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Why does bread get moldy but crackers and chips don't?
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Bread has a higher moisture content than crackers or chips. Mold needs a moist environment to grow. If you leave bread out of its bag for long enough, it will dry out instead of getting moldy.
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Why doesn't alcohol kill cells in our body?
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Concentration. When we drink alcohol we usually start to notice behavioural changes around 0.03-0.059 % and most humans are dead at more than 0.4% concentration of alcohol in our blood. The concetrations of alcohol that used for disinfectant purposes is > 70%. We would be long dead before we can reach such concentrations in our tissues.
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Why chickenpox symptoms tend to be worse in adults than in children?
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After a bit of research, it looks like it’s due to where the virus is. As you may know, chicken pox and shingles are both caused by the varicella-zoster virus. In children, the virus is often inhaled and travels through the bloodstream to the skin, where it causes the typical rash. From here, it travels to the nerve tissues, where it lies dormant until adulthood, when it reappears and causes shingles. The difference between the two, that I can tell, is that chicken pox is an infection of the skin, whereas shingles is an infection of the nerves. This is why shingles is more painful. [Here is where I got my info](_URL_1_) A little bit more research shows that the main cause of nerve pain in adults is the immune system attacking the infected cells. In children, who are immunologically naive to the virus (they haven’t seen it before) this doesn’t happen. [Source](_URL_0_)
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Why do our eyes not move smoothly?
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This is a rather complicated aspect of neuroscience, but a good starting point would be the two separate neural pathways for eye movement - [saccadic](_URL_2_) and [smooth pursuit](_URL_0_). The former describes the jerky eye motion for controlled gaze shifts, and is mediated by the [paramedian pontine reticular formation](_URL_3_), frontal eye fields, superior colliculus, and parietal cortex. The last region is notable because that is where much of your attention and orientation responses are based. The latter describes your smooth eye motion following a moving object, and is mediated by regions of the temporal cortex of the brain, which project to the frontal eye fields and the flocculus and vermis of the [cerebellum](_URL_4_). [More general reading here](_URL_1_).
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Are there planets outside of galaxies?
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Are there extragalactic exoplanets? Probably. Have we ever found one? No. The image in [this](_URL_0_) _URL_2_ article shows that we have really only found exoplanets in a very small region of our local galactic neighborhood. As for planets not bound to stars, we do know those exist. They very likely formed around a star like other planets but were ejected from the system. The [Wikipedia article](_URL_1_) has a list of known *rogue planets*. I recommend you check it out!
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Why do I look different in the mirror than on photos/videos?
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A camera rotates the image and looks like the view another person has of you. A mirror on the other hand inverts the image in the plane parallel to your line of sight, which keeps the left on the left and the right on the right but turns them inside out.
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Why do I look different on my camera than I do in the mirror? Which is what I most closely look like in person?
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When the camera digitizes the image, it interprets the colors differently than real life. In addition, each screen displays the represented colors differently. Have you ever been in a Best Buy and the same movie is playing on 100 TVs, yet the colors and luminosity varies drastically?
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If CO2 levels in the air are increasing, isn't that a good thing for plants? Will we see more vegetation in coming decades (deforestation and habitat destruction notwithstanding)?
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[Article](_URL_1_) A few notes from the article: * Rainfall will drop * Plants will 'migrate' to new geographic locations * As an example, poison ivy is prospering, and its 'poison' is more potent. * It seems as though the consensus is more for locational effects.
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Will chemistry ever be able to produce gold in a lab?Do we know how gold is formed?
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Gold and other heavy elements are thought to be formed naturally in supernovae. Other elements can be transmuted to gold in the lab, but this is extremely impractical and expensive even for very tiny amounts. But this falls within the realm of nuclear physics and not chemistry. [Here](_URL_0_) is a good article about it.
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Why do the females of a species tend to live longer than the males?
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[Here is quite a nice review detailing female longevity in animals](_URL_0_)
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When standing on Earth, the moon is about as wide as your thumb held at arms length. But pictures of Earth from the moon appear the same size. Why? Shouldn't it be 3.68 times larger?
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If you're on the moon and stick your thumb out then yes, it will look 3.68 times larger.
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Do flies and other seemingly hyper-fast insects perceive time differently than humans?
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Do they perceive time at all? Or do they operate on a level that's purely reflex?
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Do flies and other animals with higher fps see things going slower, and does that mean that their perception of time is different from ours and that they in their own mind "live longer"?
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Brains and eyes do not have a frame rate.
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Is there a difference in skin cancer risk from getting a sunburn versus tanning?
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I can't find a specific paper studying this, but the answer is fairly clear from a practicing dermatological perspective; [there is no such thing as a "safe" amount of tanning.]( _URL_1_) Simply in terms of absolute UV exposure over time, frequent tanning results in higher UV exposure compared to infrequent sunburns. Every time you are exposed to UV radiation you are playing a probabilistic game about whether your skin cells will be able to survive the electromagnetic bombardment their DNA is receiving, both of UV-A and UV-B. [Tanning **does not** fully protect against oxidative stress on skin cells due to UV-A radiation and **provides no significant protection** against UV-B radiation.]( _URL_0_) As long as the total UV exposure of the tanned person exceeds the total UV exposure of the sunburnt person over time, then the tanner will most likely have a higher risk of developing skin cancer at some point in their life.
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When aluminium cans are melted, what happens to the color?
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Colored dyes are mostly organic compounds which revert to their basic elements (eg. carbon, hydrogen, oxygen, nitrogen) when they are heated up enough.
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Does drinking alcohol kill off viruses and other diseases in your system by any amount?
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No, the concentration of ethanol needed to kills microbes in large quantities is over 60%. You would be *long* dead via alcohol poisoning before that happened. Furthermore, alcohol is not very good at killing microbes in a system such as your body (or a cell plate in a bio lab), hence why other chemicals are used for this purpose.
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When I look at the night sky I see hundreds of stars. How can photons that have had enough energy to travel billions of miles from a distant star to my eye be weak enough not to burn out my photoreceptor cells?
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Put simply, it doesn't take much energy to do that. Remember those photons were simply traveling through space with nothing to slow them down or stop them over time so they just kept on going with the bit of energy they had always had until they reached you.
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Is it Possible for a Planet to be made up Entirely of Liquid
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Do you mean a 'planet' covered in liquid or something completely liquid? It's possible but the chances are very small and the planet/oid that would be made would have to be incredibly small do to the density of the liquid in question it might be too massive and unstable since it will constantly be shifting. What would it's core be made of? A denser liquid? When I think of it it just seems mindboggling to even imagine an all liquid planet without it collapsing and forming huge fluctuations on the surface... Great question... I wonder the same thing a lot of the time!
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Does the amount of stuff in my fridge change the amount of energy needed to keep it all cold?
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The fridge must run the compressor to pump out any heat that has leaked in. The can of soda doesn't magically produce new heat, so it does not require more compressor time to keep cold. The only thing that matters is the difference in temperature between the fridge and the outside, and how well insulated that barrier is. Assuming, of course, that the fridge door is never opened. There is some small effect when the door is opened a lot. The presence of more solids in the fridge means that less volume of warm air can enter when the door is opened, whose heat must then be pumped out by the compressor. So in that sense, it probably takes slightly less energy to keep a fridge cold with an already-cold soda can in it.
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If the universe is expanding faster than the speed of light, how is it possible that we are on a collision course with Andromeda Galaxy?
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In response to the second part of the question, the space within the visible universe is not travelling faster than light so light is still able to make it to us. The expansion does have an effect on the light though. The further away and object is the more the light gets stretched out and the more red it appears. The furthest galaxies we can see now appear infrared even though they emitted light in visible wavelengths. The furthest thing we can see, the cosmic microwave background radiation, started out ultraviolet and is now stretched to microwave. The expansion rate is about 70km/second per Mega parsec. Eventually the CMB will be coming from a point in space that is moving away from us faster than the speed of light and we will no longer be able to see it. Well beyond our lifetimes. The vast majority of stars you can see are within our galaxy anyway. Being gravitationally bound to the galaxy means they are not being dragged away by the expansion of space. Same deal as Andromeda.
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Why don't more CPU's have a greater number of cores? Is there a maximum size that a chip can be?
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It boils down to Amdahl's Law _URL_0_ " .... It is often used in parallel computing to predict the theoretical maximum speedup using multiple processors." within the context that only certain classes of problems can be fully parallelized (graphic problems being a good example). Even then, there is inevitably a need to synchronize tasks, access I/O, etc.. At the end of the day, there is a decreasing benefit from adding more cores, except in a narrow class of problems. "General Purpose" CPUs are just that - general purpose - and an attempt is made to made them optimal from a cost and performance perspective across the classes of problems they will likely encounter.
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Why don't computer processors have smaller, simpler, more numerous cores?
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There are lots of computer processors like that. They're usually used as [graphics processing units](_URL_1_) because graphics processing is easily adapted to utilize multiple cores. A modern, high-end graphics card can have more than 2500 cores. But for other types of computing, multiple cores don't work very well. Lots of modern software still has difficulty fully utilizing the four cores available to them. The problem of diving a computing problem to be worked on by multiple cores is called [parallelization](_URL_0_). For some problems (like graphics or rendering), parallelizing the problem is easy. For most other problems, it's more difficult and not worth the effort. For this reason, computer CPUs have far fewer but more powerful cores.
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How does Lactose Intolerance work? And can it regress, or the level of tolerance fluctuate throughout your life?
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The ability to metabolize lactose is dependent on a protein called lactase. Those who have a non-functional version or decreased levels of the protein would be unable to digest lactose, so it would instead be "digested" by bacteria in the gut, which would then produce gas in the form of methane. This explains the symptoms of lactose intolerance. The activity and presence of lactase varies significantly throughout your life. Most infants have the ability to digest lactose, but this activity decreases as you age. The great majority of the world adult population is unable to digest lactose in great quantities, such as that found in milk, with the exception of populations from Northern European origin, where presumably high levels of lactase activity evolved to allow milk drinking late into adulthood. Your example of intermittent lactose intolerance is not something I've heard of before, but almost anything is possible when it comes to the human body. TL;DR: Yes, probably.
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When the sun expands, what will happen to the gaseous planets?
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There's a nice summary of what will happen in the late stages of the solar system [here](_URL_0_). The various planets will move further out as the Sun sheds mass. The gas giants will be far enough out not to be engulfed by the Sun. However, due to the expansion of the Sun, the region of Jupiter and Saturn and possibly out to Neptune will become warm enough to allow liquid water to exist. This push outward of the so-called habitable zone would likely have its greatest impact on the some of the moons of the gas giants, creating environments in some cases suitable for the formation of life. Later, as the Sun becomes a white dwarf, those regions will become too cold for liquid water again. The fuller account in the link I gave is worth reading. It's a nicely presented description of what will happen.
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Is there an actual reason the Sun and the Moon are the same size in the sky?
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It is a coincidence. Both of them fluctuate in apparent size throughout the year, so they're not always the exact same size (which is why there are different kinds of solar eclipses). The moon is gradually getting farther away and the sun is gradually getting bigger, so eventually they won't be as close in size.
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Is there any advantage that micro-arrays have over RNA sequencing?
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Microarrays are cheaper. My local microarray facility charges $525 (Canadian) for a microarray to measure mouse or human gene expression while RNA-seq is about $800 per sample and you usually have to do several samples at a time. The pipelines for analyzing microarrays have been around for a long time and are pretty standardized, RNA-seq analysis isn't totally settled yet, for example new alignment and analysis programs are being published all the time.
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Why do most objects in the night sky (stars and planets) look to be the same size relative to our naked eyes?
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This is because of the concept of angular resolution. Basically, any given aperture has a smallest possible angle that it can resolve, with the size of the angle being directly related to the size of the aperture. In our case the aperture is our eye, and it can see things of approximately an arcsecond or larger. Anything smaller than that, i.e. Stars, planets, etc. appears to be that size, regardless of how small it actually is because our eye simply can't bring it into focus on our retina at the true size. The light is blurred out to this minimum resolution, and thus most stars look the same size. Edit: The bigger the aperture, the smaller the size it can resolve as well. This is why we build telescopes with huge mirrors. On earth they are also limited by what is called seeing, but in space, telescopes can be made bigger and bigger and the image will become clearer and clearer. (In theory)
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Are there any other animals besides humans that can commit suicide?
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Parrots self mutilate out of boredom, just an interesting little fact.
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Why do erupting volcanoes sometimes cause such spectacular lightning?
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It produces lightning in basically the same way that thunderstorms do. It's a release of the accumulated static charge. Volcanic "ash" is actually a large cloud of rock dust. These particles bump against each other until they build up enough charge to release a spark. It's the same as when you rub your feet on the carpet except for a much larger spark. And snowstorms can produce lightning, it's just very rare. They actually have a name for it; thundersnow. It's really, really cool to experience. It almost sounds like an avalanche because the reverberations are muffled by the snow. You don't hear a sharp crack and the echos. It's more of a deep rumble from out of nowhere.
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What is the smell that metal smells? Is it actual metal that gets up your nose, or is it some effect the metal have on the air?
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The smell is not actual metal. Metals aid the oxidation of lipids on the surface of skin which results in the production of a compound called [Oct-1-en-3-one](_URL_1_), and this is the compound which has the recognizable "metal" smell. Similar compounds are responsible for the distinctive [smell of blood](_URL_0_).
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If at the time of the Big Bang everything was infinitely dense, why didn't it just create a black hole?
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See [here](_URL_0_) or [here](_URL_1_) for detailed discussion of this. The basic idea is that the universe was highly uniform at that time; as a result, at any given point the net gravitational force balanced out, which means there were no central points into which collapse could occur.
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What is happening when food becomes freezer burned?
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Are you asking about the taste or the dried out texture? I have no answer about why freezer food sometimes has "that taste." As to why food dries out: ice sublimes: goes directly from solid to gas like carbon dioxide AKA "dry ice". You can usually see it redeposited on the inside of the container. Over time enough frozen water leaves the food that it dries out. Only deep-freezing prevents this. The temperature has to be low enough that the vapor pressure of ice - that is, the amount that turns into a gas - is reduced. Usually significantly below 0 celsius or 32 F the freezing point of pure water.
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[[biology]] For bathroom sinks that are adjacent to a toilet - If toilets aerosolize bacteria when flushed, and those bacteria can land on shaving implements, why aren't infections from shaving/razor cuts more common place?
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I don't know a lot about airborne contamination from toilet flushing but I'm a little sceptical about the terrible danger that it has been proposed to be. Anyway, bacterial pathogens must reach a certain threshold amount of cells in order to cause an infection. This number depends on the host, the pathogen in question and the site of infection. For many pathogens, this number is reasonably high and therefore a minor contamination of items like razors may not be enough to cause an infection when you cut yourself.
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Does sighing actually relieve stress?
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Many people do not consciously breathe or relax during the day, while they're engaged with other things, and the sigh may be a time when for the first time that day you decide to take a full breath and relax your muscles (shoulders tend to be the worst offenders here, if you're holding them up higher than they rest while relaxed, that's tension). This is an exercise/martial arts perspective, I don't know about any neurochemistry or physiology relating to it but it's such a ubiquitous gesture across people/cultures (like yawning) that there's probably something there.
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I you were given alcohol intravenously, would you still fail a breath test at the same rate as oral ingestion?
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You would fail it much more quickly. BAC measured by using a breathalyzer is measuring the alcohol content in the air you exhale. The alcohol you drink gets absorbed through your GI system, gets into the blood, then goes into the lungs. While the blood in the lungs is picking up O2 and dropping off CO2, ethanol also makes it out of the blood and into the lungs. That is then measured and approximated to figure out your blood alcohol level. So if you give alcohol IV, you eliminate the absorption time required by the GI system.
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What causes people to see hallucinations?
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There's a lot of different potential causes for hallucinations... but what a hallucination is, is a false sensory experience, they're not just limited to vision. For example you can have auditory hallucinations of even hallucinations based on the sense of smell. They have such causes as: drugs, sleep disturbances, neurological conditions and psychosis (mental illness). edit: typo
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What exactly happens to the molecules when an object is bleached? Why does it lose its color?
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Colour in organic molecules is mostly due to staggered double and single bonds that resonate. Normal double or single bonds do not absorb photons in the visible spectrum. Bleaching agents are usually strong oxidizers that oxidize the double bonds. This leads to a loss of resonance and the molecule no longer absorbs visible light.
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Why do storm clouds appear darker than normal daily clouds?
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When you see a cloud, you're only seeing it because it's illuminated from the sunlight above. As the cloud becomes denser it obstructs more light until what you're seeing underneath is essentially a shadow. If you view that same cloud from outer space it wont look dark since the cloud is no longer in between you and the Sun.
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Why can't we move our toes as easily as our fingers?
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There is a number of reasons, not the least of which is the lack of an opposable digit. The thumb has significant special muscles (the thenar group) to aid in movements like opposition/adduction. On a deeper level though you are probably asking why don't we have the similar feeling of fine control over our feet as our hands? The answer for this is in our brains. The motor cortex is divided up into regions specific to body parts, and the hand region is huge.... It makes up maybe 25% of the motor control volume. See [here](_URL_0_). The evolutionary pressure for this should be obvious, on the ground feet are not useful in the same way as hands.
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What is aging caused by?
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We don't know what causes aging. Here is a list of the many theories [link](_URL_0_).
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How is it that some mental disorders appear at a certain age? How can someone be fine one day and then have OCD the next?
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For many disorders, they have age of onset tied to brain development and maturation. For example, schizophrenia, characterized by disorganized thought, has an age of onset in the 20s. This matches with the mylination of the frontal lobe. Similarly, Alzheimer's is thought to be a maladaptive brain process, where some of the plaques and tangles are useful and often created when your brain is younger, but perhaps aren't cleared when you are older. Finally, some disorders like autism are thought to be present in early life, but the symptoms are not observed until socialization begins. Of course, the above are examples of theories that have been presented to the field, all three disorders do not have clear etiology.
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Why can't we use animal embryonic stem cells?
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> presumably reducing the chance of rejection one of the biggest reasons for why we would want to use stem cells is to *prevent* rejection. if i donate my kidney to some guy, he will have to take immusuppressor drugs *for the rest of his life*. and we are the same species! if he got a monkey's kidney, then it would be an even worse rejection. the same thing would happen to animal stem cells. as a matter of fact, animal contamination in stem cells is a massive problem in research. at the moment, all of the NIH sanctioned human stem cell lines were just *grown* on a "rug" of mouse fibroblast cells (you have to do this, so that they stay stem cells). just the fact that they were *grown* on mouse cells is a large enough amount of contamination that we don't inject them into people. so if human stem cells grown with animal cells are bad, then animal stem cells themselves are much, much worse.
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Are all stem cells the same across species or can humans only use human stem cells? If so, what stops us from substituting animal stem cells in place of human ones?
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Stem cells are still species-specific. Mouse stem cells will cause an immune response when implanted into rats, for example. You can try to engineer the stem cells to be less immunogenic, try to immunosuppress the individual you're putting them into, try to tolerogenize the individual to the stem cells (hypothetically; I don't think anyone is doing this yet), or you could go a totally different route and bypass the problem by using the patient's own adult stem cells or make induced pluripotent stem cells.
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How prevalent was skin cancer in pre-historic times?
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> How prevalent was skin cancer in pre-historic times? A very interesting question but unfortunately not one that we can answer. Cancer prevalence is well studied in the modern era, thanks to extensive databases like [SEER](_URL_1_). What little information we know about cancer in antiquity is only due to the signs that can survive thousands of years of degradation. All we can say is that skin cancer was *present* in older times. The earliest known examples of melanoma are from a group of Incan mummies excavated in the 1960's. They had deposits in their bones consistent with metastatic melanoma. You can read [this paper](_URL_0_) or [this paper](_URL_2_) for more info.
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Why is skin cancer more prevalent now than in ancient times?
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Because tigers kill faster than skin cancer. Because cancer — any cancer, not just skin cancer — generally takes a long time to kill; cancer is a disorder of genetics, and takes several cumulative mutations before it manifests, and even then many cancers kill you relatively slowly. Life expectancy in ancient times was pretty low, because many things kill much faster — including treatable conditions, preventable conditions, treatable trauma, etc — and so you'd typically die before any cancer might kill you or even manifest at all.
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There will be an annular solar eclipse tomorrow, and in my area, 84% of the sun will be hidden by the moon. Is this enough to cause the sky to darken, as in the stereotypical eclipse?
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No, even in areas where less of the sun can be seen this will not darken the sky, because an annular solar eclipse is caused from the moons diameter not being big enough from earths perspective to fully cover the sun, otherwise it would be called a total solar _URL_0_'s called an annular because of the Latin word for little ring, annulus which it sort of makes the sun look like. ( sorry for the weird wording)
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Would Earth have been able to support life if it was the size of Neptune? If so, what about Saturn or Jupiter?
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You need to clarify your question a little bit before you can expect a good answer. When you say "the size of" i assume you mean radially etc, but do you also mean similar mass? or do you mean a planet composed of materials similar to earth that has the same radius as neptune/staurn/jupiter.
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If we eventually start mining asteroids, will their added weight on the Earth affect the Earth in any way?
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In any way, technically yes, but the amount is so small as to be practically unmeasurable. The mass of the entire asteroid belt is ~10^21 kg (which is 4% of the moon). The Earth's mass is 6 x 10^24 kg. So even if we brought the entire asteroid belt to the surface of the Earth (in a controlled method of course), the increase in mass would be 0.017%. We'll never bring that much mass down, but even a trillion kg (10^12) asteroid (which would be about 700 m across) would be a part per trillion increase in the mass of the Earth. That would never be noticed.
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Why are Quebec and Ontario so full of little lakes?
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They are the remnants of the glacier that covered the area during the last ice age, along with the generally undulating terrain. The system is not in equilibrium - the water is very gradually escaping. For example the great lakes are constantly shrinking, and in approximately 150,000 years, they will be all but gone.
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Why does Canada appear to have so many more sizable lakes than the USA?
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It's largely due to the fact that a large part of Canada is underlain by old igneous and metamorphic rocks that make up the [Canadian Shield.](_URL_0_) Water doesn't really seep into crystalline basement rock the way it can with a sedimentary basin to form aquifers. For example, look at [this map.](_URL_1_) Notice how there's a lot of lakes in the region of Canada that's colored in red (the Canadian Shield) but not as many in the region colored in green (the Western Canadian Sedimentary Basin)? Of course, the other big factor is the glaciers you mentioned. Continental glaciers, or ice sheets like those found in Greenland and Antarctica today, scoured most of Canada (East of the Rockies) flat and stripped away much of the soil that was on top of the Canadian Shield. Water collected in the numerous large scale groves and indentations in the bedrock by the glaciers after their "retreat", hence there are countless lakes.
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Can planets have liquid atmospheres?
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A lack of surface pressure will cause the liquid to evaporate and create a gaseous atmosphere (or, if the planet doesn't have enough gravity to hang onto the gas, then the gas will escape into space over time).
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Why did whales develop horizontal tails and fish develop vertical tails?
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Exactly. Whales and dolphins are descended from herbivorous land mammals, probably hippo-like. Land mammals, like us, have differently shaped spines - not like fish spines at all. Because of the way our spines work, it is more efficient for them to move vertically than horizontally. Get in a pool and try it both ways. Whale tails and fish tails are different because of convergent evolution. Like bird wings and bat wings. Not due to ancestry. That's why sharks (who share common ancestors with fish) have vertical tails, like they would.
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Do animals that develop thicker coats for winter depend on the temperature for it to occur?
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Not necessarily. If you have an indoor cat in a perfectly climate controlled house, you would still expect it's coat to change despite the temperature of the house not changing. Most animals that experience this change (among many other physical processes!) do it via light cues. Less day length results inane animals undergoing a change in the thickness of their coat. This is why many animals have a specific mating season as well!
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Do animals shed their winter coats at the same time every year? Or does it depend on whether it's actually getting warmer outside?
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It's fairly consistent - the primary driver is steadily increasing light levels. Temperature and some other factors play a smaller role, but it's primarily light affecting the level of melatonin production in the pineal gland.
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why don't the stars appear red near the horizon?
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We do see this effect for the other objects. The moon is orange-tinted when close to the horizon. The same for stars, though it's near impossible to spot by eye. Human eyes have a really bad time seeing colours at low intensity and moreover the Rayleigh reddening is quite less than the variation in the actual colour of the stars. But if you track a single star in its motion during the night and study its colour you can observe it's redder closer to the horizon compatibly with Rayleigh scattering.
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How far up can a helium-filled balloon go before it bursts?
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It's a function of the difference in pressure inside/outside, the strength of the material and the size of the balloon, which determines the tension in the material. If you look at the launch of high altitude balloons, they aren't completely full at launch, so the helium can expand, keeping the internal and external pressures equal. So, the only forces on the fabric are those of the weight of the payload, the lift of the helium and the weight of the fabric.
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Do sociopaths experience empathetic yawning?
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it's not yawning, but there is a study examining mirror neuron functioning and psychopathy: those scoring highest on the "coldheartedness" scale of a psychopathy measure showed the least mirror neuron excitability when they saw videos of other people experiencing pain. Non-psychopaths / those scoring lower on coldheartedness showed much more excitability in those mirror neurons when viewing the video. source: _URL_0_
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Do Sociopaths Have Empathetic Yawns?
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Empathy can be broken down to a cognitive and affective component which are processed by two largely independent neural networks. Deficits for sociopaths typically arise in affective empathy; 'feeling' the associated emotion for the situation. Yawn contagion is theorized to be one of the simplest forms of cognitive empathy and is processed by the mirror neuron networks. Therefore, sociopaths have yawn contagion in tact but deficits in empathy arise when it involves generating the associated emotion with the cognitive appraisal of an event.
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How does insecticide work? Particularly for ants.
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The majority of ant insecticides are [Pyrethriods](_URL_0_). These, in general, cause paralysis through shutting down Na+ channels (these channels are important for passing nerve signals around your body). Interestingly, they tend not to affect humans because we have more enzymes to break it down.
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Conundrum: If time and space are identical, how can one be infinite and the other finite?
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Space and time are related to one another; they're not "identical".
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Why doesn't it hurt/damage your eyes to look at the sun during a sunrise/sunset?
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Well, you shouldn't do it for too long... but the basic premise is that the light is coming in at an angle to the earth's atmosphere, meaning that the sunlight is both scattered by a lot more air that it has to cross to get to you, and because the intensity is reduced: for instance, check out this image. _URL_0_ same thing is happening at the periphery of the terminator, not just at the poles.
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Are all modern domestic dogs descended from wolves, or were some bred using other canines, such as foxes and coyotes?
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Wolves. Canis Lupus Familiaris is descended from Canis Lupus. There are canids like the Coywolf, but they're not part of the lineage of domesticated "dogs".
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Modern descendants of wolves are referred to as "dogs". But why are some prehistoric canines like the Epicyon also referred to as "dogs" or "bone-crushing dogs", even though they appeared before wolves on the evolutionary timeline? Where do we draw the line between wolf and dog?
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Dog is a colloquial term, it doesn’t have much scientific meaning. They are both Canis lupus, they are the same species, because they can interbreed. We add familiaris to dogs because they are a subspecies of wolves, canis lupus familiaris. The animals you’re talking about are in the same Family as dogs and wolves but are also in the same Family as coyotes, dingoes, and foxes. The word dog has been applied simply because they are shaped more like a dog than they are a panther or a bear. Both of which are examples of different Families in the Order Carnivora.
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Can animals have mental disorders?
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Nobel winner Ivan Pavlov trained a dog to fear ellipses and look forward to circles. Then he showed a sequence of ellipses to the dog which more and more turned into circles, and he basically observed symptoms of a nervous breakdown in the dog. Depression in rats is usually created through forced swimming or chronic application of unpredictable electric shocks, but you can also use attack rat robots. Sources: * _URL_0_ * _URL_1_
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Do other planets in our solar system have a magnetic field like Earth?
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Yes, some do, some don't. *Mercury* has a global magnetic field similar to Earth's. *Venus* does not, probably due to its slow rotation. *Mars* does not, probably because heating in its core is too low. But scattered parts of its crust are magnetic. The gas and ice giant planets, *Jupiter, Saturn, Uranus, and Neptune* all have magnetic fields. Of the moons, only Ganymede, Jupiter's third big moon, has a self-generated global magnetic field.
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Between distant galaxies is space stretched or created to expand the universe?
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It is, in my opinion, more appropriate to say new space is being added between galaxies. But that light crossing that distance is being stretched. The way I think is apporpriate to look at space-time is that space is the set of all possible measurements you can make with a ruler, and time all possible measures on a clock. So, as the universe gets older, there are more possible measurements to make between two points. More "space" has been added.
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Stars cannot exceed a specific mass, but what would happen if a large enough GMC of more mass than the limit experienced gravitational collapse?
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The reason stars cannot exceed a specific mass is because at large enough masses stars produce so much light radiation pressure lifts off the upper layers of the star. [The Eddington Limit](_URL_0_). If a GMC starts to experience gravitational collapse onto a single point, the growing protostar should become luminous enough to blow away most of the material. If not, it's possible you form a [Quasi-star](_URL_1_), but I wouldn't take that as certain.
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Why does the moon look so big in this picture?
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They've used a very long lens, for starters. That was shot at [400mm](_URL_2_) on a crop sensor camera (basically turning it into a 640 mm lens), which makes the moon look very large in the frame. That house is well over a kilometer or more from the photographer. Have a look at [this link](_URL_0_) and compare the 70mm against the 400 mm shot. now remember that 35mm is a natural field of view, and the moon shot is at 640mm ish. This is quite a handy visualisation tool too _URL_1_
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What makes some foods 'safe' to eat after sitting on the shelf for months but not after being opened without being refridgerated?
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Also, most canned foods are sterilized using high pressure and temperature. This kills any organisms within the can, preventing spoiling. As long as the seal is not broken, there is nothing inside the can that break down the food, ensuring a long shelf life. As soon as you open the can, all bets are off since you're re-introducing micro-organisms into the food.
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Why can I hear a radio when I touch my PC speaker plug in adaptor?
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Presumably, you're acting as an antenna. With old analog sets and broadcasts, you could grab the coax, stick your thumb on the end, and get a blurry, but visible picture if you were lucky. Holding a coat hangar in your other hand could improve the signal too. Unfortunately, I don't know enough about the physics of radios and antennas to give you a really good, sound explanation, but in short, yes you're basically acting as an antenna. You're somewhat conductive, and big enough to intercept a reasonably wide spectrum of radio waves.
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Why can I hear a buzz in my earphones (which are plugged into my laptop) when I touch the Jack/plug of my speakers (which are turned off but plugged into the mains)?
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You're making a [ground loop](_URL_0_) with your body. The nosie you are hearing is the mains hum, a 60 Hz (or maybe 50 Hz) hum from the induced current from the power grid. I assume you here that sound you can play off the audio clip on the wiki page, yours may be slightly higher pitch if you are in north America rather than Europe. Your headphones through your laptop and speakers share the same ground by being in the same outlet. You form a connection between the speakers and the laptop/headphones and you are left with two paths to ground and a ground loop to pick-up mains hum.
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How come during an eclipse theres only a real noticable light change near totality?
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Your pupil can adjust the amount of light entering your eye by about 10x by itself. Put another way, you'd have to block 90% of the sun before things looked any different to you, just from your pupil opening up. Your eye can adjust to a much fainter amount of light (eight or nine orders of magnitude darker!) via chemical changes-- but that takes longer (20-30 minutes for complete dark adaptation) so you notice when enough of the sun is blocked to exceed your eye's ability to adjust rapidly by just varying the size of the pupil.
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Do mirrors reflect only the visible spectrum of light?
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To just add a bit to /u/Cera1th 's excellent response and add that there is actually a dependence of all this on the angle of incidence. If light with a higher frequency than the plasma frequency hits a mirror at a very oblique angle it can still be reflected. This allows us to build, for example, x-ray telescopes using x-ray reflectors which effectively work through "total internal reflection" _URL_2_
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Can cancer pass through transplants?
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Yes. Absolute contraindication to organ donation include any history of cancer that has evidence of distant spread (metastasis), any history of malignant melanoma, or any non curable malignancy. Some patients with a localised malignancy, such as prostate or brain may be considered for donation, but in general terms an active cancer means that the patient cannot donate organs for this very reason. There are certainly cases when an organ donor has an unknown malignancy and the donor subsequently gets cancer.A recent Danish study suggested the risk of undetected malignancy in a donor was 1.3% with a chance of transmitting a cancer of around 0.2% [Link to study](_URL_0_)
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Can cancer be "Transplanted"?
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This is done experimentally in rodents as a model in research. It's super-effective. In your scenario it wouldn't be as effective because of tissue mismatch, but it would still work in a lot of cases (if not most). Part of what makes cancer so cancer-y is that the tumor cells are assholes and don't listen when the immune system tells them they should FOAD^1 (which is how the immune system usually deals with grafts of foreign tissue). There would almost certainly be some kind of inflammatory response, and that would cause some problems. But if you had cancer cells that are a good match for the target, or ones that are resistant to this kind of clearing, then yes, I'd say it's possible. ^1 Fuck Off And Die
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Where did the big bang come from?
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I hereby use my QI joker. "Nobody knows"
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Why do Venus (and Uranus) have retrograde rotation?
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The accepted reason is that they must have had tremendous impacts with proto-planet sized bodies in the past that changed their rotation rates.
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Does a cube of ice floating in a liquid that itself is below 0c extract the water molecules from the liquid, and make the ice cube larger?
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I'm going to say no. When I was in the Navy I was on a submarine that went under the polar caps a couple times. In doing so I studied how they form and produce keels and ridges. The ice that forms the cap is frozen so cold that it pushes out the impurities which is how you get the blue ice. The impurities, salt and dirt and such, then kind of pool up under the ice forming a layer of extremely salty water. The keels of ice that you would see forming would be from surface ice at the top melting under the sun and then draining through cracks in the ice and freezing as the entered the extreme cold beneath. Based on my understanding of how the ice caps form I would guess that it would depend on the temperature. The colder the liquids temperature the more likely it would be that the ice cube would grow.
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Why is gold used more often for electrical circuits, when silver has a higher electrical conductivity, lower resistance, and is much more abundant?
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So, gold or gold plating is usually used for electrical *contacts*, not all that often as the main conductor. The reason is that gold doesn't really oxidize or corrode and so the connection stays solid. Silver oxidizes quickly, and silver oxide is a poor conductor. So a silver-plated connector that sits around a while before you plug it in will actually make a relatively high-impedance connection.
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If gold is a worse electrical conductor than silver and copper, why are gold plated contacts considered "better" by the market?
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100% its corrosion. Copper and even silver corrode when exposed to air. This becomes a problem, it adds a highly resistive layer and adds a worse fit. If you've ever had actual "silver-ware" it usually needs to be polished on a semi regular basis.. Gold is pretty much the most inert conductor out there and the gold used can be so little that that its cost is very low.
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Why is the direction of the north-south poles for most bodies in our solar system perpendicular to the galactic plane?
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Well first of all, they're not. They are certainly preferenyially aligned with the ecliptic, which is the plane of the solar system, but the ecliptic is hoghly inclined with respect to the galactic plane, which you can see quite simply anytime there are multiple bright planets in view and in a dark enough spot to observe the Milky Way. The answer as to why most magnetic fields are aligned with the solar system is that the rotatipn of most solar system bodies is aligned with the plane of the solar system, and it is the rotation of a body which gives rise to the dynamo effect generating planetary magnetic fields.
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Do people shed more hair in summer like animals?
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No. Hair is not shed. It's the undercoat that's shed. The undercoat is the super fluffy part of an animal. You can see it if you have a dog or cat by blowing gently on their fur so you can almost see the skin. The top coat is where you see their patterns and most of their coloration. Undercoat looks like a fuzzy, lighter color than the top coat. Humans don't have this undercoat so we don't shed seasonally.
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Why do we associate certain smells with different memories?
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Here's a study that considers that very question: _URL_0_ . What the researchers found was that the old olfactory memory traces get stored in the olfactory cortex but are linked, via neural traces, to the episodic memories. In their words: "We suggest that reactivation of memory traces distributed across modality-specific brain areas underpins the sensory qualities of episodic memories."
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When we get a whiff of a certain smell that brings me back old memories, are we actually smelling something to trigger it or is our brain creating that sense of smell on its own?
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"when we get a whiff" you've answered your own question, because the whiff induced a memory. The vast majority of nostalgia is surely prompted by outside stimuli and is not an accidental subconscious yearning for past events. However, I'm positive it's also possible to smell something that's not there but I would think your 'remembering' of the event would preceed your whiff, a type of synesthesia.
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Where does all the rubber from my tires go?
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That is actually an engineering mystery. I am a third year ME student. We know that there isn't a layer of rubber on the road, and yes, some of the micro particles are motivated into the environment by wind and water (which result in some of the petrochemical polution we see in our world). But there really isn't a model that can account for the thousands of tons of rubber that disappears. Here is a non-scientific article; _URL_0_
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Does lightning strike the ocean? If so, does it electrocute nearby fish?
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a lot of people have a misconception that the ocean, which is water, is non-conductive. *distilled* water is an insulator, but with minerals (especially salts) dissolved in the water, it becomes an excellent conductor. The fish are usually okay (unless they were unfortunate enough to have been at the surface at the time of a direct strike) because the electricity is conducted through the water around most things and dissipates quickly. You're not safe swimming during a thunderstorm however, because your body sticks out of the water, and becomes a target for the lightning.
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How is a prime number as big as 2^(74'207'281) − 1 found?
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The Great Internet Mersenne Prime Search is looking for ever larger [Mersenne Primes](_URL_3_). These prime numbers conform to the function M_p = 2^p - 1. Their project has created a program, Prime95, that uses factorization and the [Lucas-Lehmer primality test](_URL_5_) to detect prime mersenne numbers, according to the readme. Prime95 also connects with a central server to coordinate the testing of the number space. There exist other methods of finding primes, as well. The [Sieve of Eratosthenes](_URL_4_) is one such method. In general, though, one can detect whether *n* is prime by testing all possible factors between 0 and sqrt(*n*)
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Can Plants grow in a C02 only environment? What effects would it have on plants to grow in a high CO2 concentrated atmosphere?
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Not sure how detailed you want the answer to be but basically plants need O2 for cellular respiration (break down of sugars for energy). Break down of sugars is needed for growth and etc. In the process of photosynthesis, CO2 is taken up by the plant to produce sugars. A process called photorespiration (different from normal cellular respiration) uses O2 instead of CO2 to create sugars but this process is less efficient to the plant. Therefore, the ratio CO2:O2 affect the rate of photosynthesis during the day. In this case, at higher CO2 concentrated areas, most plants are able to photosynthesize at a higher rate. Source: introductory course in Botany
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Is it possible there is a super nova we don't see yet within our galaxy, that is close enough to our solar system, that once it appeared would be bright enough to illuminate the night sky for the rest of human existence?
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Related: [The nearest star that could go SuperNova is 150 light years way, though one at 260 is more likely](_URL_0_) That would be entirely possible then, though there would be some lead up to the event that we would notice.
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Do neutron stars ever die out?
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Neutron stars will cool, but they don't 'die.' They're like white dwarfs in that sense, an isolated neutron star will just continue to grow colder and colder for the rest of forever.
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Can solar panels in space convert energy from particles other than photons?
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Yes, they definitely could. But there's simply a lot more energy out there in sunlight. Most of the particles in interplanetary space near Earth are ions that form a (very tenuous) fluid called the "solar wind". The solar wind is supersonic -- it flows away from the Sun at several hundred kilometers per second, compared to the sound speed (in that medium) of a few tens of kilometers per second. But the solar wind is indeed very tenuous. There are typically 1-10 particles for every cubic centimeter of space 1 AU from the Sun, compared to (say) about 2-3 x 10^19 particles in every cubic centimeter of space at sea level on Earth. The upshot is that there's just not that much energy available in the particles. Photons carry most of the free energy that's available here in the inner solar system.
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What is the inside of a nebula like?
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Nebulae are really diffuse clouds of gas, so there wouldn't be much effect at all. It's kind of like how a flight path through the "asteroid belt" has negligible chance of crashing into asteroids, unlike what you see in the movies. From: _URL_0_ > Although denser than the space surrounding them, most nebulae are far less dense than any vacuum created on Earth – a nebular cloud the size of the Earth would have a total mass of only a few kilograms.
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If the universe is really endless, does that mean "everything" must exist in it?
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Infinitely many numbers exist between two and three, but none of them are four.
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Why do humans have different eye colors? Were they ever an evolutionary advantage?
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A bit off-topic: You should take a step away from the idea that evolution only 'creates' something because it would be advantageous to the species. Evolution is much more chaotic than you may think. Things just happen more or less by accident (mutation), and if these mutated species somehow survive (even if this new mutated trait doesn't serve any purpose - but also doesn't hinder them) they just keep it and it shows up every once in a while.
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Have most of the stars that will ever be formed in the Milky Way already been formed?
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Just to throw this out there, the current star formation rate in the Milky Way is something like one a year so, assuming that it's constant (it isn't) that's 5 billion or so stars that will be formed before the Sun dies.
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Why do things taste different when cooked by different types of wood?
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Wood has three major components -- cellulose, hemicellulose, and lignin. Different woods have slightly different proportions of these materials. In addition, these basic structures will be decorated with different chemical groups or infused with other volatile components. When you cook with wood, these compounds will be liberated and break down via pyrolysis into smaller molecules. Many of these molecules are aromatic. In particular, the structure of [lignin](_URL_1_) contains a bunch of aromatic compounds that are linked together. With enough heat, these compounds will be released. They might also react with the air and land on whatever you are cooking to enhance its flavour. If you cook with [propane](_URL_0_), its molecular structure is signficantly different from that of lignin. The types of molecules that can be made will be vastly different. This results in a noticable difference to the discerning connoisseur.
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Why is it that most objects orbiting larger ones also rotate about an axis as well?
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Orbital bodies in space typically condense from large molecular clouds. As those clouds invariably have some initial motion, when they collapse, the conservation of angular momentum accelerates the smaller denser object into a notable rotation. Being in orbit around another body does not negate this process.
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A solar sail is propelled by photons hitting it, imparting their momentum to the sail. Could a "solar fan" do the opposite and impart its momentum to photons?
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This is essentially what any light-emitting device (light bulb, LED, laser) is doing. It generates photons, which have a defined momentum and go on their way. A little more loosely, any reflective surface is also changing the incident photons' momentum, because it changes the direction of that photon's velocity.
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Where does the extra energy come from to impart energy into a solar sail since the reflected light is neither slower nor lighter?
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The reflected photon has a slightly lower frequency, and thus lower energy, than the original photon. This is basically the Doppler effect. The energy lost by the photon is equal to the kinetic energy gained by the solar sail.
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When I blow out a candle, what specifically has caused the flame to "go out"?
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you are cooling the wick/fuel below it's ignition point.
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