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What is it about pi that describes a circle?
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It's the ratio of a circle's circumference to its diameter. If you have a wheel that's 1 meter across, and you roll it along the ground for one complete turn, you'll cover pi meters of ground. [This animation](_URL_0_) might help.
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It might be good to see how Archimedes calculated pi. [Here's a short video explaining it](_URL_2_). Essentially, if you inscribe regular polygons with more and more sides, into a circle of radius 1/2, then these polygons will look more and more like the circle. A polygon with 1,000,000 sides looks a lot like a circle. We can calculate the perimeter of a regular polygon using trigonometry to see that a regular polygon with N sides has perimeter Nsin(pi/N). As I increase N in this expression, I'll get an object that looks more and more like a circle so it's perimeter will get closer and closer to the circumference of our circle which is pi. These kinds of approximation methods were originally referred to as a "Method by Exhaustion", but today we all them Limits. Every single formula for pi will have to involve a limit somehow. Another one that uses a very geometric method is [Viete's Formula for pi](_URL_0_) and this works using similar ideas. [Here](_URL_1_) is a long list of formulas for pi.
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Why does winter in many areas result in more potholes?
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because water will seep into small cracks in the roads, the water will freeze, expand, crack the road even more, fill with more water, freeze some more, crack some more, cars driving on the broken up road .. general ware and tare
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Frankfurt is a big rich city, so you're seeing the best the roads get. I'm in the UK and we have plenty of potholes. I know some of the guys who work on testing the road materials used in the US, and the testing is second to none. In America there are strict rules on the quality and testing of road materials to ensure that you can make good quality roads for weather in Florida to weather in Alaska. A lot of countries in Europe have far higher population density, so there are far fewer roads that are 'out of the way'. All things being equal, your roads are actually far better and much more well looked after.
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Why do people have different tolerances to pain?
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I can't remember 100%, but in uni I remembering learning about how genetics is a huge factor, but of course environment plays a role too. So neurons in general have to reach a certain threshold to "synapse," and in the case of pain/sensory neurons, the synapse=pain felt. If you have a higher threshold to reach in order to have a synapse, then you'll be less likely to feel pain for certain triggers, whereas someone with a lower threshold will have neurons that are "triggered" more often. Different people are born with different thresholds, but like a lot of people are saying in the comments, environmental factors can modify it! So in theory, you can become more tolerant to pain.
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Pain tolerance can be trained and can also even be genetically linked. Nerves can be deadened. Similar to other nerves, constant stimuli can result in the a reduction of response to the same stimuli (think how smells are strong at first and how you no longer smell it as easily after being around it for a while). Endorphins are endogenous pain killers your body can release (endo-morphine) to ease pain. Some people have a genetic difference (or mutation if you prefer) on their melanocortin-1-receptor (MC1R) protein that is linked to decreased sensitivity to opioids, including endorphins. Unfortunately for those people, they are more likely to feel pain than others. Fun fact: MC1R is responsible for melanin/pigmentation (coloring or darkening) of skin/hair/eyes... The mutated version of the MC1R can cause people to have red hair and pale skin.
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Why is the media trying to prove that Osama Bin Ladens death is a fraud?
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bin Laden death conspiracies have been around since even before the raid in Pakistan. Part of the reasons is that, as far as conspiracy theories go, it is pretty plausible. No body, no footage, just a quickie burial at sea, you don't have to swallow too much to believe he is in a CIA prison somewhere. The story is less about the possibility that he is alive, and more about a semi-credible journalist, Seymour Hersh, is making the claims.
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Because they want to take credit for a terror attack on US soil. And, having the US media talking about that is a huge win.
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How is it that Johnson & Johnson baby powder (talc-based) is being linked to asbestos-caused cancers, like mesothelioma?
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It had asbestos in it for years and they kept that information under wraps so that people wouldn't sue them or they wouldn't be held responsible. And once the information got out...
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Whenever you hear that something kills cancer in research / in a petri dish... just remember that a gun kills cancer in a petri dish, too. Often times the most promising ground-breaking research doesn't pan out farther down the line when they start trying to apply it to full grown humans. Maybe it breaks down in our biology (e.g. in our stomachs or when injected), before it can do what it needs to do? Perhaps it has major side effects? Perhaps it works well in rats and pigs in testing, but does nothing for humans? Any number of things can, and often do, go wrong.
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Why if you don't eat if you're hungry for long enough, you dont feel hungry?
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You can survive some time without eating. Depending on how much fat stores you have. You body normally functions without needing to use those fat stores and often just adds to them. When you go hungry there is a delay in your body switching from using readily available energy and accessing the fat. This is that strong hunger you feel and then it goes away. This is the simple version. Obviously it is a little more complicated.
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Hunger is a complex mechanism, including physiology, hormones, and psychology. Its purpose is to urge you to seek food and eat it, so you stay alive. But sometimes, historically, there was just no food available for days at a time. In such conditions, it's important to be able to focus. Constant hunger feelings are distraction that would actually *reduce* your ability to do food-finding tasks.
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Anti-G suits, how do they work?
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When pilots experience high g's the blood is pulled down from the brain to the lower torso and legs by the increased force of gravity. An anti-g suit is like a pair of chaps much like the type that motorcycle riders wear but it inflates with air. The inflating g suit works like a blood pressure cuff at the doctor office and helps keep the blood out of the legs and lower extremities. Hope this helps.
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G-suits have pockets where air is pushed during high G manouvers so it compresses the body and restrains the blood from going to the extremities so the pilot won't black out from lack of blood to the brain.
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What was the -gate before Watergate?
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The terms 'scandal' 'affair' 'incident' and 'crisis' were widely used, but there wasn't a journalistic convention until Watergate.
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Interestingly, Stargate SG1 did [an episode](_URL_1_) where the gate connected to a planet that was being consumed by a black hole. It took a long while to figure out that the reason the video feed wasn't "working" was that, in actuality, it WAS working, but due to the time differential, only a handful of frames had been sent over several hours of live feed (several hours 'Earth time', of course). [The image \(which appears still to the "home" characters\)](_URL_0_) shows the terrified side characters attempting to make a run back to the gate. Since nothing could be done for them, a main character insists on closing the visual feed since, to quote him, "We are witnessing good men dying in slow motion." I thought it was an interesting way to portray to laypeople the scenario your question outlines.
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What happens to a Nobel prize if the person(s) who won it are proven wrong in their discovery?
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If they've already won it, nothing. *Every* scientific theory is wrong, either because it is incomplete or because it includes assertions that are incorrect. Nonetheless, scientific progress is made by the repeated advancement and refinement of new theories, so it's very possible for a theory with flaws to advance the state of the field in a major way. Newtonian physics would be a good example.
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Look up Johannes Fibiger, the 1926 laureate for Physiology/Medicine. One good starting point - C.-M. Stolt, *et al* (2004) "An Analysis of a Wrong Nobel Prize—Johannes Fibiger, 1926: A Study in the Nobel Archives." **Advances in Cancer Research** Vol. 92: 1 - 12. [Link](_URL_0_).
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What GitHub is and why it is important.
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From Chris Wanstrath, CEO of github: How do you explain to “normal” folks (e.g. your mom, someone you meet at a cocktail party, etc.) what your company does? GitHub is like Wikipedia for programmers. You can edit files, see who changed what, view old versions of files, and access it from anywhere in the world – except you’re working with source code instead of encyclopedia data. Companies use it to build software and websites, while hobbyist programmers use it to find and share projects. The business model is simple: if you want to share your source code with everyone and make it public, you don’t pay anything. If you need to hide your source code because it’s private and runs your business, you pay. _URL_0_
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GitHub is just a git-based code repository. It's used for maintaining a code base, including distribution and version control. There are a lot of them, but git-based ones are popular these days because they work well. Repositories are communal places to store code and code changes. They can be free and available to all, or restricted to only certain users with certain abilities. Commits are pieces of code that users have pushed up (committed) to the repository. These commits are changes to code by a user, published so that all other users can see them When I branch code, I'm taking a version that exists, and creating a new version from it. My new version is going to be a new branch, which keeps your changes separate from mine until I... Merge the branches. Which means I take your code and combine it with mine, to make a single set of code. This new single set of code can be a new head to the tree, or simply a new head to your individual branch, but it's taking multiple branches and making them one.
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Why do bodies in caskets look so different from when they were alive?
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First off, death changes a body quite a bit. Living tissue has all sorts of processes that affect the way it looks, that aren't happening in a corpse. Second, funeral homes do a lot of stuff to the body. They often stuff cotton everywhere to keep the body from having a sunken look. They glue the eyelids and mouth shut to keep them from opening, etc. Basically imaging a makeup artist, but the tools I'm using are basically from the hardware section in Lowes.
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Recently dead people won't show much. First, the internal organs break down, the last organ to break down and die is the epidermis. Think of the body as a compost pile, the inside will decompose much faster than the outside. It's a breeding pool for bacteria because of the furnace like containment. The insides will pull moisture from the skin making it into a leather like barrier thus intensifying the composting inner organs. Now, if the dead person had multiple deep lacerations and wasn't cleaned up by a cosmetic mortician, the skin would indeed turn black much faster. Eventually the entire body will turn into a black oily goo leaving not much left other than the thicker bone sections. Souce: used to be a gravedigger.
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Why are phase changes discrete?
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Well, there is, you just can't detect it. Structure is created through attraction between the molecules. You add heat, they vibrate. You add more heat, they 'vibrate' more, but they still make ice because the heat/vibrations is not enough yet to break the attraction between the molecules of water in an ice state. Finally you get enough energy and its vibrating enough that the molecules of water break off the ice and are now melted. Same occurs when it goes from water to vapor. You keep adding energy, the molecules vibrate faster, then they get enough energy and vibrate right out of solution into vapor form. The discrete jumps are due to the inter molecular forces needed to break through the phases, though from liquid to vapor is much more related to the pressure on top of the water. You drop the pressure to near 0psi, water goes to vapor near freezing. You increase the pressure on top of the water and you will need to get it far beyond its STP boiling point to get it to vaporize.
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It does not have to. It could be anything. If you're a electromagnetic wave propagating in an isotropic homogeneous dielectric medium of real scalar refractive index 'n1' and you hit the surface of a similar medium of real scalar index 'n2', then if 'n2 > n1' the reflected wave is flipped by pi. If 'n2 < n1' there is no phase flip. If the refractive indices are scalar but complex (like metals, they absorb), then the phase shift can be anything, it does not have to be 0 or pi.
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Help me wrap my head around the fact that 1+2+3+4+5..."infinity" = -1/12?
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[It doesn't *equal* -1/12](_URL_1_). It's a useful substitution in [analytic continuation](_URL_0_), which is a technique in complex analysis, a branch of mathematics.
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Not really. Infinite does not mean all-encompassing. You could count in twos infinitely and there would never be an odd number.
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How do we know modern chemicals and materials aren't toxic?
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The short answer is yes, it's possible we're using things that will be harmful in the long term. The long answer is much more complicated, and it is rooted in regulations requiring study of the safety of compounds or lack thereof. But essentially, we tend to be at least a little more careful with new compounds than we used to, and we know more about human biochemistry/physiology than we used to, so we can predict harmful effects more easily.
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you can check by applying a tiny amount to the skin and see if you experience adverse effects, then work your way up to eventually trying a tiny amount, then more, etc. I think part of how we know which plants are edible comes from historical experience. I'm sure many a gatherer has died through history from trying new plants. In modern days edibility is determined through quantitative chemical analysis of the substance in question. Chemists look for pH level, cyanide concentration, heavy metals, known toxins, etc. Look at [this paper](_URL_0_) for an example on how the edibility of Thevita Peruviana Seed Oil was determined.
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Why, on movie posters, do the actors name not correlate to their position on the poster?
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The names most likely appear the way they do because of contractual obligations by the studio, bigger names might go first etc. When the picture is being shot or created, the artist may not know or care about which order the names will be in, but instead only cares about the aesthetics of the poster.
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What order people's names are listed in, both in the credits and on marketing materials is often argued over vigorously by actor's agents, and enshrined in contracts. Going at the start of the list (or sometimes at the end, often as "and Person X", typically for start-of-film credits) is seen as more prestigious. This is why you often see posters with several people on, but the names over their heads doesn't match the position of the person. _URL_0_ When people watch the credits, they're usually interested in who played the major characters, not 'Surprised Bystander 2'. So the major characters should be earlier on. But who's the most major character? These things get argued about by agents. Alphabetical order works for films with very few actors in it, but for larger casts, Order of Appearance tends to place the major characters early on, without any insinuation of importance.
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If websites can detect when you use AdBlock, why don't they bar adblock uses from using the website?
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Some do. However, instead of encouraging the users to disable adblock, it usually just guarantees that the user will never return to that site. That's not a winning solution.
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A majority of advertisements on websites come from the same source websites: Admob, google ads, etc. Adblock acts as a filter and removes these ads before you see the page. Companies can not circumvent this because all the work is done on your end.
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Why do our hands swing when we walk?
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Provide counterbalance while walking. Just like why a lot of animals walk with opposite legs/arms and use their tails to provide counter balance while running.
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We generally like to either do something with our hands, or put them somewhere out of sight/mind. This includes folding our arms, tucking our hands behind our backs, or putting our hands in our pockets. Most people cannot stand holding their hands at their side for long as they believe it looks awkward.
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Why isn't there a shot available that contains synthetic alcohol dehydrogenase to instantly sober someone up?
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I think it would be very difficult to make. The enzyme works mainly in the cytosol of the liver cell, it is not a secreted protein that is used to functioning in the blood stream. It requires cofactors such as NAD+. Since those with a NAD deficiency have [normal serum NAD levels](_URL_0_) I would anticipate serum NAD would not be able to meet the demands of the enzyme. You acknowledge the cost, but then compare it to an Epi-pen. Epinephrine is not a protein, it is a hormone derived from a single amino acid. This means it is much cheaper to make and can be given intramuscular because it is small and can diffuse into the blood stream. Recombinant enzyme would be multiple orders of magnitude more expensive to make and would likely require refrigerated storage. You certainly would need to be drunk to consider buying it.
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Alcohol and hydrocodone are both depressants. They slow down the functions of the central nervous system. Slow the CNS down too much, and it will cause problems, up to and including death.
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Why do video games cost so much to make?
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Paying salaries is a big part of it. Say you have a team of 100 people, earning an average of $50,000 working for 2 years. That's $10 million already. If there is any licensed content such as music, sports teams, etc. that can cost a lot of money. Depending on the license that could be a few million. If the game has a big name actor's likeness and voice, hiring them will probably cost a few million. There's the cost of doing motion capture and recording dialogue. Using a motion capture suite must cost a lot. All the tools and software the developers use is a relatively small part of the cost, but it still adds up. Although if they're using an existing engine like Unreal it could be a significant cost, depending on the terms of their license (big developers tend to negotiate that instead of using the standard license for it). And then there's the general costs of running a business, renting office space, etc. Marketing the game is a big cost. It's often more than the development budget.
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Because they still make money regardless of how many mistakes they make. Despite all the disappointment with those games, they still sold millions of copies.
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Why is that same scream in every action movie
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There isn't the same scream everytime.. however there is a specific scream in tons of movies called [The Wilhem Scream](_URL_0_), yes its an inside joke. People scour through movies trying to find it, even though its usually not hidden, its just a fun joke to put into a movie, even serious movies do it.
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They use plenty of other screams. The Wilhelm scream is overused on purpose, it's an inside joke in the industry.
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Is there any difference between the light that a flashlight makes to the light that the sun makes?
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Generally yes. The color of light is determined by the length/frequency of the electromagnetic waves that make it up, and light from LED bulbs and incandescent bulbs have a [different pattern of wavelengths/colors](_URL_0_). I can't speak to the exact accuracy of the graphs in that image, but that gives you a general idea. There are light bulbs that are designed to be closer to the "full spectrum" light we get from the sun, but I assume that none of them are exactly the same pattern.
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If you're interested scaling the flashlight up a little, you can check out the idea of a [photon rocket](_URL_7_), which operates on the same principle.
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How is the Dead Sea the lowest point on Earth ( 400m) if the Grand Canyon has a depth of 1800m?
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You are comparing depth with altitude - they are not the same thing. The Dead sea is the lowest point on Earth at an altitude of -400 m **relative to sea-level**. The maximum depth of the Grand Canyon is measured from the surface, in the middle of the continent. The actual altitude relative to sea-level of that point is about +730 meters.
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The radius of the Earth is about 6400 km. The highest point on Earth is at an altitude of nearly 9km (Mt. Everest). The lowest point on Earth on dry land is about .4km below sea level, next to the Dead Sea; the lowest point covered by water is the Marianas Trench, nearly 11km below sea level. [Figures from [here](_URL_0_)] The difference in gravitational force between the top of Mt. Everest and the shore of the Dead Sea would be about 0.3%. If you could be at the bottom of the Marianas Trench and neglect the water pressure above you, the difference between the gravitational force there and at the top of Mt. Everest is about 0.6%.
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why aren't video game graphics as good as current animated features, like Zootopia?
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Movie graphics can be created over a long time and polished for release while game graphics are created on the spot. Movies are also rendered in giant computing farms while games run on personal hardware. It is the difference between needing to make a video frame every few hours vs 60 per second.
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Long story short. 3D Animated movies are on a totally different scale of detail. 3D games are optimized for performance, 3D animated movies/shows are optimized for detail. & #x200B; Texture resolutions are much higher (And I don't think they compress them), animations have many more joints to deal with, physics are totally different, lighting is much higher quality... Pretty much everything is better in 3D animated movies/shows.
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Why does old white plastic become yellow over time?
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The Retr0bright wiki has a nice explanation on this. Retr0bright is a home-made mixture that removes the yellowing. _URL_3_ _URL_3_ _URL_3_ In short, the flame retardant that was popular for ABS plastic in the 80s and 90s contains bromine. When exposed to UV light (i.e. sunlight), the flame retardant breaks down. The bromine (which is brown) then can move through the plastic, and will bond to oxygen at the surface.
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Long story short, it seems to be caused by different types of plastic being used due to government regulations. _URL_0_ _URL_1_
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How accurate is the daily recommended vitamin percent rating and why are their vitamins with more than 100%?
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The daily recommended doses for things is usually correct for an average adult human being. You can expect a deviation of 5-10% of what *you* really need (except special cases like sickness, pregnancy or being vegan*). Vitamins are catalysts. They enable chemical reactions. Having a very high concentration of vitamins will "make everything function beter". For a similar reason, you will se monstruous amounts of vitamin B12 in things like 5 hour energy shots. Is too much vitamins bad? Well, we only need 100% of the dose to function normally. Could 1500% vitamin be damaging for certain tissues? For certain vitamin, yes (like vitamin A), but not for vitamin C. ------- *Because vegans may need more proteins to cover properly all the required aminoacids that are usually found in great amounts in meat. This can be offset by eating certain food protein content similar to what found in animals (irrc, quinoa is one of them, but don't take my word on it)
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Something people haven't patronized yet on here is bioavailability & bioaccessibility; even if it says 100%, you don't really get a 1:1 ratio of access/usage from it, same as when you eat food. Also, the daily recommended requirements are often really low, more like a "this is good enough so you don't outright have an issue", not "this is optimal".
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Do different musical keys sound different in more than just a relative sense?
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Yes. All notes (except for sines) or just a bunch of sines layered on top of each other. Human ears are focussed on a specific area in the entire spectrum (around 1000 Hz) because that's the pitch at which we normally speak. So when you have a note, some of those 'harmonics' are in an area we can hear better than others. Besides that, the entire characteristics of an instrument change along with the pitch (like, a low pitch will sound more dark and a high one more mellow, depending on the instrument). But all this pretty much has to do with harmonics.
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It's not that they sound different in other languages, but that other cultures have come to develop patterns of speech independently of other regions and thus they've come to represent the sounds they're hearing with onomatopoeia differently.
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How can online games like first person shooters be so in sync across all users without hardly any delay?
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Fast internet and faster servers. Human reaction times are on the order of 100ms or so. Ping time, which is round-trip packet flight time is often on the order of half that or so. Round trip is therefore on the order of human reaction if you give the server a little time to do stuff. Also, the server only sends back just enough to run the game. For example it may just send back Headshot and some points, and your client has to take care of the headshot animation, credit, sound and then tell the server when it's done because it's not really sync-critical.
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LAN - Local Area Network. People bring their machines and link them together for the purpose of playing a computer game. The internet speed and servers have really made this practice pointless, but it used to be the only way to play together.
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Why are some animals so intrigued with laser pointers?
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Would laser dots (or maybe other light sources) look differently to (some) animals than it does to us? Is there a case where certain lasers or lights would just appear as this distracting/pulsating/unnatural object to pets or wildlife?
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When a wiggly little bead of light catches a dog's eye, nothing in the world matters more than capturing it. Unfortunately, "it" is just an ungraspable bundle of massless photons. The lack of closure in laser-beam chasing could be messing with your dog's head. Dogs (and some cats) instinctively chase these bright-red dots simply because the dots move.Movement automatically stimulates their innate prey drive, which explains why lower-on-the-food-chain animals such as rodents and rabbits often freeze in place as a survival strategy. Although dogs aren't so discerning when it comes to color, their eyes contain a high preponderance of light-sensitive cells called rods for top-notch motion detection. A laser beam's incessant movement keys into this predatory system. "They can't help themselves; they are obliged to chase it,
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Why are Tuition Hikes so Controversial when Inflation is such a widely known and accepted reality?
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because tuition hikes in the USA are vastly outpacing inflation rates.
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College costs have risen faster than inflation and faster than incomes. So the natural consequence is that it's less affordable than it used to be. The cause of tuition increases is a combination of demand (more people than ever are going to college), non-education related expansions in many school systems (the number of administrators in the school system has grown very very fast) and a lot of those administrators are getting paid a ridiculous amount of money. _URL_0_ oh, also subsidies have contributed to the cost inflation. Schools can ostensibly claim they give many scholarships when really it's government grants. How do you take in as much grant money as possible to pay yourself (when you're an overpaid administrator)? Get more students... or charge them more.
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If somebody across from me on a large field shot a gun while holding a walkie talkie with the speak button on, would you hear the sound first on the walkie talkie or from the sound itself?
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Walkie-talkies use radio frequency electromagnetic waves to transmit signals. These propagate with the speed of light, approximately 300,000 km/s. On the other hand, sound from the gunshot (or any other sound) will travel at about 340 m/s (precise value depends on atmospheric conditions). For all intents and purposes you can consider the time it takes for a walkie-talkie signal to travel from one walkie-talkie to the other to be zero. With that, you see that if the gun is shot 340 meters away, the sound will be heard on the walkie-talkie on second earlier than directly through the air. (note: I'm also assuming that there is zero processing delay in the electronics of the walkie-talkie. I don't know the engineering details of these things, but I expect that this is a reasonable assumption and that these delays are in the order of magnitude of miliseconds only)
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Rifle bullets sound like "angry bees" with a Doppler-esque "high then low" pitch change as the pass you. Probably around 80-90 dB - not loud but can hear over conversation. Better to be on the firing end than the receiving.
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how do computers know how to do math?
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Math operations are done in a part of the CPU called the Arithmetic Logic Unit (ALU), which handles arithmetic and logical operations: adding, subtracting, bitwise and-ing, bitwise or-ing. Everything is done with hardware, so it's all electrical signals. Since it is all electrical signals, the math is done in binary. So, the ALU will take in your two numbers, for example 5 and 3, and the CPU tells the ALU that it should add them. The ALU adds them using binary addition. The final product is the binary representation of 8. Multiplication and division are more complicated from the hardware perspective, ~~and is not done in the ALU.~~ A more thorough description can be found at _URL_0_
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They use one of two methods, generally: The first method is that of iterative functions; where they take what you give them, plug it into an equation, and get an answer. Then they take the answer, and plug it back in, and get a more accurate answer. Rinse and repeat for some number of iterations. As to what the iterative functions are, understanding what they are [may require knowledge of calculus](_URL_1_), or it may be "guess a number and move in the direction so as to improve the guess". The other method is to use a [series](_URL_0_) of terms which, when summed together, can get as close to the answer as you wish. This is far more common with trigonometric functions (as opposed to roots). Again, knowing what series to use will require knowledge of calculus.
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How are Criminal Disenfranchisement Laws constitutionally legal??
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SCOTUS has decided that disenfranchisement laws are constitutional based on Section 2 of the 14th amendment.
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I'm not sure what you're asking. Laws **are** the legal basis for why things can't be done. Are you asking for the justification for those laws? Are you asking how the government has the authority to pass a law like that?
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How were Integrals, Derivatives, Limits, and other calculus concepts originally discovered and applied?
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They were discovered thousands of years ago, but the methods for that were super complex. Someone ssked Newton how he knew that earth had an elliptical orbit and not circular. So he went home and invented Calculus to explain his reasoning.
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The most unhelpful, but most true answer: Basically everything. Almost everything runs on, is modeled by, understood using calculus to some extent. Newton's second law, which is the basis of any kind of physical motion, and so used in all forms of engineering, mechanics, fluids, etc, etc, etc, is an equation in Calculus. The equations that allow us to discuss how electricity will flow, what magnetic fields will do, how light will propagate, are Calculus equations. Even many things in something that may seem like it has nothing to do with Calculus benefit from it, or discrete versions of it, particularly in Computer Science. Your whole world runs on Calculus. If you take advantage of anything invented after 1700, then you're more than likely directly benefiting from Calculus. Calculus is an infection. We are in symbiosis with Calculus. Calculus tells us how things change, and everything changes, so we need Calculus for everything.
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Does anyone know who the woman is in this King George IV Coronation photo -- she is the woman to the right of the Queen Mother.
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This is a tough one, but here goes: The girls adjacent to Queen Elizabeth look to be younger than 25, I'd say 18-24. As such, they would probably be train-bearers to the Queen Consort, as the King had pages and the pages distinctly appear behind him simultaneously. Thus, according to [this](_URL_1_) it could have been 3 girls (the Duchess is presumably too old for this). After attempting to find pictures for all, it looks to me that it is most likely the future Duchess of Hamilton, Lady Elizabeth Percy at the time. Here is the [Duchess](_URL_0_) later in life, and in a similar photo to [yours](_URL_2_). I would add that it is unlikely that this girl is a member of the royal family as she is not wearing a bejeweled coronet like that of Princess Alice, et al.
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Follow up question, are there known records of a European queen giving birth to a bastard?
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Why is it that free university education in countries like Germany doesn't lead to higher proportions of college graduates?
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Free universities in these European countries are much, much harder than in America. In America you practically have to try to fail unless you're in a seriously heavy-duty school, whereas in France getting the equivalent of an A is almost unheard-of. I know France at least used to be heavily market-driven with their high-tier universities as well, like a company would say it'll need fifteen biochemists in four years and the university will open up fifteen biochemistry slots, with some extra for drop-outs.
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Because it used to not be this way. College was not that expensive 30, 40, 50, 60 years ago (and more difficult to get into, so completing a degree was actually looked upon as a real accomplishment). Now, actually looking down on the workers is a dick move, because you don't know their life, but considering how a college education used to be viewed, it can take awhile for society to shift their views. More people who graduated in the last 20 years need to get older (and demonstrate that having a degree isn't the key to wealth it used to be).
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Is this sub included in part of the new /r/popular [META] ??
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[It's probably worth noting that almost every non-NSFW subreddit is part of the "popular" set at this point.](_URL_1_) It's basically a slightly filtered /r/all. [One of the AskHistorians mods left a valuable comment in response to the admin's announcement, in which the mod notes that it might be difficult for mods to see the impacts "popular" will have on subreddit traffic for the time being.](_URL_0_)
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default subs are based on popularity, barring something happening to cause it to be removed.
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why the U.S. federal government continues to hold so much of the vast swaths of land it owns in the western U.S.
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It's a land bank. Instead of releasing all the land in the country to the private sector, large tracts are withheld so that future generations have the option of what to do with it. It's a national resource. Keeping vast tracts of land free of development preserves wild spaces and natural beauty that can be shared by everyone not just their owners. It reduces the supply of land which increases the value of the land in private hands. If all the Federal and State land were sold it would crash real estate prices. It gives the military places to practice firing artillery and bombing without endangering civilians. It earns rent. People pay money to access Federal land for grazing, timber, oil & minerals.
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In the United States, land that isn't owned by a private entity is deemed "public land," and thus is owned by the public. However, the federal government essentially says, "let us take care of this for you," so the land is held "in trust" by the federal government, and is primarily managed by the [Bureau of Land Management (BLM)](_URL_3_), and the [National Forest Service](_URL_0_). Other federal agencies control other portions of public land. More info on public land in the United States [here](_URL_2_). So, land in the United States is either owned by private entity or the federal government. And the BLM does occasionally sell land, but don't count on it. [More info here](_URL_1_)
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How do historians give us an unbiased picture of the past, when no one can agree on anything happening in the present?
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What makes you think historians are unbiased, or agree on things?
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Anything in the past is history. For example, the Paris shootings were a historical event. It doesn't matter how recently something happened to be considered history.
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Why don't we build multi wing aircraft anymore when they were the epitome of technology during WWI?
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Biplanes and triplanes were necessary at those times because the engines they had at the time weren't fast enough to generate the lift required to keep the plane in the air. As a drawback, biplanes generate more drag and are much slower than single-wing aircraft. Now that we have high-speed engines to put in planes and lightweight metals to make them out of, we don't need the extra lift of an extra wing.
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The early planes in WWI were not dissimilar to the Wright Flyer. Some of them were pusher prop planes with small fuselages*. In the interim (since aircraft were being researched in other countries as well) advances by Bleriot (monoplanes), for instance caused developments. At the very beginning of World War I, aircraft were mainly observer platforms and more or less crude compared to late war planes and four years of accelerated wartime development. * sort of a bigger deal, having framework and canvas or wood hulls.
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How does propulsion work in space?
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This is a very common misunderstanding. Rocket engines do not push against anything. They do not push the rocket "off the air". There is a concept named conservation of momentum. It states that the momentum of a closed system in conserved. (3rd Newtonian Axiom) Momentum=mass*velocity. To understand this, imagine you're standing on a skateboard, carrying a heavy bowling ball. Now imagine throwing the bowling ball. What happens? The result will be, that you, and the skateboard, will start moving in the opposite direction. This has nothing to do with the bowling ball hitting something. You are pushing against the ball in order to throw it, and are thus pushed in the opposite direction. That is exactly how rockets work, only they eject fuel, not rocks.
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_URL_0_ Newton's Third Law of Motion. The combustion reaction expels mass behind the rocket, and that pushes the rocket forward. It's not an exclusive mechanism to combustion rockets - it would work in the same basic way if a vehicle flung rocks behind it with a slingshot - but combustion provides a much stronger push than that would.
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What do the followers of Hinduism believe?
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this is not something that can be readily explained by someone who is not a devotee or even several devotees since hinduism is more a collection of religious beliefs than a religion. different areas have their own interpretations, dogmas, and laws. even the followers of hinduism defy definition since they may be agnostic, pantheistic, monotheistic, polytheistic, atheistic or humanistic. start at _URL_0_ if you want to know the basics and go from there
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Completely different religions. Hinduism is ancient, outdating Christianity by thousands of years. They worship a large pantheon of Gods and their avatars, famous examples including Brahma and Shiva, the creator and destroyer. Sikhism is only 500 years old, worships one God/power/whatever. They had 12 head-gurus, but now their holy book is treated as the top source.
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Beep sound used for censorship
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It's normally 1k tone, which is a standard for testing audio in broadcast. Basically it's used because broadcasters have always had it available. Many times silence is used, but you notice it less. There may be rules in place that I am not aware of, but generally tone is used when the person's mouth is visible. 'Audio drops' are used when the mouth is not visible. It is (usually) possible to adjust the level of the tone to match the dialogue, but it adds another step that no one (except the viewer apparently) cares about. _URL_0_ _URL_1_
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I Google it. It's because their vocal chords are structured to scream cause that's how they communicate.
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Why did it used to be mandatory to add “www” in front of a web address for it to pull up correctly, but now it’s optional?
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Some websites started pointing _URL_0_ to their website to make it easier and it just kinda caught on. You would think that teaching people that you have to go to WWW. to get to the website would be easy enough, but you would be mistaken. Even a concept as simple as how the DNS works still confuses people to this day. I can't even get my mother to understand the difference between the address bar and Bing search. The DNS was designed with sub domains in mind. You had to have a prefix like WWW or FTP to define what the service was, and that was in turn tied to an IP address. Technically though it was never required, you could point _URL_0_ to your website directly if you wanted. That kinda broke the rules but no one followed them anyway. By the rules you aren't supposed to use .org unless you're a not for profit, .net is for networks, and .com for commercial. But no one really follows these rules because they were never enforced in the first place.
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Because they want to, basically. An URL is read from right to left, and each word narrows down the area a little more. .com, .uk, .se, .me is countries. Then you have a domain, those are most often one company (even if a company can have multiple domains). This is .facebook. , .google., .youtube., and so on. Some companies also want to narrow it down a little more. They might say which server you are supposed to go to, www is the most common one. But the thing is, you don't really need that. You could just set a standard server that you always go to, and skip the www. Which is what most companies do. But you can also have something else there, such as ww28, or anything else. As for why they tend to be malicious I have no idea. I can't really see any reason for doing this at all. But then again, security isn't my field, so I'll leave that to someone else.
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What makes your eye color change after you’re born?
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Eye color is determined by the amount of melanin in the iris; which is the pigment-protein responsible for hair, eye, and skin color. The reason for this is due to the lack of exposure to light in utero. Once birth occurs, light exposure triggers the melanocyte cells to read the genes that make the pigment protein melanin. As the infant develops melanocytes increase melanin production which results in visible changes as early as 6 months of age. Subtle changes can be seen from then until as late as 3 years. It’s amazing...the processes that transpire when you are a brand spanking new human. Source(s): [Horribly Produced Video With Valid Explanation(s) Via WebMD](_URL_0_) Edit: Spelling
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Your irises are the color they are due to pigment released from melanocytes. Color change of the eyes can occur due to hormonal changes that change/increase/decrease/take-your-pick the pigment released from melanocytes, like during child development (Caucasian infants' eyes often change colors), puberty, or pregnancy.
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If the majority of people are right handed, why do some of the earlier languages such as Arabic and Hebrew write from right to left?
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The "decision" to write from right to left vs. left to right was really only made a few times, since most of the writing systems today descend from only a handful of ancient ones. It's not like every few years these cultures re-evaluate which direction to write. So how were these decisions originally made? Writing was first done not with ink or pigment, but by etching or pressing into clay, stone, etc. So the advantage to choosing one direction over the other wasn't present. The decision was most likely made rather arbitrarily.
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In English it would be the right hand that is better for writing, as your writing hand does not obstruct what you have previously written on the same line, simply because you write from left to right. Writing in Arabic, for example, from right to left, would be better using the left hand as you can see the words you've just written. If your hand doesn't get in the way of words you have just written you can maintain a constant size and straighter lines, and you wont smudge ink or lead. With vertically written languages I guess both hands would be equally proficient.
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What would happen if you introduced a current to a gas giant made largely of Neon?
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You could probably make it glow. Of course the current required would be enormous and it would only really be florescent over short distances as longer current jumps would just be huge arcs.
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Neon lights are a type of gas-discharge light that uses various *noble gases*, including neon. They glow in bright colors. They are bright because they emit light. "Neon" pigments are infact fluorescent. They include chemicals that absorb light of one color, like invisible ultra-violet, and fluoresce in another, visible color. This means that they actually do emit more visible light than they receive, making them appear brighter.
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Why are people protesting the World Cup in Brazil?
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Because the Brazilian government has spent hundreds of millions of dollars on an event that will bring in zero profit to the country when some of the largest slums on the planet exist within their borders. [John Oliver explains this pretty well.] (_URL_0_) Humorous, but still depressing.
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Because they care more about reaching a global audience during the World Cup than they do about supporting human rights. They know exactly what the situation is, and they have an insufficient financial reason to care.
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It’s the “Roaring Twenties” and I’m a gay man who is looking to have a good time. Are there any parties or places that would cater to me specifically or not mind my presence?
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This was true all over the place. Her in South Florida, I have researched this. The terminology used was "female impersonation." Between Miami and West Palm Beach there were many places where drag shows took place that from a news stand point appeared to have been popular among homosexuals. Prior to the 1950s it would appear here that gay people lived without much attention since it was something rarely talked about. These drag shows were popular among both gay and straight. There is a movement here that was known as the "Homosexual Panic of 1954" which is the year an incident took place and suddenly the general public realized there were actually *a lot* of people who were gay in this area. It was at that time the issue came more to light and seemed to be problematic. There is a great book that talks about the 1920s era at least from a Florida perspective (which i imagine echoed a lot of large populated areas at the time) called *Welcome to Fairyland.*
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It'll be very difficult to ascertain because the idea of "party" changes from era to era and region to region. Even today, parties in China aren't quite the same as parties in the US, for example, because in China people are more inclined to sit at separate tables and make the meal into the centerpiece of the party, or otherwise engage in a specific activity around which the party will revolve around. In the US this is no requirement and there's a much more laissez-faire attitude towards things and not a real requirement for everyone to do the same activity or even be in the immediate vicinity. Chinese parties are seldom house parties and there are even fewer parties that resemble American house parties. Although I'll throw you some good examples of pretty cool parties: [the 1903 Winter Palace Ball in St. Petersburg](_URL_0_) and [Truman Capote's Black and White Ball](_URL_1_)
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why did 3d printing take so long to get were it is now? The hardwear and softwear seem simpler than some in consumer tech from the 2010's
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For basic printers, both hardware and software are basically straight out of the 80s (at least on the printer side). That's because some critical idea was patented back in the 80s, and the owner never did much with it. The patent recently expired, allowing multiple people to take it and make it commercially viable. Not sure how much it would have affected things, but the slicer software (the program that turns a 3D model into instructions for the printer) actually has to be pretty damn smart to do its job effectively. That's the one part of the whole process that may not have even been possible until relatively recently. I remember writing .gcode files (the kind of files that 3d printers read) by hand for an old early 90s CNC mill, and it was painfully slow for even the simplest parts.
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3d printing is a way to turn a 3d model on your computer into a 3d model made of plastic. You use your computer to either draw an object in 3d (the model) or borrow a model someone else has created. Then you use a special program to turn the model into a language your printer can understand. Once you transfer that model to your printer (usually using an sd card) your 3d printer gets to work. It takes these long spools of plastic (sort of like huge spools of yarn, only its a bendy plastic) and melts it into a really neat pattern. You can think of It like a pen leaking ink in a cool pattern. This pen is called the "extruder." Almost as soon as that melted plastic leaves the extruder it cools back down to room temperature and hardens again. The printer melts the plastic out in the exact shape you had on your computer and it cools almost right away.
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How strong/muscular were ancient warriors? Did they know enough about muscle growth to be the same build as many athletes/bodybuilders now? When did humans start becoming adept at bodybuilding?
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For more info, you may want to reference past questions on this topic found in the "[Did people in the past exercise/work out/lift weights?](_URL_7_)" section of the FAQ, to which this question has been added.
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It's certainly possible for people to have that physique, and Greeks and Romans especially encouraged strenuous daily exercise for young men. As a matter of state policy all Athenians were supposed to be fit enough to man a galley oar all day or stand in a phalanx and push their guts out until the other side broke and ran. That said, statues were much more about politics than portraiture. Giving a senior statesman rippling abs and well-defined pecs was about conveying strength and health. If you look at Greek pottery figures, men have cartoonishly over-pronounced calf muscles, almost hemispherical posteriors, narrow waists, and broad shoulders. The message is simple: Lean, fit, strong, young. tl;dr: They musculature is based on an observable reality, but almost certainly idealized to portray it as the norm rather than the exception.
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Why is dime (10 cents, etc. See below) the smallest coin?
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The value of coins originated with the metals they were made of, so a coin's size, composition, and value were all related to each other. In the Canadian case, dimes were originally made of silver and didn't need to be large to be worth ten cents. Like many silver coins, they had grooves on the edge to keep people from shaving silver off of them. Five-cent coins were originally also made of silver, and were even smaller than dimes (exactly half by weight). In 1922, Canadian five-cent coins switched from silver to nickel, got much larger, and became known as nickels. Canadian pennies were originally made of copper, so they were naturally larger than dimes despite being one-tenth the value.
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Because it's the law. The Coinage Act (1792) describes milles (1/1000 of a USD) and other subdivisions of the dollar.
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Why do I get canker sores in my mouth when I'm stressed out?
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The stress negatively affects you immune system and mucus membranes in your mouth, which leads to the initial canker sore. After it starts it take quite a long time to heal. Stress can also cause other health problems.
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Referencing personal experience, but I assume you're talking about non-STD type of ulcers, which are canker sores. These are generally caused by crumbs of food still being in your mouth after you're done eating. As they sit there, they feed bacterial growth at that spot and the acidity from the bacterial metabolism causes sores to form. That's not the only cause, but that is one of the most common ones. If they are generally forming near the gums, that is the most likely cause.
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At what altitude would by phone stop getting signal (including from satellites)?
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Cellphone towers typically have ranges from 22 to 45 miles. From what I understand, an omnidirectional antenna is impossible, so cellphone towers probably have a shorter range going up. Space is generally accepted to be around 100 km up (62 miles), so the ISS has no reception.
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In theory, you ought to be able to work out your position above the Earth's surface, including altitude, just as well as without it - GPS units are quite regularly used at quite high altitude (several tens of km). It would even work beyond the orbit of the GPS constellation, theoretically. However, the main problem with GPS in space seems to be how weak the signals are - the signals from the satellites are [aimed at the Earth](_URL_1_) (pdf - see figure on p2), so that much beyond Low Earth Orbit, your receiver would start having trouble detecting the signals. (If anyone is interested in the space-based GPS units they were discussing in the linked article, [this paper](_URL_0_) (pdf) discusses testing the system)
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If a person with a blocked nose was gagged would they die? And has it ever happened?
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Your nostrils are generally blocked on one side or the other. I forget the reason for this, but it's natural and normal. You can unblock both nostrils by pinching your nose and holding your breath until you're desperate to breathe. Essentially your body responds to the need to breathe by clearing the airways. If your nose was clogged by a cold or something similar a similar response should prevent you being suffocated. That's dependent of course on the obstruction being something you can fix. If I put superglue up your nose before covering your mouth, obviously enough there's not a whole lot that you can do about it.
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When you have a cold your nose doesn't get blocked by mucus and snot, it's caused by the blood vessels in your nose becoming inflamed as a response to to viral infection. Your body expands your blood vessels to enable transport of stuff needed to fight the infection to happen more efficiently.
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I need a ELI5 explanation for my bosses about craft beer vs commercial, micro vs macro breweries etc. They seem to think for example Bells Two Hearted is either a "crafted" beer or an IPA (this is serious) and I need to explain this trend to them in the most simplest way possible.
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Mirco vs. macro is simply about size. Mircobreweries produce less than 15,000 barrels a year, about half a million gallons. Craft beers are about production techniques as well as amounts. They produce less than 2 million gallons a year, but also have to use certain ingredients and techniques. That means some beers are craft, but not micro, some are micro, but not craft, some are both, some are neither. In addition, while this isn't necessarily part of the definition, a craft brewer will typically have more types in smaller batches, use hire quality ingredients and more laborious techniques (like aging in whiskey barrels), and have more season or one shot specialty beers.
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Gumburcules pretty much took care of this one. But in case your 5-year-old mind can't follow everything he wrote, here's a cool [chart](_URL_1_) to look at. Basically everything is either an ale, a lager, or an offshoot/hybrid of one or both. The cool thing about this chart is that it gives you examples of each, although you might not know most of them if you haven't been into a bev center or a bar with lots of taps. Try just going to the bigger circles on that chart and looking up that style's characteristics to get an idea of how they relate to each other. That's what I did when I first started getting into craft beers. Happy birthday dude.
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I half remember hearing how a Turkish sultan banned dancing in France during his lifetime. Did I make this up or is there some truth to it?
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Suleiman the Magnificent wrote a letter to the king of France when he heard about the waltz: "I am, who the khan of forty-eight kingdoms, Kanuni Sultan Suleiman Khan. According to report was given by ambassador, I heard of it was danced by your people as cling each other, men and women. Because of we are contiguous, I'm worrying which is smudging of this sickness to my lands. İf it smudge and you don't terminate this sickness immediately, I will come with my victorious army and destroy you." [This](_URL_0_) is the best source I could find about it.
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At least when it comes to Turkey (I can't speak to Central Asia), the answer is a big fat nope. Turks still drink alcohol, in fact, I was just watching a show on the Foods Channel (or whatever it's called these days) about alcohol in Turkey, and a couple of specific drinks. IIRC, the host pretty much asked "If you're Muslims, why are you drinking this stuff?" And everybody pretty much said, "Because it's traditional". I wish I remembered what the drink was called... I'll see if I can find it on the Wiki. EDIT: [This](_URL_0_) may have been it (it sounds right). EDITII: It might have been [rakı](_URL_1_) too... Regardless, the point is is that Turks definitely didn't stop drinking.
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The plot of the Final Fantasy series.
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A long time ago, an evil scientist created a creature that would magically cause chaos wherever they were. That scientist called the creatures “chocobo” and spread them throughout the galaxy. The Final Fantasy series are the stories of all the planets that chocobos are now living on and the hero’s struggle to defeat the evil feinds magically spawned by the chocobos.
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Please elaborate. Do you want just the "Solid" storyline, or do you want to know about the series all the way back to NES metal gear?
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Why does PH affect bacteria life so differently in the gut versus the mouth?
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The mouth and stomach are two completely different environments with totally different microbes living in each. The extremely low pH in the stomach environment is very caustic and few organisms can live there. Your quote about mouth bacteria is a little misguided. Acid-producing bacteria is what leads to tooth decay. Many bacteria of the mouth are capable of metabolizing sugar and produce acidic by products as a result. These acids are what lead to tooth degradation. It's not necessarily about the bacteria "liking" acidity or alkalinity. It's about surviving in the given environment. Put it to you this way: "Why do polar bears thrive in Alaska but not in the Amazon rainforest?" The answer is fairly obvious, these are two very different environments and many animals are not fit to thrive in both. The same is true of bacteria and the environments in which they live.
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Phages already exist among gut bacteria in your gut. Apart from killing the hosts, phages actually serve an important role in transferring genes between bacteria. This is thought to be one way antibiotics resistance spreads across different species of bacteria. In other words, you likely have phages already, but my guess is you haven't noticed yet. On the second question, a dose large enough to wipe out gut bacteria will do. The Soviets actually developed a cure for bacterial infections called phage therapy. It was occasionally used to treat "stomach bugs" (Salmonella, Enterococcus, Campylobacter etc.). I do not know specific dose, but just confirming that a person would indeed notice it if a large amount of phage is artificially prescribed to him.
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why vegetables last longer in the drawer in the refrigerator as opposed to just sitting on the shelf
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The drawers are specifically designed to store vegetables and lengthen there shelf life. The drawers regulate oxygen and temperature more than the open shelves which usually allows the process of bacterial growth to slow down. -Chef
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The drawers usually have little adjustable vents, so you can maintain humidity to prevent things like lettuce from drying out and wilting. The fruit drawer will have smaller vents to allow the ethylene gas that fruits produce, and slow down the ripening.
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Is there a reason why bigger animals tend to have bigger eyes. What advantage is it having eyes in proportion to body size?
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Bigger eyes generally mean better visual resolution and better light-gathering abilities. It's basically the same reason that big telescopes are better than small ones. For example, on the reef at dawn and dusk big predators come out to hunt. They have the advantage over small reef fish because their larger eyes allow them to see better in the dim light. So big animals basically just have bigger eyes because they _can_. You couldn't stick a human sized eye on a mouse, because the poor thing would be about half eyeball. But there are diminishing returns, and eyeball size levels off. Cows are a lot bigger than people, but their eyes aren't all that much bigger. The animal with the largest eye of all, the giant squid, hunts in deep dark water and needs extra-large eyes to see. The much larger blue whale has smaller eyes, due to the fact that it doesn't rely on vision, especially vision in dark water, nearly as much.
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The size of the eye does have a bearing on its function. I was just listening to a [radio show](_URL_0_) about squid eyes this weekend (if you want to listen, go down to "Here's Looking at you, Squid" and choose the streaming version or download the mp3). Larger eyes improve an animal's ability to see in the dark, up to a point. Once the eye is larger than an orange, there is no additional benefit to having a bigger eye in terms of accuracy of vision. Because of this, scientists were initially confused about why giant squid have such huge eyes... but they figured out that even though the big eyes don't help them see more accurately, they do help them spot very large objects (like sperm whales trying to eat them) in very dim lighting conditions. TL;DR: Hawks just have to see very well in the day, but bears often roam around at night or hibernate in dark caves, so they have to be able to see large objects in dark areas, requiring bigger eyes to let in more light.
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When we look at the sun, we're seeing a past version of it...
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Not quite, the image that we see of our sun from earth is about 8 minutes old if memory serves. If it were to blow up for the first 8 minutes we wouldnt know about it, its true. We would continue to revolve around its center (even if it was no longer there) but as soon as those 8 minutes have passed, we see exactly what happened to the sun 8 minutes ago, i.e. its explosion or what have you. Does that make any sense?
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It's nothing to get yourself worked up about. Life on Earth has existed for millions of years, human beings for ~200K years. We've only been paying attention to the Sun for the past few decades (in a serious, scientific manner). Anything the Sun does in a couple of decades, or even a couple of centuries, is just a momentary concern considering how long the Sun has existed. It's not accurate to say the Sun is behaving "unexpectedly" because we simply don't know enough about how the Sun actually works to be able to accurately predict or notice an aberration of it's behavior. The Sun's just doing things that we weren't expecting because we lack a sufficiently accurate model of how it works.
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Do Plants Photosynthesize at Different Rates?
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Yes, different plants can have different light curves and different preferred DLI. _URL_3_ _URL_4_ C4 plants do not have [photorespiration](_URL_1_) while C3 plants do at higher lighting levels which affects photosynthesis rates. Different species of plants can have their [non-photochemical quenching](_URL_6_) process "kicking in" at different lighting levels. One way to measure this is with the [photochemical reflectance index](_URL_0_). More common is to used [pulse amplitude modulation fluorescence](_URL_2_) techniques. Older leaves tend to not photosynthesize as well as newer leaves. Temperature definitely plays a role in photosynthesis rates as does carbon dioxide levels. Drought conditions can cause the [stomata](_URL_5_) in the leaves to close greatly reducing photosynthesis. e- grammar
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The loss of leaves allows for less strain in producing energy. Photosynthesis is responsible for creating starch which can be stored and used in times of little sunlight. (Glucose - > Sucrose - > Starch) Also starch can be stored into seeds through ovary and ovules so when it is time to germinate, the seeds have some chances of survival in tought times And plants have an inbuilt light system and they don't determine the season via light but how long the dark is.
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Why are our lips a completely different color than the rest of our face?
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Lips have three cellular layers, just like the rest of our skin, but they are much thinner. Some things that are missing from lips are sebaceous glands--where we sweat from--, hair follicles, and, importantly, melanin, which gives skin much of its color. Lips are pink or red because blood vessels are close to the surface.
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Your blood makes them look red. It's close to the surface because the skin on your lips is very thin, so the color shows more easily.
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Why is flu type A divided into subtypes but not type B?
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Flu type B is a virus that infects only humans, and doesn't have subtypes. All the viruses are basically the same. Flu type A has "H" and "N" proteins on its surface. They infect humans and birds, and in the case of some subtypes pigs as well (swine flu). The subtypes are determined based on which "H" and "N" proteins are on the surface.
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Pathogens like bacteria or viruses can carry antigens (chemical signatures, like blood type) from other hosts. Current idea is that, if those pathogens are equipped with their former host's type B, say, then since you're type A, your immune system has a much easier time recognizing the pathogen as an invader--they're very different, after all--and can respond to it more quickly and effectively. It's just a means by which different immune systems can respond better to invaders.
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What would happen to North Korea if Kim Jong Un died unexpectedly? Who would take power?
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We don't know how NK's government works. They don't really like sharing information with anyone. We SUSPECT that the generals run the show, and Kim Jong Un is just a figurehead, but we don't know for certain.
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Think of North Korea as China's yippy little ankle biting chihuahua. China went and rescued the little shit from being euthanized (Korean War). It slobbers, snaps at people, and shits on the floor but China just doesn't have the heart to send it back to the pound.
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Is it possible to kick a country out of NATO, and what would be the political ramifications for it?
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There are no current rules to remove a member state if they voluntarily continue to remain part of the alliance. The charter would necessarily have to be updated to include a provision for removal, but a defense treaty isn't very useful if the other countries can just duck out of enforcement by saying they're kicking you out after the fighting has started. For what it's worth, there's a legal argument to be made that the NATO treaty would only include attacks on Turkey in the portion of the country existing on European soil (NW of Istanbul). I say this because Article 6 has already been interpreted to not include an attack on Hawaii, but it would cover an attack on Alaska. The writing about what territories or areas of the globe are covered are fairly strictly read by the signees.
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NATO is the North Atlantic Treaty Organization is a very large military alliance. This page lists the members: _URL_0_ Essentially they all agree to defend one another if attacked. They also sometimes take part in more offensive measures against other nations, like currently in Libya.
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Why when I put a cold stick of butter in the microwave, the middle of the stick turns to soup immediately but the ends are still solid?
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That's because of how electromagnetic radiation works. The frequency at which a microwave operates is such that the length of the electromagnetic waves is a few centimeters. Inside the microwave oven are many such waves, and some of them overlap. Where they do, they can either amplify eachother (if they're the same) or they can cancel each other out (if they're opposite) at any given spot. Where they cancel out, your food is cold. This is why most microwaves have a rotating platter.
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It's a colloidal suspension. When you whisk it, you're mechanically breaking apart the preferred groupings of molecules and beating air into the mixture. Your continued stirring prevents the mixture from re-suspending, and eventually the phospholipids will reestablish membranes around air throughout most of the mixture. At that point, it can hold its shape, and remains more or less a stable froth. If you were to continue whisking, it would separate entirely and you'd end up with butter.
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Would ancient civilizations in climates with no winter (ie ancient Egyptians) have even been aware that ice existed?
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I don't know where you get your information but it does get cold in parts of Egypt to the point of ice. For instance mount Catherine _URL_0_ All though extremely rare in it does snow in Egypt from time to time. So I believe yes some but not all of ancient Egyptians new what ice was.
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They might have been able to import it from Turkey or Greece, their mountains are close enough. The Nile has frozen twice, in AD 829 and 1010. So it might have frozen during Ancient Egypt, just not recorded. It would stand to reason that if anyone had ice, it would be the upper nobility depicted in the pictures.
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During a heart transplant, how do the surgeons not kill the patient while the original heart is being removed?
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Heart transplants, like other procedures that require stopping the heart, involve the use of cardiopulmonary bypass. The surgeons attach bypass tubes to the aorta and venae cavae. The tubes shunt blood from the heart and lungs to a machine that adds oxygen to the blood, scrubs carbon dioxide from it, then pumps it back through the aorta to the rest of the body. Other procedures include those that require opening the heart muscle itself and some forms of coronary artery byass grafts.
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The heart actually has an intrinsic ability to beat by itself. The brain, via the vagus nerve, regulates that by slowing it down, but it doesn't actually generate the beat. So, when you give somebody a heart transplant, you don't need to innervate that heart to make it work.
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Why are many manholes placed right in the path of a car's tire on roads?
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I don't know for sure but I'd guess it's because the tunnel is under the road and the ladder down is on the side of the tunnel. Which more or less places the ladder under your tire, apparently.
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I'm assuming you are talking about the friction between the wheels on a car/train and the road/rail. This is called [static friction] (_URL_3_) and maximising this allows for better acceleration and grip so that the wheels do not slip when you apply torque to them, because when a wheel starts to slip, you start to lose power. The higher the better in this case. This is why formula 1 cars (and other racing cars for that matter) like slick wide tyres to maximise the amount of static friction between the tyre and the road.
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How sensitive is our touch sense. Can we differentiate between fractions of degrees? 1/4, 1/8, etc?
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I think what you're asking about is called [two point discrimination](_URL_0_) and is dependent on where on the body you measure. It can be as fine as being able to sense 1 mm gaps and as wide as being unable to sense gaps of several centimeters. This is a product of specialized nervous circuits in the skin which help increase the resolution of the incoming signal. Additionally, there was a [study](_URL_1_) which showed humans could detect wrinkles on a seemingly smooth surface down to 10 nm in size.
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It is a biological thing. The types of receptors that allow you to perceive such information as hot and cold (as well as pressure, etc.) are sensitive to changes in temperature (or pressure, etc.) rather than absolutes. Edit: Removed a reference to pain. Pain is complicated.
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When we get drunk, why can't we remember some things in the following morning?
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Alcohol impairs the part of the brain responsible for laying down long term memories. The exact mechanism is not well understood. Alcohol, obviously, has effects on multiple aspects of brain function so it's not a specific effect in the case of memory.
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The alcohol stops the Hippocampus from creating a substance called glutamate which carries signals between the neurons in your brain. Essentially, the part of your brain responsible for making memories, stops doing its job for a period of time.
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Why was Canada never nearly as densely populated as the United States?
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hi! you may be interested in some previous responses * [Why did the US become a country with 300 million people while Canada remained comparably small despite their similar roots?](_URL_2_) * [Why has Canada's population remained so low?](_URL_2_)
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As a Canadian, I'm going to point out the the regions of Canada that look like Siberia are EXTREMELY SPARSELY populated. They just cannot support large populations. Most peoples living in these areas survived in a hunter/gatherer capacity and now pay exorbitant amounts of money to have food shipped in my airplane. The parts of Canada that are populated are much more similar to the American mid-west, east coast, and north west coast (Washington = British Columbia), than Siberia
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Why is it when I log into Windows with the correct password, it logs in instantly, but when I put in the wrong password it has to think about it for up to a minute?
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It's actually to prevent brute force attacks from trying millions of passwords per second by plugging in an automatic keyboard or the like.
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Studies have shown that mandatory password changes actually reduce security because people tend to either use simpler passwords that are easier to remember, or they just write them down in easy to find places. Edit: since so many people have asked. _URL_0_ Edit: don't know how this turned into my highest karma post. I went from 1.3k this morning, to this!! Lol
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Huckabee's "Fair Tax" model
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Our current tax system is a progressive income tax. You pay nothing on the first bit of money you make, a small amount on the second bit of money you make, a larger amount on the next bit, and then all money over a certain amount gets paid at the highest rate. What Huckabee wants is a national sales tax. It would work just like the sales tax at the state and local levels do today. The main benefit of a national sales tax is that it's a lot simpler. The downside is that poor people spend more of their income than wealthy people, so poor people would end up paying a higher portion of the tax bill than they do today.
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[He says](_URL_0_) that the IRS is a massive burden and the US needs 'Fair Tax' instead. Fair Tax replaces most taxes with one consumption tax, aka sales tax, aka VAT. This makes tax collection very simple, no loop holes, no thousands of pages of tax law. Probably a long list of products subject to different levels of sales tax, but thats much simpler. > With the rebate taken into consideration, the FairTax would be progressive on consumption,[2] but would also be regressive on income at higher income levels (as consumption falls as a percentage of income).[6][7] Opponents argue this would accordingly decrease the tax burden on high-income earners and increase it on the middle class *Personal Opinion. To tax when people spend is not as kind on the poorer people. For this reason VAT in the UK is exempt on food, childrens clothes, and there is gift aid on public schools. I hope all the redditor fans of Johnson see this proposal of his, liberals would see this as a large flaw.*
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What kind of DNA damage is not fixable by the cell?
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I think that the ability to repair DNA damage is a function of enzyme availability. If there is more damage than available enzymes there will be portions that will remain unrepaired. Other than that I think that only particular cell states will determine the unrepairability of DNA, like senescence or apoptosis.
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There are a variety of different types of damage and as many types of repair mechanisms. While I don't generally like non-answers, I'd suggest reading the wiki on [DNA repair](_URL_0_) because anything I write here would pretty much be a copypaste. If there are more specific questions you have about any of these processes we could possibly help more.
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Do antiparticles have the same half-lives as their matter counterparts?
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As far as we know the answer is yes. Antiparticles have so far been shown to be identical to their particle partners, except for having all "charges" (electric charge, strong color charge, chirality...) flipped. There are some beyond the standard model theories which predict that they will have tiny differences but no difference has been measured. In practice, anti-matter is difficult to isolate and produce in large quantities as it will annihilate with regular matter. The best result I could find in the PDG (Particle Data Group)'s latest handbook is for the ratio of the decay rate of the muon to the antimuon: τµ+/τµ− = 1.00002 ± 0.00008 Where the decay rate τ = ln(2)/half-life This result in consistent with 1.0 indicating they have the same decay rate (and half life). Source: _URL_0_
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We aren't *entirely* certain that they are different. Right now we call them differently because that's the simplest assumption to make given the known theory. They could be "the same" particle, a hypothesis known as [Majorana neutrinos](_URL_0_), in which case we're searching for a thing called "[neutrinoless double-beta decay](_URL_1_)." Anyway, the more specific answer is that antiparticles have *all* their quantum numbers reversed, of which charge is the most famous, but by no means the only one.
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Is there a difference between human nerve endings?
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Definitely! Free nerve endings are all over the body and, although most are classified as nociceptors (pain), some are also classified as thermoreceptors and mechanoreceptors. As far as different organs, remember that there are many different types of receptors and that the composition of receptors will determine what type of sensory information is being prioritized. Also, these sensations that you described are also ascending the spinal cord in different pathways. Sexual sensations ascend via the spinothalamic tract, while fine touch (which we would see in fingertips) is ascending through the dorsal-column medial lemnisucus pathway. So while free nerve endings can differ, this question is a lot more complicated than just free nerve endings.
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Different places in the body have different concentrations of nerve endings. That is to say, there are some areas that are more sensitive and some that are less. The fingertips have a very high concentration of nerve endings compared to elsewhere. This is to help with manual dexterity. So any injury to the area is more painful.
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Why are updates to video games so large, sometimes larger than the game itself?
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Code is small, because it is instructions for your computer to make something (such as a graphic). However, It's much faster to pre-make and store the graphic first, so your computer doesn't need to create it on-the-fly. But since we don't what your computer will need.. Well, We'll just pre-make EVERYTHING, so it'll be there when you need it. Therefore, much of the game files are pre-computed stuff that your computer just looks up in a table or refers to, instead of generating from scratch when its needed.
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Movie studios generally don't disclose everything about their budgets. The stuff you see is just a publicly releasable number regarding an approximation of the production cost of the movie. Thats just one aspect of the overall process, and its a fundamental part of the movie processes, so its often a pretty well known number, its not secret. Now, the rest of the money involved in making the movie, marketing it, distributing it, paying people out, all of that... well, you *never* see that publicly, ever. Game studios are unrelated. Movies are unique beasts. Asking why a game studio doesn't do this is like why asking the grocery store how much it costs to sell you milk.
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The difference between all the different blood types; A+ A-, B+, etc.
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Essentially those letters refer to protein markers on the surface of cells. If you're given the wrong blood type, it can cause coagulation to occur inside the bloodstream or even cause your immune system to start attacking the foreign blood cells.
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It's simply derived from genetics. There are 3 different alleles you can't get. A, B, and O. A and B are codominant while O is recessive. That's why there's A, B, and AB blood types without AO or BO because O is recessive. When you have an O blood type, it's because you have two O alleles.
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Are there digitized English language texts of unknown importance that haven't been read yet by anyone in hundreds of years? I would love to spend my free time reading them and do a possibly important yet tedious job to make an impact in the field.
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There is an exceptional database of digitized texts connected to the University of Michigan library - Early English Books Online. It goes from about 1400 to 1700. There is also a modern text transcription for most of the texts, which can be very helpful if you haven’t trained in reading Renaissance writing. You may need access to a university library that subscribes to it, because most city libraries won’t. You can also subscribe to it as an individual, but I don’t know the cost off the top of my head.
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We (my archives) just got word we were approved for [an LSTA grant](_URL_2_) to digitize some old stuff and put it on the webnets for free! \o/ \o/ \o/ It's some German-American stuff in cursive Fraktur ([this is real](_URL_2_)) and of no use to almost anyone in our geographic area due to the whole problem that like, a dozen people can read cursive Fraktur, so we're hoping this (along with some transcription in to standard typeface German) helps the collection get some use.
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How does almond milk curdle?
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It curdles like regular milk because it has fat, protein and sugar similar to regular milk. Bacteria in the almond milk eat the sugar and excrete acid. This acid causes the protein chains to shrivel up and form tight webs that trap fat globules and squeeze out the water. These lumps of fat globules trapped by protein webs are the curds. This is essentially how tofu is made, but with soy milk instead of almond milk, and it's how many non-dairy cheeses are made.
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Furthermore, how could they make it taste so mediocre and give it the texture of slightly curdled milk?
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How did petroleum get so far underground?
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Many fossil fuel reserves were formed under the ocean where there's a constant flow of stuff falling on the sea floor. In other cases, subduction could cause the reserves to get buried deeper than they started out. Many reserves were quite close to the surface, though. It's just that we burned most of them first. In parts of Pennsylvania at the beginning of the oil boom you could literally stick a straw in the ground and get high grade petroleum you could burn in an engine.
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> Given the range of freaky metabolisms in extremophiles out there, I'm a little surprised there's nothing underground munching on crude oil. There is such a thing: * _URL_0_ * _URL_1_ * _URL_2_ * _URL_3_
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How do we know that someone who is shot in the heart is "killed instantly", rather than having some residual brain activity for some time?
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It’s not really instant, but really quick (less than a minute). Their blood pressure drops very rapidly since the heart is where all blood flows through. They quickly go into shock, loss of consciousness and death once the brain cells stop receiving oxygen.
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It is much more complicated than that, and is a very active area of research. A professor at my school, David Eagleman, studies this stuff. He's a complete badass, check him out: _URL_0_ edit: one of his famous experiments involves using magnetic energy to slow the propagation of some signals in the brain, and if done properly it can make you think cause and effect are reversed in some special circumstances. he also dropped grad students from a tall structure with a quickly-blinking watch to see if the fear of death would help them see what the watch was displaying. they couldn't. many biological reactions happen just as fast or faster than nitroglycerin degradation. something like time perception that involves consciousness must by definition be related to higher-order neural networks in the brain.
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During the storming of Omaha Beach, did the Allies utilize any form of ballistic firepower such as the M1 Bazooka?
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The thing about the bazooka was that it was an antitank weapon. The Germans didn't have tanks sitting on the beaches. The shaped charge warhead of the bazooka round wouldn't have done much to something like a bunker. Plus remember that "DDay" wasn't just Omaha Beach. The Allies landed on 5 beaches. The other 4 were Sword, Gold, Juno and Utah. As I said below the British employed Hobart's Funnies which included a tank with a 290mm mortar for taking out fortifications. For some reason though the Americans didn't seem to think the Funnies were a good idea for the most part.
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It's easy and fun to think human wave attacks are a pre-machine gun thing but one of the most remembered feats of the 2nd world war was probably the storming of Omaha Beach on D day. Here's the armament left on the beach after the bombardment failed to hurt even a single German soldier: That beach was covered by 8 bunkers with large guns, 35 fortified smaller bunkers with smaller guns, 85 machine gun nests, 4 artillery batteries, 18 anti-tank guns, 6 mortar emplacements and 35 rocket launching sites with 4 rocket launchers each. So the soldiers storming that beach stormed against that, unsupported by artillery and with no armor to speak off. And they made it. I'd love to see a statistic or some research on the waning effectiveness of human wave attacks. But as an anecdote D day should point out that human wave attacks were not decisively repulsed every time.
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what are wood grains and how do they work? Why is it harder to work against them with a knife?
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Wood grains are the result of wood growing on the tree at different times of year in different conditions. Wood grows most during the summer and least if it even grows at all during winter. As a result you get these layers when the process stops and restarts. The reason they change direction is due to the random nature of organic stuff growing. It is like asking why the veins in a human body do not line up perfectly in straight lines. They are hard to work against because grains are basically solid strands/plates, they are tough individually but will split apart more easily. If you work into a grain and you start digging into it your sander or saw will get between two plates and start to dig. If you sand/cut with the grain you have no risk of sinking into the grain since you can't get between the plates. [this site](_URL_0_) explains it well with pictures.
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Wood is made up of long fibers. The wood's "grain" is determined by the direction that these fibers point in. The direction of the grain affects how the wood feels to cut - cutting *across* the grain chops the fibers in half, whilst cutting *with* the grain separates them from each other. You need different tools to make these cuts - [crosscut saws](_URL_2_) and [rip saws](_URL_1_), respectively. A knot is formed when the trunk of a tree grows over where a branch used to be before falling off. The grain of the wood changes significantly around a knot - up to [90 degrees](_URL_0_). So when you cut into a knot, you wind up encountering all sorts of different grain directions, and your saw is going to behave poorly *somewhere* in that cut.
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Is there a way to create artificial gravity in space?
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There is only one way to realistically create artificial gravity: acceleration. Perhaps the easier way is to create a spinning cylinder. That section will only have earth-like gravity at the on the inner surface of the cylinder--nearer to the axis the gravity will be less. In this scenario, you'd feel a centrifugal force (because you are not in an inertial reference frame). Another way is to just take advantage of linear acceleration. If a ship is constantly accelerating at 9.8 m/s^2 , then anywhere in the ship would feel like standing on earth (where the ship is moving in the direction of the ceiling). Achieving that kind of acceleration for any reasonable stretch of time is very, very hard and would require a power source that has not be invented yet.
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[Like a centrifuge ?](_URL_0_) Gravity is sensed as a constant acceleration (9,81m/s²). If you can generate a constant acceleration, you have a gravity simulator, basically.
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How do breweries/bottling companies bottle their foamy products e.g coke, beer without it foaming up since when you do the reverse, it foams up?
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At least for homebrewing, the beer goes into the bottle flat, and then gets carbonized in the bottle. There's no head (foam) because there's no co2 to make it until a few weeks later.
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It reduces the surface area of the liquid. Foam is caused by a lot of carbonation escaping from the beer all at once. Carbonation escapes more easily when there is a larger surface area, so by pouring it down the side of the glass, you reduce the amount of carbonation that is able to escape at once.
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How "strong" of a vacuum can you make by pulling a piston out of a cylinder?
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You can see see what happens by looking at the ideal gas law: PV=nRT, where P is pressure, V is volume, n is proportional to the number of gas molecules, R is a constant, and T is temperature. Assuming that the temperature and number of gas molecules stay the same, what you are doing is increasing the volume, which at the same time decreases the pressure. So as you double the volume, the pressure halves. When you quadruple the volume, the pressure reduces to 1/4. So as you can see, when you pull the piston out, you continue to increase the volume, and the pressure will get closer and closer to zero, but will never reach zero.
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Yes, the pressure increases and decreases. The function for liquid pressure is `density * gravity * depth` You can change the gravity by the "force" pushing the water against the bottom of the bucket. When you compute the pressure you can see that when the bucket is on the bottom the pressure is bigger than if it was still. If the bucket is on top of the loop the pressure can be lower or greater accordingly to the speed you spin it around. The air has a different formula but still has an acceleration component so the pressure still changes in a similar way. A vacuum would be created if you spin the bucket fast enough. But I can't really imagine how the pressure would behave from a still bucket until the vacuum was formed.
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What function do the mesh over the speaker?
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It stops foreign objects from passing through and damaging the speaker. Some are water resistant to an extent and some can help with sound quality by allowing soundwaves to pass freely through them.
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Its not a speaker, its just a hole to allow for air flow that helps create better sound in the actual speaker.
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How do electricity companies increase the supply to deal with surges in demand like big sporting events on TV and where does the spare power get kept when it's not needed?
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There's really no "spare power". The electrical grid is a careful balance of supply and demand. If the demand is low, power plants are shut down or throttled back to reduce their output. If demand is high, plants are throttled up, the aformentioned peaker plants are fired up, or additional power is connected from outside the local grid. There are some attempts at power storage, like storing heat as molten salt to be used later to drive a turbine or using the spare power to pump water uphill so it can be used later for hydro power.
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Because they have a (mostly) fixed capacity and they are a highly regulated industry. If they can push 100 units of power out... and people are demanding 500... that is a pretty big problem for them. In a free market, prices would skyrocket but in the utility market their prices are basically fixed by the government. Since their prices are fixed... and their capacity is fixed... the only thing that can give is the service provided... thus blackouts!
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Why do you feel tired after eating a big meal?
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Your body is using its energy to digest the meal you just ate. More energy to digest means less energy for your muscles and brain. It's known as [postprandial somnolence](_URL_0_).
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Your body is diverting energy to the digestive process, which makes you feel tired.
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How come some stuff like ham and cheese go hard in the fridge, yet others like pasta and rice go all watery?
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Pasta and rice do become hard in a fridge if you have them in a open container . Cooked pasta and rice have high water content compared to ham and cheese so they take longer to dry out. There is a huge difference if they are placed relative open or in a airtight container.
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Because some foods have high water content like bread that dries up when it gets stale and therefore hard while others we prefer with low ater content and absorb humidity from the air and get soft when they are stale like cereal.
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With today's technology, how come we have not been able to reverse Myopia (Nearsightedness) without permanently damaging our eyes such as Lasik?
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It's totally possible. Earlier this year I had a procedure called VISIAN ICL. ICL = Implantable Collamer Lens. Basically, they implant a contact lens inside your eye, behind your iris and in front of your eye's lens. The procedure is completely reversible; they can remove the lens, and your vision goes back to how it was before the procedure. Just an FYI, they say this is painless. They lie.
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Optical lenses have been around for a long time! I'm not an expert, but I know they date back at least to the mid-17th century because Baruch Spinoza, the philosopher, was a lensgrinder of optical lenses. His death is partly attributed to inhaling the glass dust over the years. One question, though, is who had access? When you think about it, there must statistically be a very huge population TODAY who don't have access to vision-correcting devices around the world. Another question would be how prevalent bad sight was through history. I've always assumed that if we were to go back far enough that bad sight would not be found in human communities. As human societies stabilized, more and more people survived, and people who developed genetic reasons to develop bad sight weren't readily selected out by nature.
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Why does the night sky look so bright when it is heavily snowing?
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Ground light (and perhaps moon light, depending on the cloud cover) reflects off the white snow that is in the process of falling, making the sky look bright.
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I guess if you live in a very light poluted area, and it snows, the snow scatters the light all over the place as it is crystals of frozen water. The have a refraction index and can redirect light so it might appear brighter. The same reason the winters with snow are usually brighter than the ones without. Asphalt absorbs most of the light, snow reflects most of the light. **This is my most educated guess!**
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If nothing can escape a black hole, how come there are two jets coming out of it?
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The polar jets associated with an active black hole aren't actually coming out of the black hole itself - they're formed by the accretion disk of matter falling towards the black hole. Some of that matter is accelerated and energised by the gravity of the black hole and blasted away from the accretion disk before it reaches the black hole. The black hole is the engine that drives the whole system, but most of the interesting phenomena are related to the interaction of matter around the black hole, not the hole itself.
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Jets from objects such as black holes, quasars (galaxies with a massive, luminous black hole in the center), pulsars (spinning magnetized neutron stars), etc. are very poorly understood. There are quite a few theories about what is causing the matter to be ejected -- whether it is ejected by the central object or through some sort of interaction with the accretion disk. Many of these jets are a good fraction of the speed of light which means that in order to understand them, relativity must be used. The jets often appear very collimated (focused into a beam) because the magnetic field generated by the accretion disk will interact with the jet. It's kind of a running joke in our astrophysics department that no one ever considers the effects of dust or magnetic fields because they are so difficult to fit into astronomical models.
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Why do powdered stuff seem to dissolve better in hot water?
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Heat is the vibration of molecules. The water molecules are moving around more quickly so the powder can find space more quickly and easily.
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Gasses dissolve more in colder water than hotter water. Solids on the other hand dissolve more in hot water than cold water.
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How exactly does an EMP damage electronics?
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An EMP is a large, short lived, magnetic field. A collapsing magnetic field induces a current in metal within that field, so any wires or traces in an unprotected circuit would now have induced current flowing through them. If those induced currents are more than what the circuit was designed for, it fries. More complex electronics (like integrated circuits) use lower voltages and currents, so they are easier to knock out with an EMP. Beefier, simpler high voltage cicuits, like a simple lightswitch and bulb, would require a much larger EMP to damage. This is why an EMP might fry a computer, but leave a 1956 Chevy unharmed. If you want to read how to protect against an EMP, read up on Faraday cages.
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[See here](_URL_0_). EMP is a rapidly fluctuating magnetic field, which causes fluctuating electric and magnetic fields. It can burn out transistors and other small electronic devices because of the high current it generates.
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Could diseases caused by prions, like Mad Cow (BSE), potentially be cured by some kind of human designed chaperone protein (probably modified from a heat shock protein) that could refold the prion into the correct protein structure?
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Engineering new chaperone proteins is probably a ways off. There are potentially easier ways to treat prion diseases, anyway. Essentially, susceptible protein must "nucleate", or turn into an aggregate of the prion form. This process is sufficiently slow as to be negligible in vivo, though; nucleated prion protein is what usually is responsible for infection of new cells, rather than nucleation happening anew in each cell. Existing prion aggregates are polymers, and they mostly reproduce by recruiting new susceptible protein to the ends of the polymer. According to [Masel and Jansen (2000)](_URL_1_), the most effective way to stop prion diseases is probably the use of drugs that slow down the elongation of this polymer; drugs targeted at stopping nucleation (which is presumably what new chaperone proteins would do) are likely to be too late to do anything.
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Mad cow disease and some similar brain diseases are spread by prions, which are a form on infectious protein. Prions can survive the cooking process, though for mad cow disease it is generally found in brain and spinal tissue not muscle.
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Are there specific things that can only happen while we sleep?
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There are a lot of brainwave patterns only seen during sleep, in addition sleeping lying down helps rest the heart as it doesn't have to pump as hard against gravity. The brainwave patterns/neural activity going on in sleep have primarily been linked to long-term memory as well as linking conceptual and motor skills. Other examples would include a changes in metabolic rate (you need less energy) and organ functionality. The brainwave pattern changes once you wake up, metabolic rate slowly returns, etc. Despite this there are a lot of things we still don't know about sleep but we're working on it.
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There's a chemical that your brain releases to prevent you from acting out your dreams basically a paralysing agent so when suddenly waking from your sleep that chemical is still in your system thus the paralasys effect
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