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If cooled to the same temperature, which will stay colder longer? Liquid (beer) in a can, or liquid in a bottle?
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Glass is a better insulator, so the bottle
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How do ants choose their function (e.g. soldier, worker) within the colony?
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It really depends on what species of ant you are interested in. They are a very diverse family of animals (with [over 12000 species](_URL_3_) identified). The jobs are most often determiend by [age](_URL_0_), [size](_URL_2_), or [genetics](_URL_1_). This is true for other social insects as well including bees and termites.
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Do atoms have colours?
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No. Color is a property our brain assigns to electromagnetic rays within the visible spectrum. An atom, however, can never be "seen" in visible light. The reason for this is, that the wavelength of visible light is ~400-700 nm = 4 x 10^-7 - 7 x 10^-7 m. Atoms have roughly the size of ~1Å = 1 x 10^-10 m. As you can clearly see, the shortest wavelength of visible light is still more than 3 orders of magnitudes bigger than an atom. Thus, visible light will never be able to represent Atoms. What we can do, and what we are already doing, is using particles of shorter wavelength than visible light, like electrons. This will result in an representation of Atoms in visible light, but the colors assigned to atoms on the computer display are essentially random.
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Star in the night sky got brighter than any other star and faded out in matter of seconds?
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It was likely a shooting star with a very low angle of incidence to where you were standing; i.e. it was headed right for you. (most never hit the ground)
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When I open a can of soda/pop, does the temperature decrease in the can?
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Yes it will cause a slight temperature fall. Soda cans are not at a particularly high pressure so the fall in temperature is tiny.
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If i am in a pitch black room, why do i need to close my eyes to sleep?
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As well as keeping out light, your eyelids serve as a protective barrier, and stop foreign objects entering the eye during sleep, they also help keep the eyes lubricated stopping them from drying out.
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What force caused the planets to start spinning about their axis?
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Everything spins. Essentially because everything is not *perfectly* uniform, as it falls together, it doesn't fall straight "toward" the center. It falls, but misses passing through the center and shoots off into an orbit. This is true of stuff falling into place around the sun (forming planetary orbits) and stuff falling into a planet, forming it (forming planetary rotation). This is also why *more or less* everything orbits in the same plane (a practically flat solar system), in the same direction, and generally, rotates in the same direction. (notable exceptions include Venus, which nearly doesn't rotate at all, and in fact does so "backwards" with a "day" longer than its year; and Uranus, which, for some reason, is tipped such that its pole lies almost in the same plane as its orbit)
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Can bacteria become resistant to alcohols/alcohol based hand sanitizer?
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No. The difference between antibiotics and alcohol for bacteria is like the difference between cyanide and fire for humans. It is possible for humans to some day evolve resistance to cyanide, so it no longer works as a poison. It is not, however, possible for us to become immune to being burned to death by fire. The alcohol is structurally destructive to the bacterial cells. There are some ways for them to resist limited exposure, like a fire suit for humans, but prolonged exposure will always be deadly. There is one exception to this rule: bacterial endospores can resist much more than active cells can. Endospores are the main reason that labs and hospitals use autoclaves to sterilize tools.
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Why does the water in my toilet move when it's windy outside?
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Your toilet has a vent, or stack, like [this one.](_URL_0_) Presumably, the wind causes changes in the air pressure in the stack, which results in a vibration of the water surface in the toilet.
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How come the water in the toilet bowl moves when it's windy outside?
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You may have noticed that houses will have a pipe sticking up from the roof, typically over each bathroom. That's a vent for your sewage system, and it's tied directly to the drain pipe of your toilet. Pressure changes caused by wind blowing over this pipe makes the water in your toilet move around a little.
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Einstein states that mass and energy are correlated. So something with more energy will have more mass. Why does a photon have no mass if it goes at the speed of light?
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You're probably thinking of the famous equation, E=mc^(2), but that's only the energy-mass relationship for a particle at rest. The full equation is E^(2)=m^(2)c^(4)+p^(2)c^(2). For a massless particle, like a photon, this simplifies to E^(2)=p^(2)c^(2), or, equivalently, p=E/c. A photon's energy is E=hf, where h is Planck's constant and f is the photon's frequency, and its momentum is p=h/l, where l is the photon's wavelength. Since c=fl, these agree with the relativistic equation.
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Is there anything to claim that adding a drop or two of water to scotch "opens up the flavor"?
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If it works, then you should be able to test with and without the water, and taste the difference. Do a [blind test](_URL_0_) and see. If you can't tell the difference, then you can stop watering down your scotch.
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Why does adding water to whiskey open up the flavor?
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Adding water to whiskey affects two things. 1. Cuts down on the alcohol content, so you're burned less by the alcohol and can taste more of the other flavors. 2. It releases more of the aromatics in the whiskey that are not water soluble. Smell has a huge impact on taste, so getting a bigger whiff of the aromatics helps the taste. There are a lot of other drinks you can do this with, [notably coffee.](_URL_0_)
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Does illness affect the phases of sleep in a person's sleep cycle?
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In general, the pro-inflammatory cytokines (interleukins 1 and 6, C-reactive protein, TNFa, etc.) that are released during an immune challenge will increase sleep pressure and therefore increase NREM 3, especially in the first half of the sleep opportunity. Similarly, sleep deprivation itself will increase circulating pro-inflammatory cytokines, creating further sleep pressure and increasing NREM 3 during recovery sleep. So yeah, illness will cause alterations the sleep cycle to push for more time for repairs. That said, symptoms may cause arousals that leave you stuck in N2 for more time than usual. Edit: pro-inflammatory cytokines; not hormones
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How come light travels at C speed if the earth and our universe is also moving at insane speed and rotating, doesnt this mean light on earth is faster than "outside"?
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The speed of light is a constant. This was explained by Einstein in his theory of Relativity. The speed of light is the same regardless of the speed of both the body emitting the light and the body from which the speed of light is being measured
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How can the PC open files greater than RAM?
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Well it really depends on what is in the file. It might be that not all the data from file are necessary at the moment, and they don't need to be in RAM. Also some software can perform "streaming access" to data - you can open eg. as big text file as you want, since the only part stored in RAM will be the part that is displayed on the screen (+- a bit more on both ends) and rest is read from the disk on demand.
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At what age does yawning become "contagious"?
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Possibly as early as 11 weeks after birth ([de Vries, Visser, and Prechtl, 1982](_URL_4_); couldn't find a non-pay-walled version unfortunately). However, more recent studies suggest that yawning contagion might not begin until around four or five years of age ([Anderson and Meno 2003](_URL_2_); [Helt et al. 2010](_URL_1_); [Miller and Anderson 2011](_URL_0_)), perhaps coinciding with the development of empathy / understanding emotion in others. This agrees with certain findings that children with ASD do not exhibit as much of a yawning contagion response (see the Helt et al. paper) and that they also have reduced empathetic responses (although if you get them to focus on the eyes of the person yawning, they are more likely to yawn as well). In chimps, yawning contagion also seems to develop gradually ([Madsen et al. 2013](_URL_3_)).
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Why does my internet slow down when somebody in the house is using the microwave?
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Aloha... Can I assume you are on wireless? Microwave ovens broadcast all over the wifi spectrum. As one of my many jobs, I design and maintain 3D wifi spectrum sniffing software. A microwave hits just about every wifi frequency. Edit: You would be slowing down because of interference causing rebroadcasts
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Is fluoride bad for your health?
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Occurrence of dental cavities in areas that fluoridate their water have shown an [18-60%](_URL_0_) decrease. The amount you'll find in drinking water is perfectly safe.
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Is fluoride bad for the human body?
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[Water fluoridation is safe and effective](_URL_0_). Like anything else it can be harmful if you get too much, but you aren't in danger of getting too much fluoride from municipal water, fluoride toothpaste, and visiting the dentist.
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Why does looking at bright things hurt our eyes?
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> shed some light on this It's roughly the same effect as getting a sun burn, but the photo receptors in your eyes are way more sensitive to it! The receptors, being rods and cones, have special shapes and chemical makeup that are easily affected by photons of light so that you can see. A rod cell can even detect when it is hit by a single photon of light. This happens because within that special shape the electrons are easily excitable, which triggers a cascade of other signals in which you perceive light. If these electrons are easily excitable then they are also easier to over-excite compared to your skin and start breaking/forming unwanted bonds, which yes is similar to heat energy since it causes proteins and things to become denatured (to take away or alter the natural properties). & nbsp; I hope that helped and my comment is within the rules!
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If the Big Bang brought time into existence, how did it occur in the first place?
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If you answer that question you'll win a Nobel Prize.
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Why don't antibiotics prevent secondary bacterial infections if taken prophylactically during a viral infection?
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For many reasons: 1) Which antibiotic would you take, they all don’t work against every possible bacteria. 2) Since not everyone gets a secondary infection, you would never know if it worked. 3) Using antibiotics in this way would cause a rapid increase in resistance, ultimately making the antibiotics less useful. 4) Antibiotics are not without side effects and allergies, widespread use like this would cause an increase in symptoms. Pretty much no good reason to do it.
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When you fart, the gas released is lighter than the surrounding air, indicating bouancy. Does this mean that we weigh nominally more after farting since we no longer have a gas inside our body that is slightly lighter than air?
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It depends on how rigid our bodies are. A tank of nitrogen will weigh less when you let out gas because you lost mass. If flatulence was less dense than air and your body was flexible enough that your volume decreased by the amount of gas you released, then yes you will weigh more. Keep in mind that your volume decrease likely won't be equal to the volume of gas lost because of pressure.
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How feasible is mining an asteroid?
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There are many many problems. Currently we dont have the technology to even do anything like this. We are not even close to being able to space travel, let alone carry out mining operations. If we did have the technology right now you have to realise that the platinum in the asteroid isnt a solid chunk of metal (i assume), you cant chop off a chunk and go home. Similar to how its found on earth it must be extracted from large amounts of rock. Probably the most efficient method would be to actually divert the rock to earth and have it crash. This would require some serious work to ensure nobody is hurt.
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Can anyone explain what a half-derivative means? A derivative is the slope of a function at a point, is there a definition like that for a half-derivative?
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Half derivatives are defined through Fourier transforms. If f(x) has Fourier transform g(k), then f'(x) has Fourier transform ikg(k) (for some scalings you get a 2*pi there, I'll ignore it for clarity). This is a known property for you, I hope. In general, f^\(n\) (x) (the n'th derivative), has fourier transform (ik)^n g(k), so the n'th derivative is F^-1 [(ik)^n g(k)], where F^-1 is the inverse Fourier transform. Incidentally, this expression is also valid for fractional n, assuming the inverse transform exists, so you can use this to define "fractional derivatives" of any order s: f^\(s\) = F^-1 [(ik)^s F[f]] Hope that made sense. I've only used it as a measure of regularity myself. A function f is in regularity class H^s if all of its derivatives of order s and less exist and are square integrable. A higher s means a more regular function, and it's useful to be able to talk about spaces like H^1/2 .
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Is there any significance to where a derivative equals the function?
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An important thing to realize is that the value of f at a point x is a property of the point x and only of that point while the value of the derivative at a point x is a property of it's neighbourhood and is independent from the value f(x) itself because g(x) = f(x)+1 for example has a different value but the same derivative. So it's probably no *that* interesting as long as the property f^m (x) = f^n (x) only holds for isolated points.
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Is it possible for planets and stars elsewhere in the universe to be other than spherical?
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Actually, no. The only reason our planet stays together is because of gravity. Since gravity effects celestial bodies in all possible directions evenly, the only shape it could be is _URL_0_ I want to see a cube planet, yeah. But that, according to modern physics, is impossible.
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Something I've pondered for years, with no satisfactory answer: Why are bicycles much more stable in movement than when still?
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trail angle has a lot to do with it. basically the contact patch of the tire lies behind the axis the front wheel turns about. if you lean the bike it forces the tire to steer into the fall. This is why riding with no hands is possible. Gyroscopic forces aren't really involved that much. ski-bikes for example work pretty well despite no gyroscopic forces.
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How strong telescopes do we need to see stars as a circles instead of just points?
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Taking Sirius as an example, it has an angular diameter of 0.006 arc seconds. The resolution of a telescope is roughly the ratio of the wavelength of the light you're looking with to the diameter of the telescope, so for 500 nm light you'd need a telescope about 16 meters in diameter, and bigger than this to start resolving things. This is roughly the size of the biggest optical telescopes, although with interferometry you can measure with very high resolution without needing as massive telescopes. Some big diffuse stars, like Betelgeuse, can be resolved.
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Why does snot (nasal mucus) change consistency as we progress through fighting the flu?
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The contents of the mucus changes over time. As the infection progresses you end up with dead neutrophils and bacteria as well as your own cellular debris being ejected as mucus. The green tint of your mucus when you're sick actually comes from neutrophils in the form of [myeloperoxidase](_URL_1_). Another component of mucus that makes it thicker is DNA, which is often ejected by neutrophils to form neutrophil extracellular traps (NETs). There is some [interesting work](_URL_0_) going on with cystic fibrosis and the role of neutrophils in creating the thick mucus that causes problems breathing.
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If Mars' atmosphere is predominately carbon dioxide, would it be possible to grow plants in an enclosure with proper protection from UV and dust storms?
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Mars's atmosphere is pretty close to a vacuum. It's about as dense as Earth's atmosphere [30-35 km high](_URL_0_). That's about 4 times as high as Mount Everest. The Earthly animals who reach the highest altitude (Ruppell's griffon vulture) reach about 11 km; humans require pressure suits above 19 km. I don't know about plant life, but I'm skeptical that any Earthly plants can grow at that pressure.
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How do tattoos remain if our skin cells are replaced so frequently?
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It is only the top [level of skin](_URL_0_), the epidermis, that has cells that quickly divide and are replaced. Tattoo ink is deposited in the dermis, the next layer down, in which the cells divide much more slowly. Even then, the ink will [eventually fade as the cells divide](_URL_1_), it just takes a much longer time.
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Why are song tunes much more easily remembered than the lyrics?
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While those assumptions may not apply to everyone and my answer may not be as 'sciency' but the instrumentals to music with lyrics are extremely repetitive, more so than any of the lyrics. Try playing a more classical song in your head and see if you can make it through the entire thing, I think you'll find words are easier to remember correctly.
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How is the universe ~ 78 billion light years in radius, when the universe is only 13.7 billion years old?
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1. Because the matter isn't moving that fast. Space itself is expanding. The gaps between stars and galaxies are expanding. Some bits are moving away from us faster than the speed of light. The important thing to note here is that matter isn't exceeding that speed, space is. 3. There's no center, either. Redshift increases no matter which direction you look, which implies that everything is getting farther away from everything else. 3. Your figures are focused on the observable universe. Those things that have had time to reach us at lightspeed within the age of the universe. This distance is actually larger than a 13.7b ly radius, because some of the stuff we see was within that radius way back when the light was emitted, but is now much more distant due to the aforementioned expansion of space itself.
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Why do spiders sometimes get snagged in the webs of other spiders? Wouldn't they be able to see a web and avoid it since they can spin webs themselves?
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Technically, Daddy Longlegs aren't actually spiders, they belong to an order called 'Opiliones', whereas spiders belong to the order Araneae. Both are arachnids, however. I'm not sure, but I don't think Daddy Longlegs, or Harvestmen as they're more commonly known, spin webs on any sort of regular basis. That said, spiders do indeed get caught in one another's webs--they can even get caught in their own webs, if they're not careful. Thankfully, for the spiders, it's not that hard for a spider to unstick themselves if they work on it. As for why, well... Some spiders hunt other spiders, and often times if a spider is looking for a mate, they have to enter the female's web. Further more, unless I'm mistaken, unlike jumping spiders, most web-spinning spiders tend to have fairly poor eyesight and mostly have to rely on the vibrations coming through the web.
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I was told that all the stars we see in the sky are actually galaxies, not individual stars. Is this true at all?
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No, that's really not true. Basically the only galaxies we can see are Andromeda, which is a fuzzy patch of light six times the size of the moon, and the Magellanic clouds, which looks like galaxies. There are few others that maaaaybe one could see on a very dark night.
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Why do some animals move in quick bursts (like chickens/small lizards) while others are more deliberate (like humans/bears)?
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The bigger the animal the highest is the amount of energy it takes to move. A bear would never rush like a lizard cause it would take too much energy and it's not worth in the final balance. Also, smaller animals have different metabolism, a heart rate way more higher than big animals. A horse has in average around 30 heart beats per min, a chicken has almost 200.
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Since the universe is expanding, is the space of an atom also expanding?
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I'm just thinking here: if everything expanded along with space equally, how would we know the universe is expanding?
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can there be an arctic methane release large enough to cause an extinction level event and how long would that take?
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This doesn't answer your question, but here's some info on how arctic methane relates to climate, _URL_1_
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What kind of impact do large wildfires, like the current one in Colorado, have on global warming? Would the sudden massive decrease in trees impact the amount of CO2 that stays in the air?
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The impact is two-pronged. Firstly there is the reduction in the size of the carbon sink that you alluded to. Fewer trees will mean less CO2 is 'locked up' due to being converted to glucose in photosynthesis. The second aspect to consider is the actual combustion reaction of the wood - which releases CO2. This makes sense when you consider that (polymers of) glucose and related molecules make up most of a tree's biomass. So the answer to the second part of your question is yes. Furthermore, we can link atmospheric CO2 (via climate change) to the frequency of extreme weather events such as droughts, increasing the probability of further forest fires.
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Why is the mortality rate of liver cancer so high in spite of the liver having such a great regenerative potential?
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The liver produces a version of a protein called Methionine adenosyl transferase (MAT) different from all other tissues which has a higher capacity for synthesis of a molecule called S- adenosylmethionine (SAMe). SAMe is the precursor for a number of other molecules involved in growth and repair hence why the liver has such a high regenerative capacity. In most liver cancers the Liver specific protein (MAT1) is switched to the ubiquitous MAT2 protein hence it's ability to regenerate is impaired. Interestingly this switch is also induced directly by a protein in hepatitis B explaining why patients with hepB tend to develop cirrhosis and then liver cancer.
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Does foaming make soap more effective?
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First of all, soap foams/lathers due to **foaming agents** in the soap. These are chemicals present in the soap that interact a certain way to cause the soap to foam (that's another story). These chemicals also work as **surfactants**. A surfactant reduces the surface tension of water and helps to break up oil and dirt on the skin, thereby increasing the effectiveness of the soap. Ref: _URL_0_
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Do foaming soaps work better?
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Most of the time not. The purpose of most soaps/degreasers is to form [micelles](_URL_0_) around fat, oil and dirt, so these tiny "bubbles" can "dissolve" and be carried away by water. The foaming is to give the consumer a good feeling about it, as they can see and feel it working. But the foaming does help spreading and holding the liquid in place, so it has a function in products like shaving cream, where the purpose is to keep the hair moist. Ever realized bread is a type of foam?
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How Big can a planet be?
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There is a *mass* upper limit to a planet at about 13 Jupiter masses. Above this limit are objects called Brown Dwarfs, which are capable of weak or intermittent nuclear reactions via fusion of deuterium (a heavy isotope of hydrogen), but they are too weak to be classified as stars. However, this mass limit is not the same thing as a *size* limit. Two gas giants with the same mass can vary considerably in size because one is heated more by its star than another, causing its atmosphere to expand and puff up. They can also be less dense if they are very young and have not yet fully collapsed. Also, higher masses of a gas giant can actually cause the planet to shrink due to increased gravity, at least to a certain point. While the theoretical mass limit is 13 Jupiter masses, the largest size of a planet yet detected is **HD 100546 b** with about 7 Jupiter radii and an undetermined mass.
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How big can a planet get??
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What a body accretes past a certain size gravity will trigger fusion, and the result is a star. Jupiter is big, but it is estimated it would need to be about 75 times bigger to initiate hydrogen fusion.
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Are there organisms better suited to recycling carbon dioxide into oxygen in a post-apocalyptic/off-planet scenario for human consumption than trees and if so what magnitude of efficiency do they provide?
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I believe most of the world's oxygen is produced by algae in the oceans, rather than terrestrial plants. This isn't really due to any efficiency difference so much as a difference in bulk (the oceans are huge). As far as oxygen production goes, I don't think plants are efficient enough to be utilized wide scale in something like a habitat. Instead you would probably need to use chemical means to meet and maintain oxygen requirements. This could be done through the electrolysis of water, or through the breakdown of minerals rich in bound oxygen.
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If all plant life on Earth died and stopped producing oxygen, how long until the atmosphere would no longer contain enough oxygen for most animals to survive?
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This has been asked quite a few times before. Here is one of the most recent:[If every plant on earth vanished suddenly overnight, how long would we be able to breathe before all of the oxygen were used up?](_URL_0_) I'm starting to suspect that a few professors enjoy posing this question to their classes...
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If all of our trees suddenly died on Earth, would Earth still have means of oxygen production to sustain life, or would our planet not have enough oxygen to support our living organisms?
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There are more plants in the world than just trees. About half of the world's oxygen is produced by phytoplankton in the ocean. We would be fine without trees in terms of oxygen production.
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The larger the telescope, the deeper into space we can see. Is the same true for microscopes? Can bigger microscopes see even smaller particles?
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Larger telescope can collect more light, so you can observe dimmer objects. With microscopy, we are limited by [diffraction](_URL_1_). This means the smallest subject light microscopy can reasonably resolve is ~ light wavelength/2. So somewhere ~240-250 nm, not enough for example to see most viruses or details in cellular organelles. Electrons have much shorter wavelength than visible light and that is why electron microscopy is often used to resolve small details. There are some methods allowing light/fluorescence microscopy to resolve details below the diffraction limit. These are called [Super-resolution microscopy](_URL_0_).
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What exactly is going on inside a blister?
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From the [UK National Health Service website:](_URL_0_) > > "A blister is a small pocket of fluid that forms in the upper layers of the skin. A blister usually forms when the outer layer of the skin has been damaged. Fluid collects under the damaged skin, cushioning the tissue underneath. This protects the tissue from further damage and allows it to heal. Most blisters are filled with a clear fluid called serum, which is the part of the blood that remains after red blood cells and clotting agents have been removed. However, blisters are sometimes filled with blood, (blood blisters) or pus if they become inflamed or infected. Blisters can develop anywhere on the body, but are most common on the hands and feet."
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Is there a point when a star is hot enough to undergo fusion, but does not emit light on the visible spectrum?
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At least as far as I understand it, the spectral emissions of a star are probabilistic in nature; that is, that while electromagnetic energy emissions may focus around certain wavelengths, there is a chance that a given photon can have any possible wavelength on the electromagnetic spectrum. Even a lowly brown dwarf may crap out a few gamma rays, and even some not possible star construct that emitted primarily X-rays would also emit some light in the visible spectrum according to our current known laws of physics.
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How did people deal with sunburn before sunscreen?
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They kept covered - think long sleeves and broad-brimmed hats.
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How did people avoid getting sunburned before modern sunscreen?
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I somewhat recall some documentary talking about mud being used to this effect with indigenous tribes. Clothes to cover much of bare skin also seems effective, like the common image of a man on camel's back in the desert, a white cloth wrapping his head and a long robe barely revealing any skin to the intense sun rays. Coconut oil works too. As for an applicable lotion equivalent to modern sunscreen? I'm not sure if that's a recent version of sun protection from a marketing standpoint or if its formula has been something being used in antiquity.
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Why are we able to see the cosmic microwave background? Why has the light not passed us by now?
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The cosmic microwave background is red-shifted light from when the universe first cooled down enough to allow the free passage of photons. This light was emitted everywhere, and in every direction. The entire universe is much, *much* larger than we can see (in fact, [it is probably infinite in size](_URL_0_)), so as the light from the CMB passes us, there are always photons behind it that were emitted from a slightly further away source. So technically the CMB that we measure today is from further away than CMB that was measured last year, but due to the extreme expansion of the universe since then, those photons are coming from regions of space that were right next to each other when the photons were emitted. Hope this makes sense!
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What's the difference between microwave safe and non-microwave safe plastic?
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Microwaves use microwave radiation to heat food. If the plastic absorbs microwave radiation, it will heat up and melt. If it is transparent in the microwave region of the electromagnetic spectrum, the radiation will pass through and only heat the food. It still may got hot from heat conduction from the food after that, though. Any dish that absorbs microwave radiation is not microwave safe. _URL_0_
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Do mosquitoes have positive effects in their ecosystems?
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They are a food source, along with their eggs and larva. That said, there are only certain species that bother humans. It has been theorized by responsible ecologists that yes, you could eliminate the problem species without harming the ecosystem.
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What do mosquitoes contribute to the environment?
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Besides being tasty bat, dragonfly and hummingbird food, mosquitoes primarily feed on nectar, so are useful pollinators. There may be a handful of rare orchids that are dependent on mosquitoes, and they are the primary pollinators of the cacao tree.
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Most star systems are binary. Is Jupiter a sun that never 'ignited'?
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I'm not sure if there's any more recent research, but at least as of about 2006, astronomers had concluded that, in fact, most stars are singletons, not binary or higher. You can see articles on this [here](_URL_1_) and [here](_URL_0_). The studies showed that while most bright stars were in multiple star systems, there are lots of dim stars that are singletons, which tip the overall balance the other way. As for Jupiter: It's not really close in size at all to being a star. It would have to have been about 80 times bigger for fusion to start and for it to have become a star.
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Why do I feel nauseous when I'm hungover? Isn't it too late to vomit anything harmful at that point?
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Because ethanol (alcohol) is degraded into [Acetaldehyde](_URL_0_). Which is toxic to our body; ~20-40x more toxic than ethanol itself. When you consume large quantities of alcohol, you produce large quantities of Acetaldehyde, putting your body into a toxic state. Our bodies know of a pretty dang good way to rid themselves of toxic substances: vomiting (which doesn't do anything in this case, but that is the biological response). Depending on the depth of the answer you are looking for, the complete metabolism of ethanol is described [here](_URL_2_) As an aside. A simple wiki search found this within ten seconds. [LINK](_URL_1_). I do enjoy answering science questions in a way that non-science-folk can understand, but I also believe independent discovery and research provides more learning than [/r/asksciencetospoonfeedme](/r/asksciencetospoonfeedme) can provide.
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We blame hangovers on dehydration. However, when I drink my urine is regularly clear. What is causing us to become so dehydrated resulting in hangovers?
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Inhibition of ADH (anti - diuretic hormone) while drunk allows for free flowing clear urine. This clear urine isn't the same "I'm well hydrated" sign that you think of when drinking lots of water when it's hot. In effect, you are getting rid of more fluid than your body would like, but ADH cannot regulate as effectively, and thus you wake up with the Sahara Desert being not in Africa, but in your mouth.
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What is that annoying "wind thud" noise that happens sometimes in the car when the windows are down?
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You know how you can blow across the top of a beer bottle, and make a sound? It's kind of like that. If you have just one window down, the air blowing across it can resonate the air inside of your car, causing the pressure to oscillate. The beer bottle is small, so it produces a high-pitched audible note, but the car is a lot bigger, which means the frequency is low, and you get a periodic thumping sensation instead.
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What causes the painful, pulsating sound outside of car windows to occur?
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It's probably setting up a standing-wave in the car, similar to how blowing over the opening of a bottle causes it to make a sound. Assuming it's acting as a standing wave, for a 2-meter long section, you'd see ~85 Hz, according to my quick & dirty math.
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Why can't vehicles in space accelerate to ridiculously fast speeds?
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Fuel is the reason. In a rocket propelled spacecraft, in order to make the spacecraft go faster, you have to spew hot gasses in the opposite direction. There are only two ways to increase your maximum velocity: 1) Spew more hot gasses, which requires carrying more fuel, which is expensive (and carrying more fuel also makes your fuel less effective at moving the spacecraft, because fuel has mass!) 2) Spew the hot gasses out faster. There are obvious limitations on this as well.
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Why are Galaxies a flat disk and not a sphere?
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The black hole isn't a vaccum, it doesn't suck matter in. It acts as any other massive object does, the only difference is that once you are inside it's Schwarzschild radius there is no escape. Also there reach is minor compared to the dimensions of the galaxies. Ie Galaxies are held together by their combined mass then the black hole keeping the whole system together.
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If the fusion reactions in stars don't go beyond Iron, how did the heavier elements come into being? And moreover, how did they end up on earth?
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There are a couple of processes that create elements heavier than iron. The s-process (s for 'slow') happens in large stars, where atomic nuclei capture free neutrons, increasing their mass. Occasionally they'll undergo beta decay, increasing their atomic number. This takes a long time, but because there's just so much stuff inside stars, it works out, and is responsible for about half of the atomic nuclei heavier than iron. The other half are typically created by the r-process (r for 'rapid'). This occurs when there are a lot (and I mean a lot) of free neutrons around and nuclei just soak them up. Conditions like these tend to only happen in core-collapse supernovae, and so many of these elements are created during supernovae. EDIT: Others have pointed out that we now also have evidence that suggests many heavier elements are created within neutron star collisions. I figured I should add this here since it has become a popular answer.
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Why does screaming during pain seem to make it feel less painful?
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Additional question: Why does applying pressure to the area in pain seem to help as well? For example, stubbing a toe and then pressing it against the floor to somewhat alleviate the pain.
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Is there a biological/evolutionary benefit to tickling?
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Yes. Tickling actually is much like puppies playing with each other. Your most ticklish spots are also your most vulnerable. Tickling is like practicing to defend yourself. If someone tickles your ribs, you act to cover them up and 'defend yourself' from the attack.
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How can we see the galaxy z8_GND_5296, which is 30 billion light years away from Earth if the universe is only 14 billion years old?
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This question seems to come up a lot. The idea is that the galaxy used to be closer to us (less than 14 billion light years). Light was emitted from the galaxy in the past when it was much closer. But while that light was "in transit", the universe is expanding and the galaxy got more and more distant "behind" the light it emitted. So it's 30 billion light years away *now*, but the light didn't have to travel that far.
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How do colors fade in the sun?
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It depends on what the colors are coming from exactly, but most likely the fading comes from the molecules in the pigment degrading or reacting into different colored compounds. Many organic based pigments are complex hydrocarbon molecules that have extended ring structures that are good at absorbing particular frequencies of visible light. These molecules absorb photons which puts them into a higher energy state, and they usually get rid of this energy by radiating it away as heat through vibrations. Sometimes though these higher energy states will instead react with something nearby or bonds will break and that can destroy the molecules ability to absorb the same frequency of light anymore. Inorganic pigments can have similar degradation, or they will slowly react from one compound to another in response to being near oxygen or water and plenty of energy to go from a chloride to an oxide or something similar.
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Why don't comets ever wither out?
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It's a HUGE amount of ice on them, it's gonna take a long time to slowly melt it away. And the real answer to your question is they do. Once all the ice melts off you're left with just the rocky core. An asteroid.
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Why does the recommended number of hours of daily sleep decrease as we age?
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I don't think we really know why sleep is important in the first place. People will say things like this is when brains repair themselves, but I think that's just a guess. I suspect that sleep is somehow important for learning and consolidating long-term memories, and the reason babies and young people need so much of it is because they need to be learning at much higher rates, whereas when you get older, it gets easier to coast on what you've already learned. But that's just a guess too. We have a lot to learn here.
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If friction creates heat, why does a fan cool things down? Isn't it just causing more friction by propelling and pushing air?
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Your body tends to be much hotter than the environment air due to your internal metabolism producing heat. The fan sends much cooler air at you. It does heat the air up some small amount but this tends to be a much smaller effect than your body temperature.
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Why do we not have crystal-clear, very close-up images of the surface of Mars (or any planet) from the Hubble telescope?
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At its closest, Mars is about 40 million kilometers away. The Hubble can resolve details down to a tenth of an arcsecond, which means that it's best resolution would be an object about 20 kilometers wide.
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How come I can only see stars and other small lights in my peripheral vision?
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The periphery of the [retina](_URL_0_) is more sensitive to dim light than the center. The center has more cones, which give you color vision but are not as good at detecting light as rods. There are more rods on the periphery.
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How many photons does a star produce?
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The total power output of the sun in the form of radiation is about 4x10^26 watts. Dividing by the energy of 1 photon at the sun's peak wavelength (4x10^-19 Joules), you get roughly 10^45 photons per second, which is a pretty large number. But again, Ruiner has a good explanation for why they don't act like shooting billiard balls.
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Photon density emitted by a star?
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Very approximately, at its surface the sun outputs about 10^26 photons per square meter per second. You would have to be roughly 10^13 solar radii away to get that down to 1. That is about 700,000 lightyears, about a third of the way to Andromeda.
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Why is cosmic background radiation from the big bang only found in the microwave spectrum?
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It's not only in the microwave. Black-body radiation covers the entire spectrum, but [the intensity curve](_URL_1_) has a peak and then tapers off quickly. Ever since the emission of this radiation this curve has been red-shifted, so the peak is at the microwave part of the spectrum now. [Here's the Cosmic Background Explorer's data](_URL_0_) plotted along with the red-shifted blackbody radiation curve, as predicted by our cosmological models. You can see that the curves match precisely, and that the intensity becomes very small very quickly in the rest of the spectrum.
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Tomorrow we find out that Pi is not infinite. What implications would that have?
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We don't think pi is infinite because we can't find the end with a computer. It is provably, incontrovertibly infinite. That is not happening tomorrow, or any time. Mathematical proofs are not like scientific theories that can be challenged by observations. The implication, I suppose, is that everything we've done since Euclid (or since 1761 to be less general) has been wrong. _URL_0_
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Why are camera lenses always round if they take square/rectangular pictures?
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The reason cameras produce rectangular pictures, because it’s easier and more cost effective to produce a rectangular sensor and work with pictures it produces. As for the lens, they require very precise manufacturing to work well. It is much easier to manufacture a surface with complete angular symmetry, rather than some arbitrary shape. In cases where non round shape is preferable, like eyeglasses, it is easier to cut the required shape out of the round lens. There are some reasons, why camera lens are rarely cut to non round shapes. The only benefit of such cut would be reduced size and weght. However, disadvantages are more numerous and important for many uses: increased cost, the use of helicoids for focusing and zoom requires cylindrical assembly anyway, lens would collect less light, the shape of defocused areas would be less appealing.
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Is it possible to get drunk by undergoing alcohol enemas, and still be able to pass a breathalyzer test?
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I don't think so, but I'm not an expert. Breathalyzers test for expelled blood gases coming from the lungs, not for things like remnants of alcohol in the mouth. (These can interfere with readings but that's not the point of the test.) Since you would still be absorbing alcohol into your bloodstream, it would still show up on the breathalyzer. If you mean blowing under the legal limit by "pass," then it might be easier to ingest your alcohol traditionally, in moderation. Alcohol enemas result in incredibly quick absorption and you can easily overdose.
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Why is there a breathalizer test for alcohol levels but there isnt one for any other drugs? Do other drugs not escape through the lungs like alcohol, and why does alcohol exit the lungs?
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Breathalyzer tests detect the presence of acetaldehydes that are the result of alcohol being metabolized and are passed easily out through the lungs. Other drugs just don't result in the same sort of molecules. The metabolites of THC are present in urine for weeks and that's what the tests look for.
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Could you shoot a gun in space?
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yes because the gunpowder contains its own oxygen, similar to how rocket fuel has oxygen in it so it will work in an oxygen free enviroment.
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Why do space ships enter the atmosphere at such a high speed? Would it be possible to "ride" a thruster straight down to the ground?
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Give Kerbal Space Program a try, you will be surprised what you can learn about aerospace design principles just thru trial and error.
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Why can't an object/ship in stationary orbit just use thrusters to descend straight down in a controlled manner?
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Because while it has the same angular velocity in stationary orbit, it has vastly different linear velocity. Both are going around 7E-5 radians per second, but the ship is going around 3000 m/s while the surface moves at around 460 m/s. Which means a big change in velocity, its just more effective to use the atmosphere to slow you down than to use a whole bunch of fuel to slow you down. But that being said it is possible to follow a path that would look like its coming straight down, but you would have to pay for all that 2500 m/s delta V yourself instead of using the air.
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Can a tidally locked planet still rotate on an axis if its pole is pointed at its star?
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Hm, the poles of astronomical bodies are where the axis of rotation meets their surface. For an object to be tidally locked to another, its axis of rotation must be perpendicular to its orbital plane... so the pole of a planet tidally locked to a star cannot be pointed at the star. In other words, if you draw the orbit on a piece of paper as a circle, the axis of rotation of the planet must be pointing out of the paper, otherwise the planet won't be able to rotate so that the same face always faces the star.
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Do trees die of old age? Is it common? If I plant 100 trees of the same type in the same area, will most of them die around the same time?
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Trees die of old age. Palms for instance only have about a 50 year life expectancy. Alaska Red Cedar can live up to 3500 years and some trees are even older, there is a 5000 year old tree somewhere i believe. & #x200B; If you have 10 palms, some will die after 40 years and some will die at the age of 60. They can die of sickness too just like animals, and just like animals they all have variation in genetics, strengths and weaknesses. & #x200B;
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Are there any problems in Computer Science that *can't* be solved with classical computers but *can* be solved with quantum computers?
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Not that we know of. Computational Complexity problems are all solvable with different kinds of resources. For example, problems in EXP take exponential space and time to solve, but are still 'solvable' in the sense that you are describing. The class of problems that are 'unsolvable' are known as 'undecidable'. And no, quantum computers are not known or believed to be able to solve undecidable problems.
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Are there any real quantum computers that have actually solved any problems that conventional computers could not have?
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Two parts of this question. Firstly, a classical computer can solve any problem a quantum computer can given enough time and space. The time may be exponential, but the space is known to be polynomial. In very rough terms it means that if you are patient enough you can get you normal computer to do anything a quantum computer can. Secondly, are there any problems quantum computers have solved that classical haven't been able to solve because of time or space constraints? My answer would be no. Quantum computers are still very much in their infancy. D-wave claims otherwise, but it's complete garbage. but that's a story for another day
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Does a car run more efficiently on a full tank vs. a half-full tank?
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The less gas in the tank the less the mass you have to lug around meaning it is always more efficient to carry less. That being said a full tank of gas weighs about 100lbs while a car weighs 4,000lbs so the difference in efficient is quite small. About 1% at a 1/2 tank assuming 20mpg.
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Can candle light make your body produce vitamin D just like the sun? If not, why not?
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We know candles are insufficient because people still suffered from vitamin D deficiency when they had plenty of candles. Photons from candles are not individually energetic enough to cause the necessary chemical reaction. This is determined by the color of the photons, with red being low-energy and blue being high. Sunlight has very energetic ultraviolet photons in its mix, while candles do not reach into the blue spectrum. Synthesis of vitamin D in the skin requires UVB, which simply does not exist in candlelight, so even if you had enough candles to rival the sun's brightness you would still get rickets.
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Why do we get vitamin D from the sun? Could we make a light that gives off vitamin D?
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Vitamin D is produced in the skin in a reaction that is triggered by exposure to UVB radiation, which is a particular subset of the UV spectrum. So we don't get vitamin D from the Sun, but rather get the necessary component to make it ourselves from the Sun. UVB light can be produced artificially, so in principle you could build a replacement for the Sun when it comes to vitamin D production. However, UVB light is also one of the main contributors to sunburn and skin cancer. Therefore it's considered better to provide vitamin D in the form of oral supplements for those that need it.
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How long does it take UV rays absorbed by your skin to be converted to vitamin D?
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The conversion is is pretty well finished in an hour, and absorption is rapid. But your skin doesn’t hold much of the precursor to vitamin D. So the best way to get more vitamin D from the sun is to lay in the sun with as much of your skin exposed as possible for about an hour. Note that sun from behind a window is nearly useless, as it blocks the necessary wavelengths. Alternatively, look into a vitamin D supplement and/or increasing your calcium intake. One of those may offer a faster resolution to your problems, but it depends on what is actually going wrong.
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Why does looking at a computer screen for a prolonged period of time make your eyes bloodshot?
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You're not blinking as much as you normally would.
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Would trash decompose in outer space?
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Well, I think this is essentially identical to putting some item in an extremely high quality vacuum and waiting to see if anything happens. All the volatile gases will escape. Water will go away. Volatile components of plastics will escape into space. Heavier oils and solvents will start to disappear. In other words, the trash will undergo an extensive outgassing. I suppose some residual colonies of anaerobic bacteria hiding in some microcosm of the trash that isn't directly exposed to space could do some decomposition, but generally speaking, I think the rate at which desiccation will happen is fast enough that this effect is essentially negligible. The stuff that is left will be at the mercy of whatever random particles and energy that the lonely floating trash is exposed to. On occasion some chemical bonds will break, but this will happen awfully slowly. Space is pretty cold, and pretty empty!
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Did dinosaurs shed their skin?
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No. If anything, research has shown that many dinosaurs likely had feathers, meaning they might have molted, but not shed their skin.
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Did dinosaurs shed their skin like modern reptiles?
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There's no way of knowing for sure, however, evidence suggests that [all Jurassic dinosaurs had feathers](_URL_0_). The fossil discovery was from the *ornithschian* branch of dinosaurs; we already knew that *saurischian* branch dinosaurs had feathers. Therefore, a common ancestor of both must have had feathers. Since birds don't shed their skin, it's likely that dinosaurs, at least from the Jurassic Period and later, did not shed skin either. Edited to add: Dinosaurs descend from archosaurs, which are more closely related to crocodiles, who also do not shed skin.
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I looked on google, couldn't find. How does a water cooler dispenser not leak where the bottle connects to the dispenser?
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Air pressure is preventing the water from emptying out of the bottle. The neck of the bottle extends into the reservoir below. Once the reservoir fills to the point where the water level reaches the bottle opening, no further air can move into the bottle to replace the water being emptied and a slight vacuum forms within the bottle as a little more water empties. Eventually, an equilibrium is reached in which the external air pressure acting on the water in the reservoir (this is transferred to the bottle opening, plus a little bit extra for the height of the water in the reservoir above the bottle opening) counteracts the pressure at the opening due to the weight of water in the bottle (and reduced air pressure within the bottle) and no more water empties.
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Is "blacking out" directly caused by alcohol or is it some sort of defense mechanism? If so why does it happen and how?
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It is caused by ethanol binding to GABA-A receptors in the brain (and to a lesser degree a number of others), which causes an inhibitory effect in neural activity. Alcohol tends to selectively affect the cortical regions of the brain first, those more tied to higher reasoning and thought, which is why the first few drinks tend to make people "think less" about what they're doing and become more sociable. After a while, the ethanol starts to affect deeper brain regions, those responsible for balance (being unsteady), speech (slurring), and eventually memory -- the hippocampus region. If one drinks enough, they pass out entirely. The danger is when alcohol concentrations are so high that the ethanol starts to inhibit more vital brain regions affecting breathing and the heart.
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What does "blacking out" from alcohol actually mean?
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i'm drunk right now. not blacked out. here's my question...how do some people build tolerance to alcohol?
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