title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Red and blue images on my phone look 3D through my corrective glasses. What gives?"
] | [
false
] | Normally I wear contacts constantly. One night a few months back I was giving my eyes a rest, wearing my glasses while perusing the web on my old first gen Moto Droid. I opened an image and was shocked to see a red typeface practically leaping out at me from a darker blue/black background. I thought it was neat, but easily dismissed it as an optical illusion. Today the same thing happened, and the red in the image was so intensely 3D that I decided to do a GIS for "red on blue." I looked through a dozen images, all with the same result - they appeared to be 3 dimensional, with the red or warmer colors leaping forward, and the more blue, cooler images receding in the background. I took my glasses off to see if the effect persisted - it did not. Finally I had my girlfriend come and try my glasses to see if the effect was replicated for her. It was, she was amazed. Next I went to my computer monitor to see if I got the same effect - nope. The only combo that works is my glasses with my cell phone. What gives? TL,DR: My glasses seem to create the illusion that images on my phone are 3 dimensional. Why? How? | [
"It looks like the polarizer on your phone and the anti-glare coating on your glasses Real interacting to create a ChromaDepth effect.",
"This website explains the phenomenon quite well:",
"http://jaredjared.com/chroma.html"
] | [
"Fascinating, thanks! "
] | [
"This effect ",
" be visible all the time while wearing glasses, though interaction with the phone screen may be accentuating the effect.",
"Traditional lenses bend light of different wavelengths by different amounts, meaning, in stereo vision, that different colours appear at different depths.",
"I can see t... |
[
"When a boat travels over an aquaduct, does the aquaduct carry more weight?"
] | [
false
] | I think this would have something to do with buoyancy and water displacement, but that is beyond my knowledge. | [
"The boat displaces an amount of water equal to its mass. So, the answer to your question depends on where the displaced water goes. If any of it remains on the aqueduct, then the aqueduct carries more weight. This will happen only if the water level rises when the boat goes onto the aqueduct, which doesn't seem... | [
"Dropping a boat into a body of water (or, just adding more water) causes the water to rise everywhere. Try stepping into a half-full bathtub, and note that the entire water level rises simultaneously. But that's a simplified description. In more detail: suddenly adding more volume to a body of water will creat... | [
"The displaced water would be displaced along the entire length of the aquaduct and the rest of the canal, so if it was 10 miles between locks and the aquaduct was half a mile long then it would only have to bear the weight of a twentieth of the boat and that weight would spread evenly over the entire aquaduct. "
... |
[
"Can the Universe be bigger than we think it is?"
] | [
false
] | I was working in a R&D lab over my coop and was chatting with my boss when he mentioned that one possible explanation for dark energy & dark matter was that the currently cited and used approximation for the size of the universe was incorrect. According to him if we adjust the calculations for how big the universe is then dark energy and matter are just the effects of gravity acting from beyond the limit of our currently defined universe. I don't think he would just bullshit a claim like that, is there any evidence to support such a theory? | [
"we know that it's bigger than the observable universe for sure. Most likely, it's infinite in size."
] | [
"Can the Universe be bigger than we think it is?",
"Many physicists believe the universe is infinite. So no.",
"According to him if we adjust the calculations for how big the universe is then dark energy and matter are just the effects of gravity acting from beyond the limit of our currently defined universe.",... | [
"For staters, we currently think (inasmuch as a whole cohort can think alike) that the universe is infinite in size. However this isn't something that's testable, as we will never be able to observe this, which makes it more a question of philosophy.",
"As for dark energy and matter being explainable by more matt... |
[
"How do plants \"out-compete\" algae in my aquarium?"
] | [
false
] | In freshwater planted aquariums, controlling algae growth is a big problem. Some people use high light, injected CO2 and fertilisers to promote healthy plant growth and it that when your plants are growing happily, algae is not a problem. It is often said that the plants "out compete" the algae. I am not a biologist and my understanding of this is lacking, I'll try and explain why. In an aquarium in which plants grow happily, it seems like there is no competition for resources. CO2, oxygen and nutrients all exist as a concentration in the water, are all in excess and are never totally consumed. Light, too, would seem to be abundant. For example, if you consider a square inch of the front glass of the aquarium, that square inch would seem to have everything algae needs to grow in excess. Yet aquariums seem to reach a balance in which plants grow happily and algae does not. The square inch of glass does not become covered in algae despite having lots of light, CO2, oxygen and nutrients available to it. In this case, how do the plants out-compete the algae? Or perhaps a better question is why does the algae not grow? | [
"This is a really interesting question, and there are several possible contributing factors. Plants can in fact out-compete algae for some nutrients, basically starving them. CO2 can be limiting in a brightly lit aquarium with no supplemental gas added. Rooted plants especially have access to nutrients below gro... | [
"And finally it is possible that plants release some chemicals detrimental to algae",
"To me this is the only thing that makes sense. If both algae and plants have all the things they need to grow, but only plants are growing, it seems like there must be another factor at work. However, I have asked on an aquariu... | [
"True, activated charcoal should absorb most kinds of algacidal compounds. I wouldn't be so quick to discount the possibility of nutrient competition though. It's quite well documented in various aquatic situations, though usually between species of algae, for simplicity's sake. Unfortunately, the specific name ... |
[
"Is there any place in the solar system that one can see a moon as big as ours?"
] | [
false
] | I assume gas giants would be quite spectacular to see in the sky from their moons. But where else in the solar system would be a good place to watch the sky from a glass dome? | [
"Pluto's moon, Charon, orbits at only 19500 km from Pluto. That's much closer than our Moon at 380000 km. Even if Charon is considerably smaller, it should look very big from Pluto.",
"If I didn't mess up with the math then the angular diameter (apparent size) of Charon seen from Pluto should be 3.76 degrees. Com... | [
"As far as I can tell, the only moon that would appear bigger from the surface of its primary than our Moon is Io as seen from the surface of Jupiter (whatever that means). But only about 15% bigger in diameter compared to the Moon as seen from Earth.",
"However some moons as seen from another moon do appear bigg... | [
"Does Charon count as a moon now that Pluto isn't a planet?"
] |
[
"Is it possible to learn something without being consciously aware that you have ever learned it?"
] | [
false
] | null | [
"Yes! In fact, I'd argue that most learning is like this. Here are a few examples of what you might have in mind though:",
"Statistical learning: picking up regularities in the environment. We do this all the time naturally, but we can do this in the lab as well. ",
"Fiser and Aslin (2001)",
" showed particip... | [
"The patient HM is an interesting example of this. HM had severe epilepsy and underwent a lobotomy to decrease the frequency of episodes. An unfortunate side effect of the surgery was he lost the ability to form new memories. He could recall things before the surgery, and his short term memory was still working, bu... | [
"Indeed. In the Saffran paper, they refer to relationships between syllables as transition probabilities, but I didn't want to get into it in the post. This is also the idea behind ",
"artificial grammar",
" learning. ",
"Here",
" is a paper on extracting structure using such models from natural languages i... |
[
"How did the dinosaur destroying asteroid affect the aquatic life at that time?"
] | [
false
] | [deleted] | [
"The Cretaceous-Paleogene (K-Pg, or sometimes still referred to as the Cretaceous-Tertiary, K-T) Extinction event killed off both marine and terrestrial species. You can get a sense of the variability of organisms which died out in the ",
"wiki article on the extinction event",
". As described there, in the mar... | [
"Only in underground bunker. The entire world was hot as a pizza oven within a few hours of impact. Our ancestors were burrowing critters."
] | [
"The heat was temporary. An asteroid that size carries the energy of many, many nuclear bombs. That fades rather quickly though, and then the 'nuclear winter' situation kicks in."
] |
[
"How to turn HCl into Citrate Salt?"
] | [
false
] | null | [
"What is the chemical in question? We can't answer the question without that knowledge."
] | [
"I've added Phenethylamine HCl to Sodium Carbonate (Washing Soda) Water, \nseparated the Oil on top, \nThen added the Oil to Citric Acid.",
"I'm pretty sure that did the job."
] | [
"Phenethylamine ",
"Why did you bother? Chloride in your diet?"
] |
[
"Atomic mass is calculated by averaging the masses of all isotopes of an element in their natural ratios. Could the natural ratios fluctuate as we explore and colonize places in the universe where the amounts of different isotopes may be different than in our solar neighborhood?"
] | [
false
] | If so, will whatever atomic mass that is printed on our periodic tables today have to be revised? | [
"Sure. This is how we know certain rocks are probably from Mars, for example. ",
"Here's one paper in specific."
] | [
"Yes they can, and yes the accepted values in the textbooks will have to be revised. Some of this is due to the atomic age and all the radioactive stuff that has been let loose on earth recently. But the revision won't be by much. But it is enough to be able to prove that cognac really is 100 years old and not a fa... | [
"That mass is used because that's the mass that's important in doing chemistry on Earth. If it turned out that the abundances varied widely in the universe, the periodic table as it is would still be useful to chemists on Earth. "
] |
[
"Why does a shortage of hormons like estrogen or testosteron lead to depression?"
] | [
false
] | I'm curious. Everywhere I searched for an answer to this question they never brought up reasons for it, only the notion that it does cause depression or at least gives you a shitty mood (I'm not sure if it was the clinical definition of "depression" or the "depression" that many people talk abotu when they "only" feel down) What is the cause behind this? Is it to complex for a layman to understand? Are these hormons providing anything needed or blocking something you don't want to have? Does science know for sure yet? | [
"The endocrine system is highly integrated with itself, meaning many hormones are involved in pathways and often times one hormone will signal the release or inhibition of a 2nd hormone. I can't remember off hand what the steroids may or may not initiate but most likely reduced hormones will cause reduced levels o... | [
"Low testosterone levels in men manifests itself in a lot of the same symptoms that are common in depressed people: fatigue, low sex drive, muscle loss, fat gain, brain fog."
] | [
"Low testosterone levels in men manifests itself in a lot of the same symptoms that are common in depressed people: fatigue, low sex drive, muscle loss, fat gain, brain fog."
] |
[
"Could a natural nuclear fission detonation ever occur?"
] | [
false
] | null | [
"Not quite, but close.",
"For a detonation to occur, you need a nuclear bomb, which is a very complex and precise machine. This is probably too complex to be assembled by random natural processes. The closest which happens naturally is when Uranium ore deposits form, and then reach a supercritical concentration o... | [
"Don't the isotope purities have to be much higher in a bomb so that the energy release is very quick? Like the difference in taking apart a building Brick by Brick or hitting it with a wrecking ball."
] | [
"There is that. But mostly, you have to factor in that depositional processes in ore deposits are incremental, so that when a supercritical mass of fissile material is reached, it will be marginally so, not massively so. And of course, a lot of gangue will be involved which would interfere with any kind of bomb-lik... |
[
"Why are the rings of Uranus turned sideways?"
] | [
false
] | I understand that the going theory is that Uranus orbits with its poles nearly level with the plane of the solar system because of a collision with significantly-sized body. But why would that turn the rings as well? | [
"You're assuming that its rings were present when it first got its tilt. It could have easily picked up its rings long after it got blasted over on its side or they could have formed from the debris of the impact itself coalescing around its (repositioned) equator. Uranus and its system has been around and evolving... | [
"Thank you!"
] | [
"If the rings were formed from debris from the collision (or I guess from moons that were formed from debris from the collision and then got within the Roche limit and disintegrated), then their alignment with the equator of Uranus makes sense. But it sounds like you're referring to another possibility when you say... |
[
"Is there a limit to the size of an element?"
] | [
false
] | I saw that the four new elements were recently discovered. I was wondering, is there any limit to the atomic mass an element can have? Sorry if this is a repost! | [
"Well, you can theoretically have an atom of any size, but the larger it is, the weaker it is at holding itself together. ",
"So yes, you can have an atom some huge, 10th row element if you want, but only for a few nanoseconds. "
] | [
"To add on, this is because nuclei contain protons, and protons repel each other. However, there is a stronger force, the \"Strong Force\", which causes attraction between protons and neutrons, holding the nucleus together. However, this force is a very short-ranged force, so the larger the nucleus, the weaker it i... | [
"No, the strong force does hold gluons together but it is the residual strong force that provides attraction between nucleons. It is sort of analogous to the way neutral atoms are internally held together by EM forces, but neighboring neutral atoms can still attract each other via Van der Waals forces.",
"The wea... |
[
"Could we just send a couple \"cleaner\" bots to Mars?"
] | [
false
] | null | [
"No the current rover Curiosity (and the next one) are nuclear powered."
] | [
"Most of the cost of a mission is just landing something on the planet. It is vastly more interesting to design a whole new robot that can do much more than what Opportunity did than sending a cleaning robot that would cost 75% of the price to build, launch and land. "
] | [
"right, but I'm assuming that whatever the next robot we sent is, it'll have the same problem eventually right? Or is technology just expected to progress at a rate that by the time any rover runs down it'll be about time to replace it anyways?"
] |
[
"Does a heightened sense of smell in dogs mean they smell *more things*, or that all things have a *more intense* smell?"
] | [
false
] | And if it's the latter, are they absolutely freaked out by certain smells? | [
"Both. Their threshold for most compounds is lower than ours. Therefore, some things we cannot detect at all (below human threshold), are detectable by dogs. Some things we do detect (above human threshold) will probably be more intense for dogs because of their lower threshold.",
"Although, how odour concentrati... | [
"Both kind of, dogs smell all smells individually, like if you’re in a restaurant and you get steak, but at the table next to you a man’s been farting all night, and 3 seats down someone is smoking weed, we smell the blend of weed and steak and farts as one smell, a dog smells weed as it’s own thing, farts as their... | [
"Does a heightened sense of smell in dogs mean they smell ",
", or that all things have a ",
" smell?",
"A dog's sense of smell supercedes its sense of sight! That is, a larger portion of a dog's brain is devoted to its nose than its eyes. ",
"Oddly enough, this is something that some dog researchers ove... |
[
"How long to disrupt for?"
] | [
false
] | I am running a DNA extraction protocol on rat liver, and we are starting off the protocol by using a disruptor with bead to grind up the sample. A piece of tissue will be in the tube along with extraction buffer (water, Tris, NaCl, and SDS) and of course the bead. We are using the Scientific Industries Disruptor Genie and will be using it at full speed, but I can't find anywhere online how long we should run this for. Thanks! | [
"Haven't used that, used a sonicator before though... I just blasted the damn stuff until it was a liquid goo with no pieces (only took a short time though like 30 seconds maybe). Varies depending on tissue though.",
"Happy homogenising!"
] | [
"dunno, but thanks for sciencing! We need all we can get."
] | [
"When I've homogenized cells in the past using a rotor-stator homogenizer, I think I only needed around 15 seconds. But that was cultured cells, not tissue. If I were doing your experiment, I'd start with 30 - 60 seconds as a guess. (Actually I'd call the company and ask them before actually doing it.)"
] |
[
"Why does an open cut sting when alcohol is applied to it?"
] | [
false
] | [deleted] | [
"There are special cells called VR1 receptors that tell your body when your skin is getting hot. If you hold you hand over an open flame or boiling water these receptors trigger to let you know it's hot.",
"When alcohol and these cells meet, they react chemically and the alcohol reduces the threshold needed for t... | [
"This is a similar but not exactly the same reason why alcohol burns going down your throat.",
"Why does it burn when swallowed?"
] | [
"Does this relate to when you've consumed alcohol, your body doesn't feel cooler temperatures that well?"
] |
[
"Given our knowledge of the formation of elements in stars over the course of the existence of the universe, what is the earliest time we should have expected to see life as we know it to come into existence."
] | [
false
] | As I understand it, the first stars that were formed produced only hydrogen and helium which was used, after those stars went supernova, to form new stars which in turn used those elements as fuel to make the rest of the gamut of elements with carbon being one of the earlier ones. Given that information and our knowledge of the age of the universe, can we make general assumptions as to the earliest possible time that life could have existed? Thanks for any help in answering this question. | [
"Wouldn't \"give or take a few billion years\" be a rather significant deviation, given the accepted age of the universe?"
] | [
"What are population I/II stars?"
] | [
"Pretty much when when it did. The heavy elements that make up our planet had to form in population II stars and our sun needed to be a population I star.",
"I've not seen any compelling evidence that the Earth could have formed any earlier than it did, perhaps give or take a few billion years."
] |
[
"When in a dark environment, why does objects which you are looking at directly appear darker and harder to see, but objects which you see at the corner of your eye or in the peripheral vision appear brighter?"
] | [
false
] | null | [
"The answer has to do with how different types of photoreceptros are distributed in your eye. There are two main types of photoreceptors that are responsible for human vision called ",
"cones",
" and ",
"rods",
". Cones come in three main varieties, which allows us to see the world in color under well-lit c... | [
"That blind stop is called the ",
"physiological blind spot",
" and it exists in all vertebrates. The reason it exists is that as you can see from ",
"this diagram",
" in our eyes there are nerve fibers that sit in front of the retina (where all the photoreceptors are). At one point these fibers link kink i... | [
"accounting for 80% of total supplied oxygen in humans.",
"Perhaps I'm misunderstanding what you were saying, but I'm fairly certain that is not even close to correct. Could you elaborate or provide a source? "
] |
[
"Are there any positive effects of stress?"
] | [
false
] | There are many books and articles about how stress can hurt your mental and physical health over time. However, like most things there seem to be positive effects in addition to negative ones. | [
"Actually, stress is very important in our lives. It activates our adaptation systems and allows us to learn, to adapt and to survive. There is of course bad stress, dis-stress, and good stress, eu-stress. Too much of anything is bad for you but in moderation can be beneficial. Look up the work of Hans Selye, he wa... | [
"I watched a science documentary on TV some time ago, that linked moderate amounts of stress (not prolonged), being hungry (lowering food intake to bare minimum) and drinking red wine (because it has ",
"Resveratrol",
") to a longer lifespan. All i can remember is that it was on Discovery and a Viasat channel."... | [
"Ah thank you, that article was very interesting and seems to flesh out much of the question. I suppose that there is healthy stress and unhealthy stress."
] |
[
"Is there a proof to say why the sum of all the digits of every multiple of 9 results in a multiple of 9?"
] | [
false
] | eg 56*9=504 5+0+4=9 | [
"NB.: X mod Y or X%Y is the operation where you integer-divide X by Y and take the remainder.",
"This is trivial for single-digit numbers.",
"For two digits, the number AB is equal to 10A+B. If we write it as 9A+(A+B) we can see that (A+B) mod 9 will be the same as AB mod 9, or more related to your question, if... | [
"/u/dontspillme",
" gave a short and correct explanation but I'm going to try and be more precise and formal, in case anyone wants to see an actual proof.",
"When we write a number as a series of digits, we actually write it as a sum of powers of 10. Take for instance 2014: it's TWO times 10",
" plus ZERO tim... | [
"More generally, for any base N, it works for any factor of N-1. For base 10, the only factors are 1, 3, and 9. For base 16, it works for 1, 3, 5, and F. Basically, the proof given by ",
"/u/dontspillme",
" shows this. The number AB in base N is N*A + B, which becomes (N-1)*A + (A + B). If (A + B) contains... |
[
"What kind of geological processes must occur for terrain of this sort to be produced?"
] | [
false
] | I saw of Phong Nha-Ke Bang Park in Vietnam, and thought about it a little in a geological context. I noticed the flatness of the pasture below, but the steepness of the hills. It almost doesn't seem natural, as if they are meteors, covered in foliage. I figure they're probably not, but have no idea what causes terrain like this. What's going on in Southeast Asia that causes such flat marshes, and such steep hills jutting from the surface of the Earth? | [
"I love you. I love askscience. I love reddit. I love science. I just can't believe how I can ask a question about a picture I was interested in, and have someone teach me things I never knew I never knew!",
"Thank you so much."
] | [
"Being easily impressed just makes life that much more exciting!"
] | [
"This type of landscape is called ",
"karst",
". The underlying bedrock is usually limestone. These ",
"towers",
" develop when dissolution by water charged with ",
"carbonic acid",
" proceeds along fractures, causing them to widen. Other weathering processes widen the fractures further. In this picture... |
[
"Why does the human immune system not have a cummulative effect?"
] | [
false
] | To be more specific, shouldn't our immune systems become more efficient as we get older and our body recognizes more and more pathogens? For example, i believe its true that you cannot get the same cold virus twice because your system remembers the virus, and has the antibodies to kill it. Why does this system not accummulate as we get older, and become more effective? | [
"There are a couple of things here. For one, your immune system does get better as you get older - to a point. Once you hit a certain age, though, your body begins to deteriorate. That's why we age. Cells mutate, they die. There's no getting around that, and it plays a pivotal role in our immune systems. But it's n... | [
"Thank you so much for taking the time to answer this is such detail. Also, thank you for setting this up very simply for me. Immunology is not my area of expertise. ",
"So, my next question, in the adaptive branch of our immune system, do we find an overall strengthening during our lives until we reach an apex,... | [
"Glad I could help! I'm by no means an expert in immunology. I study bacterial pathogens, and I prefer to understand how the bacteria is doing its thing. ",
"That being said, your immune system doesn't really hit an apex.It strengthens because it recognizes a certain antigen, and then the T cells and B cells prol... |
[
"Black holes swallow light. However, do different wavelengths of light behave differently when reaching the event horizon?"
] | [
false
] | null | [
"Not so much. Light travels at the same speed regardless of wavelength because photons are massless, so all colors of light are equally affected by the black hole's gravitational field. ",
"This paper",
" summarizes previous experimental efforts to put an upper bound on the mass of the photon (and the graviton)... | [
"Because ",
"systems of particles may have mass, even if the individual particles may be massless",
". In fact, most of the \"normal\" mass in the universe comes from all the gluons in protons and neutrons, and gluons are massless."
] | [
"not really. They blueshift (relative to some external observer) on the way in, but they all fall in and add to the mass of the black hole."
] |
[
"Will a spacecraft coated with Vantablack be “blind”?"
] | [
false
] | null | [
"This hypothetical questions is probably be better suited for ",
"/r/AskScienceDiscussion",
"However, here are some things to think about:",
"black body",
"pinhole camera"
] | [
"Thanks for the feedback, viscence! Much appreciated :) Following your suggestion, I have posted this very same question in AskScienceDiscussion.",
"As for your comments, I will certainly look into the pinhole camera idea. While on Earth, to be sure the pinhole camera is not very cost-effective, for the aliens wo... | [
"Quite the opposite I'm afraid. The vacuum of space may be cold (in places) but it's an excellent insulator. That's why vacuum flasks can keep stuff warm for so long. ",
"The three main ways of transferring Heat are conduction, convection, and radiation:",
"Black things radiate thermal radiation very well, whic... |
[
"Does increased mass at high speed also increase an objects gravity?"
] | [
false
] | For example, if I took the earth/moon system and accelerated it to some appreciable fraction of light speed, would it cause the moon to 'fall' to earth? | [
"To answer you example question, no. It doesn't matter what speed the Earth Moon system is travelling at, you can always go to the Earth Moon rest frame where the Earth Moon system is stationary.",
"To answer your question, things don't gain mass at higher speeds, they gain energy and momentum."
] | [
"This answer seems to contradict some other upvoted ones given on Reddit and elsewhere.",
"From another question on the /r/askscience front page right now",
":",
"mass is energy, and ",
" The stress-energy tensor is what creates gravitational fields in GR, and some components of the stress-energy tensor for... | [
"I_know_physics_AMA is absolutely correct. ",
"Only if there are relative differences between two systems does the energy/momentum effect on gravitation matter. If an ",
" system is accelerated to any speed whatsoever, the physics ",
" that system will be unchanged - no different than if the system was \"at r... |
[
"Chemical that reacts with Rust to ‘seal’ a surface?"
] | [
false
] | Has anyone come up with some type of sealant or protectant that can be applied directly to a rusty surface and the chemical actually reacts with rust itself to create the sealant? Whereby the rust itself can be converted to something better? Iron oxide must have some “potential” to it and not need to be removed every time? | [
"The problem is that if the rust is at all thick you end up with a brittle coating which can shear off when stressed. A surface which has had the majority of the rust mechanically removed (e.g. by wire brushing) can be painted on. Historically, red lead was the primer of choice for such surfaces as it reacted to fo... | [
"There are commercial products that combine a rust reducer with primer. One was sold as NeutraRust. The rust is converted to a black substance, probably either a sulfide or Fe3O4, and when it dries you have a paintable surface. But I doubt there is anything that does it without the paint-sealer additive doing most ... | [
"Basically phosphoric acid. You can also purchase phosphoric acid for this purpose as a thin liquid that can be brushed on."
] |
[
"Is the nucleus best visualized as many discrete quark triplets or as a sea of quarks?"
] | [
false
] | Since gluons mediate over both inter- and intranucleonic distances, which is the better mental model: Many quark triplets (protons and neutrons) reasonably spaced apart, or rather a largely seamless sea of quarks? Looking up the relative sizes of say a uranium nucleus and a proton, it seems like it could cut either way. | [
"Quark triplets (properly termed Baryons). We have another type of material that's a seamless sea of quarks, called a Quark Gluon Plasma."
] | [
"It's best visualized in terms of protons and neutrons. You can understand pretty much all you need to know about nuceli without quarks"
] | [
"It really depends on the nucleus. For small (light) nuclei, you can cleanly resolve different nucleons, and those are the \"optimal\" degrees of freedom. As you move towards larger nuclei, the relevant degrees of freedom are collective modes. A good depiction of this comes from Scidac-UNEDF collaboration, (",
... |
[
"Frost on your car occurs when there is direct line-of-sight to space (e.g. no clouds or carport). Why is this?"
] | [
false
] | I've heard it has to do with something called latent heat of radiation (maybe?). What does this mean and how does it work? | [
"Overnight cloud cover tends to keep the underlying area warmer than if there were no clouds. The clouds absorb outgoing longwave radiation and emit them both to space and back to the surface. While it is certainly still possible to have frost occur, it may be less likely because those surfaces (i.e. Car) may not c... | [
"It's loss of heat by infrared radiation. We usually think of heat being shed from an object by it heating up its surroundings by direct contact (air, anything touching it). But heat is also shed radiatively, which is how infrared imaging devices can pick up on body heat, etc., from a distance. The wavelengths are ... | [
"Thanks for your answer! I'm still a little confused though. I was under the impression that, given 2 overnights where both reached, say, 20 F, one with clouds and one without, it's only going to frost the car on the night without clouds. This seems to be the case given my observations, but I never wrote these down... |
[
"If gravity is so weak, how did things even start attracting each other in order for new stars and etc to form?"
] | [
false
] | null | [
"The strong and weak forces have very short ranges, so they're effectively zero on the length scales relevant to this simulation. And as for the electromagnetic force, when you have a cloud of matter which is macroscopically neutral (all charges cancel out), electromagnetic forces effectively have a very short rang... | [
"So by process of elimination, the only force which \"survives\" is gravity.",
"But it's extremelly weak in that scale of mass, so it's also effectively zero"
] | [
"No, that's not true."
] |
[
"Based on existing and practical theoretical methods and texhnologies, To what extent can we realistically expect to lessen our dependence on fossil fuels?"
] | [
false
] | [deleted] | [
"Entirely dependent in economics: it would cost an enormous sum, but we could do it almost immediately if we were willing to abandon all existing fossil fuel infrastructure. I'm assuming that bioethanol is considered a fossil fuel for this, since burning it produces carbon dioxide just like traditional fuels.",
"... | [
"Actually, biofuels are generally able to be produced in a carbon-neutral manner, since the carbon burned was extracted recently from the atmosphere. "
] | [
"I know this is anecdotal but there is nothing here yet so it may give the OP somewhere else to look. Also, I think this is a technology question, not a science question.",
"As a technologist, I have to say that technologies are adopted not because they are the best solution but for many other reasons. Humans d... |
[
"If you could have a conversation with a founder of your field: who would it be? What would you like to ask them? What would you love to be able to explain to them?"
] | [
false
] | [deleted] | [
"Alan Turing",
", to tell him that things will get better for homosexuals.",
"(Sorry, not really about the state of his field, but I'm just saddened by the way he died. Who knows what more he might have contributed)"
] | [
"Darwin. I imagine that he'd cry at the elegant beauty of the underlying mechanisms of reproduction, inheritance and the expression of traits - the double helix, meiosis, and the genetic code - and the vindication that genetics has brought to his ideas. And I imagine him having a good chuckle when told that he had ... | [
"Depends on what you call 'his field', but, well, the languages used in the software industry could have actually ",
" ideas from math and computer science. Specifically(I don't really know what else is useful for languages), lambda calculus, categories. Languages exist like ML, Haskell, lisp, but aren't all too ... |
[
"Is there a limited number of protons, neutrons and electrons or they are created all the time?"
] | [
false
] | If they are limited, can they be destroyed? | [
"TL;DR: This is an unsolved problem.",
"If the universe was in thermal equilibrium at very early times, there would have been equal amounts of matter and antimatter. As the universe cooled, they would have nearly completely annihilated, leaving a universe with very little matter (and an equal amount of antimatte... | [
"Creating a proton, neutron, or electron, requires creating the corresponding antiparticle at the same time. Destroying them requires annihilation with an existing antiparticle.",
"It is easier to create electrons and positrons, because they are much less massive than protons and neutrons, so much less energy (m... | [
"Protons and Neutrons can be converted into one another in fusion and fission processes."
] |
[
"What specific qualities/personality traits do you need to be successful as a researcher?"
] | [
false
] | null | [
"Hm, OK. I understand what you're saying - that there's also a lot of both creativity (in coming up with ideas) and \"grunt work\" (in setting up experiments) involved.",
"However, if I may, I'd like to say that these also require honesty: Finding the questions that really challenge your hypothesis (not like what... | [
"dedication and endurance,",
"ability to accept mistakes and learning from them,",
"critical thinking,",
"and, because you asked \"succesful\", not \"good\": from my experiences unfortunately it often requires a lot of brown-nosing or at least playing the \"social games\" (until you reach a certain position o... | [
"I think by far the most important quality is intellectual honesty, which supports ",
"critical thinking",
". You have to be able to accept that your favourite hypothesis was ",
", if the evidence shows so.",
"But even with that, success is not guaranteed. You have to be a bit lucky, too, and get to work on... |
[
"Is it possible to completely eradicate human diseases?"
] | [
false
] | I heard smallpoxs was completely eradicated declare by WHO, but they still exist, so can it reappear back? | [
"It is highly unlikely to the point of not possible. Smallpox was eliminated as a disease in the human population with the last cases being in 1978. There are two official samples left in highly controlled labs where they will not get out and will eventually be destroyed.",
"However there have been at least two c... | [
"Right. And even if you completely eradicated all humans many of their diseases would live on, living with other vectors. ",
"The only reliable way to completely eradicate all human diseases would be to completely eradicate all of life."
] | [
"Probably no. There are so many kinds of disease (genetic disease, infectous disease etc.) and they operate in such a complicated system. If you erdicate one type of infectious microorganism you can bet on that there will be another one taking it's place sooner or later. The same goes for genetic disease. DNA will ... |
[
"Apparently Jupiter has around 67 moons, would you always see at least one full moon if you were standing on the surface looking up?"
] | [
false
] | null | [
"No. If you are at the equator at noon then all the moons you see are closer to the Sun than you - they are at most half full. The full moons are behind Jupiter. You can only see full moons if you are on the night side.",
"While Jupiter has many moons most of them are small and far away. Io is similar to Earth's ... | [
"\"Full moon\" isn't that impressive if you have a 2 km rock 20 million km away - you don't even see it with the naked eye.",
"Just to add a couple specifics: Io is curiously almost the exact same diameter as our Moon, as well as almost the exact same distance from its parent planet. As a result, it would look ab... | [
"Metis could be recognizable as extended (and non-spherical) object if you are somewhere near the equator. 130,000 km semi-major axis, subtract 70,000 km equatorial radius so its closest approach is 60,000 km. With its size of 60 km × 40 km × 34 km the long axis is 1:1000 and the short axis is 1:2000, similar to 1 ... |
[
"Do the viruses that cause the common cold leave lasting damage to any part of the body like covid variants do?"
] | [
false
] | null | [
"Post viral syndrome/Post viral fatigue",
" are both quite nasty and can be quite like long lasting and can happen after colds/flu.",
"I was ill for ~6 months after a particularly bad bout of flu. Probably wasn’t completely right for 18 months or so. ",
"After a bad cold one year I had post viral fatigue for ... | [
"Yes, any infection has the potential to cause long lasting disease or damage, either by harming tissues ( like polio) and/ or never being fully eradicated ( like mono and Lyme).",
"In my opinion the biggest silver lining of this pandemic is that we are recognizing that infections can can cause long term complic... | [
"Wow, on first reading this comment I was very surprised to hear that microtubules have any relationship to CoV-2 infection, but it seems like it is indeed hypothesized to be involved in part of the replication cycle, e.g.",
"https://doi.org/10.1371/journal.ppat.1009246",
"Very cool!",
"I am interested in you... |
[
"Is there a process to reverse electrolysis of water?"
] | [
false
] | I'm curious if there is a way to combine hydrogen and oxygen to form water in a way that is as simple as electrolysis of water. | [
"Yes, it's called a match. It's even simpler than electrolysis, actually. ",
"But, if you want a method that's about as complicated as electrolysis, you're looking for fuel cells."
] | [
"This",
" looks like a fine introduction.",
"If it was the first part you wanted elaboration on: mix two parts hydrogen and one part oxygen. Light match. Products are water and a ",
" big boom."
] | [
"Specifically, oxidation of the Hydrogen through combustion."
] |
[
"How do we know the amount of carbon in the atmosphere in the past?"
] | [
false
] | I understand ice cores from deep glaciers can tell us the makeup of the atmosphere for the last few hundred thousand years but how do we know what makeup of the atmosphere from before the glaciers existed? | [
"I'll assume by \"carbon\", you're primarily interested in CO2. Beyond air bubbles trapped in ice (which gives us a direct measure of CO2 concentration), there are a range of different proxies used to reconstruct ",
"pCO2",
" of either the atmosphere or ocean. A (probably non-exhaustive list) of common proxies ... | [
"Are there any methods based on carbon content in sedimentary rock? Or is that too imprecise?"
] | [
"Depends on what you mean by \"carbon content\". Some of the proxies discussed above rely on carbon isotope ratios in particular minerals from specific sedimentary rocks, specifically, paleosols (e.g., ",
"Cerling, 1991",
")."
] |
[
"Matter can be neither created nor destroyed. What then is happening when Atoms smash together in the Large Hadron Collider? Is matter then destroyed?"
] | [
false
] | I see the collisions on shows like 'The Universe' and everything seems to go out of existence. Is this matter being destroyed? | [
"Matter can be neither created nor destroyed.",
"This assumption isn't true -- matter is created and destroyed all the time in ",
"pair production",
" and ",
"annihilation",
" processes.",
"What you are probably thinking of is that ",
" can't be created or destroyed -- and the law of conservation of m... | [
"Only the more exotic conditions allow it though",
"Allow what exactly?",
"If energy is produced, then mass is lost. It's true for matter/antimatter reaction, of course, but it's also true for fusion and fission, and even for chemical reactions (even if the change of mass is too small to be measured). A CO2 mol... | [
"Allow what exactly?",
"Conversion from mass-energy to other forms of energy (edit: in significant amounts), or vice versa.",
"If energy is produced, then mass is lost. It's true for matter/antimatter reaction, of course, but it's also true for fusion and fission, and even for chemical reactions (even if the ch... |
[
"If you spin or flip in zero-gravity, would you get dizzy?"
] | [
false
] | null | [
"Yes, they would eventually get dizzy. Dizziness is caused by the centrifugal acceleration while their body is rotating, and centrifugal acceleration is not caused by gravity."
] | [
"Didn't you mean ",
" acceleration?"
] | [
"Sorry, yes."
] |
[
"Why does the oxidation of a hydroxy group to a ketone (like morphine to hydromorphone or codeine to hydrocodone) make the drugs more potent pain killers?"
] | [
false
] | null | [
"The answer is quite simple these little tweaks cause they drug to become more lipid soluble. These drugs can only act mu1, mu2, kappa and delta cells if they can get there. \nThe blood brain barrier only allows the nonionized (another factor) lipid soluble drugs through."
] | [
"Morphine is lipid soluble, but not as lipid soluble as for example fenantyl, and sufentil even more so"
] | [
"I’m a microbiologist who has never even taken a neuroscience course, so this is not a definite answer. That being said, this seems like enough of a basic biology question that I think I can chime in.",
"People talk about protein-substrate binding as a lock and key model, where the substrate “key” fits inside of ... |
[
"How do animals evolve to blend in with their environment?"
] | [
false
] | null | [
"A whole bunch of mutations happen. Lots of things change. Some of those help and some don't. If the organism reproduces, all of those changes are passed on. Some might be tweaked even more while others might not. Over time (generations) the changes that help accumulate and may be pushed further. That's the rough i... | [
"Ones that have mutations that make them blend in a bit better are slightly less likely to get eaten than ones that stand out. Their children are also more likely to survive and reproduce and pass on those mutations and additional ones if they look even more like their environments, etc."
] | [
"That makes sense, but how does the body know it’s the color it is that helps instead of other factors?"
] |
[
"What is the evolutionary advantage to having a \"shy bladder\"??"
] | [
false
] | null | [
"That isn't how evolution works. Why do people have Parkinson's, what is the reason for that? Evolution works through random mutation. A new variation of a gene is created, and if it makes the person better able to reproduce, it gets passed on more. Sometimes bad genes get passed on too, and lots of them are ne... | [
"You're making the mistake of assuming every random variation in genes and brain chemistry only occurs because it has a survival advantage. There are plenty of quirks that have nothing to do with survival or reproductive success. Your question should be \"",
" an evolutionary advantage to having a shy bladder?\" ... | [
"You are quite vunerable to attack from predators while actively excreting waste, in addition to leaving a nice smelly marker for predators to help track you. "
] |
[
"Salt: Sodium or Sodium chloride?"
] | [
false
] | I'm not a chemist or scientist, but I thought salt was = sodium chloride. Yet most of the general public calls salt, "sodium". Is this just a general and accepted misuse of the word, or am I confused here? | [
"It's just a general and accepted misuse of the word, table salt really is sodium chloride."
] | [
"Table salt is sodium chloride, but to a scientist, salt usually refers to a group of compounds of which sodium chloride is one. In nutrition (as I understand it) sodium content is what's important not necessarily salt content, so that is probably why people use them interchangeably."
] | [
"In chemistry, ionic compounds that result from reacting an acid and a base are called salts. The \"salt\" we eat, table salt, is sodium chloride. Of course, there are also other sodium compounds that isn't sodium chloride, such as baking soda. So the \"label\" in the nutritional data includes all sodium compounds.... |
[
"Why do some people have photographic memory, yet a normal person without one can still remember a huge quantity of information, such as the meaning of hundreds and thousands of words? What's the scientific difference between those two types of memory?"
] | [
false
] | null | [
"i'll second the \"photographic memory is a myth\" post. there's no such thing. there are great ",
"mnemonists",
", usually people who have developed/trained a method for quickly organizing information to be recalled later. some of these people have extraordinary skill for memorizing visual scenes, e.g. ",
"s... | [
"The correct term for this is 'highly superior autobiographical memory' or 'hyperthymesia'. There are a very few individuals who exhibit the ability to accurately recall very specific details of their lives. It's not precisely the same as the mythical 'photographic memory', however. For example, they could tell you... | [
"The correct term for this is 'highly superior autobiographical memory' or 'hyperthymesia'. There are a very few individuals who exhibit the ability to accurately recall very specific details of their lives. It's not precisely the same as the mythical 'photographic memory', however. For example, they could tell you... |
[
"Why might one's hands and feet get excessively cold and damp when they're a little bit chilly?"
] | [
false
] | [deleted] | [
"The dampness is likely just a perception. Many people have an excessive vasoconstrictive response to a mild cold stimulus called Raynaud's syndrome."
] | [
"What do you mean by \"just a perception\"? "
] | [
"Sometimes when digits get cold they feel damp even if they're not. The vasoconstriction in Raynaud's can have goofy effects on sensory nerves, so for instance your feet might get way too cold in relation to the ambient temperature and they'll feel damp but if you feel them with your hands they'll be dry."
] |
[
"If space is expanding outwards, would part of the night sky eventually get darker?"
] | [
false
] | Mainly referring to stars that are getting farther away but also other factors if relevant. If everything is moving away from a point, would that point eventually be darker/emptier than the rest of the sky? | [
"Our galaxy is not expanding, because its stars are gravitationally bound. The sky will go dark eventually, but because of the decrease in available fuel for fusion reactions, not because of the expansion of space. "
] | [
"Everything is not moving away from a point. Everything (at intergalactic scale) is moving away from each other. Except that things are not really moving but the space itself is stretching so the distance between large-scale objects increases. As ",
"u/Heavensrun",
" said, \"small\" scale structures like indivi... | [
"This is not true. Like sharlinator pointed out, light is redshifting because of the Expansion of Space. Light from Stars of other Galaxies will eventuelly redshift out of the visible spectrum and all one can see will be Stars from ones own galaxie and probably the respective cluster."
] |
[
"Is there any real difference in sexual desire between males and females? Is something like this even possible to measure?"
] | [
false
] | [deleted] | [
"It's actually a topic of scientific interest for many social/gender psychologists. The short of it, is we still don't know. While physiological signs of sexual excitement (e.g., blood flow to the vagina or penis) are relatively easy to measure, the emotional differences that the two genders attach to sex are extre... | [
"This isn't how science works. Just because it sounds plausible to you doesn't mean anything at all. Which is why a lot of bullshit is circulated as facts relying on Just-so explanations to justify."
] | [
"I have mixed views about evolutionary psychology. I think most psychology nerds do. The problem is, evolutionary psychology often stretches itself past reasonable/supportable ideas into some ideas of downright silly. It seems to often switch sides to make evolution fit a theory rather than theory fit to evolution.... |
[
"How strong is human skin relative to other animals?"
] | [
false
] | null | [
"A human raised in similar conditions to animals winds up with very thick skin on the hands, feet and sun exposed areas. ",
"Look at the skin on the feet of individuals who regularly walk barefoot and it's often quite thick, then combine that with the increased need for thick skin on uneven, rocky ground.",
"Mo... | [
"It's important to consider scale. To a rhinoceros horn you're not very thick at all, but on the scale of insects we are quite tough. There are areas of your skin that are tough enough that a mosquito can't bite you there, for example. We are definitely more vulnerable than most mammals, but to some creatures we ar... | [
"Would the same apply to domesticated animals like cows and pigs that live a pretty sheltered life compared to their relatives in the wild?"
] |
[
"In programming, we can manually define functions for computers to perform tasks, but how do we program computers to actually understand what multiply, divide, add, subtract and equal actually mean and how to use them?"
] | [
false
] | null | [
"Circuits. We have something called an adder circuit. This can take two inputs in binary and output them added together, in binary. Multiply is just short hand for adding. Indices are just short hand for multiplication. And there's a way to subtract by adding which I don't fully understand but it's a thing. ",
"A... | [
"Subtraction can be done through addition by negating the sign of the second operand, so a-b becomes a+(-b). Changing the sign of a number is quite easy in two’s complement, the system most computers use to represent integers in binary (it’s also very simple for IEEE-754 floating point numbers, the standard for rea... | [
"Computers don't understand anything. They flip bits according to the instructions we give them. Just like your washing machine doesn't understand the concept of clean or dirty clothes. It just goes through its wash cycle according to its computer chip (washing machines are computers these days) and the instruction... |
[
"Does the delayed choice quantum eraser experiment necessarily imply retrocausality or determinism?"
] | [
false
] | I'm talking about where what I've called the "first" photon hits D0 and the "second" photon hits one of the other detectors. Won't the first photon of an entangled pair hitting a detector in a certain way mandate that the second photon's action, either passing through a splitter or being reflected, is a non-random event? Or that the random event of the second photon passing through a splitter or being reflected mandates how the first photon hits a detector? All in spite of the fact that the correlations between entangled photons can only be known after both have been measured (thus barring any FTL transmission of information)? Am I missing something fundamental about entangled particles? (Also where I'm talking about determinism I mean absolute determinism) | [
"A few more details here. (trying to explain the phenomenon more simply). A photon passes through the double slit and doubles into two photons. One of these photons quickly hits detector D0. After some time, the second photon passes through its mirrors and beam splitters and lands in some detector D1 through D4. ",... | [
"I've been thinking for a long while about this question, trying to answer it best. I may be entirely wrong in the answer I'm about to give, so I welcome criticism if that's the case. ",
"The answer is that it's philosophical, not scientific. A rigorously pragmatic view of science says that science can only tell ... | [
"If I'm not understanding your answer correctly or have made any mistake in my writing below please disabuse me of my ignorance.",
"I guess what I'm more interested in is the mechanism. If we think about this in terms of wavefunction collapse I don't understand the experiment. The first photon hitting detector D... |
[
"Is there a limit on how small the wavelength of light can get?"
] | [
false
] | I was thinking about 'no preferred reference frame' and blue shifting - is there a limit on how blue-shifted light can get? | [
"none that I'm aware of."
] | [
"I dunno, I'm really not strong on electroweak forces. (pardon the pun)"
] | [
"none that I'm aware of. For exactly the same reason as OP. You can always change your frame of reference such that the wavelength shifts smaller or larger."
] |
[
"What causes your tongue to appear 'furry' and how can you counteract this?"
] | [
false
] | And I am not talking about oral thrush, I know what that looks like and entails, are there other environmental factors, food or lack of ceratian minerals, vitamins, love to know :) | [
"Brush your teeth, use mouthwash, and stop smoking."
] | [
"You mean the white stuff that builds up on your tongue? You can get rid of that by just scraping it with a toothbrush. Will make your breath a ",
" fresher."
] | [
"Thrush?",
"http://www.medicinenet.com/thrush/article.htm",
"or",
"http://www.medicinenet.com/hairy_tongue/symptoms.htm",
"http://en.wikipedia.org/wiki/Black_hairy_tongue"
] |
[
"Why do certain musical scales sound happy, scary , eerie, etc?"
] | [
false
] | Some of my oldest memories is of being scared and saddened by songs in minor scales, and cheered up by songs in major scales. Is this something learned or in our DNA? | [
"i am not a scientist, but a reasonably educated musician.",
"the associations with scales is largely cultural. minor scales are not sad in all cultures. however, minor scales, because of how the notes compare to the harmonic series, tend to resolve downward to structural pitches rather than upward, which accoun... | [
"Im not aware of a ton of work in this area, but one guy who is sorta studying this is Gilden at UT Austin. Though he mostly focuses on the nature of musical \"groove\". It's a bit of a new line for him, but he talks briefly about it on his site (",
"http://homepage.psy.utexas.edu/homepage/group/GildenLAB/groov... | [
"I'm not sure how well versed in music you are, but the primary difference between a major and minor scale is the 3rd note of that scale. Most of the others stay the same (the rules changing depending on the type of minor scale, but that is more of a music theory question than a psychology question). ",
"So let... |
[
"What exactly happens when an acid touches something? Specifically, how does a protonation work and cause damage?"
] | [
false
] | I was trying to find some stuff online and on here, but couldn't find much aside from mentions of Bronsted and Lewis acids (I think proton donation only happens with the former)? Thank! | [
"There are 3 types of acids:",
"Essentially the acids are very reactive, and they're \"unhappy\" in their current energy state, so they want to move to a lower energy state by giving energy to another molecule in the form of a proton (let's exclude Lewis acids for this discussion). Now when the receiving molecule... | [
"Great question. I'm a little unclear what you're asking specifically, but I'll try to explain the best I can.",
"Strictly speaking ionization is just taking an ",
"uncharged molecule and removing an electron",
", but acids don't generally release electrons. They may cause the formation of anions have unbonde... | [
"This is going to sound a bit foolish on the surface, but how is this different from ionization? Aren't they essentially the same thing, only high energy radiation strips away an electron vs a chemical interaction? Wouldn't that mean ionizers change what makes something an acid? "
] |
[
"What is the feeling of falling when laying in bed caused by?"
] | [
false
] | null | [
"It's called ",
"Hypnic Jerk",
" and according to a study done by the Mayo clinic in '06, over 70 percent of the human population of the earth experiences them. ",
"They seem to happen more frequently in people who are having trouble sleeping/irregular sleep patterns/reasonably severe lack of sleep. ",
"Res... | [
"I speculate that he'd be unhappy if any scientist was freed from the burden of proof."
] | [
"Tsk. It's just speculation. Take it with a grain of salt. It's not science without evidence."
] |
[
"Why are plants mostly green and solar panels mostly black?"
] | [
false
] | null | [
"The difference is due to the fact that solar cells and plants have simply have different requirements. The key goal of a solar cell is to convert as much sunlight as possible into electrical energy, which means that the ideal solar cell will absorb all incoming light. While we never get to this ideal case, the mos... | [
"Very informative. TIL, thank you :)"
] | [
"the slight difference being due to the choice of anti-reflection coating used.",
"And the crystallinity (monocrystalline having the most favourable orientation and no grain boundaries causing both internal and external reflections), as well as the depth of doping (thinner active areas look progressively reddish,... |
[
"How is gravity capable of bending light? And does this mean it can change light's speed?"
] | [
false
] | Okay, first off, in classical physics, Newton taught us that gravity was the inherent attraction between the centers of two masses. Einstein elaborated upon this by saying that matter warps space time, and the change is perceived by us as an attraction in gravity, like the age old analogy of placing a bowling ball on a trampoline. And I know new revisions on Einstein's work are created by physicists all the time. But what I still don't understand is how light can be affected by gravity. I know light can act as a wave and as a particle, and that the "particle" of light has a mass of zero, and according to (at least how I understand it) there must be at least two masses for a gravitational force. Light doesn't have that. And yet I know that even light can't escape black holes because of their immeasurable gravitational pull, and that scientists can detect stars behind their planets because the planets bend the light around to reach us, and in one sense that makes sense to me, but I don't know why. For my second question, accepting the premise of the first question, does this mean that gravity can change the speed of light? If gravity can bend light with centripetal acceleration, wouldn't it naturally follow that it could cause linear and/or angular acceleration? But according to what I've heard, the speed of light is constant and cannot be changed. Is this true, and if so, why? I've always chalked it up to being the foundation of space-time and left it at that, but I'd really really like an explanation that gives my brain some peace. Perhaps I can't wrap my head around this because I've stuck myself in the comfortable world of Newtonian physics, where everything is tangible, and I don't feel so insignificant. Thanks. tl;dr - just read the whole thing otherwise you'll just confuse me with an unclear answer. also I'm not sure if this goes in physics or astronomy so perhaps someone can tell me conclusively? | [
"This ",
"comment",
" I made a few weeks ago should mostly cover it. Let me know if there's anything that needs following up on:",
"Light does exhibit both particle-like and wave-like behavior. However, photons (light particles) are massless. It is for this reason that they move at a constant c, the speed of... | [
"I think you have it, but your summary isn't quite right.",
"\"It's an absolutely necessary requirement for the universe to function\" doesn't really make much sense. It's how the universe fundamentally works. There's nothing that must be done to keep it that way, and there's nothing that could be done to chang... | [
"Newton's law of universal gravitation is a nice description but it's not the whole picture. For that you need ",
"general relativity",
". Gravity is the warping of spacetime. It doesn't change the speed of light, it just changes its direction."
] |
[
"What if we cannot find the Higgs?"
] | [
false
] | What would be the implications of not finding the Higgs boson? To be more specific, not that we don't find it, but we it simply isn't there or even exists? What would this mean to particle physics and quantum theory? What branches or theories would benefit from it "not existing" and which ones would it hurt (if any at all)? | [
"Quantum mechanics and all are completely fine. The Higgs mechanism specifies a lot of things for the Standard Model, though, which is our current understanding of how all the particles we've seen get their masses, and our best explanation for the ratio between the masses of the W and Z bosons, among other things.... | [
"Theorists would have a lot of work to do."
] | [
"One immediate implication is that unification probably doesn't work like we think is does. ",
"The higgs boson comes from what is effectively a phase transition (symmetry breaking). When the symmetry group of E&M and the weak interactions is broken, U(1)XSU(2) (ie they are no longer the same force), the higgs b... |
[
"How do jets know they've been locked onto?"
] | [
false
] | in movies, the pilot always has a warning when theyve been locked onto. is this real or just hollywood? how would it work? | [
"Check out ",
"this post",
"."
] | [
"https://en.wikipedia.org/wiki/Radar_warning_receiver"
] | [
"IR seekers still get an initial lock from the radar of the airplane that is carrying it. After the jet locks radar, information is sent to the missile so it knows where to look for its target. "
] |
[
"It is said we are 99% genetically similar to chimpanzees. But also that siblings are 50% genetically similar, cousins 12.5% etc. Can someone explain the different metrics of 'similarity' being used in each case?"
] | [
false
] | null | [
"None of the answers here have given the correct answer. The 50% number refers to genetic similarity directly through descent, while the 99% number refers to just how similar the genomes are when compared base by base.",
"When we say, for example, a son shares 50% of his DNA with his father, what is actually mean... | [
"For a given DNA strand, the entire strand is 99% identical between humans and chimpanzees. For siblings, of the DNA that can be different between people, approximately 50% is identical, so about 99.5%. And so on. The general idea is that there are unspoken assumptions when you compare between species, between sibl... | [
"It's actually about 96% with chimps. But in reality that means practically nothing. We share 5o% of our DNA with bananas. \nHumans share about 99.8% with each other and the percentages listed for differences between cousins and distant relatives are all within that .2% "
] |
[
"Why is Rabies treatable up until it reaches the Central Nervous System? What exactly happens during this time to make it untreatable?"
] | [
false
] | null | [
"One major problem is that there is something called ",
"blood-brain barrier",
" - and ",
"once the virus gets beyond that the immune cells are ineffective on it",
".",
"The other problem is of course that the virus is causing major damage once in the CNS - generally even with the ",
"Milwaukee protocol... | [
"Thank you for your response and that was a very good read. "
] | [
"Is this essentially the same mechanism that makes the eradication of the herpes virus in the body impossible since it hides in the nervous system? I am not knowledgeable enough to understand where exactly that is (not in the brain?), although it sounds like the peripheral nervous system has its own version of cere... |
[
"Why are our fingers of different lengths?"
] | [
false
] | My brother guessed that it is because this way we can better distribute our weight when hanging from something, because our center of gravity would be at the center of our hands, which allows us to balance better. Is that correct? | [
"Varying lengths of fingers give us more agility holding objects with odd shapes,they also promote better balance on hands."
] | [
"As common in biology, form fits function. Looking at other ape hands you see orangutans with long palms and fingers fit for excessive hanging. As for humans, i'd guess this is just what an apes hand looks like if it isn't used for swinging through trees all the time. Our structure is better fit for holding objects... | [
"Was gripping tennis balls an environmental factor that influenced our evolution? What's the advantage of having your fingers line up when you grip something? When I grip my tennis racquet the tips of my fingers don't line up at all."
] |
[
"How do they determine how many calories any specific food has?"
] | [
false
] | For example, a strawberry, how do we know how many calories are in a strawberry? | [
"They burn it in a calorimeter to measure how much heat it generates. Heat = energy = calories.",
"It's horribly inaccurate though. You absorb fewer calories from a rare steak than a well done one, fewer calories from wholefoods than the processed version, fewer calories from raw food than cooked food. But the ca... | [
"In short, the food's composition is determined through various means and through knowledge of the caloric content of each of those components, the caloric content of the total food is obtained.",
"The food Calorie (big C) is equal to 4.184 kJ, which is the heat energy required to heat up one kg of water one degr... | [
"The average calories in the four major energy-providing macronutrients (protein, fat, carbs, alcohol) was determined by burning a bunch of different molecules and seeing how much heat it generated. These values were then (",
") corrected to account for the actually biologically extractable energy by subtracting ... |
[
"3D Graphics Over 2D Footage Match-Move Conundrum"
] | [
false
] | I've noticed a strange thing in every 3D engine I've ever worked with. If I have three identical objects in a line in front of me such that when viewed from the top, the arrangement of myself and the three objects is that of the "T" shaped Tetris piece, in the real world, the objects on the left and right should appear slightly smaller than the one in the center since they're slightly further away, but in a 3D engine, all three objects are identical in size. I understand the linear algebra for why this is so (shape of frustum), but my question is how does this not negatively affect compositions of 3D effects superimposed over 2D motion pictures where the 3D art is match-moved to the video? I feel like a more lifelike virtual camera would have curved near / far clip planes. | [
"Hmm, you've really got me thinking. You're talking about overlaying 3D effects over 2D video. I think it's possible that the output of a typical 3D engine does accurately reflect the output of a typical camera, or at least, an ideal pinhole camera, if not the human eye.",
"Looking at some perspective equations... | [
"I've done similar tests by pointing my cell phone camera at a grid of tiles in my bathroom. I feel like I should see some curving in the lines that are created by the tiles but I don't. I know I have seen this effect in other images where the photographer used a fish eye lens, I guess I just thought the effect wou... | [
"I found a youtube vid of a 3d engine that does exactly what I was imagining (taken to extremes)!",
"I'd imagine making a 3d game engine that does this with raytracing would be rather taxing on a system and destroy performance, but do you think this effect could be achieved with a post-process effect?"
] |
[
"Are the feelings in dreams really happening at the same time in real-life body?"
] | [
false
] | null | [
"This is from Dr. Stephen LaBerges book Exploring The World of Lucid Dreaming:",
"The experiments just reviewed supported the conclusion that the events you experience while asleep and dreaming produce effects on your brain (and, to a lesser extend, your body) much the same as if you were to experience the corres... | [
"Your body and mind is not separate. It's not like your brain shuts off from the rest of the body when you're sleeping. The two are still interacting, and the rage/sadness/happiness you feel while dreaming is happening in the same way it would when you're awake."
] | [
"Does this mean a dream could cause PTSD if it was traumatic enough?"
] |
[
"Why is oxygen so special?"
] | [
false
] | I'm not just talking about for life. For instance, why does combustion require oxygen specifically? Why can't things burn without oxygen? I get that because of the number of electrons in its outer shell it's really reactive, but shouldn't sulfur and selenium behave the same way, given their position on the Periodic Table? Are they just rarer, so that's why oxygen gets all the attention? Or are they actually less capable of filling the role oxygen does in things like combustion? (That may be a very stupid question, but my degrees are in psychology and history, not chemistry... obviously. :) ) | [
"Things can burn without oxygen, it's just not as common. Most compounds/gases that are more powerful oxidizers than oxygen are rare in nature, since they've reacted already.",
"Oxygen isn't a uniquely powerful oxidizer, but it does have a unique feature, which is that it has what what we call a 'triplet ground s... | [
"You have a pretty good feel for what's going on. Because of the number of electrons, sulfur and selenium can form the same type of molecules as oxygen. H2S (hydrogen sulfide) actually forms in combustion processes if oxygen isn't around. Hydrogen selenide (H2Se) is similar.",
"For another piece of the puzzle,... | [
"Things can burn without oxygen, it's just not as common. Most compounds/gases that are more powerful oxidizers than oxygen are rare in nature, since they've reacted already.",
"And oxygen (gas) hasn't simply because photosynthesis keeps producing more? Or is it just that there's much more oxygen out there (on Ea... |
[
"How can the universe have a shape? This is mind-boggling to me..."
] | [
false
] | I cannot understand the concept of If something has a shape than that something "borders" something else. Please read the link above (it's from NASA's official website). It considers three possibilities: 1) The universe is spherical 2) The universe is curved like the surface of a saddle 3) The universe is flat "like a sheet of paper", and infinite in extent In the first scenario, the universe being a sphere, what surrounds that sphere? It does not say that it is infinite, so there must be a "beyond it", right? I could say more or less the same to the second "saddle" hypothesis. In the third case, if the universe looks like an infinite sheet of paper, I understand we couldn't travel to its extremities to reach the end of its extension, but how about traveling "up" or "down" its "height"? Does that make any sense?!? Please help, I'm having an existential crisis... (hopefully the matrix will open up) | [
"Actually, the terminology is somewhat confusing, but they are not talking about the shape of space but its global curvature. The universe could have a global curvature that is like that of a flat sheet of paper, i.e. zero, but it doesn't have to be a flat sheet of paper.",
"Also, the universe could actually have... | [
"First, we don't have an exact measurement of the curvature of the universe.",
"Second, you're talking about different parameters. The ",
" is zero for a flat universe, negative for a hyperbolic (saddle) universe, and positive for an elliptical (sphere) universe. The ",
" is 1 for a flat universe, greater th... | [
"First, we don't have an exact measurement of the curvature of the universe.",
"Second, you're talking about different parameters. The ",
" is zero for a flat universe, negative for a hyperbolic (saddle) universe, and positive for an elliptical (sphere) universe. The ",
" is 1 for a flat universe, greater th... |
[
"Would electron degenerate matter behave similarly to a solid, gas, or liquid?"
] | [
false
] | In the book “The Collapsing Universe” by Isaac Asimov, he claims that degenerate matter would behave like a gas. He explains that while the electrons are compressed into a free flowing goo, the nuclei still remain relatively spaced out, and would thus act like a gas. Given that this book was written in the early ‘70s, is this an accurate statement, or do we have a better understanding of degenerate matter? | [
"The answer is basically yes, but it depends on your point of view. It's hard to imagine the kinds of forces involved that would cause the material to flow. Under such forces, normal matter wouldn't stand a chance.",
"Note the compared to the confinement pressure required to create EDM, the forces of molecular b... | [
"Electron degenerate matter is supported against further collapse by the degeneracy pressure of the electrons in the material being unable to occupy the same quantum states and isn't very dependent on temperature. As the material cools eventually the motion of particles in the material will slow and the blackbody r... | [
"I do work simulating neutron stars, which are composed of neutron degenerate matter, but the same concepts apply to electron degenerate matter. It's best to say that matter under these conditions acts as a fluid, something that in physics terms encompasses both gasses and liquids. All this means for the most part... |
[
"What happens to your eyes when you look straight at the sun?"
] | [
false
] | Just wondering what exactly damages your eyes from looking at the sun | [
"Same thing that happens to the rest of your body. They get sun burned. Also known as photokeratitis. ",
"And just like your skin. Your eyes will swell and burn and the cells will die off and shed. ",
"You’ll need to get antibiotics because if your eyes get infected they can scar over and become opaque. ",
"... | [
"Does this just happen to the outer surface of the eye, or can it damage the retina as well?"
] | [
"Are you talking about all the warnings that were given with the eclipse?"
] |
[
"What caused all the giant underwater reptiles to die out at the Cretaceous Mass Extinction but not other ocean life?"
] | [
false
] | Basically, what caused underwater dinosaurs to die specifically? | [
"Two things. Firstly, it’s important to remember that the Mesozoic Era, the ‘Age of Dinosaurs’ lasted 190 million years. The Cenozoic, or the ‘Age of Mammals’ has only lasted 65 million years. During the Mesozoic many different groups of plants and animals waxed and waned, and they did not all exist at once. Secon... | [
"This theory has been around for a long time, and was pretty prominent before the discovery of the iridium rich K-T boundary and the tsunami deposits in the Carribean and the Gulf of Mexico. I'll try to address each of the points in turn, and keep in mind that geology is a subject that is always open to new evidenc... | [
"I have a side question for you:",
"I remember seeing an show on the history channel (i think, looking for it now) and they interviewed a paleontologist who was making the case an asteroid didn't cause the kill off of the dinosaurs. His basic reasons was, ",
"1) lack of dinosaur fossils in the ash layer. ",
"... |
[
"What causes Ice ages?"
] | [
false
] | [deleted] | [
"We should distinguish between ice ages, which are long term cold periods, made up of many glaciations and interglacials. The current ice age started 2.58 million years ago, but the present interglacial only started about 11,400 years ago. ",
"For glacial and intergacial cycles, the ultimate driving factor appea... | [
"There is widespread agreement from paleoclimatic and modeling evidence that Pleistocene glaciation cycling is driven by small, periodic changes in our movement and position relative to the sun called ",
"Milankovitch cycles",
". These changes are amplified in the climate system by feedbacks, such as albedo and... | [
"I'd say that estimate is a bit dodgy. Ignoring the effects of global warming is like saying \"other that that, did you like the show Mrs. Lincoln?\" Human contributions at the present are the overwhelming effect. Moreover, the end of the interstadial is not really well dated, some people think it would naturall... |
[
"Earth is made up of tectonic plates, will the number of these plates ever change over time?"
] | [
false
] | Earth conists of a number of tectonic plates that, as far as I know, seem rather stable. However, will some plates subdivide into new plates over time? Will current plates combine into larger "superplates"? Or is Earth just not geologically active enough for the tectonic plates of Earth to change? On a slightly related question, the tectonic plates present on Earth seem to be identical to the ones of Pangea, so is it possible that the number of tectonic plates has been stable for quite some time? | [
"Neither the number of plates or the geometry (i.e. their sizes/shapes) of plates are fixed. It's first worth noting that even the current number of plates is somewhat contentious and depends on how the criteria / data used to define them (e.g. ",
"this paper",
" which both lays out a set of criteria for defini... | [
"This is completely fascinating. When a plates rift/suture, is this process quite catastrophic with volcanoes/earthquakes or is it so long that its effects aren't directly observable?"
] | [
"It is a process that happens slowly, over geological timescales - for example, the Indian plate moves northeast at about 5 cm per year, while the Eurasian plate moves north at about 2 cm per year. It isn't really observable much on human timescales with the naked eye, but definitely measurable.",
"Especially the... |
[
"How much power could you generate if you put a water wheel in urinals that when spun generated electricity?"
] | [
false
] | Every guy wants something to aim at when he pees at a urinal. What if you put a pinwheel that spins when hit by the force of urine and generates electricity? Assuming you placed one at a bathroom at Disneyland to ensure a constant supply. | [
"But a lot of microscopic things don't add up to jack. ",
"Disneyworld has 52million annual visitors. Assume half are men and they average 2 pees per day that's 52million total pees. ",
"80mW * 30s gives you 2.4 joules/pee. Multiply by 52million and you get the energy saved per year, for which ",
"Wolframalph... | [
"If you have 500 grams of pee that fall half a meter over the course of 30 seconds, you have about 80 milliwatts of power. Not much."
] | [
"This would be a game-changer and allow us to send a manned spaceship to Alpha-Centauri every week."
] |
[
"What causes aftertastes? Why don't all tastes occur immediately?"
] | [
false
] | null | [
"Taste is caused by molecules in food binding to receptors on the tongue (plus a lot of scent stuff but we'll simplify that away for now because it's a similar mechanism anyways).",
"Some of those molecules stay bonded for a longer time than others."
] | [
"Because probably the \"tasty\" molecules from the food are not bonded to the taste receptors on the tongue as long as the \"nasty\" molecules are."
] | [
"But how does the aftertaste taste completely different to the original food? If I eat something with Stevia, for example, it tastes ",
". But maybe a minute later I get the aftertaste and it's vile, filthy, ",
". Why the big difference?"
] |
[
"Why don’t hotspots in the earths mantle move with the continental plates?"
] | [
false
] | I’m currently taking a geomorphology class in college and we were talking about plate tectonics. Our professor said that the plates move due convection of magma within the earth. However, hotspots tend to stay in place and cause volcanoes as the plate moves over them. Why are the hotspots not effected by convection? | [
"The mantle and the crust are - at least partially - decoupled.",
"In the most simplified way you can imagine the mantle as a convecting fluid, with rising portions (mid ocean ridges), coooling surfaces (oceanic plates) and sinking portions (subduction zones). Movement is in the order of 0.01 - 01 m per year. ",
... | [
"Just to add a bit on the 'plumes wobbling', there is a pretty vigorous debate on the extent to which plumes are fixed either at their base or their surface expression, as just one example ",
"Tarduno et al, 2009",
" (and references therein) argue that the surface location of plumes can be influenced by a varie... | [
"It seems like there is a little misunderstanding here. First of all, the evidence of convective cells is at least in some places not quite given. Also plates are also to a large part moved by ridge push and slab pull, but this is besides the point.",
"Commonly Hotspots are theorised to originate at the Mantle-Co... |
[
"Is sugar content higher in ripe vs. unripe fruit?"
] | [
false
] | You have two bananas, one ripe, one green and unripe. The ripe banana will taste sweeter, leading me to believe it has more sugar, but I would assume both bananas have the same total calories. | [
"In the case of bananas, commercially produced bananas are almost always treated with ethylene gas which acts as a plant hormone that helps the fruit ripen (it's also responsible for the yellow colour). When this happens, enzymes in the fruit convert starch to sugar, which makes it taste sweeter and also makes the ... | [
"Don't know how this went off on a tangent regarding ethylene gas... Yes, when most fruits ripen, the starches in their tissues are lysed to form sugars. This, along with changes in color, is in order to attract animals which will eat the fruits and spread the seeds."
] | [
"Don't know how this went off on a tangent regarding ethylene gas... Yes, when most fruits ripen, the starches in their tissues are lysed to form sugars. This, along with changes in color, is in order to attract animals which will eat the fruits and spread the seeds."
] |
[
"What is the relationship between energy savings and visible light reduction when dimming incandescent light bulbs?"
] | [
false
] | Levitron makes the following claim about their incandescent light dimmers. It appears on the dimmer package and : If "Dimming" means decrease in light output, then I find these claims hard to believe. As the filament cools down, emission shifts towards infrared and the light bulb becomes less efficient at producing visible light. Because of this, I was expecting much less of an energy consumption decrease. Is the table reasonably accurate? If not, can I find more accurate information elsewhere? I realize that different light bulbs would behave differently. I'd prefer information for something common, like 120V 60W or 100W incandescent bulbs. Edit: I just found some information at : For a supply voltage V near the rated voltage of the lamp: This means that a 5% reduction in operating voltage will more than double the life of the bulb, at the expense of reducing its light output by about 20%. | [
"I'd assume based on my EE knowledge that \"reducing power by 10%\" is actually just increasing resistance by the correct amount to give 10% less power. Basically every dimmer switch utilizes a sliding resistor as seen ",
"here",
"."
] | [
"That was my EE suspicion as well. However, I wouldn't be surprised if that decreased power traveling to the light bulb itself did actually increase the lifespan of the filament as the OP's PDF suggested. "
] | [
"You are right!",
"I suspect dimming by 10% means reducing power by 10%; not reducing light output by 10%. The light probably reduces by even more. But I am curious to know the answer as well. Upvote!"
] |
[
"What is the basis for having a sense of rhythm?"
] | [
false
] | It seems to be more involved than just good coordination. Has neuroscience ever studied it? | [
"Yes :) in my undergrad developmental psych class, we read a book that compiled a doctor's experiences after working in the emerging field of children's psychological trauma (boy who was raised as a dog, all the trigger warnings). There's plenty of research available indicating that musical training in some way ac... | [
"This is less my area, but an exciting new paper just dropped looking at the genetics of a sense of rhythm. It's open access, so you may find many interesting answers to your question in the introduction and discussion sections.",
"Choice bit from the Abstract: \"Genetic correlations with breathing function, moto... | [
"I read the book This Is Your Brain on Music way back in high school and the author did say that rhythm originates from the cerebellum, which is the part of the brain that controls rhythmic motor skills like your gait while walking and I think also our passive rhythms like breathing and heartbeat. It's the most \"b... |
[
"So the colors we see can be placed on a linear chunk of the electromagnetic spectrum, red to violet. Why can we represent them in a circular \"color wheel\" then?"
] | [
false
] | So rainbows and images like show that red corresponds to low wavelength and violet corresponds to a high wavelength. Then how the heck is it that when we look at a color wheel ( for instance ), the difference in color between red and purple (massive difference in wavelength) looks about equal to the difference in color between red and orange (significantly less)? For that matter, why does combining red and purple give you a reddish-purple and not, say, cyan, the average of their two wavelengths? | [
"What it comes down to is that ",
"magenta isn't a real color",
", not in the same sense as all the other colors. See that article for a better explanation."
] | [
"There is a great ",
"MinutePhysics",
" that may answer your question."
] | [
"What it comes down to is how your brain processes color. We only have red, blue, and green photorecptors in our eyes. For whatever evolutionary reason (probably for better visual contrast), the brain mixes the red, green, and blue signals to try to recreate an original color rather than showing you a superpositi... |
[
"If projectiles were launched at Escape Velocity from an electromagnetic gun, wouldn't they eventually loop toward the Sun, regardless of which way the Earth was facing at the time they were fired?"
] | [
false
] | [deleted] | [
"Escape velocity from Earth's orbit around the Sun is about 43 km/s. But the Earth is already orbiting the Sun at about 30 km/s. So if we shoot something \"forwards\", we only need to give it an extra 13 km/s for it to escape the solar system - otherwise it goes into orbit. If you want the junk to fall into the Sun... | [
"It's incredibly difficult to actually shoot something into the sun. One of your qualifiers is that you don't want it to \"go into orbit around it (the sun)\", but everything on earth is already in orbit around the sun because the earth is. So you have to launch something off of earth, then you have to \"de-orbi... | [
"Besides the technical problems there is one relatively simple rule of orbital mechanics: If you are in an orbit, you will encounter the same point over and over again.",
"That means, if you shoot something away from Earth and it escapes the Earths gravitational pull, but doesn't fall into the Sun or escapes the ... |
[
"Perceiving an object moving near the speed of light..."
] | [
false
] | [deleted] | [
"Sally goes to a point 5 years away traveling at < C and comes back immediately. 10 years have passed and Bob experiences more time has passed depending on the speed.",
"Bob experiences 10 years no matter how fast Sally is traveling.",
"So he would see the spaceship moving slower than it actually is?",
"No, h... | [
"Bob experiences 10 years no matter how fast Sally is traveling.",
"Well, if she's going much slower than c then he'll experience quite a bit more than 10 years.",
"For example, if she's traveling at 0.5 c, then he'll experience 20 years before her return while she'll experience about 17.3."
] | [
"Maybe I'm misunderstanding OP's question. It's inconsistent, but I'm not sure what OP was intending to ask."
] |
[
"In a rear-end collision is it better to be slightly further away from the car in front? Or really close?"
] | [
false
] | null | [
"Please follow road safety and vehicle rules. It is always best to be as far away as necessary to have enough time to react and brake effectively.",
"For homework problems and calculations, please submit questions to another subreddit like ",
"/r/HomeworkHelp",
", etc.",
"Thank you."
] | [
"This isn’t a homework problem, so I’m not sure if it belongs there. It’s just a question about physics I have wondered about. I imagine a rear end collision kind of like That little Newton’s cradle toy you put on your desk. But always wanted to know the science behind it. Sorry i rarely post on reddit so if it’s... | [
"/r/askscience",
" is probably not the right venue for getting a lecture on mechanics. I would suggest going through a textbook (elastic/inelastic collisions, conservation of momentum, etc) first, then submitting a more specific question for our Physics panelists.",
"Cheers."
] |
[
"Are black holes traveling through space?"
] | [
false
] | From what I understand, all heavenly bodies travel relative to each other through space. When a star collapses, does this change, or does the black hole continue moving through space? If so, how? If not, why not? | [
"Yes, they will. They have momentum relative to other objects and that will be conserved. In addition, we see evidence of supermassive black holes in orbit around each other."
] | [
"There is no such thing as absolute motion (excluding for massless objects). Each black hole is either moving or not depending on your reference frame."
] | [
"Yes. Due to conservation of momentum, a black hole will (ignoring asymmetries in the supernova) still have the same momentum that the star it was formed from had. Additionally, they are affected by gravity just like any other object with mass."
] |
[
"If I took a spoonful of a neutron star and pulled it away from said star, would the spoonful expand to a larger size? What would the matter look like (metal, glass, gas, liquid)?"
] | [
false
] | I heard a spoonful of matter in a neutron star weighs the same as Mount Everest. Would a spoonful of the stuff expand to that size? | [
"Neutron stars have a density of around 10",
" kg/m",
" which means that the total mass in a teaspoon is somewhere on the order of 10 billion tons. You'd want to take the scoop from the center of the star as the outside layers are more likely to be heavy elements and stuff.",
"So lets assume we can teleport a... | [
"I didn't fully answer the question... ",
"Here",
" is a wiki article that may help.",
"What would the matter look like (metal, glass, gas, liquid)?",
"It depends on the temperature of the object. ",
"Right now, at the current age of the universe, all neutron stars are gonna be pretty intensely hot. It ta... | [
"There wouldn't be any other light in the universe by the time neutron stars have cooled down. So you might describe it as translucent, maybe shiny if you shine a light on it or just black - due to the extremely low energy levels (at that stage of the universe) and cool temperature under intense gravity.",
"Of co... |
[
"Why Do Beef and Lamb Have Such Distinctive Tastes?"
] | [
false
] | Just a thought I had: they both have pretty much the same diet (grass) so there can't be a huge amount of different compounds going into their diet and yet lamb tastes completely different to beef. Is it some chemical that one species produces that the other doesn't? Fat content? Thank you for any answers | [
"You're looking at this the wrong way. It is coded in their DNA, of course, but not with the evolutionary goal of tasting great to humans.",
"If you imagine asking the question \"why do sheep look different from cows?\", or \"why do cows and sheep smell different?\". Your question is essentially the same: the dif... | [
"Because of differences in the number and type of long chain fatty acids that each animal tends to produce and store. "
] | [
"Actually, if you try grass fed beef. It tastes different from corn fed beef."
] |
[
"Why is infrared radiation usually associated with heat even though UV, X ray, and gamma radiation are much higher energy?"
] | [
false
] | null | [
"Ugh this is such a cool question! The answer get's at some very real-life applications of quantum mechanics. ",
"The basic answer is infra-red radiation is a more effective way of heating up common materials (water, plastic, organic things) because photons in the infra-red part of the electromagnetic spectrum ... | [
"Because the black-body emission spectrum at room temperature peaks in the infrared region."
] | [
"Welding torches can give you a suntan. They are one of the few common objects hot enough to emit significant UV through blackbody."
] |
[
"Does the earths rotation have an influence on our weight?"
] | [
false
] | In other words, would we weigh more/less if the earth spun faster/slower due to centrifugal force or other factors? Is this difference significant? What might we weigh if the earth did not rotate? | [
"It does, but the effect is very slight. ",
"At the equator, where the apparent centrifugal force is strongest, it causes you to weigh about 0.3% less than you otherwise would.",
" ",
"Also, the same centrifugal force causes the Earth to be slightly oblate, i.e. it bulges out at the equator. The Earth's gravi... | [
"I believe you are off by a factor of 10. Earth's rotation makes you 0.0034 Gs lighter so you are only 0.5 lbs lighter"
] | [
"I believe you are off by a factor of 10. Earth's rotation makes you 0.0034 Gs lighter so you are only 0.5 lbs lighter"
] |
[
"Why can you see fire when the US Navy railgun shoots?"
] | [
false
] | a video of it :) | [
"What you are seeing is known as shock heating. The projectile is travelling fast enough that it is compressing the air in front of it to extreme pressures which creates heat as energy is given up to the air. The air around the projectile heats rapidly to the point that it becomes plasma. This is the same effect th... | [
"Precisely, I was simply referencing the heat of compression specifically."
] | [
"The same phenomenon is responsible for the light you see with lighting or other electric arcs like ",
"this one",
" : the air recieves a considerable amount of energy which is converted into considerable levels of heat, resulting in a plasma."
] |
[
"What is the current thinking on the relationship of Arthropods?"
] | [
false
] | I know that it's been a matter of debate as to whether hexapods and myriapoda or hexapods and crustaceans are more closely related. The last I read was that crustaceans were the more likely, but with constantly evolving theories, it can be hard to locate the current thinking using the web. I presume Chelicerata are still classed as an outgroup. Any thoughts on where Trilobites would fit in? Also, I read that what we formerly classed as hexapods might no longer form a monophyletic group... Any info on that? Sources, as always, appreciated :) | [
"Phylogenetic data seems to be coming down firmly on the side of ",
"pancrustacea",
". Usually you have to take these studies with something of a grain of salt because of a myriad of artefacts, such as long branch attraction (which is widely responsible for the misconception that eubacteria are monophyletic. Y... | [
"Thank you. I actually found this paper quite enlightening (I found it myself in the time between posting and your reply XD)",
"As for the trilobites, further investigation seems to put them within arachnomorphs as opposed to Mandibulata... Although the evidence for this is rather sketchy, as you might expect for... | [
"Yah, well, the monophyly of the eubacteria is only supported by molecular evidence, and I'm just not sure I trust molecular evidence any further than I can throw it when it comes to resolving events older than 2 billion years or so (the origin of eukaryotes). There is a group of bacteria with a membrane surroundin... |
[
"If a gamma ray burst had hit earth in the past, could we detect it in the crust of the earth?"
] | [
false
] | Or would that have happened so long ago, it's now a moot point. | [
"I seem to recall seeing something on this very thing on [a SciShow Space episode](",
"www.youtube.com/watch?v=inIFO5ZvdqM",
"\n) not long ago. ",
"Anyway, the gist of it was that scientists noticed something weird in some ancient tree rings, and ice cores from the same period.",
"I guess that's not exactly... | [
"The problem becomes in finding a strata of rock/sediment to do so. Depending on how long ago it would have been, evidence might be eroded away by environmental processes. And then half life of the ionized / isotopes need to be considered.",
"Not an easy task, but plausible!"
] | [
"The problem becomes in finding a strata of rock/sediment to do so. Depending on how long ago it would have been, evidence might be eroded away by environmental processes. And then half life of the ionized / isotopes need to be considered.",
"Not an easy task, but plausible!"
] |
[
"Why do healing wounds itch?"
] | [
false
] | I recently had some minor surgery and the area is itching like crazy. I know this is generally a good sign, but why does it happen? | [
"There are several theories that explain why scabs itch. There are histamines in scabs that irritate the skin around the wound. Some doctors think this is the body’s way of getting rid of the scab which is no longer needed. When it itches, you scratch it and it is comes off. There is a flaw in this theory, because ... | [
"There is a flaw in this theory, because sometimes the scab itches before the wound is healed.",
"Why is that a flaw? Perhaps that mechanism is good enough, better than the alternatives, or even beneficial."
] | [
"Do scars itch for similar reasons? If so, can these reasons explain why the itching can come and go, even years later?"
] |
[
"How can the sum of infinite rational numbers be an irrational number?"
] | [
false
] | There are convergent series where every term is a rational number, and the sum (the limit of the sequence of partial sums) is an irrational number. An example is the serie formed by the sequence 1/n!, whose sum is e, an irrational number. On the other hand, the sum of two rational numers is always a rational number. How is this possible? | [
"This is actually how the reals are defined: the reals are defined by a collection of values such that for each value v some series of rationals that \"Cauchy converges\" (roughly, a series where all partial sums sufficiently far into the it are all arbitrarily closer to each other) cannot be separated from v.",
... | [
"One way that's helpful to think of things: The rational numbers are the numbers that can be constructed through a finite sequence of arithmetic operations (+, -, *, /) on integers (or really, just from the number 1). Any rational number has some arithmetic sequence that constructs it. Anything that can't be constr... | [
"It is not, in general, true that properties of the partial sums are also properties of the limit.",
"Consider 1+1+1+... : every partial sum is finite, but the limit is infinite.",
"Or, x",
" in [0,1] : this function is continuous for all n, but the limit as n->infinity is discontinuous."
] |
[
"Are our toes thumbs?"
] | [
false
] | Did our big toes evolve from thumbs into the toes we know today? If so, why? Did we sacrifice having awesome feet thumbs in order to walk upright? | [
"Our big toes and thumbs develop from the same genes, as shown in experimentation by taking these genes, modifying them to produce blue phosphorescent dye, and injecting them into fetal mice."
] | [
"here is an article from wikipedia",
"\nFoot ",
"Main article: Foot",
"\nThe human foot evolved to act as a platform to support the entire weight of the body, rather than acting as a grasping structure, as it did in early hominids. Humans therefore have smaller toes than their bipedal ancestors. This include... | [
"I actually recall seeing someone whose thumb was amputated and replaced by their second toe. I'm on my phone right now, so I can't look it up, but it was an interesting story."
] |
[
"Do all planets with magnetic fields have iron cores, or can they have cobalt/nickel cores instead? If they can, how common are these planets?"
] | [
false
] | When talking about terrestrial planets, we seem to always assume an iron core to the planet - is this simply because Earth has an iron core, or are there other factors involved that mean planets always form around an iron core? | [
"No it does not have to be Iron. A good example would be Jupiter which is thought to have a core of hydrogen in a form called metallic hydrogen. The crazy pressure compresses the hydrogen gas to the point it can conduct. So providing a planet has an internal core made up of something conductive it is thought a magn... | [
"No. Metallic hydrogen is either a solid or a liquid. It's no different than iron or mercury. It's not some new state of matter. ",
"However, it's a new state for hydrogen. Like diamond and graphite are states of carbon. "
] | [
"Are the metallic versions of matter considered a phase like gaseous, liquid, frozen and plasma?"
] |
[
"AskScience AMA Series: We study Animal Weaponry, Fighting Behavior, and Narwhal Tusks, Ask Us Anything!"
] | [
false
] | Hi Reddit! We are two behavioral ecologists who study the evolution, diversity, and function of animal weapons! Weapons such as elk antlers, beetle horns, and crab claws are fascinating (and badass) structures that puzzle us because of their extravagant sizes, shapes and colors. In the broadest sense, we use a combination of observational, experimental, and theoretical studies, to understand everything and anything that relates to animal weapons. Although we both spend most of our time working with animals that are easy to catch and study, we recently studied one of the most charismatic animals in nature: the narwhal. Narwhal tusks are perhaps one of the most bizarre traits that exist today. Why bizarre? Well, the tusk is actually a modified tooth that can grow up to 8ft in length and protrudes from the head of male narwhals (females rarely have them). So, you can imagine how it would feel to walk about doing your daily business with a pool stick sticking off the top of your head. Despite being bizarre, little is known what the narwhal tusk is used for. Some researchers suggest that the tusk is a hunting tool, while others suggest it is a weapon used during fights. Dozens of hypothesis regarding the function of the tusk have been proposed. In our study, we examined the growth and variation of 245 male narwhal tusks to gain insights on this mysterious structure. We found that that the largest male narwhals have disproportionately long tusks, and that there was immense variation in tusk length within males. These trends align with what would be expected of a structure that has sexual functions, whether it be as a weapon use in male combat, or a signal used in female choice (or both). Furthermore, we know that male narwhals often have a lot of scars on their heads, which may have resulted from "tusking" behavior, where two male narwhals will display and cross their tusk. This study is just one example of how we both try to learn about animals and their unique weaponry. So, if you are interested in learning about animal weapons, fighting behavior, and narwhal tusks, join us at 14:00 PST (17:00 EST, 21:00 UTC), and will try to answer as many questions as possible! Usernames: zagraham0, palaoro-av | [
"Speaking of teeth: wild boar have tusks and domesticated pigs don't. If a domesticated pig turns feral, does it develop tusks or not? If so, does it do so immediately or does it take a few generations before it comes back?"
] | [
"How does being raised in captivity effect size of animal weapons? Someone mentioned tusks in pigs, but without domestication is there any effect? Elephant tusks, narwhal or rhino horn?"
] | [
"This is actually true. It is not necessarily adaptation, but it is what we call developmental plasticity. This plasticity is just a fancy word to say that some structure is a bit maleable during development, so it can change depending on the environment the animal is raised.",
"Check two-legged goats: ",
"ht... |
[
"If looking into the night sky is the same as looking into the past (speed of light from star/galaxy etc. reaching earth), what if you shot a camera at the speed of light at the object you were looking at?"
] | [
false
] | Would you see a time lapse of the object as the camera got closer or would you just see the object in its present state or something else i cant think of? What would you see? | [
"Sorry good sir, I won't lose the sir stuff. I have way too much respect for you and for the answers you provide to this forum.",
"Then have some respect for the fact that ",
" Get me?"
] | [
"This is not right. There's no physical way to talk about going at the speed of light for massive objects. You also don't take into account time dilation, which can let you perceive things at an arbitrarily high rate, depending on your speed."
] | [
"Cameras can't go that fast."
] |
[
"If a choir of people sing a note off pitch (some above, some below) would you hear the \"average\" of their pitch as a whole?"
] | [
false
] | . | [
"Musician here. I expect this answer will be modded away because I'm not linking to anything (I'm in an old iPad) so grab it while you can.",
"What you would hear is the central note - the pitch around which the voices are singing - with a shimmering timbre called the chorus effect. This is due to interference be... | [
"Wow. Really intuitive answer. Thanks so much !"
] | [
"Gonna add to this guys answer with some physics. When the waves interact they interact in either a destructive or constructive way. So if the waves are out of phase, they can destroy each other. In phase, they increase amplitude."
] |
[
"How much of the Earth's water is floating around in the atmosphere?"
] | [
false
] | We all know around 70% of Earth is covered in water, but how much of Earth's water is up in the atmosphere? | [
"Only about 0.001% of all the Earth's water is in the atmosphere",
".",
"If all of the water in the atmosphere rained down at once, it would only cover the globe to a depth of 2.5 centimeters, about 1 inch."
] | [
"To make sure there's no confusion, it 70% of the surface of the earth that is covered in water. The earth is not 70% water by mass (like the human body), it's much much less. It's certainly less than a percent. Some unverified web searches pull up 0.02%."
] | [
"I didn't realise the percentage of earth's surface and water was that close to the percentage of the human body and water.",
"Edit: added the word surface for clarification and to avoid confusion. Thank you ramk13"
] |
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