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Why does bread get moldy but crackers and chips don't? | Bread has a higher moisture content than crackers or chips. Mold needs a moist environment to grow. If you leave bread out of its bag for long enough, it will dry out instead of getting moldy. | They're attempting to reach an equilibrium with the water content of their environment. Bread, despite being dry to the touch, actually has a fairly high percentage of water bound up in its structure. Chips and crackers, on the other hand, have most of their water driven off during the cooking process. When presented with a typically humid environment, water will (slowly) migrate out of the bread and into the air; conversely, water will be absorbed by the chips and crackers from the air. |
what's happening to egg whites when they whip from running to fluffy? | Think of whipping up a sink of soapy water. The foam forms because of bubbles of air being trapped by the enhanced surface tension. Egg Whites are just like that but their surface tension is even higher allowing even smaller bubbles to be locked in. If you were to view the results under magnification you would see that its really just a very fine foam. | The age of your eggs. Older eggs peel better. > If your aim is beautiful, pristine hard-boiled eggs for deviled eggs or a similar dish, the only sure-fire trick we know is to **use old eggs.** As eggs age, they gradually lose moisture through the pores in their shell and the air pocket at the tip expands. The pH of the whites also changes, going from a low pH to a relatively high pH, which makes them adhere less strongly to the shell. [Source](_URL_0_) |
When did nail cutting become common? | There's a whole section in the [Popular Questions](_URL_1_) section about personal hygiene. [Here's](_URL_2_) the bit about nail trimming. [This](_URL_0_) link from there says that nail clipping/trimming has been around before recorded history. I hope this helps. | Specific nail trimming implements do extend into ancient history, possibly prehistory. Beyond that, ancient peoples tended to have a lot of work with their hands, which would contribute to general wear on the nails themselves, and even relatively primitive tools (or even unmodified objects) would be capable of cutting or wearing down nails without too much difficulty. |
Were Norse runes ever written down on parchment or paper, or just carved into wood and stone? | Yes, many medieval (post-Christianisation) texts in Scandinavia were still written in runes rather than Latin alphabet. Unlike Latin, Runic texts and inscriptions seem to be primarily used for mundane, common communication, whereas Latin (including the script) is tied to the Church and official stuff. The Novgorod birch bark letters are a good example of the use of runes for common, everyday communication on perishable material during the Viking age. One would not waste expensive parchment or paper on that, but the same is true for Latin. It is entirely plausible that formal communication during the Viking Age would also have taken place in runes, on parchment. I do not know of any pre-Christian Runic books though, these are all Medieval. | No. Someone took the modern English alphabet and assigned a rune to each letter. Except English letters don't match up to a single sound (e.g. cinder vs. candor), and modern English uses different sounds than Old Norse. Whoever put this together did the best they could, and then made up the rest. The 'y' and 'ng' runes look especially far out. Scandinavians writing Old Norse during the Viking Age would have used an alphabet called the Younger Futhark. It was the alphabet used, for example, on many of the runestones from the later Viking Age. The Nationalmuseet in Copenhagen even has a [church bell](_URL_0_) with the Hail Mary written in runes in Latin! This [site](_URL_1_) seems to be a decent introduction to the Young Futhark, and there's even a [memrise](_URL_2_) course. If you have any questions, I'd recommend using /r/Norse as your first resource. They can be a lot of help over there. |
What are some quality history books for laypeople of all ages I should include in a family library? | The Horrible Histories series would be a good entry level into history for children. Although it has traditionally focussed on British history they also cover other countries and civilisations. The British children's television series of the same name is also available to buy on DVD. | Many books are engaging to a historian and at the same time "horribly dry" for a layman. So take my recommendations with a grain of salt. That being said, I have some suggestions for you. For Native American history, it is *1491* by Charles Mann (and maybe *Facing East from Indian Country: A Native History of Early America*) and for linguistic history *Mother Tongue: The Story of the English Language* by Bill Bryson (who is not a historian!). Just look them up on Amazon, read a few pages and decide if you like the style and subject. Generally, you will find books less "dry" the more you are interested in the subject. If you are more specific than "Asian histories", you will get better recommendations. Especially books with titles like "A short history of Asia/Europe/the World" tend to by dry and filled with facts. |
Why will an outside observer never see someone cross the event horizon of a black hole? | Because you see things by receiving the light they emit that then travels from them to you. Any light emitted by the object inside the event horizon cannot reach you because it cannot get out. All light you'll ever receive will have been emitted by the body outise the horizon. | From the perspective of a distant observer that never falls into the black hole, things falling toward the black hole *don't* ever enter it. Such an observer will see the falling object getting closer and closer to the event horizon for all time without ever actually crossing it. From the perspective of the infalling observer, they just do. They drop toward the black hole and eventually get destroyed by tidal forces. Whether that destruction happens before or after entering the event horizon depends on how massive the black hole happens to be. Note that the above is the general relativistic description of events. When we try to go to a quantum description of black holes, it becomes somewhat less clear what's going on as (1) the black hole can evaporate and (2) we don't have any really good models for the event horizon. |
Have we tried performing the double slit experiment using a wavelength sensor in one of the slits? | The spirit of your question is correct. It *is* possible to make certain measurements of quantum systems without collapsing the wavefunction. They're called [weak measurements](_URL_0_). The idea is that you get very little information from each measurement, but by taking millions of measurements you can build up some information about the quantum system. You can also measure two quantities in a QM experiment as long as they [commute](_URL_1_). Unfortunately, wavelength and position do not commute in this case. | unlikely. the wave pattern from the double slit works because you have a single frequency of light, and thus the wavelength of the interference pattern will be the same for all the light. With white light, you have all the frequencies coming through, each which have a different interference pattern. I would imagine there is some diffusion effect going on, but unlikely the biggest cause of your pattern |
General relativity is not correct on small scales. Has this error ever been observed in large-scale experiments? | No. If we could test gravity on the sorts of scales where GR breaks down, we'd have experimental clues pointing the way forward! As awesome as that would be, such a thing seems likely to be a long way away. *That said*, there are a couple of observational signs of new physics in cosmology - particularly [dark energy](_URL_0_) and [inflation](_URL_1_) - which *may* be relics of that breakdown of GR. Or they may not. There are plenty of theories in which the small-scale behavior of gravity *does* trickle down to give these phenomena, but also plenty in which it doesn't. So far, even the really excellent data we have probing these are still not yet good enough to distinguish between those possibilities, and may not be for a while. | Here's an experiment from "back in the day" that measured the gravitational constant: _URL_0_ It was done about 75 years after Newton's death and gave a value for *G* about 1% off from its modern accepted value. |
Do modern HVAC units contribute to global warming? | The hot air they pump out is negligible in the grand scheme of things. They do, however, use a ton of electricity. If this is sourced from fossil fuels, it'll certainly emit greenhouse gases. In addition, most modern refrigerants won't harm the ozone layer, but they are extremely potent greenhouse gases, thousands of times more potent than CO2, though I imagine this isn't a large effect compared to the CO2 emitted from the power generation. | There were scientists then proposing "global cooling" as a result of aerosol pollution blocking the sun (a problem that is now much reduced and which rich countries have now largely exported to poor countries). The "new ice age" was a popular media scare story at the time which may have helped boost the apparent credibility of this narrative. However, at the time theories about cooling were not published anywhere near as often as theories about warming and were based on over-estimating the cooling effect of aerosols and under-estimating the warming effect of CO2. [Who sparked the global cooling myth?](_URL_0_) is a useful short article from the New Scientist which links to a number of relevant academic sources including the literature survey which initially debunked the myth by counting the number of papers falling on either side of the debate. |
Why have Jews been persecuted all throughout the world for thousands of years? | One very practical reason is that usury, the lending of money for interest, was forbidden to Christians. Jews were therefore the only people who could loan money. Nobody loves their bank manager. | There's a Holocaust AMA on with a panel (including me) elsewhere on this subreddit. Your question might be good to put there. |
Are Branded And Generic Drugs identical? | By law (in the UK at least), the active ingredients have to be identical (and of identical quality), if they are described and advertised as the same product. As a consequence, the ibuprofen you find in branded goods is exactly the same as you would find in 'unbranded' goods. Furthermore, the doses are also usually identical, but if not, the dose of the particular packet *has* to be described on the packaging. However, some differences include; branded goods often also contain other adjuvant substances such as caffeine, and sometimes utilise the *lysine salt* of ibuprofen, which, is more water soluble and acts more quickly (Geisslinger G, et al. (1989). *"Therapeutically relevant differences in the pharmacokinetical and pharmaceutical behavior of ibuprofen lysinate as compared with ibuprofen acid."*. Int J Clin Pharmacol Ther Toxicol 27 (7): 324–8). If you ask me, I'd rather have the 28p pack of ibuprofen and have a cup of coffee! | tl;dr: The cost. Edit: Should have re-read your prompt. It really is just the cost. Long version: Generic drugs are equivalent to brand-name medications in every way, or at least that is how they are supposed to be and the FDA does have a hand in ensuring that this is the case. Generic drug manufacturers however can offer them at a cut rate for two reasons: 1: They just make the drugs they do not do research. 2: They do not market their drugs nearly to the extent that the big Pharma companies do. If you want to learn about how much Pharma companies spend on marketing, go check out Last Week Tonight from this past Sunday. It is a staggering amount of money. |
How did derivatives cause the worldwide recession | Derivatives is a very very general term for a financial instrument. You are also assuming derivatives are the sole factor for the worldwide recession, which is false. Nobody alive or dead can explain fully why the recession happened, derivatives is one of factors of many theories of why the recession happened. | A lot of things: * In the 1920's low food prices supported by WWI price floors caused a mass wave of farm foreclosures. * The crash of 1929 shook confidence for lenders (though the stock market recovered briefly before plunging again). * The Fed constrained liquidity rather than easing borrowing, so the economy experienced widespread deflation and a loss of demand. * A few bank failures led to runs on more and more banks, paralyzing the financial sector. |
What's happening when my body craves a certain food or a certain taste? | It's a case of desire being stronger than love. Certain foods trigger "reward" centres in our brains. In your case (the cupcake craving), it's simpler to explain because sugar has analgesic effects. Some foods enhance or amplify our craving for dopamine and the effects can last years, more so if they're repeatedly satisfied. The slightest trigger can set you off, so if you see/hear/smell/think of cues associated with the substance, you might have what's called a "hyperactive dopamine response", especially if you've come across those things in a state of emotional stress/excitement. The result is abnormally intense cravings and often waves of nostalgia, which is why things sometimes are never as tasty as we imagine them to be. | Your body automatically rejects new bitter flavors, as many poisons are bitter. But once you have tasted them several times and suffered zero ill effects, your nervous system (basically your brain) starts to adjust. |
Why is each coin flip 50% heads or tails, regardless of the X flips that came before? | Because you are still asking about the odds of a single coin flip, the odds are different if you are asking for the odds of 10 in a row or the odds of 9 heads then a tails. | Gambler's fallacy: "I flipped tails four times. THE NEXT flip MUST be heads because of this." Rule of averages: "If I flipped the coin a million times, I would have around 500.000 occurances of heads and tails each. So always betting on the same one (either heads or tails) will have the same outcome - me not getting (much) richer or poorer." Doesn't seem at odds to me. |
Why are organizations like the NRA allowed to spend money shifting a politicians viewpoint? | This sounds like bribery, but in theory it is not. The legal definition of bribery is "If I pay you X, will you do Y?". The NRA goes "Here's a check from the NRA to your campaign. I'm making a donation because we feel the same way about gun control". "X for Y" is never stated, although it's heavily implied. It's like the difference between a prostitute saying "We can have sex if you pay me $100" and "We should have a little party. I got us a hotel room, you should pay me back the $100 for the room". Sex isn't specified, but both sides understand the exchange. Personally, I think the definition should be changed. Or keep it, but force politicians to recuse themselves if involved in a vote that they took funding on. | Any special-interest group (e.g. National Rifle Association (NRA), National Organization for Women (NOW), United Auto Workers (UAW)) gains power from membership. The more members an organization has, the more money it has to promote its cause and the more voting power it can wield at the ballot. |
Could you detonate a grenade by shooting at it? If yes, would the type of gun and bullet matter? | Military grade grenades would not detonate in this fashion. As an example, here's a MKII US grenade (used in WW2) ; _URL_0_ Grenades activate when the primer lights the fuse, which then descends down the grenade and into the metal powder, which then ignites and causes the chemical reaction which makes the grenade explode. Because it uses metal powder, it has a very high ignition point (it has to get really hot) before it will explode. A bullet, no matter where it strikes on the grenade, would not cause the chemical reaction to take place; No boom. | Likely not. Grenades are not designed to explode due to shock, but rather by chemical ignition. Unless the rifle bullet had the means to ignite the explosive material inside, the chances of it setting off a grenade are slim to none. |
What is the proper way to begin a sentence: One space after the period or two? | They used to teach using two spaces, but one space is the correct way now. Two spaces were leftover from typewriter days. | One thing to keep in mind is that for a long time putting spaces between words wasn't a thing. Punctuation developed during a period of time that the transmission of technology was pretty active. People were moving all over the place in ships and their were trade routes connecting europe to asia and such. It was standardized in the later 1400s when printing became a thing. Everybody went "cool, that seems like a good idea", and started using it. [The wiki covers it in better detail](_URL_0_) |
Why is there so many male buddhist monks and i don't ever see female buddhist monks? | The nuns dress the same as the monks, and shave their heads. As East Asian men tend to have softer facial features than other ethnicities, it's not so easy to tell the difference. | I believe there are a few Catholic tomes that address this issue such as The Life of Theresa of Jesus but not as a subject in total. Most individuals in monasteries and convents were there for economic and safety issues during the era you are referencing (as well as the obvious political internments and faith issues). Bits and pieces will be found in memoirs of nuns and clerics and reading was encouraged as a form of biblical and faith training but not much else. To find real educational training one would have to turn to the elite families and even there females were discouraged from learning anything beyond their status as wives and mothers. There is little historical fact but much speculation on this topic. See; De educatione liberorum, 1440, Matteo Veggio for common views of the churches view of female education and Christine de Pizan, The Book of the Three Virtues, for an opposing view. (edit spelling error) |
the cause of death through being burnt alive. | Usually suffocation. Fires are hot and the air around is hot. When you breath in you scorch your lungs. If you can't breathe you're boned. | what happens is the family and doctors agree it is not worth determining what the actual cause of death was. actual cause is often heart failure, but frankly could be almost anything that isn't blatantly obvious from an external inspection. edit: stroke is another common cause. may actually be even more common that heart attack for "old age" deaths, as it can hit suddenly with less obvious symptoms. |
If a number can be represented by a series of fractions, can this number be said to be rational? | Nope. While the *finite* sum of rational numbers is rational, the *infinite* sum of rational numbers need not be rational. In fact, it turns out that *every* irrational number can be written as the limit of a sequence of rational numbers. For 2^(1/2) in particular, one has (according to Wikipedia, at least) 2^(1/2) = sum[(2k + 1)! / [(k!)^(2)2^(3k+1)]], where k runs from 0 to infinity. Every partial sum corresponding to this series is a rational number, and that sequence of rational numbers converges to 2^(1/2), but 2^(1/2) is [definitely not rational](_URL_0_). | If someone could conceivably have a fraction with any number as the denominator, does this mean there are infinite numbers between 1 and 2?: yes. If so, would this imply that infinity has an end?: no. |
Why it's possible to stop breathing voluntary but not your heart beat? | Here's the real answer: Your diaphragm and intercostal muscles (the muscles that allow you to breathe) are under voluntary control. Your heart is an involuntary muscle. Your heart can also become denervated (lose it's nerve connections) and still beat relatively fine. This is why people who are C2-3 quads don't die but need to go on ventilators. This is why heart transplants work. | With training, people can and do slow down their heart rate as well. As for why we've evolved the ability to temporarily control our breathing, that's just speculation, since it may have occurred before humans existed. Try r/askscience |
What makes dinosaurs different from other reptiles? | Dinosaurs are a specific clade of reptiles, meaning they all share a common ancestor. Primates, for example, are a clade of mammals; all primates share a common ancestor and mammals that predate or aren't descended from that ancestor are not primates. Dinosaurs were a very diverse group, but their main similarity betraying their relationship to each other is that they held their hind limbs erect beneath their bodies (like humans do) instead of splaying them out to the sides like crocodiles or lizards or turtles. Modern birds are descended from dinosaurs, so they are technically dinosaurs too. Depending on who you ask, that also means that birds are technically reptiles. | Similarity to other reptiles. Their skeletons show clear similarities to crocodilians and various groups of extinct reptiles, and to the untrained eye they do look like oversized lizards, especially the large quadrupeds that were many of the earliest finds. |
what is the “lump in your throat” feeling you get when you’re fighting back tears. | Fight or flight nervous response. To increase oxygen intake, the autonomic nervous system makes us breath faster, and expands the glottis, the opening in the throat that allows air to flow from the larynx to the lungs. The expansion of the glottis in and of itself does not create a lumpy feeling, until we try to swallow. Since swallowing involves closing the glottis, this works against the muscles that open the glottis in response to crying. We experience the resulting muscle tension as a lump in the throat. | Brain gets excited/aroused and activates the [sympathetic nervous system](_URL_0_). This is a plexus of nerves that comes off the the spinal cord at the level of the ribs that branch into your various organs. One action is the release of adrenaline from the adrenal medulla in a gland above your kidneys. This, combined with direct nerve stimulation speed up the pacemaker in your heart causing it to beat faster as well as stronger via action on the muscle. The feeling is known as "palpitations". The sympathetic nerves affect other things such as glandular secretions and is probably responsible for the sensation in your throat. They also trigger sweating and the well known "fight or flight" response. |
How do muscles become hard when they are flexed? | Muscles consist of two *major* proteins, myosin and actin, that result in contraction of muscle fibers when they receive a nerve signal. When muscles are relaxed, they are "limp" and extended to their maximum length. Contraction results in a shortening and thickening of the muscle tissue, and this results in a perceived hardening. | Similar to the process that muscles go through to get larger. They develop micro fractures and heal harder and tougher |
What are some good documentaries and books about China after the 1949 revolution? | There are many good books about the People's Republic of China and the Republic of China, but one assumes that you wish only the former. * [Mao's Great Famine](_URL_0_) * [Zhou Enlai: The Last Perfect Revolutionary](_URL_2_) * [Dilemmas of Reform in Jiang Zemin's China](_URL_1_) * [Prisoner of the State: The Secret Journal of Premier Zhao Ziyang](_URL_3_) | **Modern Chinese History** *The Search for Modern China* by Jonathan Spence. This is quite literally *the* book for understanding everything from the mid-late Qing (1600s) up to the 1980s. Spence does a great job of charting the change and continuity of a society like China which is incredibly organized around tradition but at the same time had some of the most radical leadership of the 20th century under Mao. Honestly, I think its like 500+ pages but it's one of those books I will own and reference for the rest of my life. |
Have any animals or creatures ever made it through the Panama Canal and damaged the other side's ecosystem? | Most of the Panama Canal is [fresh water](_URL_0_). This probably prevents most salt water species from freely moving from the Caribbean to the Pacific. However, the major damage is always the ships carrying ballast filled with invasive species. I couldn't find anything in the numerous environmental impact studies about the Panama Canal. There was a story about a poisonous sea snake that there was some worry that it would go from the Pacific to the Caribbean, but it hasn't so far. | The Panama Canal has locks, and a freshwater lake in the middle. This means marine life generally can't cross from one side to the other, though some species have managed it. The Suez Canal is a sea-level canal with no physical barriers and various species from the Red Sea have invaded the Mediterranean via the canal. It's taken some time because when the canal was first built it went through very salty lakes, but over time those lakes have been diluted towards normal ocean salinity. It's rarer for species to go the other way because the Red Sea is a harsher environment. In general, marine species from one part of the world can be taken somewhere else in the ballast water ships take on and discharge. This is behind the introduction of many problematic invasive species such as (freshwater) zebra mussels, no canals required. |
Why does the cross product of two linearly independent vectors create a vector orthogonal to both vectors? | /u/Charski's will tell you the answer to your question, but I'd like to add this question is a little backwards: this is why we care about the cross product at all. It's not a nifty property, it's the *raison d'être*. Basically, you want a way to get an orthogonal vector to any two linearly independent vectors, so you define the cross product by starting with ixj = k, j x k = i, etc. and extend it through linearity. The cross product is the unique way to take two vectors and get an orthogonal third such that it is linear in each component and uxv=-vxu. | It's purely a human convention. We could define a cross product to give a resultant vector pointing in the opposite direction if we wanted, like how in linear algebra there are different conventions of the order of writing an inner product (usually with regards to whether the left or right element is the complex conjugate). It wouldn't change how the universe works. |
Are several copies of the same memory stored in the brain? | Memories, contrary to popular belief, does not work like a video record. There are, in effect, no "copies" of memories at all. The brain is a cluster of neurons, roughly 100-150 billion neurons, or that is the estimate (to put that into context, that is a higher number than there are stars in our milky way). Memory, or everything else, for that matter, is when a cluster of neurons fire together. So a memory is only a pattern, so to speak. That pattern can, and will change, usually just a tiny bit, everytime it's fired. This is why creating false memories is so easy, and why our memories are an extremely fallible source of information. For more information about how fallible our memory is, I recommend the book "Suggestions of Abuse" by Dr. Michael D. Yapko, and here's an excerpt from and interview, which you might be interested in: _URL_0_ | We tend to think that memory, etc is stored in the brain as a pattern of synaptic strength - that is, how readily one neuron can cause another to fire. Neurons can either be firing or not, so in that way they can be treated as binary, but it's not their state of activation so much as the *patterns* of activation that carry information. |
Why do I get 'car sick' when reading a book in a moving car? | Whenever there's a disconnect between what your eyes see and what your sense of balance detects, your body is hardwired to interpret that as poisoning, hence the nausea. The trick to reading in any vehicle is to look out a window when you turn, speed up or slow down so your eyes and balance stay calibrated. When the car is moving at a constant speed, you can read without nausea. | Car sickness happens when what you're looking at doesn't match up with the motion being reported by your inner ear. For example, you're looking at a book, which your eyes tell you isn't moving, but your inner ear reports that you're moving forward, with some slight jostling left and right and maybe a few bumps in the road. These mismatched reports about your body's motion makes you feel uncomfortable - something's not right - either your eyes are wrong or your inner ear is wrong. This discomfort takes the form of nausea. When you sit in the front seat, you can easily see outside, whether by looking directly out, or through peripheral vision. This allows your eyes more opportunity to see something that matches with what your inner ear reports, so there are no mismatches, and you don't feel discomfort, therefore no nausea. |
What's the difference between renaissance, baroque and classical music | What you are describing are both styles and eras. These are the major ones as I understand them, from oldest to newest. I added a little description of what I experience personally: * Medieval - 1400's and earlier - haunting, beautiful, I'm in a mossy forest sharpening my battle axe * Renaissance - 1500's - I'm in a dimly lit cathedral with chanting monks * Baroque - 1600's - I'm at Versailles eating cake and sipping bubbly * Classical - 1700's - I'm going to the Vienna opera in my horse-drawn carriage * Romantic - 1800's- I'm canoeing through the wilderness with my native guide * Contemporary - 1900's - I'm going to the Met in my tux | I think the title and the body of your post don't match. The title is one question, and the body is a completely different one. About the question in the title: very different forms of music were considered good in the past. Music changed, a lot. It's not like people were listening to the same kind of music for centuries (quite the opposite). Some people would stand against some particular change, other people would be support the new music... > Like, up until fairly recently (a century ago), (Western) music was basically just one genre (different variations of just one genre). What genre would that be? There were different kinds of music, frequently meant for different situations. We can't lump all music from the past in one uniform corpus. |
how are dish sponges considered sanitary enough to use to clean something? | In the same way a loofah or bath scrubber is not efficient by itself for actually cleaning yourself, it's a tool used for applying a lather of soap and water, with a material conducive to physically removing food debris | This is outside of my panel expertise, but I spent a summer working for a major consumer products company in their soap areas. The primary reason that consumer soap lathers (makes bubbles) is because consumers are conditioned to believe that if the soap doesn't lather, then it isn't cleaning anything. There are many commercial soaps that do not lather, like dishwasher soap, which is why you're always told to never put your sink dish soap in the dishwasher. The bubbles do serve the helpful purpose of letting you know where you haven't properly rinsed yet, and what parts of the dish you have cleaned. And yes, for dish washing soap you're intended to use by hand, bubbles are indicative of a higher local concentration of soap which by their very nature will tend to be at the surface of the water. |
Why do some fighter jets need two "pilots" while other only need one while doing the same task? | The guy in the back is the weapons system officer. He frees up the pilot to focus on pilot things while he takes care of locking on to targets, dropping bombs, and firing missiles There are versions of the F/A-18 with one seat and two. The F/A-18E has a single seat so the pilot is running everything. The F/A-18F has two seats with a weapons system officer in the rear It depends on the needs of the mission | They don't dogfight like in the movies. It's done nautical miles apart from each other. Evasive maneuvers are countermeasures and machine guns are guided missiles. If it's truly one on one, the fight is over long before either plane is actually hit. |
Why do fires/candles smoke more once they are extinguished? | when a fire/candle is roaring, its quite hot. At those temperatures, the fuel undergoes what is called complete combustion. This means that the byproducts or "smoke" has been oxidized or burned completely. Its reacted completely with the oxygen in the air. These end products (like carbon dioxide and water) are generally colorless. When a fire/candle is extinguished, it is cooling down, but still warm enough to "burn" some of the fuel that is still there. However because the temperature is lower, there isn't enough energy to burn the fuel and release all the energy. In that case, alot of other products are produced like carbon monoxide. These are the "smoke" you see. | Because the stuff that burns and stuff that smells is the same thing. As candle burns most of it is destroyed by flame, but you prevented the last batch of it from burning when you've blown the flame out. |
- Why do some people's faces turn red after drinking certain alcohol beverages? | You may have a deficiency in the enzyme that breaks down alcohol. [Here's a link that might help explain it better than I would.](_URL_0_) | Alcohol dilates your blood vessels. This brings you blood (which is at inner body temperature) closer to your skin (which has a lower temperature), warming it. This also has the added effect of actually lowering your body temperature. |
Would it be possible to separate electoral districts by something other than geography? | This is already done at the district level via [gerrymandering](_URL_0_), i.e., drawing districts to take advantage of demographic differences between areas for the current party in power. The geographic requirements are arguably the only thing that limit the ability of incumbent governments to ensure their own re-election. | Congressional districts serve an important purpose. Look at the state of Washington, for example (my state). We are divided between a lot of liberals along the coast, and a lot of conservatives east of the mountains. If we allocated our entire congressional delegation based on the popular vote, they'd all be democrats, and all of the conservatives in the east would effectively have no representation. Bad idea, no? So, we divide the state into districts that theoretically group together communities that have some geographical and cultural basis for being represented by 1 congressperson. Now, the definition of these districts is prone to politicization (gerrymandering), which is another problem to deal with. But using purely the popular vote doesn't make sense either. A better plan might be electing delegates proportional to statewide vote. |
Can you 'cook' pasta in cold water? Otherwise why do you need hot water to cook pasta? | Dried pasta out of a box, or fresh-made pasta? Dried pasta is cooked already. So yes, you can just soak it in cold water and it'll be fine. Fresh pasta is dough. It's raw, and you need to cook it. Eating it would be like eating raw bread dough. | Many cooks do this to season the pasta. They don't do it, as others have suggested, to increase the boiling point of the water. |
if speed of light is not the limit, does this mean Einstein's special theory of relativity is wrong? | The speed of light is the limit as far as we are presently aware. The experiments which stated that there was a faster than light neutrino have yet to be independently verified. If such a particle existed then Einstein's theory of special relativity would need to be reworked. It would not be wrong, it would need to be tweaked in the same way Newton's theory had to be corrected to account for Einstein. A theory can never really be wrong, it might be considered useless in light of new evidence or it can be reworked to correct for new discoveries, but wrong is not a good word to use. | The speed of light is not a limit to be broken. It is a conversion factor between dimensions in space and the dimension in time. You can go very fast if you have very little mass, but you cannot exceed c because at c, transit time for you is already zero (all space no time). |
What made the early islamic conquests so successful? | I've written on [this](_URL_1_) before, largely arguing that there wasn't anything particular special about the Arabs, except perhaps their quality of leadership and their approach to dealing with their defeated enemies. Another useful answer is [this](_URL_0_), in which I explained that it had always been Arab clients of the Romans/Persians who defended their desert frontiers, and that the two imperial capitals' neglect of these chiefs' interests had led to the initial losses during the Arab conquests. You might also be interested in textandtrowel's [answer](_URL_2_) on why the Arab conquests were perhaps less 'Islamic' than you think, so the view that the Arabs had better morale due to their faith is highly debatable. | Since being a peasant was so low on the socio-economic tier, not a whole lot would change. This was a time before nationalism, so dynasties ruled over lands and people. I can for sure say they will be responsible for the [Jizya](_URL_2_) tax that non-Muslims had to pay in order to practice Christianity. It also came with other exemptions. This created a tax and political incentive to convert. Most Muslim conquests did not follow forced conversions at sword point. Peasant boys would be at risk of being enslaved and pressed into service and converted Islam to become a [Janissary](_URL_1_). These were a class of soldiers in the Ottoman Empire that became rather influential politically. Edit: This wasn't meant to be comprehensive of all of the changes in a Balkan Christian peasant's life, just two of the most well documented. As Smackaroo stated The [Devşirme](_URL_0_) was the system that recruited Balkan boys into the military and government. |
Can someone please dumb down the theory of Relativistic Mass?? | As u/Midnight___Marauder mentioned, we don't really talk about relativistic mass anymore. Back in the day, the idea was that because things going near the speed of light seem to behave differently (such as time on a speeding spaceship slowing down, which I can explain further if you want) we can represent some of those changes by treating the moving object as if its mass has changed. In reality that tweaking of the mass is redundant and confusing because that change doesn't really happen, compared to things like time dilation where a clock on a fast spaceship will literally move slower than your clock on earth. You can describe all the important things that happen to a fast object by what happens to its energy, time, and length, so you don't need to say anything about mass. | They are considering relativistic mass which sounds fancy, but isn't used often by the physicists I know because it leads to confusion and questions exactly like yours. :P The idea of relativistic mass is that it's the hypothetical rest (not moving) mass of an object that has the same energy as the lighter real object which is moving at high speeds. > m(relativistic) = E(of object)/c^2 For instance, the relativistic mass of a particle of light with a wavelength of 1 nanometer would be 2.2\*10^-30 grams. So a hypothetical object with a rest mass of 2.2\*10^-30 grams would have the same energy content of a 1 nm light particle. Therefore, a better way to imagine this is to consider the full energy equation: > E^2 = p^2 c^2 + m^2 c^4 As you add energy to a particle, like at the LHC, it's the momentum of the particle which increases indefinitely while the mass stays the same. |
Is there a way to create a super-gas-o-phobic surface similar to super-hydrophobic materials? | This isn't exactly a "gas-o-phobic" material, but in the aerodynamics world right now a hot area of research is so-called [plasma flow control](_URL_0_) which works basically in the way you describe. You can attach them to a wing and they produce an electrically charged plasma which can be used to induce momentum in the airflow. The usual objective of this in practice is to prevent flow separation which creates a large amount of drag, or it can be used at high angles to maintain attached flow and hence delay stall. Because these plasma flow control devices can be used to create (somewhat) arbitrary flow characteristics on an aerodynamic surface, I can imagine a massive number of ways in which they can be used when the technology matures. Congratulations, you seem to have independently invented plasma flow control ;) | If you mean hydrogen and oxygen, they come together to form H2O, which is a completely different molecule with completely different properties. You can actually compress the gases into liquids with enough pressure/low temperature. If you mean how does vapor turn to liquid, when you compress the gas/ lower the temperature enough, the individual molecules do not have enough kinetic energy to fly around freely like a gas would. Instead, they form this weird clump, which is essentially what a liquid is. This happens because the molecules have attractive interactions, which, for water, has a lot to do with attraction between opposite charges. When you don't have enough kinetic energy to break these bonds, you can't have a gas. |
Why do A List celebs not do reality shows like Strictly (UK) or Dancing with the Stars (US)? | Primarily because they're a massive time commitment, but also because they serve mostly to promote a forgotten/lesser-known star's image, which A-listers don't need. Plus, if an A-lister decided to go on one of those shows, they would be putting themselves on the same level as, say, Bristol Palin, which is not what Matt Damon's career needs. | Generally neither side exchanges money. Its a tit for tat situation, the celeb gets to promote something and the show gets a guest. For the major shows usually the publicist for the movie or the celeb will contact the show to book an appearance. For smaller shows or really in demand stars the show will contact the representatives of the celeb and try to book them. |
Why do newspaper and magazine articles often use [square] bracketed words in quotes. | The brackets signify words that weren't part of the original quote, but which the editor added in for clarity. Like let's say that they're interviewing a baseball player about a game, and the player says "This was a great game, he was on fire today," while pointing at his teammate. Well it might not be apparent to the reader who "he" is, so the quote might show in the newspaper as: "This was a great game, [Rodriguez] was on fire today." That way they aren't misquoting anybody, but they're making the quote clearer to the reader. | As far as I'm aware the square brackets or [ ] are used when the quotation is missing something which the author of the new text is writing. So if I were to write a post where I needed to quote you, I might do something like this: > On the second of May, pieandablowie wanted to know how to use square brackets, he claims that "*[he's] never quite sure what the rules are with this.*" The post was originally made on the Explain Like I'm Five subreddit. The original quote *doesn't* say "he's", it says "I'm", but in the context of what I was writing I'd modify it in a way that shows the reader that whatever is in the square brackets is my change, and not part of the original quote. |
Bring Your Kids To Work Day | Bring Your Kids To Work day started in 1992 as Take Our Daughters To Work Day by the Ms. Foundation for Women. Their arguments behind starting the day was that girls/women had been kept from/discouraged from joining the labour force and by showing them their parents working, it helped normalise that and helped combat harmful gender roles (a woman should be a housewife and that nonsense). While the program wasn't officially expanded to include boys as well until 2002, many companies from the start encouraged their employees to bring both their sons and daughters with them. Of course, if you are encouraging both boys and girls to come Take Our Daughters To Work day doesn't really fit the bill, so in these companies it was usually renamed to Bring Your Kids To Work day or something similar, which is also what the official name of the program was later changed when it officially opened up to boys in 2002 as well. | You work 9-5 in a lot of jobs, meaning that you see your kids in the morning and evening. |
Why do we sometimes say "what?" Even after explicitly hearing what someone says? | To give ourselves time to respond and allow our thoughts to catch up. The same reason we say stall words like um or uh | because they think that speaking gibberish is helpful to a child's development, when instead it's stupid. so those adults are just simply misinformed. |
How are we able to determine how old a star is and how long it will probably live? | Stars "live" for a characteristic *approximate* lifespan based on their mass, composition, and luminosity (how brightly they burn). We can pretty accurately estimate all three of these, by splitting the incoming light from a star and examining it. Different elements absorb light at different frequencies, so by studying the gaps in the spectrum of light we can tell what the star is (mostly) made of. Because stars all start off as balls of mostly-hydrogen, this also gives you some information as to how old it is. Luminosity is a matter of figuring out how far away the star is from us, and how bright it appears to be. Mass is a little more tricky, but can be inferred to some extent with a number of methods. Put it all together and you compare this star to the many others we've observed and classify it. Once you've done that, you have a pretty good idea based on its composition and luminosity just how long its lived, and how long it's likely to live. | This has been posted a few times already, but the basic answer is they know how old the host star is, by examining its spectral class (what type of star it is), and determining in what stage of life it is and what it's luminosity is compared to its mass. The Sun, for instance, steadily increases in luminosity during its main sequence, it has been doing this all its life and it's only getting brighter as it ages. But its mass isn't changing significantly, only slightly lowering. So, you can tell how long a Sun-type star has been existing by these two parameters. Other stars behave slightly differently, but have similar luminosity changes over their lifetime to be able to estimate their age. And of course, a planet would be about the same age as its host star. |
How muh gear would a WWII British Commando carry into the field? Also: beret or helmet? | Not sure about the packs, but the steel helmet protects against shrapnel, not direct hits from bullets. Since the commandos were involved in small raids and unconventional warfare, it's not unreasonable that they would have preferred to save on weight when shrapnel would have been unlikely. See this youtube video for a steel helmet penetration test: _URL_2_ | Short answer! Depends on the helmet. Long Answer: The US Army currently issues the Advanced Combat Helmet (ACH) to all of its soldiers. They're pretty cool with primarily kevlar construction. This kevlar protects against shrapnel and fragments, as well as providing penetration protection against small caliber pistol bullets. Glancing blows from rifles will also be deflected. The marine corps issues the "Lightweight Combat Helmet," which is basically the same thing, but a big bigger in size. The ACH/LCH WILL NOT stop full caliber rifle rounds from penetrating (They're not designed to). We're working to replace the ACH/LCH with the "Enhanced Combat Helmet" (ECH), which has been redesigned to stop 7.62x39 bullets fired by the AK-47 family. This comes at a rather steep weight penalty. Source, Soldier Also: _URL_0_ |
How come Mosquito Bites are itchy? shouldn't your body tell you "don't scratch here" | When a mosquito bites you, their saliva gets under your skin. The saliva is an irritant and your body sends histamines (the same stuff released during an allergic reaction) to the site to alert you of it. Histamines cause itchiness, redness, swelling, etc. | Vet student here, Bug bites itch because bugs "leave a little bit of themselves behind" after they bite you. Be it saliva or some other substance. In any case, they have deposited something in your body that is foreign to your body. Your immune system actually has cells waiting in areas like the skin, and these cells are constantly on the look out for anything they don't recognize as something from your own body. If they find something, let's say bug saliva, they will respond by producing a bunch of chemicals designed to destroy foreign particles. These chemicals actually do damage to your own cells in the vicinity of the foreign substance, and also cause swelling and redness known as inflammation. It is this damage to your own cells and induction of inflammation that you feel as itchy. In essence, your body is "inadvertently" making itself itchy, while it tries to remove/destroy a foreign particle (such as bug saliva). |
the United States' corporate taxes, and why ours are the highest in the world. | The American tax code is like swiss cheese. There are so many loop holes that in order to actually **make** money off of it, you need to raise the overall tax rate so high that it outweighs the loop holes. | The US tax system is not much more complex then in other nations. The main difference is that in most countries the taxes are calculated by the tax office with the help of banks and other businesses and then sent to citizens for review. However in the US it is the other way and citizens are required to gather all the information and figure out all of their taxes themselves before sending it to the tax office for review. |
What are those weird lines in your eyes, and they move when your eyes move? | They’re called “floaters”. Here’s a pretty good blurb from the Mayo Clinic. Eye floaters are spots in your vision. They may look to you like black or gray specks, strings, or cobwebs that drift about when you move your eyes and appear to dart away when you try to look at them directly. Most eye floaters are caused by age-related changes that occur as the jelly-like substance (vitreous) inside your eyes becomes more liquid. Microscopic fibers within the vitreous tend to clump and can cast tiny shadows on your retina. The shadows you see are called floaters. | They're tiny pieces of tissue that either broke off the inside of your eye, or were left over from embryonic development. They're floating around inside the clear goo in your eye. |
Why people find it distasteful/disrespectful to embellish the performance of a national anthem | The national anthem of a country is supposed to honor *the country*. Singing with gusto is fine, but when the song becomes more about *the singer* than the song, or the country, that's disrespectful. | I thought I was the only one! Anyone get it during large groups of people doing to the pledge of allegiance or star-spangled banner? Really just any large group collectively saying anything positive. |
how does eye tracker work? (The thing that shows what on a monitor you are looking at.) | It is a high speed camera that looks at your face. It finds the pupil (the black spot in the middle of the eye) in relation to the white around it. From this data it figures what direction it's pointing, like finding the Sun by looking at the crescent Moon. | They remove a really small piece from top of your eyes which is a "lens" that focuses incoming light. This makes the light go correctly where it's supposed to go. |
I was reading about antimatter, and was wondering, how can you tell that gamma rays came from anti-matter and matter reacting, versus some other source (GRBs, etc.)? | The energy spectrum. Electrons and positrons have a very specific amount of rest-energy, and when they combine they naturally produce gamma ray photons of corresponding energy levels (511 KeV). Note that even proton/anti-proton annihilations will result in the creation of electrons and positrons as well so they will end up having the same gamma ray photons produced. If you look at a source of gamma rays and you see a strong peak around the 511 KeV line that's pretty conclusively the result of matter/anti-matter annihilations. | Not directly; the spectra would look the same. However, you'd probably see some pretty brilliant flashes of miniature gamma-ray bursts as the antimatter came into contact with regular matter and annhilated. |
Are there any theories or evidence suggesting the average life-span of a dinosaur? (Any species?) | Two different Apatosaurus, [age estimated](_URL_0_) maturity of one at 21 years, died at 28; the other 19 and 31, respectively. Some speculate sauropods may have lived to over 100 (some suggest over 300 years), but nobody has proof of one over the age of 48, and damned if I can find the peer-reviewed reference for THAT age. | For one thing, they didn't live at the same time as the dinosaurs, but in the Carboniferous period about 100 million years prior to the appearance of dinosaurs. For another, they can indeed leave fossils. They had tough exoskeletons, and even soft body parts can be preserved under ideal conditions. |
How are kids in Africa eating for only 5 cents a day and how can I eat for only 5 cents a day? | Move to Africa. The cost of living is extremely cheap. If you want to save money here, buy a Costco bag of rice and beans and have that every day. Lots of nutritional value for pennies a day. | They are not commonly eaten and so they are not commonly raised for food. Their supplies are much smaller and that means the prices are higher. |
Why the Saudi government would have backed an attack on the US? | I think it's important to note that the government per se did not back 9/11, but that some people IN the government may have. That's a pretty significant distinction. Edit to add that the Pakistani government is far more guilty of this sort of thing than Saudi Arabia. | It lets 9/11 victims sue saudi arabia. It's popular among a lot of people because Saudi Arabia probably did have a ton to do with 9/11 in a way that hasn't really been dealt with well. It got vetoed because the whole concept of random people suing foreign governments is a real huge mess and is unenforceable and politically super sour and the US is the last country on earth that wants people to be able to sue it for things like war crimes, real or imagined. |
Why did artists start painting angels with wings? | > 2 Above him were seraphim, each with six wings: With two wings they covered their faces, with two they covered their feet, and with two they were flying. Isaiah 6:2 > The cherubim are to have their wings spread upward, overshadowing the cover with them. The cherubim are to face each other, looking toward the cover. Exodus 25:20 The concept that angels have wings of some sort is in the Bible. | and how can there be birds with wings and insects with wings? |
So how does cooked spaghetti get in your mouth? | Sucking lowers the air pressure in your mouth. The pressure imbalance pulls your cheeks in, you may have noticed. It also pulls spaghetti in. Both are the result of the pressure outside being greater. In other words, the air molecules outside your mouth hit your cheeks and the spaghetti with more force than the air particles in your mouth can counterbalance. Only the spaghetti at the pressure interface feels this force. The rest is just dragged up like pulling a rope. | Spaghetti, or any tomato sauce has a compound called Lycopene in it, which is a red pigment related to beta-carotene. It is insoluble in water and tends to get stuck in porous things. Since plastic is porous at the microscopic level, Lycopene gets stuck inside and makes it difficult to remove. |
Why aren’t all food jars manufactured to be as easy to open as a plastic salsa jar? | The hard-to-open ones are typically glass jars that use both a vacuum seal and a heat-set plastic or wax layer under the cap. These form a very secure seal for items meant to last on the shelf for up to years without any risk of contamination/disease. By contrast, plastic salsa jars are typically meant for short-term use inside a refrigerator. | Because the jar is heated during the canning process to sufficient temperatures to kill all bacteria and pathogens likely to grow in your salsa. During this process the lid of the jar is also hermetically sealed so that no new air (and thus no bacteria) can get in. So you have a bacteria-free salsa in a sealed environment, which is safe to eat. As soon as you open it, you let in air and bacteria which can then begin growing. This is also why foods such as salsa have that lid that "pops" the first time you open it. This demonstrates to you that the seal was still airtight at the time you opened the jar, and thus the food inside is still safe to eat. |
Why do some earthquakes occur regularly? | The plates on the earth surface are moving at certain average speeds as they move tension builds up between two plates at subduction zones when the tension becomes too great earthquakes occur and the plates "jump". Generally the longer the tension goes on without being relived the larger the earthquake will be. Given friction, rock types and other factors there is normally a limit to the amount of stress certain places will endure before they "give". So the average time between large quakes can be estimated but when precisely one will occur cannot. | Earthquakes aren't really caused by the collision of plates as many tend to be in contact anyway it's more of a slipping kind of movement as the plates push against each other or alongside each other and one gives way. If you press your palms together tightly facing forward and pull one towards you and the other away from you they'll eventually slip very suddenly this is a bit like what happens along the san andreas fault. Not all earthquakes occur at plate boundarys but those that are can be predicted to a reasonably high degree of accuracy because they tend to travel along the fault lines. we can't predict when an earthquake will occur at that specific point only where the next earthquake along that specific faultline is likely to occur. |
What happens to electricity in a cable when it is cut? | A good way of thinking about electricity is 'movement'. If you envision a cable as a tunnel which cars are passing through, and you collapse the tunnel, the cars stop. The movement - the electricity - vanishes. There are still cars in the tunnel - meaning, still electrons in the wire. But they're not passing electrical current, the cars aren't moving. So, the current flowing through the cable isn't some physical entity, it's the actual fact that the cars are _moving_ in the tunnel. Once the movement stops, the current disappears. Doesn't matter how many cars there are, how heavy they are or how fast they went. If they're not moving, there is no current. | The resistance of the cable affects how fast electricity flows through it. Longer cables, and cables with thinner wires have higher resistance. [Here's an article that goes really in depth on the subject.](_URL_1_) In a lot of ways, [electricity moves like water](_URL_0_). In this case, it's like hooking up a hose. If you use a longer or thinner hose than usual, you get less water out the other end. Less water can fit through a thin hose at a time; and it takes more energy to move water through a long hose because the same pressure has to move more water. |
A member of the flight crew that bombed Hiroshima stated: "I never heard the words 'atomic bomb'... We were only told what we needed to know, and to keep your mouth shut." What about the flight crews who bombed Nagaski days later? Did they know what they carried, given Hiroshima's bombing? | On Hiroshima, [see this recent question](_URL_0_). The second crew definitely new they were carrying an atomic bomb; they had been training as part of the same unit as the Hiroshima crew, and the payload of the _Enola Gay_ was no secret after it was used. | No, and the term used is usually not "evacuation" which implies being done for their protection. I don't know of any convicted spies, but there were those arrested for violating curfews specific to the Japanese-American population. > so I was also curious as to how the Japanese knew to attack Pearl Harbor in the first place. Are you kidding me? Pearl Harbor was a major fleet anchorage going back to the 19th century. It's like asking how the terrorists on 9-11 knew to attack the Pentagon. |
Question about magnetism, and energy. | Magnets don't create energy, they just redirect it. Imagine you're trying to create potential energy by pushing one magnet up a hill with a second magnet. The only way you could do it is by continually applying an external force to the second one as it repelled the first. In the end, the potential energy you gained would equal the work done on the second magnet. The magnet isn't creating energy any more than a table is creating energy by holding your computer up. | Listen to what Feynman has to say about [magnets and why questions](_URL_0_). |
Why do lines of poetry abruptly end, even when there is no punctuation and no pause intended? | Any time a line in poetry abruptly ends *something* is intended. What that is depends on the poet. Off the top of my head an abrupt ending *could* mean the narrator trailed off, they were interrupted by someone off the page, or the line was cut short for emphasis. It's up to you as the reader to interpret the meaning for the cutoff, if there is no explanation elsewhere from the poet. In the case of very famous poems, literary critics often have theories as to what a poet meant when the meaning is ambiguous. | It gives a sense of closure when you know there is a rhyme scheme being followed. The pattern allows you to know where to stop and how to read the poem with definitive clarity. It's the same reason why poems with complete rhyme that end with a slant rhyme bug people so much. |
are things actually louder after your ears pop while gaining elevation? | No, things aren't actually louder. It's just that before your ears pop they aren't working as well as they should be and things seem quieter than they should. After your ears pop they are back to normal which seems louder than before. | There is a space inside your ear filled with air. When you change altitude the pressure of the air changes around you. Your ear popping is when the pressure inside your ear equalizes with the pressure outside. |
If a radio station (or other similar media organization) were to broadcast information on wavelengths in the visible light spectrum would we be able to see it? | In a way, you have answered your own question when you link to the EMS article. Radio and light are simply two different sections of one continuous energy spectrum. If a media broadcaster were to send out signals in the visible spectrum, it would no longer be "radio" but visible light, and it would appear to you as flashes or a varying pattern of light. If your question is instead whether we could "see" the information being broadcast, like TV pictures in the sky or something - think of the signal as a coded message: in order to understand what information is contained in the message, we would need to transform it from signal (a time-varying pattern of electromagnetic waves) back into source (something our human brains can understand, like a picture or a song). This is the case for all EM signals we send around, whether the spectrum you use is radio, visible, or some other section of the EMS, like microwave or infrared (as you said, assuming the technology for such spectrum use exists). | Yep. It's may be difficult to realize, but radio waves have identical properties to visible light. This is because they are both forms of electromagnetic radiation. Radio waves travel at the speed of light and do not deteriorate in space. In the same way that you can see the light from the sun 300,000,000 miles away, radio waves can travel that far too. Sending radio waves back in certain patterns allows us to discern massive amounts of information from the original message. |
Why is the D-Pad on the left? | Also, on the NES controller, why is B to the left of A? | To protect what you are holding from further damage or pain. |
What is that random pain on the side of your stomach when you're running or doing any exercise? | This is known as a [side stitch](_URL_1_), and we don't definitively know what's happening. All I know is that people with good fitness rarely experience it. | It's called [Delayed Onset Muscle Soreness](_URL_0_). We don't really know what it's all about, but the current theory is that it's caused by microtrauma to the muscle. |
What's up with Americans and Black Friday's violence? | To turn it around and help you gain a European perspective, think about the soccer games you've watched, either live or on television. I'm willing to bet that 99.99999%-100% were relatively uneventful in terms of violence. But, if you listen ONLY to the soccer games you hear about over and over again on TV, you'd think every soccer fight lasted for 3 days and ends with the local town burning down. It's the same way with black Friday. You don't hear about the millions of uneventful sales, just the extraordinary ones. It's part of the nature of news, they only report the unusual and sensational. | Christmas shopping traditionally begins the day after Thankgiving, when all the sales begin. Many stores, even larger ones, make a significant portion of their yearly profits on the days on and after Black Friday. The term "Black Friday" came about in 1961 from Philadelphia police officers, who knew they would face much more work due to traffic jams, packed sidewalks, and mobbed stores. The media picked up on their usage, and the city attempted a campaign to change their usage to "Big Friday" (Obviously, not very successfully). The city's fight against the term only wound up spreading the use farther and wider than it had gone before, and "Black Friday" stuck. |
When and why did fluorescent green get associated with radiation? | For many years we used [radium to make glow in the dark stuff](_URL_0_), it had that ominous green glow in the dark. That has been discontinued because of all the cancer, but the association remains. | They are fluorescent, which means that they emit light using energy absorbed from other light. "Regular" colors only reflect light. |
What causes the clouds to look purple during a thunderstorm? | The sky is usually blue. Similar to a sunset, the storm clouds cause a small amount of red light to scatter. Blue + red = purple. | "Researchers remain undecided about the exact mechanisms that cause the sky to appear green in certain thunderstorms, but most point to the liquid water content in the air. The moisture particles are so small that they can bend the light and alter its appearance to the observer. These water droplets absorb red light, making the scattered light appear blue. If this blue scattered light is set against an environment heavy in red light—during sunset for instance—and a dark gray thunderstorm cloud, the net effect can make the sky appear faintly green. In fact, green thunderstorms are most commonly reported in the late afternoon and evening" |
Why is it that humans are so notoriously terrified by Spiders more than anything else? | They are potentially dangerous if they are a poisonous variety, which gives a rational reason to be careful around them. We are raised in a culture that says, "hey, spiders are scary," which tends to make people perceive them as scary. They also have a very unusual look and they behave weirdly, compared to humans. It's a natural reaction to be anxious about a creature that moves/looks in a way you're not used to (see: fear of the unknown). | Because how many spiders would THAT take? And who wants to be around *that many spiders*? Unlike spiders, [genetically engineered goats won't eat each other. Also, they're so much cuter!](_URL_0_) :) |
Why is scorched Earth policy outlawed by the Geneva Convention? Seems to me that it's a successful strategy for a country being invaded by an aggressor. | It's the destruction of civilian property, especially food production (that's what is banned......... burning factories that produce bullets is totally allowed even though it's part of scorched Earth), and it's not only done in defence of a country but when an invader is being pushed out and they burn everything in sight . So, scorched Earth itself isn't banned, just the bits that result in the civilian population starving to death. | Geneva convention is largely a gentlemen agreement. No one wants their soldiers getting gassed or having to patch up wounds from hollow points. Its easier to just say no one gets chemical weapons and fight with conventional weapons, then it is to say "there are no rules" and everyone have them. Its already illegal for citizens to use tear gas on cops, so there is no objective reason to outlaw it for law enforcement. The question of its something is humane or not doesnt really tend to stand in the way of most governments. |
Why does it seem like every gas station has flats of water stacked up out front of the store? Is there a special reason for this? | Water is a big seller as we approach the hotter months of the year. Most gas stations don't have a lot of storage space (basically none). So for a very high volume product like bottled water they just stack it up. | [Why do you often see 2 or 3 gas stations right next to each other?]( _URL_0_) [This video explains it ](_URL_1_) |
Do animals avoid incest when mating in the wild? | Yes! Many animals exhibit inbreeding avoidance, consciously or subconsciously. Visual recognition as well as scent / pheramones often play a role in determining kinship. Some animals have a very low risk of inbreeding because they disperse far from where they are born or they are a member of a very large population; these animals tend to have less developed kin recognition! | This is not so much a question to historians, as one to behavioral biologists, since incest is also a "taboo" in many animal species, or rather the instinctive logic of "don't breed with it if it smells like me". So it also remained a "taboo" in primitive people before the appearance of the concept of royal blood and other cultural phenomenons, such as the holy Zoroastrian marriage. |
I read that General Relativity and Quantum mechanics cannot both be correct? Which one seems more likely to be disproved at this point? | They are both correct to within the accuracy that we can test them. There may be situations that we cannot currently test, such as radiation from a black hole or the universe in its early stages, where our current theories do not suffice, and we will need a more complex theory that encompasses both of them. | Quantum mechanics and relativity are scientific theories that describe how the universe behaves using mathematics. You take your variables, input numbers, crunch the equations, and you get answers. Quantum mechanics deals with things that are very small and very light. Relativity deals with things that are very heavy and very large. In most cases, you use one or the other. In some cases, where you are dealing with stuff that is both very heavy *and* very small (as with black holes and the Big Bang), you need to use both. The problem is, with the equations the way they are, using both produces nonsensical answers. Our theories break down when trying to describe these things. We are currently trying to resolve this, to modify existing theories or develop new ones that will work to describe these aspects of the universe without breaking down. Quantum gravity and string theory are efforts to try and do this. |
During the 1800s, how did the mostly Protestant Americans reconcile their racism against blacks with fact that most Biblical figures would have been olive-skinned or even black? | Not a direct answer but there was a [Jewish](_URL_1_) population in the antebellum and confederate south. The Confederate secretary of state was a Jewish - American Judah P. Benjamin. There wasn't the same level of anti-semitism as there was racism. The [bible itself](_URL_0_) was also construed as justifying and explaining slavery in the south as well. | The standard works are by Frank Snowden, Jr. (don't confuse him with his son, also named Frank Snowden, who teaches at Yale). The ancient world didn't care much about skin color. They did notice these things--it's easy to see in Egyptian art, for example, the difference between native Egyptians and black Nubians from further south. But the fundamental distinction for Greeks and Romans was not white / black, but civilized / barbarian. It was perfectly possible for Africans to be civilized, and for people we see as white (like Germans and Celts) to be regarded as barbarians. |
When did Republicans and Democrats switch places? | The '[Changing role of Republicans and Democrats](_URL_2_)' section of the Popular Questions pages might interest you. | Not to dissuade further discussion, but this section from the FAQ's may give you some answers/starting points: [Changing Role of Republicans and Democrats](_URL_0_) |
why If r divides p and q then r would have to divide the difference of the two numbers | Write p = r p' and q = r q'. Then p - q = r (p' - q'). | When you're dividing, you're seeing how many times one number fits into another. Since fractions are smaller, they will fit into a number more times than a whole number will. |
Why would a business person buy a money-losing sports team like the Phoenix Coyotes? | For many people simply owning a professional sports team is worth $20 million a year. But really that's the downside but there is plenty of upside. If the Coyotes lose a combined $50 million in the next 5 years they can move the team to a more profitable city (hopefully Seattle) where they can recoup their losses. Or they can turn the team around. They've done better in recent years and even won their division last year. So there's plenty of potential for the team to start winning. And winning teams tend to make money. On the other hand if you buy a team that is already making money you'll pay a premium for the team and they would cost a lot more than $170 million. | The teams they play for make many times more than that from ticket sales, advertising, merchandising and so on. Those teams make more money when they have better athletes, enough so that it's a perfectly sensible business practice to pay that much to get the very best ones they can. |
In the various societies that practiced concubinage, what typically happened to concubines who became pregnant? | As an additional question for when this gets answered, what about children birthed to concubines of royalty? Would they be royalty as well? | What essentially you're asking for is a history of monogamy, and I'd imagine the answer would be contextually dependent on the cultures you're specifically asking about. |
If I am a Jewish Merhchant in the mid 1700's, what cities do I visit often, and what cities do I avoid? | Could you specify a particular region? I'm assuming Europe, but it probably makes sense to consider Eastern, Central/Western, and Southern Europe separately. You may be interested in [this article](_URL_0_). The answer is essentially everywhere. Having a large network of potential buyers and sellers is essentially what makes being a merchant work, so there were Jewish merchants everywhere. That said, a Jewish merchant wouldn't need to visit every town to get that effect--merchants held fairs, in which a large number of merchants would conduct commerce in a central location for trading. So a Jewish merchant in the Rhine Valley probably wouldn't be frequenting towns in southern France, but another Jewish merchant might. | No so very many Jews went to Singapore in the interwar years. The Jewish population of Singapore never exceeded 1,500 persons. Are you thinking of Shanghai? |
Why can some computers run PC games without meeting the minimum requirements, while other games perform like garbage on the same computer even though their requirements are overall lower? | The requirements for a game are basically a marketing tool. There's no clear performance criteria a system must meet for a game to have minimal requirements listed. It's completely up to the publisher's discretion. Put the requirements too high, and people won't buy. Put them too low, and people will be disappointed. And if your game is hot enough, people might upgrade to hit the min requirements in some cases. | One of the main reason is that games often exploited bugs in the target machine/OS. You have to consider how little resources were at the developer's disposition. If you discovered that the OS behaved in an undocumented way that you could exploit in order to run your game faster and/or make a cool effect happen, you can bet it was going to be exploited for your game. This has the interesting effect that newer computers must not only replicate how the older machines were supposed to work, but also replicate all the bugs that the machine had. This is a lot harder than looking at the old spec and implementing it. |
Why do people say that cows are "killing the environment"? | Two reasons: global warming, and resource consumption. Cows produce lots and lots and lots of methane. They are gigantic highly productive engines of fart. Methane is an intense greenhouse gas, much more effective at retaining atmospheric heat than carbon dioxide. So they're heating up the planet. They also drink LOTS of water as they munch away at grasslands that would be much more productive if used instead for farming vegetable crops. A steak has a lot of calories, but if the energy that went into that steak went instead into efficently grown crops you'd have many times the calories to eat. So cows though tasteful, are considered very wasteful. | A cattle farm produces as much waste as a small city. Meat production is highly inefficient; they have to grow grain to feed to the cattle, and the animals produce waste and gaseous emissions. It takes 3 times as much crops to feed the animals we eat than if we just ate the plants we grow. Animal farms use a third of the world's fresh water and 30% of all the land on Earth, which generally means people have cleared out forests which leads to higher levels of carbon dioxide, which leads to global warming etc. |
Do we know what water molecules actually look like physically? | A water molecule consists of 2 hydrogen and one oxygen atom, with the nuclei arranged so the H-O distances are 96 pm and the angle is 104.5 degrees. [Here's an electron density map](_URL_0_) in the plane of the molecule. (there's a sharp peak on oxygen that's been chopped off so it fits the picture). You can find many other plots of that data. That is as much as you can say about what the molecules "actually look like". They do not have a surface. These are scales shorter than the wavelengths of visible light. You can't look at them in any sense that's analogous to how you look at everyday objects. All fluids can cause erosion. The shape of the molecule has no direct relevance to it. Water molecules are not 'abrasive'. Erosion is a phenomenon that occurs on a much larger scale than the molecular one. | We would predict the melting and boiling points to be unusually high for so light a molecule as water. We would know water is capable of what's called hydrogen bonding, which means the molecules stick very strongly to one another, keeping together at high temperatures. We would still know the shape of the molecule as bent at about a 104.5-degree angle, and from that I believe we'd get an idea that hexagonal crystals aren't inconsistent. Not sure about predicting density, slipperyness, or other properties, but we'd certainly know some things. |
How accurate is the statement that we are all made of "stardust"? | Not every element. The hydrogen on Earth could be primordial (produced in the first few minutes of the universe). The helium on Earth is mostly from radioactive decay (any helium that was here to begin with has long since escaped Earth's atmosphere). But any element heavier than lithium - aka most of them - was produced in stars. | Earth has existed for only about a third of the age of the universe. The two thirds before that was full of stars living, dying, exploding, and seeding the births of new solar systems, including ours. The matter that coalesced into our Sun and its planets (and other nearby star systems) was seeded by a supernova from an earlier star generation, and thus has a higher proportion of heavier elements. |
Why do climbers get below the treeline when thunderstorms come? | Don't hang me up on this, but as lightning tend to strike down on the tallest object in the area, I assume they crawl down so the trees are the tallest object, and not the climber. It is probably just a safety precaution. | Trees are a significantly better conductor of electricity than air, what the higher amounts of water and minerals in them, increased by the fact that it is usually accompanied by rain, combined with the fact that trees are higher than most other objects around. However, when a lightning bolt hits a tree, the bolt travels down between the dead inner parts of the tree and the bark. Your body has significant amounts of salt in it, which make an even better conductor than just water and trace minerals! Electricity, as you probably know, follows the path of least resistance. So, the reason a tree is a terrible place to stand in a thunder storm, is because the tree attracts the initial strike, then you attract the last couple of feet. You don't want to attract any feet of lightning. |
Why does the US keep arming rebels when years later history shows those same rebels kill us with those weapons? | > history shows those same rebels kill us with those weapons? History also shows sometimes they don't. It's always a tricky process of arming rebel groups. Sometimes its right, sometimes its wrong. It's also hard to predict the outcomes if they are or are not armed. The future isn't known, we can try to influence it to our advantage, and certainly the US does try to--just as every country does. | Well, people will probably stop arming the rebels. There might even be NATO sirstrikes on rebel extremists to keep them from gaining acess to the weapons. A big part of the decisions that will be made is how the rebels organize to keep these weapons secure, who they give acess to, and what they use the weapons for and who on. Obviously, the rebels managed to keep the possession of the weapons a secret until they used them, that shows some semblence of a organized effort to control them. Or they might have just hijacked some government forces weapons and then immediately used the weapons. |
I read that Pearl Harbor was not meant to be a surprise attack and that the Japanese embassy failed to deliver the message to Washington in time. Does this have any validity? | The intention was for the Japanese embassy in Washington to convey the breaking off of diplomatic relations less than an hour before the attack was to take place. Japanese military planing of the operations critically depended on the American military facilities to be unprepared and not be able to defend themselves. It was for all intents and purposes, a surprise attack. | While there’s always more to say on the subject, you might be interested in these previous answers by u/DBHT14: * [Is the theory that Roosevelt purposely allowed Pearl Harbor to bring the USA into WW2 any credible?](_URL_0_) * [Did America know that Japan was going to attack somewhere in the pacific and purposefully do nothing about it to get into the war?](_URL_1_) |
How do insect and bug sprays kill insects but don't harm us | > How do insect and bug sprays kill insects but don't harm us Most insecticides target specific aspects of the insect nervous system which are different from those of humans and mammals in general. These neurotoxins have various different types so getting into the details can be quite complex, but the general idea is that insects are sufficiently different for specialized substances to be toxic to them and not really for humans. | If you mean the kind that kills bugs instead of the one that keeps them away, I got this one. Generally, in the hands of most users, it drowns the cock-roach or whatever. The average user sprays and keeps spraying until the bug is no longer moving or showing signs of life, and then sprays some more. Very wasteful, and you don't need to do it. Just zap the pest with a quick spritz and it will die soon enough. The way it works is most bug sprays are mild nerve agents. The nerve agent messes up the way the neurons fire and makes the muscles (or whatever bugs have resembling muscles) tense up and twitch uncontrollably. The insect won't be able to breath, the circulation will go crazy, and the insect will quickly expire. |
Why does the US look for oil in the Middle East if it has enough at home and in Canada? | The oil isn't for us; it's for everyone else. The US makes money when the rest of the world is productive. And the rest of the world is generally productive when oil is cheap and plentiful. | Because there is a long history of the US starting fights and overthrowing legitimate governments for the sake of stealing the people's oil down there. The first leader they got rid of was a democratically elected intellectual trying to give the people their oil. The US came and later the oil went away also. |
Why is redbull considered worse than coffee? | Coffee has no sugar in it, Redbull has 27g. Coffee also have no calories in it (unless you add sugar and milk), while Redbull has 110 per small can. Which looks like this. _URL_0_ | A red bull is the same as a cold cup of coffee (with sugar in it). Your body processes the caffeine slower. Otherwise there are no benefits in the drink. There is a very well detailed breakdown of what it does (trying to find the link). _URL_0_ And this. _URL_1_ |
When we dream are the emotions we feel genuine reactions to the fake stimuli, or are they part of the dream? | I would like to see this answer. Also, do you mean: do the emotions felt due in f the dream, replicate neural pathway activation from emotions during waking life? Furthermore, can someone get PTSD from an extremely traumatic dream? Or does the lack of memory retention disable long term effect of those emotions felt? Can you get PTSD from a dream that you don't even remember? Could effects from negative emotions from dreams influence childhood bred mental illness? | Don't listen to some of the ignorant comments here. The only truth we know about dreams is that we don't really know what their exact purpose is. There are many interesting theories about it, but the true purpose of dreaming is not yet understood. That being said, you can definitely choose to find meaning behind your dreams through your own interpretations of them. But that's all it would be at this point- interpretations. |
When writing an essay you need citations but, can i write using what i know or would that be considered plagerism since im not listing the sources of my knowledge? | The purpose of citing sources is to show that it isn't just what you made up in your head. Good sources show actual evidence of what you're trying to state as a fact. | The services advertise themselves as plagiarism free in that *their* work has not been plagiarized from other sources. They are not stealing other people's essays to do their work. As a result, software programs designed to detect plagiarism will not catch them. However, if you submit such an essay to your school, *you* are plagiarizing, as you are claiming somebody else's work as your own. |
Can you contract cancer? | Generally cancer cannot be contracted, but there are exceptions. These are called clonally transmissible cancers. There is a transmissible cancer that is currently in the process of killing off all Tasmanian devils called Devil facial tumour disease. Dogs can be affected by a sexually transmissible cancer called Canine transmissible venereal tumor. Note: This refers specifically to directly transmissible cancers. Another comment points out the existence of cancers caused by viruses which are transmissible while the cancers are not. Edit: Here's a recent article on the topic: _URL_0_ | The technical name for this is [clonally transmissible cancer](_URL_0_). Short answer: possible, but extremely unlikely, especially in humans. |
Has suicide been observed in animals? | During the ["Pit of Despair"](_URL_0_) experiment in 1970s a couple of rhesus macaque monkeys at the University of Wisconsin–Madison starved themselves to death. The experiment was an attempt to see if animals could suffer an animal model of clinical depression. | I suppose you could say that some do, though the actual death is probably accidental- I don't know that many animals have a true concept that "doing action A will cause me to die" or even really what death is. As an example, parrots in captivity who are under stimulated, improperly raised, neglected, sick, etc will often "overgroom" where they will pick out their own feathers. This can progress to "self mutilation" where they will tear into their skin. I have seen one case (and I'm sure this happens relatively often) where a self mutilator hit an artery and bled out. |
How come before I type, my fingers can "sense" if my hands are placed "off" by one key? Each key is the same exact shape as the other, isn't it? | It's not your fingers, it's your brain. Your muscle memory is used to being in one position, so when it's off you notice. Plus, the keyboard has a dot or raised mark on the F and J keys, so if your index fingers don't feel that mark, you're most likely off key. It's he exact same way that a pianist knows what they're playing without having to look. A typing keyboard and a piano are, in concept, the same process: pressing keys to create a specific combination. | My theory is that you all are used to typing with the left hand while jacking off with the right. |
Why are people protesting this week, and why weren't there protests after Obama was elected? | The short answer is *selective memory*. There were massive protests following President Obama's election. Many protesters believed Obama was Kenyan and illegally running for office due to the many year racist campaign fronted by... Our next president Donald Trump. Obama's election really kicked off regular protests by the Tea Party Movement. _URL_0_ | _URL_0_ is kind of what i was looking for but I want to know why people are protesting today. |
Why does water make smelly things more smelly? | Adding water to, e.g., dog hair causes any water-soluble material to dissolve. Some of this material is smelly in large enough quantities, but usually is spread out across the dog's hair and skin. At most human-friendly temperatures, the smelly compounds will enter the air via evaporation and from being volatile chemicals. When aerosolized, the smelly compounds are much more concentrated than on dog hair, making them smell much worse. | You are surrounded, all the time, by millions upon millions of tiny microorganisms. You are also coated in them, even after you shower. Getting your towel wet makes it a hospitable environment for this host of creatures. Many of them, when they become numerous enough, smell pretty funky. |
why do pimples form under the skin? | Pimples are a result of an infected hair follicle, which grow from deep in your skin _URL_0_. Dead skin cells and sebum will clog a hair follicle sometimes. When they do, the hair follicle keeps pumping out sebum, but there's nowhere for it to go. That's what creates the initial problem. If there's no other problems itll result in a blackhead. But the environment inside the hole amade by the follicle creates a great environment for bacteria to breed. Thats when your immune system attacks it, resulting in a build up of pus along with the sebum, and the emergence of a pimple. | Pimples are simply infected clogged pores in the skin. Other mammals get them, but humans have rather strange skin for mammals and so we get strange pimples. Asking 'why' we evolved a thing is always conjecture, but in this case it seems to be like asking 'why' we evolved to have absessed teeth, or ingrown toe-nails. In all likelihood it is something we suffer in order to enjoy other benefits, like a skin which is self-oiling and has hairs. |
Are no two fingerprints alike because of the sheer number of possibilities or does something in our DNA create unique fingerprints? | Finger prints are random. They form before birth based on the middle layer of skin. If they were represented by a number (folds/directions, etc), the number would be so big that, if each human were randomly assigned a number, no two humans would have the same one. Is it *possible*? Sure. Will it happen? No. | Fingerprints aren't exactly as unique as claimed, and they're often compared by a guy with a magnifying glass. Print scanners that use a glass plate like the door security type you see in movies can also be fooled by using a piece of raw meat and some cling film, making it register the last print used. It would require a massive fingerprint database that would have to be maintained by someone for everyone else, and registering prints for everyone at incredible costs. |
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