection flat. Because your screen is flat. So in the end, you have all this 3D geometry being transformed into 2D geometry. So now you have some light source. It typically boils down to a single point of light. It has color and intensity. You need to "cast a ray", which is a line with a starting point and a direction, and it goes on forever. You need one for every pixel on your screen. You point it outward into your universe - you cast it, and then do some math to find out what's the first physical thing in your universe it intersects. It's going to be a surface, and that surface is going to have a lot of information, like "material" properties, which are just color properties, and textures, which is more color for blending, plus all this normal data we talked about earlier. These days, every pixel of a texture has it's own normal. These normals work into the maths to decide just how that ray, is going to reflect off. There's also some maths behind if or how the ray splits, because the color on that surface you've first encountered is the sum of all the light that shines on it. But the sum of all the light that shines on it includes all the surfaces that are shining their light onto it. The color of my hands as I type this is more than just the sunlight, it's the air, the clouds, even the walls in my room which are illuminated by the sun, the light bouncing off my hands and into my eyes. So you need to trace rays from that first intersection outward to their next intersection, and outward again, and again, until all the rays find themselves back at a light source. You know how pool is a game of geometry and angles? That people bounce billiard balls off the walls and other billiard balls to score pockets? Same thing. The pool que is the initial ray cast, the first billiard ball is the first intersection, the bouncing and scoring in pockets are the last rays finally hitting light sources. Now that you know the paths the light took to get to your pixel, you can sum the colors and intensities and do all the blending to end up with the final color for that pixel. Now, for a 1920x1200 monitor, just do that 2,303,999 more times, 60-120 times a second. | 3 |
jwperd | Biology | Why do we have different handwriting even though we all learn to write the same letters(in our respective languages, of course)? | Probably because people are just overall different. People have shaky hands, steady hands, or don’t practice overall. Same applies for art, I’m horrid at it while my other friends are so much better at it than I am | 2 |
7ohthi | Biology | Why do men and women orgasm so differently? | Because each sex has a different goal during the act of reproduction. A man's role is to achieve climax and deposit the sperm before other males can potentially interfere, while the female's is to achieve a convulsion of the vaginal walls to facilitate the sperm's movement towards the potential egg and future offspring. Anything else that we've created about the sexual process is self-created. Orgasm is the brain's way of making sure sex is pleasurable enough to attempt again but is infrequently achieved without direct sex in most mammals capable of orgasm. Humans have placed the emphasis on it because of our sexual culture. This is neither a bad nor necessarily good thing, and has implications on our behavior as well. | 2 |
hs17al | Biology | why is it when you take a portrait photograph of somebody it looks way worse when you mirror it; and does that mean we look better in the mirror or worse? | Oddly, the image you think of yourself isn’t the image people see when they look at you. We see our reflection more often than our front-facing view (unless you’re a movie star?) and that is partially why some people claim they aren’t “photogenic”. They truly believe they don’t look “as good” as themselves in pictures - because they aren’t used to seeing themselves except reflected. Mirroring a photograph of you presents the mirrored-version of the face you wake up to each morning. Further, mirroring a picture of someone else makes the reverse change - altering their appearance to a less-known “version” or presentation of their facial features. To that person, though, the pic will probably look more “like them”. That said - some people are more symmetrical than others and that complicates matters to an extent that is explored in aesthetics and beauty or whatever you want to call that field of thought. | 2 |
b5w6wd | Physics | When on a trampoline, why does someone bouncing near you send you much higher, and also how does 'stealing' someone's bounce work? | When they get close to you, the trampoline is stretched even tighter than it usually is, allowing you to bounce higher when it’s being stretched by your friend. When your jump is stolen, their weight pulls the trampoline away from you, and so the trampoline has less tension underneath you, and thus can’t launch you back up as high. | 1 |
6kpgdc | Biology | How do we know what colours dinosaurs were? | We don't, for the most part. [Whilst some fragments of colour have been preserved in dinosaur feathers]( URL_0 ) (and this is cool as shit!), this is a recent discovery. So most of the artwork you see depicting dinosaur colour is guesswork. But it's educated guesswork. It's based on what we know about the animal and comparisons to living day animals that share similar traits. | 2 |
iq101w | Mathematics | How do doctors make predictions of how long someone will live or if they'll ever walk normally again? I was rewatching an old video on YouTube and the guy was able to walk again after 10 months of practicing yoga and losing 140 lbs. If no one on earth can exactly predict when someone will die or if they'll be able to walk again, how and why do doctors come up with these predictions? URL_0 | I'm an MD. The question is so broad because it's a very different question/anwser in different clinical settings (geriatric patient dying in the ICU from sepsis vs pediatric cancer diagnosis) , and crosses different diagnoses and pathology. Usually these types of assessments are multi-factorial but a few points: 1. "Doctors told me I only had 2 days/weeks/months to live" or any permutation like that is almost never said in that format. That is usually a marketing or self-promotion trope that is used to sell you on a story or product. Doctors talk more broadly. "For stage 4 cancers the 6 month survival is usually low, honestly we could be looking that time frame or less because of x,y, or z factors". 2. I always look for reversibility. End-organ damage is a big one for critically ill patients in particular. If tissue is dead there is no way to make it un-dead. If your kidneys fail and don't respond to treatment and you are suddenly dialysis dependent we crossed a certain threshold. If your ejection fraction of your heart is low because that heart muscle is dead (it can be low for other reasons..excluding those) then we can't expect that function to recover only managed. 3. Always consider the broader context of the patient's health. If someone's grandparent has dementia and has lost function every year for the last 5 years and now they have a diagnosis with limited reversibility... It's silly to expect them to every have a quality of life better than what their established baseline has been if there is a major insult requiring ICU care as an example. 4. For patient in the hospital that are really entering the phase of actively dying (signs of death, nothing medicine can reverse) we look at trend in vital signs, end-organ damage, failure to respond to treatment. Later signs include agonal breathing, skin mottling. By then we've usually already spoken to the family about changing or goals from treating the pathology to treating any pain and air-hunger and making the patient comfortable (i.e. we are shifting our goal in particular because there is no demonstrable reversibility). Prior to that we always give a warning shot before giving bad news and then say something like "\[the patient\] will not survive this hospitalization, it's hard for doctors to predict but there isn't much time". For certain situation it needs to be direct. It's always nested in a long sweeping summary of what has happened, why there was no improvement, and how we can move forward. 5. So a summary to that is: it's a combination of blood work, imaging, vital signs , physical exam, reversibility of problem + the context about the patient's health + what the published data shows about that particular disease stage. (Sorry not a great ELI5) | 18 |
itu7j9 | Technology | How does Disney+ prevent screen shots?I'm having a hard time imaging that a website can do that.Like cant you just snip it or us another program? | They use something called Google Widevine, and basically the way that works is the encrypted video stream is passed directly to the hardware, the OS draws the window as having a black box where the video player should be, and the processor at the hardware level decrypts and draws the media over that black box. So to the OS, because it doesn’t have access to that portion of the hardware rendering the video, all it sees is the black box it was told to draw. Actually, iOS and Android apps work in exactly the same way—this is why you can’t get around it with just a jailbreak or root tweak to bypass the screenshot security restriction. Because this is a feature the hardware has to support, that’s why on older devices and TVs you get an error saying Netflix or other streaming services aren’t supported—they don’t have a chip certified for secure processing of the video stream. I believe in order to record these streams at the moment a hardware mod is needed since the data is simply never passed to the OS, but I have been out of that scene for a while. | 3 |
gouql9 | Other | why are guitar tabs upside down? I just started learning and it having the tabs this way looks very counterintuitive looking at it from a beginner's perspective. So why are they this way i would really love to know. | If you look down at your guitar you will see something similar to the tabs on your screen. The tabs are not really upside down. | 2 |
elbyu3 | Biology | Why being in any pose in bed in the morning is so comfortable yet it takes time to find comfortable pose trying to sleep? | When you go to sleep it takes time to process how reality rawdogged you with bullshit all day, then the mental gymnastics of convincing yourself things will be better soon, finally relax. Takes awhile. When you wake up from the dreams you had from buying into your own horseshit, you are in a fog for a bit. everything seems fine before the fog begins to lift and reality begins to pound you with its hard on for your suffering. Duh. | 9 |
64qckh | Culture | Why do people from the US never identify with English culture? I often read about Italian-American, Irish-American, Chinese-American, you name it, but not a single time have I read someone proud of her/his English origins. | When I asked my parents why we don't celebrate anything to do with our heritage, my mom replied "we moved here for a reason" Idk if it adds to the topic, but might have something to do with it. | 34 |
i10qww | Physics | how come the splitting of atoms makes an explosion? | From what I recall from my nuclear chemistry class, its about the energy economy of the universe. Elements, compounds and molecules need energy to be put in to form. That's why naturally occurring elements are formed in the cores of stars or during supernovae. When you split an atom or start a chemical reaction, you are altering the energy economy. Splitting the atom releases the energy stored in it when it formed. AFAIK you could get the same result splitting any element, but radioactive elements are inherently unstable, which is why its possible to split them *relatively* easily. EDIT: Radioactive elements are already shedding their excess mass and/or energy and become more stable elements over time. A fission reaction is a different process, but the general concept is similar; the reaction is us forcing the element to release all of its energy at once instead of over a long period of time. EDIT2: actually, I think I have the energy economy thing backwards, at least for the formation of elements in stars. | 2 |
dmas7e | Biology | How does my body know to blink and stop something from hitting my eye that I couldn’t even see? I was cooking earlier this evening when the grease popped in my pan causing me to blink. This stopped a piece of grease from hitting my eye, and instead burning my lower eyelid. There is know way I could have seen that projectile, much less time my blink perfectly. | The corneal reflex (blink reflex) can be triggered when sounds greater than 40-60 db are made. I'm guessing the sound of the oil popping is why you blinked. | 3 |
ajcs7e | Physics | Why is the temperature usually less cold when it's snowing? | If it's snowing that means there is cloud cover. Cloud cover acts as a blanket over the land and holds in heat. When there are no clouds the heat from the ground can radiate directly out into space. That's why it tends to be colder with no clouds. | 5 |
bj99ba | Other | Why is lumber sold based the size it was before it went into the planer? | In the UK it is based on whether the timber is planed or not. Unplaned timber is called the nominal size, so 50mm x 100mm (which is near enough 2 x 4) actually is 50 x 100. Unplaned timber has a rough finish and is generally used a lot outside or where it can't be seen. Planed timber, (finished) is now mostly sold as 50 x 100 but is actually 44 x 94 ish. (Sizes differ a bit between different timber merchants.) The 50 x 100 unplaned timber is run through a planer thereby losing 3 mm on each side. In some places you can buy accurate stated sizes. Planed timber feels smooth and doesn't need much finishing. You could paint straight onto it generally. Its the wood you would see inside your house - skirting boards, plank, floorboard, door liners, trims and architraves. (Your doors, windows and furniture are probably not made from planed timber since joiners who make these tend to size and plane their own better grade lumber.) Sheet material sizes are accurate. It's a pain basically, especially when you are using a lot of different sizes and trying to design and cost something. It's another 'economy' passed onto the customer to sort out. | 6 |
86u0qv | Biology | if fruit is sweet to encourage animals to eat it and carry the seeds away from the parent tree, how do lemons and limes fit into this mix? | Some animals like lemons and limes the way that some people like mint or cinnamon. With taste is all about how you choose to feel about these things. You also need to understand that animals are different, they have different taste receptors. Cats don't like sweet things at all, but there could be animals that love bitter flavors. Carrots and beets back in the day had the highest sugar content for readily available food, so they made carrot cake out of carrots when sugar was scarce. Concerning the aforementioned fruit someone made limes and lemons. They were made through having specific grandparent fruits have family trees that would end up being the way they are when you eat them. Thin skinned and full of fruit instead of thick and less fruity. Although it sounds like a bad idea, orange juice reigns supreme over apple,and all other fruit juices, in the grocery store. Bananas used to be more nutritious, and apparently tasted more like the banana runts than the taste that you are likely familiar with. | 13 |
9j2bh5 | Mathematics | How do calculators find square roots? Is it just brute forcing? Like computing for some 'a' (number for which square root is to be found) divided by some number 'i' until it equals i? Like so: ***a/i = i , computing through all values of i. Like 256/i = i is satisfied by 16.*** Is there some other method they use? Thanks | Pocket calculators often use the [Babylonian method]( URL_1 ). *Edit: This is the same as Newton's method/the Newton–Raphson method [as shown by /u/X7123M3-256 here]( URL_0 ).* --- ELI15: **You have a number `n` and you want to find its square root `√n`. You also have a guess of the square root `x`** (many calculators just start with `x = 1`). As `x` gets bigger, `n / x` gets smaller. They're "balanced" when `x = n / x`, which is the same thing as `x * x = n` or `x = √n`. This means that when `x < √n`, `n / x > √n`. (It also works the other way around: when `x > √n`, `n / x < √n`.) This also means that **the average of `x` and `n / x` should be closer to `√n` than `x` is**. **So we just set `x` to the average `(x + (n / x)) / 2` and repeat.** `x` gets a lot closer to `√n` every time, so we have to repeat less than 25 times to get every digit on our calculator right*. --- Example: We want to find `√100000` to 5 decimal places**. Start with `x = 1`. `n / x = 100000`, so the average is `(1 + 100000) / 2 = 50000.5`. Then `n / x ≈ 1.99998` and the average is `(~1.99998 + 50000.5) / 2 ≈ 25001.24999`. Full set of steps: Step | `x` | `n / x` | Average of `x` and `n / x` -|-|-|- 1 | 1 | 100000 | 50000.5 2 | 50000.5 | 1.99998 | 25001.24999 3 | 25001.24999 | 3.9998 | 12502.6249 4 | 12502.6249 | 7.99832 | 6255.31161 5 | 6255.31161 | 15.98641 | 3135.64901 6 | 3135.64901 | 31.89132 | 1583.77017 7 | 1583.77017 | 63.14047 | 823.45532 8 | 823.45532 | 121.4395 | 472.44741 9 | 472.44741 | 211.66377 | 342.05559 10 | 342.05559 | 292.35014 | 317.20287 11 | 317.20287 | 315.25566 | 316.22926 12 | 316.22926 | 316.22627 | 316.22777 13 | 316.22777 | 316.22777 | 316.22777 We can see that it only took 12 steps to reach our desired accuracy. We can also see that once we get close, we get a lot closer a lot faster. (14 steps would be accurate to more than 15 places after the decimal for this example.) One way to improve on this would be to start with a better guess. Setting `x` to the first half of the digits in `n` is an easy and effective option. Starting with `n = 100000` and `x = 100`, we only need 5 steps to get 5 decimal places of accuracy. --- \* Starting with `x = 1` and `n = 999,999,999,999`, 24 iterations is enough for 12 digits of accuracy. ** I used 64-bit floats for these computations and rounded all the results to 5 places after I was done. | 4 |
6levy8 | Culture | How did 4chan become so heavily affiliated with/occupied by members of the alt-right? | 4Chan provides absolute anonymity, and therefore no accountability for what you say. This means you can say literally anything, and not only will it disappear in a few days (or a few hours on fast-paced boards) but you can never be tied back to something horrible you've said. This means the the entire culture is based around the most stripped back and primal thoughts and interactions with no filter. On Reddit, you might think about what you're saying, you might research your point, or you might be kind to an "opponent" because what you say and do is tied to your user name, and your "karma" pool, if you're into that sort of thing. On 4Chan, you can say or do literally anything you want, and it can never have a negative impact on your experience, except for a couple of very egregious acts that can earn you a ban. This leads, over time, to an INCREDIBLY toxic horrifying atmosphere that attracts people who feel like they can't express their emotions and feelings and ideas on "hugbox liberal fag fest" places (like Reddit). Over time, spending hours and hours there, day in and day out, week after week, transforms people into that sort of thinking, and continues to attract the people who are drawn to that environment. Alt-Right people tend to feel attacked and held down by "PC culture" and seek a place where they can "Tell it like it is" and express their feelings without repercussions. Non-alt right people tend to want to avoid that sort of atmosphere as it becomes filled with more and more insanity, so it slowly empties of rational fun conversation, and refills with the dregs. | 14 |
d7b7yi | Other | How does one distinguish between good acting and bad acting? | Do you see a person playing a role or just the character itself? A good actor is invisible within the character they perform. | 2 |
lx94lc | Biology | Why do we sometimes wake up, say a bunch of random/nonsense stuff, and don’t remember it? | When you sleep, you enter a phase called REM, or 'Rapid Eye Movement'. It's that point in your sleep where your body essentially reorganizes the messy clutter in your brain to, amongst other things, store memories. This is the deepest point of your rest, so you need time to rise to a light sleep before you wake up in the morning. **So,** if you go to bed too late, your body won't have enough time to get back to that light sleep mode and you're left waking up sort of groggy or hit the snooze button. Your brain isn't ready to be active for another 12 hours, so it's sort of switched off. | 1 |
k2arl1 | Earth Science | Why does smoke from a cigarette or steam from a pot tend to lose shape nearly instantly, yet clouds seem to maintain their shape for a longer period of time? | Ever flown through a cloud on an airplane? You're not headed towards some big wall of cloud - you go through wisps of fog that get thicker and thicker. But there's a whole lot of it. So if you see it from a half mile away, you don't see that wispy edge, because it's too far away. You just see the thicker-and-thicker part, which looks solid because of the contrast with the background and the light reflecting off of it. | 4 |
5vzhgz | Technology | how do traffic lights know when to change? | It depends on the lights. There are a wide variety of control mechanisms for traffic lights, so I'll try to break them down and list their pros and cons, and where they're more commonly used. I should clarify that my experience of traffic systems is UK based, and while much of this is international, regional differences will exist. First off, I'm going to explain some common terms, which will make this conversation easier. To do so, I'm going to take a sample junction in London, which is a simple crossroads with a "scramble" style pedestrian crossing. Stages are they different steps a set of lights can go through. This junction has three stages, 1-3, plus an "all red" stage, 0. The traffic light controller can send the junction to any of these stages. Phases are individual traffic movements. In the above example, you have phase A for the traffic coming from the South arm of the junction, B for the North, C for the West, D for the East. E is the standard pedestrian crossings, and phase F denotes the diagonal "scramble" movements. Phase G is used to refer to the all red stage, although really there are no phases active at all. Intergreen times are the time gaps between two stages. For example, when you go from stage 3 to stage 1, you have to wait for the lights to go amber, then red, then amber again before the lights on A and B are green, and the stage is considered to have started. I'm mainly mentioning this because it's important to remember that the timings below include their intergreen times as well. So, the different forms of control. Fixed Time: This is the simplest form of traffic control. The controller will just go through all the numbered stages, in order, regardless of any other considerations, on a set schedule. On the above sight, for example, it might look something like this: Stage 1 for 30 seconds Stage 2 for 14 seconds Stage 3 for 16 seconds This would cycle every 60 seconds, and keep doing that forever. It's not very efficient, so it's rarely used as a primary control method. It's sometimes used for temporary signals during roadworks, though, or as an emergency fallback if your primary control method fails. Vehicle Activated: Vehicle Activated control is quite common on less frequently used junctions. Essentially, the junction will sit at its "rest" state until a detector at the junction detects a vehicle on one of the other arms. In our example above, the site would sit on stage 1 as standard. Then if a vehicle approached on phase D, it would be detected, and the system would change to stage 3 for a while until that vehicle had passed. There's usually a minimum time the site will have to spend back on stage 1 before it could be pulled away again. V.A. works pretty well on sites with low traffic volumes - particularly when one of the arms has very low usage and you don't want to give it time unless it's necessary. It's still pretty inefficient for busy junctions, though. UTC: UTC, or Urban Traffic Control, is how the most important sites in London, and a lot of other cities around the world, are controlled. Every site has a comms connection (usually ADSL these days) to a central control server. This server monitors all the sites, and sends out commands based on the way it wants the site to work. UTC allows a lot of flexibility, but it generally operates on a similar cycle to Fixed Time, except for a few factors. Firstly, stages can be demand dependent. Most pedestrian stages work this way - when someone pushes the wait button, the controller will tell the central server a demand has been placed. Then, when the pedestrian stage's time comes up, it will be instructed to call it. If there's no demand, it will stay on the old stage, avoiding unnecessary calls to stages that aren't needed. Secondly, the timing of the cycles can be varied. This is usually done based on the time of day, to give important trunk roads more time during peak hours. At midnight, for example, the cycle time of our junction might be 42 seconds. This is very short, and means that the side roads and the pedestrian stage gets a lot of the time, but means shorter waits for each stage. at 8:30 am, though, the cycle time might be 72 seconds. That extra time will go almost entirely on the main North-South road, allowing it to get that busy commuter traffic through. The side road and the pedestrians will have a longer wait, but it's more efficient in terms of getting large volumes of traffic through the junction. SCOOT: This isn't really a separate form of control so much as an extra system run on UTC sites. It stands for Split Cycle Offset Optimisation Technique, so called because it optimises the junction based on Split, Cycle time and Offset. It does this based on SCOOT loops, detectors placed in the road that measure how much traffic is coming into and going out of the junction. The cycle time, as already covered above, is how long it takes for the whole system to cycle through its different stages. the split is the amount of that cycle time associated with each stage. It's used on busy intersections where all the roads could be busy, to identify which arms of the junctions have the biggest queues, and give them the extra time they need to clear traffic there. The offset is only used for sites that are linked in SCOOT corridors. The idea is to link the sites together so that their green lights line up with traffic flow - the so-called Green Wave effect that means that the lights change just as you're getting to each junction. It's very hard to get this right, especially if traffic is moving in both directions, but if you're able to do it it saves a huge amount of wasted time coming to a stop and then starting again. CLF: CLF, or Cableless Link Facility, is the system that UTC sites use when they lose communications with the main server, either because the comms line breaks or because the server isn't responding. It uses estimates of cycle times and splits for the junction based on time of day and day of week - obviously not as effective as live control, but better than nothing. | 1 |
5tv3w5 | Economics | Why do we still have to file taxes? | What you are describing can definitely be achieved using pre-filled forms. Ideally, the IRS would send you a tax return with all numbers available to the IRS filled in the correct spots. You would then review and make sure it is correct. You could even bring it to a tax professional to look it over for you. What's stopping this from happening is the many parties that are interested in making sure your return remains complex. These parties include companies like Intuit (TurboTax) and H & R Block. A lot of their business would disappear overnight, as they handle a lot of the more basic returns that only include income and the standard deduction. More info here: URL_0 URL_1 | 37 |
am9pwe | Culture | Why do Australians and Brits consider it proper grammar to say “go to hospital” and leave out the “the”? As an American I would say “go to THE hospital” but I would happily say “go to school” (no “the”) | You would say "go to the school" when thew school is just a place you were visiting. "Go to school" implies going there as a student. "Go to the hospital" is something we say when we are rendezvousing at the hospital for whatever reason. "Go to hospital" means we're going to one as some kind of patient. | 5 |
8sfq89 | Culture | Why didn’t white Americans enslave Native Americans systematically on a wide scale rather than shipping slaves all the way from Africa? | One of the main reasons was the fact that Native Americans were not able to keep up with the rigors of labor. Also some Native Americans were not able to withstand some of the diseases that the Europeans brought over . The Africans could with stand those diseases for the most part could work for a reasonable amount of years . | 7 |
awpmxa | Chemistry | How do some foods "melt in your mouth"? | Well "melting" via the heat of the food or your mouth causes some of the solid matter like lipids and proteins to desynthesize. But your saliva also breaks down carbs in your mouth through enzyme activity, making them more liquid like and therefore easier to absorb. | 1 |
deux2r | Technology | Why do downloads take so much time? Why do downloads take longer than like 2 seconds? Couldn't it all just get sucked up like a caprisun? What is the reason for the device to slow the intake of data? Like I'm downloading a game on my PS4 and it's going to take 5 hours, why is that? Thanks in advance! | Because internet bandwidth works like water pipes, the flowing water is the data. The size of the pipes represent your internet speed and the pressure of the water flow represent how fast the download server is hosting your download. The files come in specific sizes and you need to download each portiom of the data gradually. The bigger the download, the longer the time. You can download a file like sucking a caprisun if it's small and can be consumed by your internet speed quickly. | 1 |
6s92hm | Repost | Why do toilets(in america) use clean potable water? | I mean I would guess one of the reasons is so that our pets and children wouldn't get poisoned from drinking toilet water. | 58 |
91idqg | Technology | Why don’t viruses in virtual machines effect the host computer? | A virtual machine is just that— virtual. Your computer is basically figuring out “if I was a computer following this code/instructions, what would I do?” rather than doing those things in a way that affects its own system and files. So if the code says “take tax/financial documents stored on your desktop and send it to Russia” your computer will look at *the virtual machine’s desktop* and send anything *stored there* to Russia. It won’t look through files on the host computer because as far as the virtual machine is *and code the virtual machine runs* is concerned, the virtual stuff is a normal, complete computer system. The virtual desktop folder **is** the user’s desktop folder. It could be possible to trick the host computer into doing something during this simulation process, but it would look very different from code used to infect/trick normal computers operating normally. So the number of people affected would be lower and the motivation to make those viruses less... especially because VM users are often aware/smart enough to patch and update as vulnerabilities become known, while many regular computer users don’t realize the importance of updates or know anything about security. | 4 |
6xpk1r | Technology | With blockchains whats the difference between proof of stake vs. proof of work protocols? | In proof of work, computing power is used to validate blocks of transactions. This system uses the high cost of the limited supply of computation power in the world as its incentivise for miners to play nice. Attacking the network would cost a lot because of the high cost of hardware, energy, and potential mining profit missed. In proof of stake, collateral like Ether on Ethereum is staked or put on the line to verify a block of transaction. The threat of losing the collateral forces people to be honest. Also attacking the network would hurt the value of the collateral you'd have staked. | 1 |
aeeen7 | Technology | Fiber Optic Cables | In very very very very layman's terms, based on my understanding, light goes Bing boing boing boing bong all the way through out the other end. | 6 |
kxqw7k | Biology | Why do we sneeze if we look at the sun for a second or rub a feather on our nose? | The photic sneeze reflex (also known as Autosomal Dominant Compelling Helio-Ophthalmic Outburst (ACHOO) syndrome[1] or photosneezia, from the Greek φῶς, phōs, "light" and colloquially sun sneezing) is a reflex condition that causes sneezing in response to numerous stimuli, such as looking at bright lights or periocular (surrounding the eyeball) injection. The condition affects 18–35% of the world's population,[2] but its exact mechanism of action is not well understood. (Source: wikipedia) And from what ive learned in school. The nerves that normally trigger a sneeze are somewhat connected to the nerves that get triggered through light. Thats why when you feel the urge to sneeze but cant really do it, looking at a bright light could make you sneeze. | 1 |
a8gv3g | Other | why does chocolate milk from the store taste so much better than chocolate milk you make at home? | It’s all about the mouthfeel, store bought will have a thickening agent added to it at the factory. I doubt you’ve ever done anything at home to thicken your own chocolate milk. Mouthfeel refers to the physical sensations in the mouth caused by food or drink, as distinct from taste. But despite the fact that it’s a different sensation, the two closely overlap. I used to love to brew beer, and it’s amazing how different the same beer would taste after altering the mouthfeel. | 3 |
bx4ckw | Biology | Why do powerlifters wear a strap around their stomach? How does that help them lift more weight? | Simple analogy. Stand on an empty coke can and it crumples Stand on a full pressurised coke can and it has strength A lifting belt turns your body into the full coke can - it makes it more rigid by increasing internal pressure | 6 |
a1ht67 | Engineering | How do nuclear fusion reactors generate electricity In a nuclear fission reactor I know they heat water into steam which turns a turbine but how are they planning on making a fusion reactor work? | There are no commercial scale fusion processes that have yielded useful energy yet. In theory, once they are perfected they'd operate like a regular Fisson/Coal/Gas plant and use the heat to power a steam turbine. While there are other more sophisticated ways to get electricity from fusion, the tried-and-true steam turbine has long been the champ for low cost and high reliability. | 2 |
a5c9de | Biology | Why the Top of my Mouth Becomes Slightly Sore After Eating Some Foods Title. After eating some foods - especially ones that require more chewing, as one might expect, the top of my mouth becomes (slightly) painful to the touch, and the feeling fades until it goes away after a few minutes. | Some things have a rougher texture than you might realize. I notice this effect after eating tough breads or crackers. I think this might cause extremely small abrasions on the roof of the mouth, that eventually get progressively worse until you stop eating the food equivalent of brillo pads | 2 |
7v0idv | Culture | Why did the sun appear on the North side (on their right as they traveled West) of sailors doing around Africa in Herodotus' Histories? | I'm not familiar with the story you're talking about. But in the Northern Hemisphere the sun sweeps across the southern part of the sky, and in the Southern Hemisphere it sweeps across the northern part of the sky. Half of Africa is in the Southern Hemisphere, so as you sail around it you're going to see the sun in the north (it still rises in the east and sets in the west, but while it's up it will be north). This would have been of interest to the Greeks since they didn't get that far south very often. | 3 |
bp5mwq | Biology | How is mustard zero calories? Or is this just like a “round down”-ish type scenario? | Well thanks everyone! I expected this to be more chemically complex, but now I feel bad about not googling it. I truly feel 5. Well done all around. | 4 |
d4jjsu | Biology | why does our voice change when we hold our nose? | The human skull has a fair amount of void space, most of which is near and around the nose. This allows sound to resonate and if you hold your nose when you talk that effect is lessened. | 1 |
6v6a7v | Culture | In ancient times when armies of 20,000+ would march/sail into battle how could they possibly afford to feed that many men for that long. | Another aspect not mentioned yet was rationing. It was in everyone's self interest to make sure they weren't gorging on food or supplies that might save their life if they made it last. | 9 |
e7r3x3 | Other | Where do black market organs end up going and why? I've heard about how much human body parts are worth on the black market, but I'm curious as to why and where they end up going? Surely anyone able to afford a black market liver for a liver transplant can just go to a hospital and find one somehow right? Are hospitals receiving black market organs? | The "problem" that black market organs solve is not the lack of access to a healthcare system for wealthy individuals, it's a lack of organs available through ethical means. Someone can wait for a very long time on a donor, or they might not be prioritized depending on what system is used to determine who is eligible to get a transplant. Perhaps the person is worried about their health deteriorating too much while they hope for a donor because they are not at the top of the waiting lust, or because they don't fulfill whatever demands the healthcare system makes on a receiver, and they want to circumvent that. | 2 |
93zdwi | Biology | [deleted by user] | Pressure differentials. Basically, water is more dense than air, so going under it means there is more pressure trying to push into the holes in your body. Water is trying to go into your ears and nose, but there is already air in there, so the air gets trapped. As the water tries to fill these spaces, it's going to equalize the pressure between the water and air until they are the same pressure. That increase in pressure against your inner-ear and sinuses is what you are feeling. | 3 |
gs2tt5 | Biology | Why pure oxygen is poisonus? | If there is too much oxygen in the air you breathe, all of your red blood cells will be carrying as much oxygen as they can, but the remaining oxygen that hasn’t been absorbed will coat the surface of your lungs. This will cause a number of things to happen: fluid will build up in your lungs, you will have to breathe more to get the same amount of oxygen into your blood, your volume of your lungs where gas exchange occurs will decrease by 17%, and you will have chest pains. Tl;dr: too much oxygen bad | 1 |
fvo8rf | Physics | Why is it that when both a man and woman sing the same exact note in the same octave, the man's voice still sounds lower than the woman's? Is it an auditory illusion (we only perceive it to sound lower), or something with the vocal chord structure? | Because voices are not a single frequency. They have harmonics and atonal variations. That's what gives people their distinct "voice." And why some voices sound "better" than others, even if they are both on key. When singing a note, the loudest frequency would be the frequency designated by the note being sung, but there are other frequencies that are layered with it. Men tend to have lower pronounced harmonics than women, so when they sing, more low frequencies are blended in than when a woman sings. Think of it kind of like some sparkly car paint. You can have the same red base paint, and add different colors and amounts of sparkles and thinners to achieve different effects, from big silver sparkles, to a slight purple sheen, to color changing prismatic effects. | 3 |
8chdih | Technology | How did people get domain names before domain name registries were available? I don't know if I'm asking this right,,, | They didn't. There has always been domain name registration. If you mean the companies like GoDaddy etc, they're just registering you with the actual registrar (Network Solutions) for you, for a fee. | 2 |
nkqu4y | Biology | How did primitive humans, with a top speed of 28 mph, hunt large mammals like deer, bears, wolves, etc, that can reach speeds of near 35 - 40 mph? | Most animals can outrun humans, but only for short distances. Humans run slower, much slower, but we can go forever. There is no marathon running in the animal Kingdom, but if there was humanity would be champ. Ancient humans would track animals through the bush, the animal would run away, and the primitive humans would just lope after it. The animal would get scared run, and the humans would run after it again. We also had the brains to track it. Rinse and repeat after 6 hours and that fast gazelle is too tired to continue anymore. It's now dinner. Basically, it's like zombie movies, but to animals we're the relentless zombies. Later on, as our brains developed, we did as humans do and use our brains to save on effort. Why chase an animal when you can set a trap? Later on still, clever humans discovered animal husbandry. Now we only use our long-distance skills to hunt 26.2 stickers for our Priuses. Edit: when I say "we", I refer to humanity. I am not *personally* optimized for running. | 10 |
kldvda | Biology | Why dosen't Melatonin cause tolerance like other drugs that act in the brain? | You might be confusing tolerance with dependence/addiction. For something to be addictive, it has to create a reward in your brain, usually by causing an increase in dopamine. Melatonin has no affect of dopamine or rewards, so addiction/dependence doesn't develop | 2 |
83vmuj | Biology | Why are most of the herbivores mammals like elephants, rhinos, hippos, giraffe, etc. so big in size? Even in the jurassic era the largest dinosaur was a herbivore. | Metabolism is more efficient in primary consumers, the top of the trophies food chain gets less energy. Also, higher levels of oxygen in the Carboniferous period led to highly efficient aerobic respiration resulting in larger animals. Those animals you mentioned have evolved slower to fit with the lower oxygen levels. I like to think of Meganeura as a good example of this. | 11 |
8etlq3 | Other | In regards to colleges/universities, how does "tenure" protect someone from being fired? In TV/Movies, you often will see people mention that they have "tenure" which somehow protects them. In the US at least, 49/50 states have "at will" employment which essentially means you can be fired for any non-discriminatory reason at any time. How does tenure provide protection for educators? | I'm far from an expert, but I believe it's essentially an employment term that acknowledges an advanced academic skill set and offers permanent employment to retain access to those skills even if they're not currently required or aren't meeting any desired output criteria. I think it effectively protects you against being made redundant and adds a lot of red tape, rather than actually making it so that you literally *cannot* be fired. I'm sure if a tenured professor committed some act of gross misconduct or breached their employment terms in some significant way they'd end up just as fired as anyone else, right? | 2 |
gbc8ea | Biology | Why do dead bugs and mice 'stiffen up' in specific positions where as other dead animals simply go limp? | I don't know about bugs, but animals don't go limp, I mean immediately after death they do, but within hours rigor mortis sets in. That's because the SERCA pump required to sequester calcium in storage (terminal cisternae, sarcoplasmic reticulum) needs energy (ATP) to operate. No oxygen and metabolism upon death means no more ATP generated, so calcium starts to diffuse out of storage, go to the sarcomeres (force generating units), bind and shift proteins causing many cross bridge formations (tiny flexes) which slowly contracts the muscle. In order for the proteins in the sarcomeres to let go (myosin let go of actin) it also needs ATP, so you slowly flex more and more but you can't relax, because that requires energy. So you get rigor mortis. | 3 |
cyrutj | Psychology | What is the memory palace technique and how can it be of benefit in certain situations? | The memory palace does not need to be based off a real city. In fact I bet that would be way too complicated and wouldn't even be helpful unless you're a complete expert in this technique. The technique is to "place" information in a mental map of a physical location, usually like a house (or a palace for the pretentious kind of person like the new BBC Sherlock which I believe popularized *that* specific expression). You meet a new person at work named Sarah, so you, in your mind, go up the stairs and into the room where you keep all of your work colleagues and put the information "in that location", but yanno it's just a mental game. The logic behind this is that the problem with memory is locating the memory, not that the information is actually forgotten, you just can't find it. This technique gives you two separate paths to the memory - the normal way we all do where you think, "what was that woman's name?" and a new path you can follow where you send your mind back up the stairs and into the room with the information, and going through that process brings you to the same memory/information and you remember her name. Much like when you walk into the kitchen you might suddenly remember you forgot to buy milk on the way home, location is actually a pretty good memory device. I don't actually practice this. Maybe I should start. Anyway, I hope this makes sense. | 1 |
712012 | Technology | 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? | Trains are already largely automated, at least on the road. Two people run most trains in the USA, the Engineer and his Conductor. Together, the monitor/control anywhere from a few cars to several hundred. There are several issues with totally automating trains. Computers are fairly good at handling expected situations, they fail miserably at handling the unexpected. People on the other hand excel at pulling information out of noise and acting. It might not always be the most optimal, but generally it is an improvement. Then we have to look at the possibility of hacking your train system. You can't hack people. While they can be fooled by switch information that is wrong, they'll typically react to a situation where they have conflicting inputs. An automated system might not do as well, or it might be the target of the attack. One final note: In the USA, the vast majority of trains are freight trains. Automated systems might be able to handle decoupling cars, but until robots get far better, those air hoses are cheaper and easier to be coupled by someone walking the train than they would otherwise. Railcars might go in and out of several yards, getting rearranged to meet traffic and their intended destination before finally arriving. At each of those points, the cars are disconnected, and reconnected. This is largely unseen by the public, but it is an important part of the problem. The Bailey Yard near North Platte NE handles some 14,000 railcars/day, a significant portion of which will be coupled/uncoupled as they pass through. | 40 |
a9sdfy | Physics | the difference between a ground and neutral line in electricity. | Ground is earth ground. Neutral is a current carrying wire just like a hot wire. In an electrical system the neutral wire acts as a return pathway for AC power. The neutrals are all tied back to a "neutral bar" and the neutral bar is tied back to earth ground. | 2 |
86qdtj | Physics | How do we measure and calibrate time? A second isn't necessarily a second. If I set the time on the microwave and oven at the same time, in a month one will change over to the next minute before the other. Is it just a guess when programming? How can we be certain we have an accurate measurement when needing an extremely precise measurement if manufacturers may vary? | A second is defined internationally as the time that elapses during 9,192,631,770 cycles of the radiation produced by the transition between two levels of the cesium 133 atom. That's the most precise, scientific definition of a second. There are a number of atomic clocks around the world that are all synchronized to keep time accurately (they still accumulate error, albeit very slowly. The most accurate atomic clocks would be off by no more than 1 second in 100 million years). These atomic clocks keep the time for all the things that need that level of precision, like satellites, cell phones, the internet, power grids...etc. As for the clock on your microwave or oven or even in a high end watch, they might accumulate error in the neighborhood of 1 second per week, but for those things it doesn't really matter. | 1 |
8ziyh3 | Biology | How does the brain/body measure dehydration? And is it possible for it to make mistakes? | Being thirsty is our best indicator that we're starting to become dehydrated. When you start to feel lightheaded after feeling thirsty, you've become more dehydrated. You should drink water or eat something with a decent water content if no water is available during those stages, as that's when it's easily fixable, and isn't going to cause any lasting harm. If you feel lightheaded or have a headache for too long, start pinching the skin on the back of your hand. As long as the skin is taut enough to spring back, you should be fine while you continue your search for water. If the skin takes longer than usual to go back to its resting position you need to find water soon. If there is none available, you should start trying to contact emergency services. After that stage you start risking organ damage. We in first world countries will almost never find ourselves in situations where we are without water that long, but it's useful information to know what the relatively safe stages of dehydration are so that you can catch it and reverse it. | 2 |
cxu1va | Other | What’s Fermi’s paradox? | That given how long it takes to colonize the Galaxy, aliens shouldn't just be here they should be everywhere, but we don't see them anywhere. So is the Galaxy not colonizable or do aliens not exist? And why don't they exist when we do? | 6 |
8e49th | Biology | How do electron microscopes work? | I'll briefly say why we need one before attempting to answer your question. Why an electron microscope is needed? We see objects because light reflected from that object enters our eyes. There is a limit to how small an object can be to reflect light. If an object cannot reflect light, it can not be seen. This is why we need an electron microscope to see objects smaller than the theoretical limit of light. How an electron microscope works? Light is made of photons which are both a particle and a wave. An electron is also both a particle and a wave. Instead of using light rays to illuminate an object, an electron ray is used. For example, Imagine a flashlight that does not produce photons 'light' but rather electrons. We can't see the reflection of an electron wave from an object. However, a computer can detect the reflection and add effects on it depending on how much of the ray has been reflected to generate a grayscale image which is what we see using an electron microscope. | 1 |