title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Why does water make a buzzing sound right before it begins to boil?"
] | [
false
] | [deleted] | [
"Could you elaborate? I've never noticed this. It may be coming from the pot that you are boiling the water in, since the metal in the pot is expanding a bit as it heats up."
] | [
"Agreed. Boiling water over a bunsen burner in a glass beaker makes no such sound."
] | [
"Are you sure it's the water and not the heating apparatus, especially if it's electrical. "
] |
[
"What particles emitted by the Sun pass directly through the Earth as if it (Earth) wasn't there?"
] | [
false
] | null | [
"Neutrinos."
] | [
"I guess you win the award for most accurate and succinct answer to any question in this sub.",
"Fun facts about ",
"neutrinos",
". They come in 3 tasty flavors (electron, muon, tau) and each has a different but immeasurably small mass (meaning we still don't know what they are), which means they're almost al... | [
"they're almost impossible to detect ",
"Because they're not impossible to detect! ",
"/u/astrocubs",
" even gave the example of the experiment that first detected them. The key is that even though they are incredibly unlikely to interact with anything, there are also a ",
" of them. Roughly 100 trillion pa... |
[
"The atomic bombs that were dropped on Japan in WW2 were huge. How small could modern science make bombs of the same yield?"
] | [
false
] | null | [
"Modern designs are probably highly classified."
] | [
"Im sure they are. But what is theoretically possible is what I am asking. What limited the bombs to the size they were and how small could we make those components now? "
] | [
"/u/RobusEtCeleritas",
" is correct that designs and often even the shape of weapons components are classified to prevent giving away how the weapons work. ",
"However, we can set a lower bound: If you are a nation with an advanced nuclear weapons program, sufficient infrastructure and are interested in build... |
[
"Is there such a thing \"oversleeping?\" Is there really a perfect number for hour-to-sleep?"
] | [
false
] | What's the science behind statements like "too much sleep is bad for you?" Is there really such a thing as "oversleeping" Also, there seems to be a lot of studies suggesting that there is a perfect number of hours to sleep (usually suggesting its somewhere between 6 and 9). What's the deal with that, and why do people think that such a number even exists? There seems to be a lot of pseudoscience around sleep, so I'm hoping the experts here can clear things up :) | [
"I am not an expert but I have a family friend who is. I have tried to find the research papers that he has described to me, but failed, so you should believe any responses that have research papers to back them up instead of mine. According to this sleep researcher, you cannot sleep too much unless you are clini... | [
" The abstract conclusion states",
":)"
] | [
"There are multiple papers that I've seen that shows that sleeping more than 8 hours a night is ",
"detrimental to your health",
". Just googling something like 'average sleep death rate' turns up other corroborating sources. "
] |
[
"Where is energy stored in the human body for short term use?"
] | [
false
] | As I was finishing a jog the other day, I was wondering where all the energy to do intense physical activity is stored. Is it mostly in the blood in the form of glucose? That seems like a lot of energy for just blood sugar. I remember that the liver stores glucose but it's been a long time since I've taken a biology class and I can't remember much. Also I know that fat buildup is energy reserved over a long period of time, but ultra-marathoners and the like are all very skinny looking so I get the feeling that that isn't it. | [
"The body stores a polymerized form of glucose called ",
"glycogen",
" in the liver and the muscles. When the blood glucose level drops, the glycogen can be broken down into glucose and used."
] | [
"Glycogen is not doing all the work when you jog. There is a misconception that when you do low level activity, you only burn one fuel source and when you start doing intensity activity you switch to another fuel source. All sources are being used (fat, protein, carbs) it's the proportions that are different duri... | [
"Individual cells produce ATP (usable energy for our bodies) from glucose (obviously from what we ingest) in the mitochondria. My understanding is that this is a continual process, and the difference between running for 45 minutes at a constant jog and standing still for 45 minutes isn't that enormous for our bodie... |
[
"Why supermassive black holes have low density?"
] | [
false
] | From a Wikipedia article about the Shwartzchild radius: supermassive black holes have low densities. The average density of a supermassive black hole can be less than the density of water This is very surprising to me, my idea of a black hole reguardless of its mass is that it is a dense thing. Can anyone explain where I'm wrong? | [
"Here the density is defined as the mass of the black hole divided by the volume contained within the Schwarzschild radius. The radius increases in proportion with the mass, so the volume increases as the cube of the mass, so the density goes as mass over mass cubed, which is the negative-two power of mass.",
"H... | [
"The size of a black hole is defined by the mass, and by the diameter of its event horizon which, for supermassive holes, is very large, and encompasses a lot of empty space. So, if you take the total mass, and divide by the total volume to get density, it is quite low. However, this is misleading (and confusing)... | [
"As an extreme example, if you compressed all the mass in the observable universe into a point, the Schwarzschild radius would be very nearly the size of the observable universe.",
"It is ",
"unclear if that is significant or not",
" but it certainly ",
" profound."
] |
[
"[Biology] Why do human babies take so long to become capable of many activities, while animals do it very quickly?"
] | [
false
] | null | [
"\"Animals\" don't really \"do it quickly\". In fact there is quite a vast gradient. If you imagine two main ways of being born.",
"\n1. You develop quickly we will call this precocious",
"\n2. You are useless. We will call this altricial. ",
"In both ways there are many driving evolutionary factors that impa... | [
"Bigger brain must be relative to size thats why whales and elephants have different skills than chimps"
] | [
"Bigger brain must be relative to size thats why whales and elephants have different skills than chimps"
] |
[
"What does space-time bend respective to?"
] | [
false
] | I typically see models like but what about the space-time above? Or even the space-time outside the planet, if there is no matter in between to bend it into a bubble is it thought of as a 2d plane? | [
"Spacetime does not bend respective to anything. Curvature is an intrinsic property that can be measured from within a space without making any reference to an embedding of the space in something else.",
"In the most fundamental sense, curvature is a measurement of how much a vector moving around a closed loop wi... | [
"This",
" is a better representation of the curvature of space-time; or to be more specific, the curvature of space. Space is 3-dimensional, to to see its curvature we need a 3D grid rather than a flat plane.",
"No no no no no no please stop.",
"Spacetime is 4-dimensional. It has 4-dimensional curvature. You ... | [
"This",
" is a better representation of the curvature of space-time; or to be more specific, the curvature of space. Space is 3-dimensional, to to see its curvature we need a 3D grid rather than a flat plane.",
"Secondly, these visualizations are only analogous to the actual space-time curvature. We cannot draw... |
[
"Are electromagnic wavelengths limited ?"
] | [
false
] | Are there bounds ? Or is it theoretically possible to create waves at a frequency that we can currently not detect at all ? | [
"There is no known limit. Our current understanding is that photons can have arbitrarily long or short wavelengths. That said, it is suspected that there is probably some limit (far beyond our capability to produce them) for wavelengths approaching the ",
"Planck length",
", basically because if we ever try to ... | [
"The only bound on electromagnetic radiation is whether there is enough energy to create one photon of light at the frequency specified. The energy content of one photon is given by E=hv, where h is Plank's constant (6.64x10",
" Js) and v is the frequency.",
"Whether we have the technology to produce high energ... | [
"Could there possible a way to transform the wavelength artificially ? I mean, maybe SETI just can't find anything because there are way more efficient ways of communication which we can not access yet. Or is that as unlikely as moving faster than light ?"
] |
[
"Can you approach a black hole from any dimension and experience the same result?"
] | [
false
] | I don't mean as a human, but as an observer that doesn't affect the stability of the black hole. | [
"What do you mean from any dimension? Do you mean from any direction?",
"If the black hole isn't spinning very fast then yes. If it's spinning fast enough it depends on your direction relative to its equator."
] | [
"Yes, I suppose I mean direction. I think a common misconception is that a black hole is shaped like hole in the ground...a 2D surface with hole protruding normal to the surface. This is clearly incorrect, right?"
] | [
"This would be correct in a 2D world. It's just much harder to draw in 3D.",
"A black hole is generally spherical. If it's rotating very fast, it can be a bit flattened but it's still 3D."
] |
[
"How do you measure what force is stronger?"
] | [
false
] | I've read about how electricity is a billion-billion-billion-billion times stronger than gravity. How can you make such a judgment when each is dependent on the amount of mass or charge and not some common factor? | [
"The charge/mass ratio of the proton is fixed, so if you take two protons, you can (in principle) measure both the gravitational and electromagnetic interactions, and when you do so, you'll find that electromagnetism is ~ 10",
" times stronger.",
"More practically, consider the fact that a refrigerator magnet t... | [
"This comes from dimensionless natural numbers known as coupling constants. In E&M this number is roughly 1/137, for gravity its something like 10"
] | [
"You can illustrate this with an even more banal statement: Your arm does not fall off. Why is that? it's because the electrical forces in the chemical bonds that hold the atoms in your arm attached to the atoms in your body are so much stronger than gravity."
] |
[
"Since all our mitochondria (and therefore its DNA) comes from the mother, does that mean we are more genetically similar to our mothers than our fathers?"
] | [
false
] | null | [
"Yes, you could say that. However, as the mitochondrial genome is about 16,000 bases long compared to the about 3 billion you get from each of your parents, that's not going to be the deciding factor in which of your parents bestows you the most DNA. ",
"That will probably come down to whether you're a male (in w... | [
"Gobbedyret:",
"a small Y-chromosome from your father \nand \na big X-chromosome from your mother.",
"Warning: talking sex-determination, both come from father.\nBetter say: the father gives less genetic information to a boy than a girl because Y is smaller than X."
] | [
"The difference is miniscule, and since the mitochondrial genome only codes for genes used within the mitochondria themselves, it's unlikely to have any noticeable effect on the final phenotypes. Unless you have an inherited mitochondrial disease, of course."
] |
[
"Why is expansion work by the gas in thermodynamics sometimes considered positive and sometimes negative?"
] | [
false
] | [deleted] | [
"The sign depends on who is getting the energy. In the expansion process, the energy of the piston is decreased and moved elsewhere, perhaps raising a weight or compressing a spring, thus the piston has a negative energy change. Conversely the expansion causes a positive energy change to the weight being lifted.",
... | [
"In regards to:",
"Different textbooks will use different sign conventions ... It doesn't matter which you use as long as you are consistent ",
"I believe the key phrasing is either work \"on the system\" or \"by the system.\"",
"The way its presented in texts is always confusing, I'd say. Clarity only comes... | [
"That looks correct. Where Q is positive heat supplied to the gas by the surroundings.",
"It is often required of you to decide the sign of dQ. If the surroundings have a lower T than the system, Q will flow out. If not, Q will flow in. "
] |
[
"What is the explanation for the fact that most cells are small and have cell membranes with many convolutions?"
] | [
false
] | I am not entirely sure if I can give anymore knowledge on the subject other than the semipermeable membrane may or may not have something to do with it. Thanks in advance for any help. | [
"Stuff moves in/out of the cell via the cell membrane. More cell membrane = more stuff able to move in/out. For cells of increasing size, the cell membrane size grows as the surface area (A = 4 pi r",
" but the cell volume grows faster (V = 4/3 pi r",
" "
] | [
"In addition, various protein structures are often found outside the cell membrane (known as the extracellular matrix) in eukaryotic cells. Especially those in more complex, multi-cellular lifeforms, like people and fish. That means there needs to be enough surface area to echange water, food, wastes and still have... | [
"To elaborate on this a little bit, more cell volume=more \"cell\" you have to feed. So, since volume grows faster than surface area, you reach a point where the surface area can't supply enough food to feed the volume of the cell. This limits cells to being pretty small."
] |
[
"How do cells know when to stop multiplying?"
] | [
false
] | As the first cells that make up an organ begin to multiply, and without a "director" telling the cells "enough is enough", how do they finally know when to stop? | [
"Typically during cell division, you also establish the fate of the resulting daughter cells. Typically what you'll have is one cell remains in a pluripotent (stem cell) state, whereas the other daughter cell differentiates into a cell type that will undergo a set differentiation and proliferation program that will... | [
"The complete answer is likely vastly complicated, since development is a time of many and complex intercellular and intracellular signalling. Even more confounding is that different cell types in different areas will be more sensitive, less sensitive, or completely insensitive to a particular stimulus. Thus, a swe... | [
"I'm going to look into the formation of digits. It seems like it may answer a lot of my questions. Thanks!"
] |
[
"After looking at various photos I am wondering; are there stars scattered around between galaxies, or is it completely empty in area between them?(in other words, are they all drawn in by gravity towards different galaxies)"
] | [
false
] | see here : it looks like there are a few stars in front of Messier 31, but they may be other smaller galaxies. And I think that the lights in the back are mostly other galaxies too. Far far away. | [
"Stars form",
" only in (relatively) high density regions that are not found outside of galaxies. So, more or less, all stars are inside galaxies.",
"However, sometimes because of the weird non-linear dynamics, stars can get flung out of the planes of ",
"spiral galaxies",
" (I don't know if this exists in ... | [
"rouge",
"rogue"
] | [
"ivenoneoftheanswers's answer is pretty thorough and clear. There are some other ",
"stars in between galaxies, and there are some photos of them here",
". But they are very, very rare, and nearly all stars are found in galaxies."
] |
[
"A friend posted this \"fact\" about gravity on Facebook. Is this true?"
] | [
true
] | [deleted] | [
"Due to the fact that gravity travels the speed of light, and that the sun is in relative motion with the galaxy and everything, we don't actually orbit the sun. We orbit where the sun WAS 8 minutes ago.",
"This one is actually a lot of fun (or maybe not fun, depending on who you ask). ",
"No gravitational infl... | [
"Instantaneous as opposed to retarded."
] | [
"Electrodynamics, which is also a relativistic theory, has this same property. The forces between charges point towards the instantaneous positions of charges. "
] |
[
"Are they any cases of animals using covering or \"clothes\" to protect themselves from the environment as humans have done?"
] | [
false
] | null | [
"Hermit crabs are an obvious example.",
"Pigs will slather themselves in mud to cool off. ",
"You could call a burrow a kind of \"clothing\" that animals \"put on\" to protect themselves from the environment.",
"The biggest problem is that the natural world doesn't present a lot of things which you can really... | [
"Well, I'm not sure it's exactly what you're looking for, but it's pretty common for insects to use inorganic matter in their environments to cover themselves for protection.",
"\n",
"Caddisfly larvae",
" are a great example. They'll build a case for themselves out of anything around them. In that first pic t... | [
"Its probably the same instinct that drives humans to do it. Need for shelter. I didn't really think of it till you asked this question but wouldn't ",
"this video",
" constitute an animal using its environment to cover itself? Granted the dog doesn't actually make the blanket or use any other materials but i... |
[
"Would the insulin of the 1920s be acceptable for use in patients today?"
] | [
false
] | In the 1920s, insulin co-inventors James Collip and Charles Best sold the rights to the University of Toronto. Since that time I believe the formulations of insulin and its manufacturing method have changed quite a bit. My question: If you were able to transport the insulin from the 1920s to today's market, would it be approved by the FDA? Would doctors agree to prescribe it? | [
"The insulin back then was isolated from animals. Today’s insulin in recombinant humanized insulin manufactured in batch fermentation reactors. As a result, you are much less likely to have an immune response against today’s insulin. I think a side effect of the insulin back then is that you would gradually build u... | [
"You would not become tolerant of the porcine or bovine insulin but you could become allergic and that was a major issue. ",
"The FDA never rescinded the approvals of the older products. They were just abandoned. The companies which are interested in biosimilar insulins are going to make versions of the analogu... | [
"Today’s insulin in recombinant humanized insulin manufactured in batch fermentation reactors.",
"Significant correction. Recombinant human insulin is the 1980's insulin, it was approved for market in 1982. (it's fully human, not \"humanized\" which means an animal protein which has been modified to be more human... |
[
"How do rocks like the lions rock form?"
] | [
false
] | Saw this picture on the frontpage and wondered how rocks like these form. Do they just pop op out of the ground? | [
"I believe this particular rock is a volcanic plug. It basically forms when magma solidifies in the vent of an active volcano. They become exposed when the surrounding, less resistant rock is eroded away.",
"This",
" diagram should be pretty helpful. The orange magma cools and solidifes, usually blocking off th... | [
"Igneous rocks are usually a lot more resistant to weathering than the surrounding rocks, which can be from \"plugs\" or sills or dykes. One of the more famous examples would be Devils Tower in Wyoming. "
] | [
"Interesting aswer didn't think of it that way. Thanks"
] |
[
"What Do You Think Of Marko Rodin?"
] | [
false
] | A friend of mine showed me some of his work. I've now read a lot of his stuff and find it interesting, but I'm not quite sure how much I believe of it. What really caught me off guard is when I tried to do research on him from sources not directly linked to him. For such an acclaimed genius with break through revolutionary ideas, I expected him to be a bit more famous. At the very least a wikipedia page or something. This is just weird. | [
"I made it through about 30 seconds before my BS detector went into overload. ",
"If you spend more time studying the fundamental fields of math and science (algebra, calculus, physics, chemistry, etc.) your intuition will develop as to what are and what are not solid ideas or theories. My personal intuition, w... | [
"Woah, he claims to have found a way around the Heisenberg Uncertainty Principle, ",
"So he's claiming to violate a fundamental law of physics, among other things",
"He seems to be part of a big movement these days of people trying to mesh new age thought and quantum physics..."
] | [
"Thanks.\nYea, I thought he sounded a bit crazy. What caught me was his graphs on the efficiency of his \"Rodin Coil\" versus a normal coil. If the graphs were true, his coil was absurdly more efficient. ",
"What is weird though is that I can't find any evidence of anyone using his coils industrially, nor any ... |
[
"How does H. Pylori bacterium increases the amount of HCl produced? Or how does H. Pylori increases the activity of the proton pump?"
] | [
false
] | null | [
"I assume you're referring to why H. Pylori causes stomach ulcers. It doesn't increase HCL or change the activity of the proton pump at all. H. Pylori causes stomach ulcers by attacking and infecting the cells that line the stomach. With these cells damaged the acid within the stomach eats away at the tissue that's... | [
"It is a bacteria, so antibiotics are used along with a PPI to allow the stomach to heal"
] | [
"H Pylori is a bacteria that is very well adapted for infecting the stomach. It is a motile organism that releases a substance called “urease,” which converts a common substance urea into CO2 and ammonia. Ammonia is a base and HCl is an acid, so this will neutralize the local environment around the bacteria just en... |
[
"If a tree were grown lit entirely from below, what might it look like?"
] | [
false
] | null | [
"It would depend partly upon the species of tree (and thus its usual growth patterns), and at what point in its development the uplighting as sole light source was introduced.",
"In general though, in the case of a tree, you would expect the main stem/trunk to grow upwards, but for the leaves to be angled so that... | [
"oops, I missed the \"grown\" in the title, thinking you were just wondering if the tree would look spooky or something like when people put a flashlight under their face"
] | [
"I think you missed the point."
] |
[
"is Earth's helium really running out?"
] | [
false
] | null | [
"Yes its a finite resource. Its very expensive for that reason.",
"I used to be a commercial diver. Its used in certain diving gas mixtures, and because of how expensive it is, divers wear hats that reclaim what they exhale instead of letting it exhale into the ocean. Its collected back into a tank, and recycled.... | [
"While helium does escape earth's gravity, it's not just because it's lighter than air (otherwise it would just be a layer on top of our atmosphere).",
"Once helium rises high enough, it can be bumped into orbit and even into escape velocities by solar winds and other cosmological phenomenon (like cosmic rays). I... | [
"Technically yes, helium is lighter than air, so as long as it can escape a pocket under the ground, it can escape gravity. But I have also heard this too. There are probably many pockets of helium humans aren't aware of, so in that way it's probably not running out any time soon unless someone has mapped all of th... |
[
"Is there rhyming in sign language, or a way to convey that two words rhyme in sign language?"
] | [
false
] | null | [
"There is indeed rhyming in sign language, although because sign language is visual rather than oral & aural, sign language rhyme is based on visual similarity between signs rather than aural similarity between sounds. This video has an overview of rhyming in English and in ASL.",
"Since the concept of rhyming ex... | [
"This quotation from ",
"Pfau et al. (2012) ",
" might interest you:",
"One of the key elements of many signed poems is the repetition of sub-sign elements\nto create patterns that increase the poetic significance of the signs. Clearly, rhythm\ngenerated by timing of movements might be regarded as repetition ... | [
"Woah that's awesome! Thanks for posting!"
] |
[
"How does the chromosome number change over the course of evolution?"
] | [
false
] | This one has been bothering me for a while. I don't think even my high school bio teacher knew the answer. The way biology gets taught at the intro level it sounds like an organism usually won't be able to reproduce with other members of its species if it has a different number of chromosomes. Is chromosome number not as well-defined as we're taught initially? | [
"I think he might have been asking more along the lines of: \"Great apes have 24 chromosomes but humans have 23. It's not important the mechanism through which chromosomes can fuse so an offspring has have 23 chromosomes, but when it happens, how does this mutation pass to other members of the species (and eventual... | [
"I think he might have been asking more along the lines of: \"Great apes have 24 chromosomes but humans have 23. It's not important the mechanism through which chromosomes can fuse so an offspring has have 23 chromosomes, but when it happens, how does this mutation pass to other members of the species (and eventual... | [
"This can happen in one of two ways: an exiting chromosome is either duplicated or split. If it is duplicated (and the offspring don't die), the new species has extra copies of genes and therefore the copies can mutate to new genes without problems. If the chromosome is split, then the new organism doesn't have any... |
[
"Do Bones Get Stronger Through Constant Damage?"
] | [
false
] | I've seen Shaolin monks been stricken with sticks to strengthen their bones. Does this much damage actually promote bone growth when done multiple times a week, or does it do more harm than good? How much is overdoing it and does it work for muscles as well? | [
"The scar tissue that forms when broken bones knit back together (correctly, that is) is actually stronger than the original bone, but this only applies to particular kinds of breaks. I suppose deep-tissue trauma, repeated over a long time, will cause the bone to develop calluses just like skin, which will make it ... | [
"It becomes more interesting when describing the processes underlying bone remodeling. Remodeling results in laminar bone and development of Haversian systems (blood vessels surrounded by circumferential lamellae). Some amount of remodeling is driven by bone strain (ie deformation) but it's unclear exactly what st... | [
"When a bone break heals the area around the break is thicker, like a scab almost, but not necessarily denser. Because of the extra thickness the bone is actually ",
" likely to break again either over or under the thicker part. After a year the bone goes back to normal because the body takes away the extra thick... |
[
"Why are Gold and Silver relatively unreactive compared to other elements even though they only have one valence electron, like the alkali metals, which are extremely reactive?"
] | [
false
] | [deleted] | [
"I'd like to piggyback on this question:",
"Why are transition metals so chemically different? They only differ by d orbital elections, right?",
"I thought the d orbitals were not as... Exposed? As the outer s shell.",
"Now, this question is based on dim memories of chemistry, so I'm sorry if it's dumb."
] | [
"It's because of their ",
"d band structures",
". The Fermi level of a noble metal (+ absorbate) for instance is above the energy of the antibonding orbitals when an absorbate bonds to the surface. This isn't the case for Ni where the antibonding states of the bonded species are found as unoccupied states. Occu... | [
"Chemical different in what ways? There are a few reasons depending on what phenomena your thinking of."
] |
[
"Does the temperature rise during a large fireworks display?"
] | [
false
] | We had a very overcast December 31st here in Copenhagen, Denmark but, of course, that did not stop anybody from launching TONS of fireworks during the course of the evening. This made me think about large, hour long firework displays (New Years, Chinese New Years, etc.) as to whether or not the ignition of the fireworks would give a noticeable rise in the local temperature? Would the mean daily temp in an urban location or city actually get warmer during that time period? of not, how many fireworks would it take before we would notice using regular methods of detection? Thank you all. | [
"I don't think it would make any difference really.",
"I could be wrong, but my logic tells me that if anything, fireworks would only briefly warm the air around them. \nThe warm air would rest on the cooler ground level air, and as warm air rises, it wouldn't really warm temperatures at ground level.",
"Refere... | [
"It wouldn't make any sort of difference in air temperature.",
"However it does make a HUGE difference in air quality, and some areas end up having absolutely atrocious air quality for quite a while after. I just read a read a really good write up about it, I'm on mobile right now but I'll link it later. It's qui... | [
"Let's give everyone 1 kg worth of explosives (that is ",
" more than a typical person will use). That gives everyone something like 20 MJ or 5.6 kWh - the average per capita electricity consumption of 8 hours. Copenhagen has a population of 600,000 and an area of 86 km",
" (municipal population/area). 20 MJ * ... |
[
"What would happen if you ate nothing but carrots?"
] | [
false
] | Just curious. Over any period of time, what would happen to your body? | [
"If you could somehow eat enough carrots to get 2000 calories, about 5 kilos, you'd also get about 45g nearly complete protein. That should be enough to avoid any protein deficiency disease."
] | [
"If you could somehow eat enough carrots to get 2000 calories, about 5 kilos, you'd also get about 45g nearly complete protein. That should be enough to avoid any protein deficiency disease."
] | [
"Color me skeptical* that the human digestive tract could handle 11 pounds of carrots daily. Eliding past GI tract capabilities though, the overload of other nutrients from that amount of carrots would have health problems, particularly vitamin/mineral toxicity.",
"*Orange, being the color of skepticism in this c... |
[
"Is there any correlation between certain names, and behavior? Are certain names more likely to succeed than other names? I imagine some names might cause bullying more than others. But I’m more curious if there are any names with a positive social correlation."
] | [
false
] | null | [
"Freakonomics did a thing on it. Basically if your name was more common and easy to say you are more likely to get picked. Also if your teacher called you up based on alphabetical order, people that got called last felt a negative psychological impact.",
"http://freakonomics.com/2013/04/08/how-much-does-your-name... | [
"Woah, that alphabetical order thing is the exact type of thing I was wondering."
] | [
"For men, there is a correlation between short, single syllable names, and senior/powerful positions in business. Even with different versions of the same name. I.e., \"Bob\" is more likely to have a higher title than \"Robert.\""
] |
[
"How was helium discovered?"
] | [
false
] | This question bridges history and chemistry but I'm wondering if anyone has better information about the history of Helium's discovery. Did Janssen and Lockyer work together to determine that the yellow line was proof of a new element? And how did Frankland factor in? Did Langlet and Cleve isolate Helium from Uranium ores or did Ramsay? Did two independent discoveries occur at roughly the same time? How controversial was the yellow line discovery? Did most or all of the scientific community accept that as proof of Helium's existence? | [
"The wikipedia ",
"article",
" seems quite conclusive and seems to fit with what I remember: First discovered as an emission line in the suns spectrum (hence the name \"Helium\" after greek ",
", sun) and later it was found (again by its emission line) on earth."
] | [
"While I look forward to the kind of rigorous, informative, and accessible answers ",
"r/AskScience",
" does so well, I can only say that I've happily given hours of my free time reading and jumping-off from ",
"this Wikipedia entry",
". "
] | [
"If you don't get an answer here, you can try ",
"/r/askhistorians",
", ",
"/r/historyofscience",
", or ",
"/r/philosophyofscience"
] |
[
"Does cold medicine actually help make you better, or does it just suppress your symptoms while your body heals itself?"
] | [
false
] | [deleted] | [
"Cold medicine is a broad group of pharmaceuticals that typically include a combination of cough-suppressants, decongestants, painkillers. There are no approved treatments that actually target any of the viruses that cause colds. And the only drugs that target influenza are prescription only. They're only for suppr... | [
"Mostly they only suppress the symptoms (as always there are exceptions). And in the case of cough suppressant can actually make it worse. By not allowing the body to cough naturally and eliminate the mucus in the lungs, it can cause a build-up of mucus in the airways and prolong or worsen the illness. Some physici... | [
"There are no approved treatments that actually target any of the viruses that cause colds. ",
"There is some evidence that zinc (found in many nasal sprays) directly inhibits rhinovirus replication. Most research shows that zinc can slightly reduce the duration of a cold. See this Cochrane review: ",
"https://... |
[
"Does cutting food decrease cooking time in microwave ovens?"
] | [
false
] | A microwave oven is said to cook food from the inside and out. I would think this nullifies the need for greater surface area. Am I wrong? | [
"I can't give you a clear answer but I can provide some relevant information.",
"Microwaves work by filling a chamber with high-energy, gigahertz-frequency electromagnetic radiation. A 1 gHz microwave is a time-varying electric field: at any given point in space, the electric field will change polarity (positive ... | [
"That sounds accurate... But considering if you cut the food, you now have greater surface area for the waves to hit, wouldn't that speed up the heating process?",
"Wouldn't a spread out mm thick pancake heat faster than a fat inch thick pancake of the same mass for the same reason?"
] | [
"Possibly, based on what the \"food\" is. If you are referring to slicing it into thin pieces, (as opposed to random cuts into the meat) it should. Microwave ovens operate via dielectric heating, so the microwaves exert work on the polarized molecules (like water) because they attempt to align with the rapidly ch... |
[
"Why do the world's governments and media EXCLUSIVELY talk about COVID19 vaccination rates, when studies have shown that natural immunity is far superior?"
] | [
false
] | null | [
"Everything you say is wrong."
] | [
"Sorry how is it wrong?"
] | [
"It doesn’t match reality. They do talk about infection immunity, and infection immunity isn’t “far better” than vaccine immunity (both of which are “natural”)."
] |
[
"Does modern sedentary lifestyle contribute to the rising amount of depression?"
] | [
false
] | Hello ! Nowadays people are less physically active, and the rate of depression has been rising. Physical exercise is regularly advised as a remedy for depression and other mental health issues. Could it therefore be, that normal mental health requires a "homeostatic" amount of physical activity? Does sedentary lifestyle play a part in the grand scheme of more people becoming depressed? Thanks for the answers :) | [
"A gigantic meta-analysis from the British Journal of Sports Medicine says yes.",
"Thirteen cross-sectional studies with 110,152 participants and 11 longitudinal studies with 83,014 participants were included in this meta-analysis. The summary RR of depression for the highest versus non-occasional/occasional sede... | [
"Many of the brain's core functions--balance, peripheral vision, proprioperception, heat regulation, &c--are only fully engaged during physical activity. Just walking down a flight of stairs requires a lot of mental processing. ",
"When you're sedentary, big elements of your brain's capacity are idling, even if ... | [
"I think you make an interesting point. Of course getting active isn't a cure all for people suffering from depression but I do wonder if someone \"didn't have time\" to get caught in the cycle of depression by being stimulated in a variety of ways if it would be as prominent a problem.",
"So many people (myself ... |
[
"Why does the center of the earth never cool down?"
] | [
false
] | It must be constantly losing heat, why doesn't it level off? | [
"First, a clarification, the core of the Earth (and the Earth as a whole) is losing heat, but it is relatively slow. The reason it is slow is a combination of four main factors: (1) The core (and more broadly the Earth as whole) started off with a lot of heat, i.e. enough for the entire planet to be ",
"a liquid ... | [
"Tidal heating of Earth from the Sun (or Moon) is negligible compared to primoridal heat and radiogenic heat. ",
"This paper",
" on the possiblity of tidal heating of Earth like exoplanents might be useful for thinking about why this is not a significant source of heat for the Earth."
] | [
"Pressure does not generate heat, pressurising (the process of increasing pressure) does."
] |
[
"Is rinsing your mouth with water after drinking coffee good enough to prevent staining your teeth?"
] | [
false
] | Or do you need to brush your teeth every time you have coffee? And how safe is sprinkling baking soda on your toothpaste when you brush your teeth? How does teeth staining occur? Is it instant or does it take a while to sink in? So for example, if you have a cup of coffee and you go to bed..I presume that would be pretty bad for your teeth right? | [
"Correct, the acid in food and drink softens your enamel, so brushing after eating or drinking is ",
"harmful to your teeth"
] | [
"I was under the impression that brushing your teeth after eating or drinking something acidic you end up with added abrasiveness, I'm not sure how acidic coffee is (and I guess it varies depending on milk quantity and how sweet you have it), but brushing right away might even be damage to your teeth. My understand... | [
"coffee stains just like any other stain/ dye does.......the longer and more frequent the exposure...the deeper the stain(typically).......",
"so theoretically, yes, wasshing your mouth out with water should help (kind of like hosing off a piece of wood you just applied stain to....but im not sure its going to ha... |
[
"What causes hair to \"get used to\" being combed or done a certain way after awhile?"
] | [
false
] | null | [
"Oils will slowly accumulate and solidify on your scalp. This preserves the general position of your hair at its base, forming a kind of grain that the rest of your hair follows. If you have longer hair, you'll notice that when you wash your hair with shampoo, it falls in random directions. This is because you've f... | [
"I am a Master Licensed Barber in the state of Minnesota. Not to be confused with a Masters DEGREE which I certainly do not have."
] | [
"Is there any evidence for this lasting longer than until you shower? Like an actual permanent change in the way your hair falls?"
] |
[
"Do we know how much your mental or physical condition at conception effects the outcome of a fetus?"
] | [
false
] | Say the woman is an alcoholic at the time of conception, or the man is on a week long LSD trip, or either are in the throes of a clinical depression at the moment, would the fetus be more predisposed to addiction or mental health issues as opposed to if they had been conceived prior to these events? Or if this makes more sense, would a baby born to teenage parents who have never smoked, drank, done drugs, or experienced any major life problems or mental illness yet have a better genetic predisposition than a baby born to the same couple 20 years later after heavy drinking and drug use had occurred and the development of a mental health issue or two? I'd imagine it would be hard if not impossible to research, but if I, the least knowledgeable (of science) person I know, am wondering about it; there must be someone out there who's thought about the same sort of thing and found the answer, right? Any and all answers are welcome. Thank you in advance!!! | [
"So the parents' past experience or current condition won't generally affect the ",
" the offspring inherits, but it can affect the individual's traits/phenotype.",
"The most important factor is going to be the mother's state during pregnancy, as she provides the developmental environment, which, for example, "... | [
"Yeah, the whole business is badly overhyped. Some neat results, but no basis for all this \"rewriting our understanding of biology\" nonsense."
] | [
"Yeah, the whole business is badly overhyped. Some neat results, but no basis for all this \"rewriting our understanding of biology\" nonsense."
] |
[
"Why is smell so tightly linked to memory?"
] | [
false
] | I think I understand why, from a physiological standpoint, smell is so tightly linked to memory in comparison to the other senses. I remember reading something in a psychology class about how the olfactory system was closely linked to the amygdala and hippocampus, which control emotion and associative learning. This means that whenever we encounter a new smell we tend to associate it with the emotions and surroundings at that moment, and when we encounter it again those memories are immediately brought back. So this I understand. My question, is why did the human olfactory system evolve this way? Why was it advantageous from an evolutionary standpoint to have olfactory perception so tightly linked to emotions and memories, but not our other forms of sensory perception? | [
"Think of it from another angle - is sense of smell really that much more related to memory than the other senses?",
"Sure, you can open up an old suitcase from your attic and get a whiff of some smell that makes you think of some vacation you took 15 years ago. Sure thats amazing. But what about the other senses... | [
"A lot of people don't know this, but it's actually the nose that is the part of the body directly responsible for memory. Take elephants: big nose, good memory.",
"You shouldn't feel bad though. Just a short time ago people didn't know that sex led to babies."
] | [
"I saw you didnt have any comments, so ill give you one :) And a interesting read good job! "
] |
[
"If you point your phone camera at an IR LED (like in a TV remote) it is visible but why does it show up as blue/purple rather than red?"
] | [
false
] | null | [
"The explanation has to do with how digital cameras try to determine the color of an object. Cameras usually use a sheet of silicon sensors to detect the intensity of incoming light. However all the intensity tells you is how much total light falls on a given pixel (weighted by how responsive the sensor is in that ... | [
"Thanks for such a detailed answer :)"
] | [
"Thank you for taking the time to properly explain that! "
] |
[
"What did we leave behind on the moon?"
] | [
false
] | Is it correct to assume they left a bunch of junk/equipment on the lunar surface? Or did they just leave a plaque and footprints? What manmade objects are sitting up there right now? | [
"Link with out the let me google that for you:",
"http://en.wikipedia.org/wiki/List_of_man-made_objects_on_the_Moon"
] | [
"Link with out the let me google that for you:",
"http://en.wikipedia.org/wiki/List_of_man-made_objects_on_the_Moon"
] | [
"Wait, so you're telling me it's possible to pass along information ",
" being a dick? Fascinating..."
] |
[
"Does light speed up as it moves away from a sun and its gravity?"
] | [
false
] | I know that light travels at c in a vacuum, but it is also affected by gravity, and can bend around planets, stars etc. As light is emitted from a star, does it travel (relatively) slower ah first and then speed up as it moves away and becomes less and less affected by the star's gravity? | [
"Depends on who you ask. An observer watching the photon pass closely by them will always see it moving at c.",
"But a far-away observer won't necessarily see the photon traveling at c.",
"Let's work it out for a photon moving radially outward in the Schwarzschild metric. So this would describe the outside regi... | [
"I didnt understand all that you wrote here. Just wanted you to know i enjoyed reading it!"
] | [
"In more simplified terms. An observer near the photon will see it travelling at c. An observer far away will see it travelling initially at a fraction of c and then speeding up. The discrepancy is due to the fact that space is different where one observer ia standing vs the other.",
"Space near the first observe... |
[
"Why is it that L'Hospital's rule only works when the limit is to an answer that is in indeterminate form?"
] | [
false
] | null | [
"The proof uses the fact that it is indeterminate. The special case ",
"here",
" is fairly simple to go through if you'd like."
] | [
"You can actually call it l'Hospital or l'Hôpital. Both come from french. The os has been transformed to an ô. So, while old, the \"Hospital\" term isn't inherently false."
] | [
"Yeah, it's silent in both cases"
] |
[
"Zero Gravity and Fire"
] | [
false
] | If you were to strike a match in Zero Gravity which way would the flame burn? Because heat rises in gravity I have a hard time wrapping my head around how a flame would look in zero gravity. | [
"Here's a short video of a flame being lit in a microgravity environment, ",
"http://www.youtube.com/watch?v=Q58-la_yAB4",
" and an article that provides some insight into fire in microgravity ",
"http://www.smithsonianmag.com/science-nature/In-Space-Flames-Behave-in-Ways-Nobody-Thought-Possible-179731321.htm... | [
"Archimedes principle doesn't exist in zero gravity. That means that Cold air doesn't flow below the hot air. ",
"On earth: \nWhen a candle is on fire, oxygen is turned into other chemicals which are evacuated upward by Archimedes principle because they're hot.",
"In zero gravity :\nthe candle would create a c... | [
"As the video you linked explains the candle or fuel won't die but will instead burn at a much slower rate through the diffusion of oxygen molecules which enter into the flame allowing it to continue burning."
] |
[
"Is there a fundamental constant that all other constants are based on?"
] | [
false
] | I'm curious to know if there is single constant that all other constants can really be derived from. A) If so, is that constant always the same no matter what? For example, if it is measured in a vacuum vs. in a black hole. B) If no, how many basic constants are there? And why is it that we cannot derive one constant from another? | [
"No, that is not the case. There are many physical constants, and you have to make the distinction between dimensionless constants (like the fine structure constant), and constants whose numerical value depends on what units you are using, like the gravitational constant.",
"John Baez discusses about 25 dimension... | [
"As ",
"u/iorgfeflkd",
" noted, there are about 26 dimensionless constants that determine how physics works. We would like to reduce that number by finding a theory that could predict some of their values, but for now they are all determined empirically.",
"But to address your secondary question:",
"A) If s... | [
"(Well, that's what he says, but he talks about quark masses)",
"What matters is the mass ratios, not the value of the mass in one particular set of units. As long as you express each of those masses as multiples of the Planck mass you will still have dimensionless constants."
] |
[
"How do ants navigate while holding food?"
] | [
false
] | I was watching ants carrying things around today and the ones that weren't on a defined path or were carrying a heavy load would walk backwards. My question is, how do they know where they're going if they can't use their eyes or antennae? | [
"For some ants (perhaps all?) this can be due to chemical trails. As they go out to forage, they'll lay down a chemical trail that they can follow back AND that others can follow out to also find food. One nifty trick I learned from an entomologist was that ammonia based windex can be great to help get rid of ant... | [
"They lay one trail to find their way back. If they find food they lay a different one on the way. This prevents ants from following the same trail as someone else with no payoff. Once an ant comes back with the food trail, the rest jump on it."
] | [
"You are quite correct, and that's what I get for rushing through writing my answer."
] |
[
"If Mars has around 1% the atmosphere of Earth, would the windstorms actually feel that strong, or would they be like a gentle breeze?"
] | [
false
] | [deleted] | [
"This is actually pretty easy to estimate. The extra pressure you would feel can be estimated from the ram pressure formula, P = rho v",
" where rho is the mass density of air on the martian surface and v is the wind velocity. ",
"We can find rho by using the ideal gas law, P = (rho / (mu*mH)) * k * T. The M... | [
"do you really call that easy? I envy your innocence."
] | [
"The scaling of the wind to do work (such as turning a wind turbine, or how you feel it) is a function of its kinetic energy, which goes as mass times the velocity",
"As you mentioned, the density of the atmosphere at the surface is quite a bit lower than here on Earth, about 1/100th that of Earth's. That 1/100 g... |
[
"Are there convection currents in boiling water?"
] | [
false
] | And where do the bubbles in boiling water come from? The bottom or from the middle? | [
"The bubbles are steam and they form at nucleation points on the surface of the pan in the case of a pan being heated from the outside. The water absorbs enough heat and changes from liquid to gas. The churning that you see in boiling water is not a convection current. It is caused by the phase change rapidly incre... | [
"There are, they're just minor compared to bubble buoyancy if you have a rolling boil."
] | [
"Unless it's a perfectly insulated sphere, heated uniformly, a single isotope, in space, etc. it's going to have a thermal gradient and density differences/buoyancy."
] |
[
"Would pulling planets into the sun extend it's life."
] | [
false
] | In Invader Zim, there is a race of "planet jackers" who pull planets from other star systems into their on star. The idea is that it's like stoking a furnace and that it will extend the life of their own star. My question is: Is that what would happen? | [
"Leaving aside how adding mass to the sun would change its lifetime (big stars usually burn out quicker, not slower) it is important to point out that the sun contains 99,85% of the mass in the solar system. ",
"So even by throwing ALL the planets into the sun plus all the asteroids and comets you would not even ... | [
"Adding an earth-like planet to the sun would do almost nothing. The earth is not nearly massive enough to have an effect. It also doesn't have the materials you'd want. ",
"You want high hydrogen and helium content, low metal planets like Jupiter or the gad giants, but even at that you're increasing the mass o... | [
"Wouldn't you shorten the life if a star by introducing iron to its core?"
] |
[
"Why must we postulate a Higgs field?"
] | [
false
] | I understand that the question of why stuff has mass requires there to be some mechanism that imparts mass to objects. However, doesn't the same apply to charge? In other words, why do we need a Higgs field for mass but not for charge? Or is it the electric field that is imparting charge to charged objects? | [
"(Hyper)Charge like mass is one of the properties of the elementary particles in the Standard Model of Physics (SM).",
"Charge is mediated by the exchange boson that we call photon and that part of the SM becomes quantumelectrodynamics and simplied even more the classic Maxwell equations.\nSo as you see, we do ha... | [
"You could say that interacting with the Higgs field is what gives things mass, and interacting with the photon field is what gives them charge. That's a bit of a simplification but it avoids math."
] | [
"When you say \"photon field\", is that different from the electric and/or magnetic field? "
] |
[
"What would Earth be like if it was tidally locked with the sun (earth only faced sun on one side). How would life evolve?"
] | [
false
] | How would life evolve to cope with living on a planet like this? What would the weather patterns be like with one side basically a desert and the other an arctic waste? What kind of challenges would be faced living in a slim temperate zone in between the two? | [
"I can comment on this, as I do research on planetary dynamos.",
"So this is a big misconception regarding magnetic fields, especially among scientists who know only a bit about dynamos.",
"Yes dynamos as we know them require the planets to be a fast rotator, but the key word here is \"fast\", which is a relati... | [
"I'm not a scientist and can't comment on the evolution aspects. However I am most certain that life probably wouldn't exist at all on Earth, due to the fact that without the Earth rotating as fast as it does, there wouldn't be a magnetic field. Without a magnetic field, the effects of photodissociation would be mu... | [
"It's questionable whether significant non-ocean-bottom life would exist at all, and that's assuming all the water isn't energetically 'boiled' off the planet.",
"The slowing of rotation would change the distribution of the oceans, which would be an important consideration - the constant sunlight on the Pacific o... |
[
"What would happen if I swallowed a ball bearing and went for an MRI scan?"
] | [
false
] | [deleted] | [
"Its fairly likely that as you enter the MRI room that the metal detector would go off, and you wouldn't get anywhere near the magnet. (At the ~10 MRI machine rooms I've been to, all have had a metal detector surrounding the door that will go off if you are wearing any metal it detects -- usually they are very sen... | [
"I'm not exactly sure what the clinical protocols (I tend to stay on the research rather than clinical side of things), but I believe they wouldn't MRI an unconscious person (without medical history or someone vouching for metal not being in their body) for fear they had metal in their body/pacemaker etc. So you'd... | [
"This is why Magneto kicks ass."
] |
[
"Chimp Feet versus Human Feet"
] | [
false
] | Chimps appear to have "hand-feet" with "toe-thumbs" which I assume would give them greater dexterity and grabbing ability. Humans lost this feature in the transition from ape to human. I am curious about the following: Is there a biomechanical advantage to the human foot? For example, does it make us faster? Does it make it easier to walk/run for extended distances? | [
"The human foot is often described as a rigid lever during human walking and running. This is in contrast to what we see in apes, which is an opposable big toe, which resides on a foot that is much more loose (the foot joints are generally more mobile). ",
"A rigid foot is definite a benefit when you're constant ... | [
"Ah very cool, I expected an answer like this but I am very glad to have it confirmed. Thank you for taking the time to type it up."
] | [
"Would you say the condition seen in humans represents a change from a chimp-like foot, or are chimp feet and human feet derived from a common ancestor who looked like neither/both? I think the OP is assuming the former."
] |
[
"AskScience AMA Series: Summer is tick season. We are experts on the science of Lyme disease (and other tickborne illnesses), and we are here to answer your questions. AUA!"
] | [
false
] | Lyme disease, an infection caused by the bacterium Borrelia burgdorferi that is primarily transmitted by Ixodes scapularis (also known as blacklegged or deer ticks), . Beyond the characteristic erythema migrans ("bullseye") rash, symptoms range from arthritis to damaging nervous and cardiac systems. With so many cases every year, it is imperative that everyone learn what steps can be taken to minimize and prevent Lyme disease infections while also getting up to date on the current scientific and medical interventions being used to treat and cure Lyme disease in infected individuals. Join us today at 2 PM ET (18 UT) for a discussion, organized by the American Society for Microbiology, about all aspects of Lyme disease (and other tickborne diseases). We'll take your questions and discuss what people can do to prevent Lyme disease, how Lyme disease is best diagnosed and treated, and what to do if you suspect that you have Lyme disease. Ask us anything! With us today are: Links: Please note that we will NOT be making medical diagnoses or recommending any medical treatments or procedures for individuals. | [
"Why are lymes disease vaccines readily available and recommended for pets, but not for humans?"
] | [
"Yes, there have been different Lyme disease vaccines available for pets, mainly dogs, for many years. One type, based on the OspA protein of the Lyme disease bacterium, is essentially identical to a human Lyme disease vaccine that underwent a large clinical trial and was approved by the FDA for human use. It was a... | [
"After contracting Lyme Disease, at what point is it actually incurable? As in, what is the timeline after being that it is considered permanent?"
] |
[
"How do pulsed neutron sources work and when are they utilized?"
] | [
false
] | I know that the pulsed sources have been used in particle accelerators, but don’t most of them use proton beams? | [
"You can produce a beam of protons using a proton accelerator. To reach high enough energies in a reasonably-sized accelerator, you will need some kind of RF or induction accelerator as opposed to an electrostatic one. ",
"Using an RF accelerator necessitates that the proton beam be bunched longitudinally.",
"T... | [
"You can also use a 'chopper' to turn a continuous neutron beam into a pulsed one, which is essentially a rotating disk or drum made of neutron absorbant material with slits/holes. One big advantage of pulsed neutron sources is that it is generally difficult to measure the energy of a neutron at the detector, but i... | [
"Interesting! Is the only way to create a pulsed neutron source from a proton beam?"
] |
[
"If I get bitten by a snake, does it matter how many times I am bitten?"
] | [
false
] | For example: I have been bitten by a snake whose venom will kill me. I obviously need to get to the hospital for anti venom. Should I try to grab the little fecker who bit me for identification? As I have been bitten anyway, am I immune to extra bitings? | [
"It depends on where you are in the world, as different snakes have different venoms and different countries have different procedures to deal with those venoms.",
"No, being bitten once does not make you immune from being bitten a second time. The amount of venom plays a role, and multiple bites usually means yo... | [
"If you're in Aus, you don't really even need to worry about polyvalent antivenoms now that we have the venom detection kit. It's why it's super important to not wash the bite site."
] | [
"That would cause huge problems. Antivenom has ",
"a variety of side-effects",
"-- the more vials of it you need, the more problems can occur.",
"Antivenom isn't a single \"magic bullet\" injection, by the way. It's given through IV in hospital slowly over half an hour or so, with adrenaline standing by in ca... |
[
"Why does the shower curtain pull inward when I turn the shower on?"
] | [
false
] | null | [
"\"Bernoulli effect theory:",
"The most popular explanation given for the shower-curtain effect is the Bernoulli's principle.[1] Bernoulli's principle states that an increase in velocity results in a decrease in pressure. This theory presumes that the water flowing out of a shower head causes the air through whic... | [
"The other responses here are saying 'hot water', which probably has some affect, but does not explain the 'shower-curtain effect' given it still occurs when the water is cold. ",
"This is actually a well discussed phenomena with no definite conclusion. ",
"Have a read",
"."
] | [
"A physicist by the name of David Schmidt won a sort of joke Nobel prize for his research in this area. He ran a simulation of the fluid dynamics within a bath with a shower curtain and found that a \"horizontal vortex\" formed inside.",
"Basically, the running water causes the air in the bath to rotate on a plan... |
[
"Is sweating an indication of burning calories?"
] | [
false
] | If I'm laying completely still in the sun, and sweating profusely, am I burning calories? | [
"Everything your body does requires energy. Sweating is more an indication of overheating since evaporating sweat is a cooling mechanism. Although people can also sweat because they are nervous. The act of sweating requires energy as water is excreted from the skin but it is not a direct indication of high energy u... | [
"Sweating is primarily about heat regulation as ",
"/u/applemonkeyman",
" says. Evaporating sweat cools you down, so you sweat when your internal temperature goes beyond a certain point. Sweating can also be a response to stress/anxiety. Some people have been known to sweat after eating spicy food.",
"There a... | [
"I think so, sweating is the body's way of regulating temperature and any process such as this requires energy. The amount of sweat released depends on a lot of factors, for example, if the person is overweight, they will sweat more as the body needs to exert more energy to cool down. So use of energy = burning of ... |
[
"In math, are there any proofs that can only be completed by contradiction? If so, how would someone go about proving that?"
] | [
false
] | null | [
"(in this post I'm using ",
"~",
", ",
"V",
", ",
"^",
", and ",
"->",
" for negation, logical OR, logical AND and implication, respectively)",
"It depends on what you call by \"proof by contradiction\". If you are trying to prove a negation the only way to do that is by contradiction (if P being ... | [
"As a computer Science major, proof by contradiction is the most popular method for proving the Acceptance Problem for Turing Machines is undecidable."
] | [
"Sure, proving that something can't exist (a negation) is precisely what you need proofs by contradiction for."
] |
[
"If Alternating Current changes the direction of current periodically then how do we have positive wires at our home?"
] | [
false
] | null | [
"Its not actually positive. It's hot. One wire sends power out to the switch, which interrupts the hot, then from the switch to the device. Imagine the electricity surging back and forth by the smallest increment of distance that you can at that switch 60 times per second waiting to jump through it and complete t... | [
"This excludes 240v devices, where both wires are always hot. ",
"This is only true in the US/North America, correct?"
] | [
"Yes, according to Google, European 240v is 1 hot, 1 neutral and a ground as opposed to NA where its 2 hots at 120v a neutral and a ground.",
"I learned something today, thankyou."
] |
[
"When was Darwinian natural selection accepted over other theories of evolution such as Lamarckism?"
] | [
false
] | I suspect the discovery of DNA and genetics provided the evidence the theory needed but I'm not sure. | [
"It was a pretty gradual process. First off, it's worth noting that most of the time when we talk about Lamarck we don't fully appreciate to what degree he ascribed agency to nature. He believed not just that acquired traits were inherited, but also that organisms evolved because they were responding to a sort of i... | [
"Great summary, we really do treat Lamarck as a caricature today. He wasn't totally giraffe-neck crazy, he was just wrong.",
"The process of epigenetic inheritance, where information not written in the DNA code can be passed on to the next generation, is far from settled. It definitely occurs in plants, but it's ... | [
"Honestly, I feel almost the opposite about Lamarck - the contemporary conversation about him ",
" just how crazy his views were by modern biological standards. That said, it probably said more about his time than it did about him as a thinker. Teleological reasoning didn't leave evolutionary science until well a... |
[
"pros and cons of popular disinfectants?"
] | [
false
] | null | [
"We don't offer any form of medical or safety advice on this sub including product evaluations. Please see the guidelines. "
] | [
"I am not deciding on which one to use and i am in no need of using one i’m just asking why doctors use them in those situations (sorry for any troubles but i do truly believe it fits within the guidelines)"
] | [
"Oh I see. In that case, I recommend making a new post with a different phrasing; perhaps something like: why are different kinds of disenfenctants used in different situations? "
] |
[
"Given a closed small closed system that doesn't expand, would baking soda and vinegar create enough pressure to where some of the reaction would not occur?"
] | [
false
] | If given a closed container with infinite strength, what would happen if baking soda and vinegar were introduced? Would it eventually create enough pressure that they don't react with eachother? | [
"According to the parameters you have laid out (and assuming this experiment was taking place at room temperature): No.",
"Vinegar is an aqueous solution of acetic acid, typically at a concentration of 4-12%. That leaves the remaining 88-96% water.",
"The reaction acid-base reaction in this system is:\nCH",
... | [
"I didn't even know Reddit had subscript formatting. You have enlightened me.",
"For those wondering, it's ",
"*_subscripttext_*",
" to get ",
" (hooray for RES's Source feature). "
] | [
"Yes, because LeChatlier's Principle and the change in pressure due to closed boundary conditions (e.g., fixed volume). ",
"A change in one of the variables that describe a system at equilibrium produces a shift in the position of the equilibrium that counteracts the effect of this change.",
"At some point the ... |
[
"Is it possible to solidify a pure noble gas?"
] | [
false
] | null | [
"Yes it is. Even though the Noble gases don't have large IMF (inter-molecular forces) they still have London dispersion forces which if you take enough energy out of it in theory it could be a solid around absolute zero"
] | [
"Yep - for instance Radon, which is admittedly one of the easiest has a melting point of - 71 C, which isn't even that cold (you can get that cold with a dry ice/acetone bath)."
] | [
"Actually it's way lower. The average temp of the universe is only a little more than 2 K, the lowest number I'm seeing is 100 picokelvins, just 0.0000000001K. They have all sorts of fancy equipment they use to do this like the ",
"dilution fridge",
". ",
"Here's",
" a pretty cool video where someone descri... |
[
"Burning question: how does Magma emit light?"
] | [
false
] | How ~ does ~ magma emit light? And - in the hypothetical scenario that we have access to a heat-resistant camera that could survive a submersion in a magma pool or stream - what would we see? Would there just be darkness? Or would we still see the radiant light that we see at surface? Thanks in advance! | [
"All objects in the universe emit so-called ",
"thermal radiation",
". This radiation is electromagnetic radiation (just like radio, visible light, etc.) and it is emitted across a wide range of frequencies. The frequencies that are emitted, and how ",
" of each frequency, depends on the temperature of the ob... | [
"Just so you're clear, visible light isn't the only 'light' out there. It's a small chunk of the ",
"electromagnetic spectrum",
".",
"The radio waves we use to communicate, that's light. The microwaves that heat your food, that's light. Just because it's not visible doesn't make it not light.",
"The common ... | [
"Yes, the light is moving between every little bit of rock under the surface, as well. Your camera would see light down there (then melt, even if made of magical force fields, because the very same light it needs to image anything cannot be dumped back out again, so every photo you take must heat it up... but I dig... |
[
"How good are we at identifying sexual dimorphism in extinct animals?"
] | [
false
] | Sexual dimorphism can run a huge gamut between simple size/coloring changes to things like the angler fish that look completely unrelated. The differences between species in the fossil record is often extremely small, sometimes involving tiny distinctions in certain bones. Is there a reasonable chance some of these species are really just different sexes of the same species and how do paleontologists approach that? | [
"Obviously this depends a lot on the particular type of animal in question, but the point you raise is certainly an important one.",
"Firstly, for many extinct animals it is non-trivial to identify sex ",
", let alone start to build a picture of sexual dimorphism. In the case of dinosaurs, for example, it is s... | [
"As you suggest, there have indeed been at least some cases where what we now think of as different species were once considered different sexes of a single species, and its very possible that the reverse also occurs.",
"Wasn't Triceratops found to be the juvenile/young adult form of Torosaurus?"
] | [
"That's a whole other can of worms, but yes, that idea was proposed by ",
"Scannella and Horner 2010",
". However, there has been a fair bit of pushback from other researchers on this (e.g. ",
"Longrich and Field 2012",
", ",
"Maiorino et al. 2013",
"), and so in general I believe the majority consensu... |
[
"How accurate is the notion that all human embryos start out on a female path of development?"
] | [
false
] | I've seen it claimed before that all human embryos start out on a female path of development and that male development kicks in due to the SRY gene, while female embryos continue on the default plan of development. How true is this? Is it more accurate to call male development the variation and female development the default, or is it more accurate to call embryos undifferentiated initially? Is female embryonic development influenced by sex specific genes in a manner similar to male embryonic development? | [
"Short answer: yes and no, depending on how you want to phrase the question.",
"Long answer: So genetically, X is the basic plan and the Y chromosome changes things up. This makes sense, considering that you can't live without at least one X chromosome while the Y is a very stripped down chromosome with SIGNIFIGA... | [
"Essentially, if you're walking on a path that forks to the left and the right, you weren't on the left path the whole time, nor the right. You're on ",
" path. did I get that right?"
] | [
"Yes. But you can only go down one of those paths unless you have a key for the door of the second one."
] |
[
"Why do computers use base 2 instead of base 10?"
] | [
false
] | null | [
"You ask",
"Wouldn't a computer that uses base 10 natively process calculations in those disciplines faster than a computer that has to translate everything to base 2 and then back?",
"There's two aspects to an answer:",
"Radix 10 computers did exist. Babbage's engine and the \"Witch\", for instance. They wer... | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"If you disagree with this decision, please send a ",
"message to the moderators."
] | [
"thats fine. just curious would you mind steering me in the right direction so i can learn why it's fundamentally flawed? i dont mind googling it, but if you know off hand that would be helpful. thanks"
] |
[
"Is it possible for a brown dwarf to emit enough light that a human on an orbiting planet would be able to see (to some extent)?"
] | [
false
] | I'm working on a science fiction setting in which a small planet orbits a brown dwarf. A group of crash survivors live in a crater at the north pole. The climate is temperate but dark, akin to a summer's evening. The warmth comes partially from the planet itself (for reasons that can't be revealed quite yet). The sun stays low against the horizon, visible perhaps due to refraction in the atmosphere or from the permanent rain/fog at the crater's lip. I've done some basic research but I'd love to hear whether thinks this is feasible. If it's not entirely plausible, do you feel you could maintain a suspension of disbelief in such a setting? | [
"I love astronomy. IIRC, your planet will have to be very near the brown dwarf to provide a livable temperature and it will be ",
"tide locked",
" with one side permanently facing the sun.",
"Survivors living in a crater on the sun-facing side with a huge, dim sun the color of dried blood hanging overhead li... | [
"A typical brown dwarf will have a luminosity of 10",
" - 10",
" Watts. Some have temperatures above 3000K, meaning there would be plenty of emission in the visible spectrum, even down to the coolest stars at several hundred degrees. ",
"The light you see decreases with the square of the distance from the s... | [
"Thank you! Could (something like) constant volcanic activity be enough to keep the planet warm at further distances from the sun?"
] |
[
"Why is recovering data from a failed external hard-drive so complicated?"
] | [
false
] | This has happened to me twice now. Brought my failed drive to a computer store only for them to tell me it needed to be sent off to some specialist, costing upwards of $1500, to recover the data. The tech at the store said the process is quite complicated. I'm definitely ignorant of how data storage works but it seems like it should be a relatively straightforward process. Is bad design of these drives the problem or is the nature of data storage much more complicated than I'm giving it credit? | [
"I wouldn't be able to give you any details, but I can give you a high level idea with what it likely involves.",
"Hard drives having moving parts in them (the disk is spinning, an arm is moving back and forth, etc), if those mechanical things fail, or if there's a more detailed problem with reading it apart from... | [
"Also, it would need to take place in a clean room (not cheap) to avoid the smallest particles of dust. The data density on modern disks is amazing, so a single bit of dust on a disk can cause havoc. ",
"Sometimes, it's as easy as swapping the heads and/or platters (to a similar HDD donor drive). Other times, it'... | [
"Thanks for your reply"
] |
[
"Why do we still use conventional current?"
] | [
false
] | We now know that electrons move in a circuit not the positive charge. If we consider Physics as the model of our reality, why do we still use conventional current. Doesn't it get annoying if you think about the situation practically? Are there any situations where using electron current is a better option than conventional current model? | [
"Currents don’t always consist of negative charges. It makes more sense to have the current density point in the direction of motion of positive charges. If you’re dealing with currents that are made by the motion of negative charges, it’s not that hard to remember that the direction of the current density should b... | [
"The problem is the process of switching over.",
"Say tomorrow Congress instructs the US government to reverse the definition of charge. The next day, every company who sells an electrical device in the US has a panicked staff meeting. Every battery maker needs to come out with a new line of batteries with the ... | [
"Another way to put OP's question is: why not consider that the electron charge is the positive one?"
] |
[
"Did the Hanford B reactor generate steam?"
] | [
false
] | I know they piped in huge amounts of cold water from the Columbia river to keep cool. I was wondering if this river water was heated enough to boil in the reactor. | [
"Cripes, my apologies - I hadn't even thought to check whether the Hanford reactors were research ones, rather than standard power generation one.",
"I can find spurious references to the water pumps being able to run on steam power (e.g. ",
"page 12 of this document",
" (pdf)), but can't see anything definit... | [
"Edit: I really need to learn to read first."
] | [
"The reactor was a graphite moderated, water cooled reactor. The water was taken from the river and it flowed in tubes within the reactor. Here is an interesting paper on the reactor. It talks about the water flow. The water would not boil within the reactor. That would reduce its ability to absorb heat.",
"h... |
[
"Does the legality of virtual child pornography affect the number of incidences of sex offending against children?"
] | [
false
] | [deleted] | [
"There is approximately zero research into this area. Obviously, you can't change one of a region's laws for the sake of a control group. If you replace \"legality\" with \"availability\" then it becomes slightly easier to research, but still nearly impossible.",
"There are various ways it could possibly be res... | [
"While this post is accurate in some ways it also presents an incorrect narrative that there is no research being done into pedophiles or treatments for pedophiles. ",
"Germany proved providing free of cost therapy works to treat those sexually attracted to children: ",
"http://www.spiegel.de/international/spie... | [
"This article",
" describes sex crimes against both adults and children in several countries before and after online access to porn in general and child porn.",
"In multiple countries they saw a large drop in assaults with the timing correlated to the availability of pornography.",
"The findings support the t... |
[
"If dark matter has no electromagnetic interaction, what would touching it feel like?"
] | [
false
] | I understand that the vast majority of forces we encounter in everyday are due to the electromagnetic force. So if dark matter does not interact electromagnetically, what would it feel like to submerse your hand in a bucket of dark matter? Do we even have an inkling of an idea? | [
"Yes."
] | [
"It would feel a lot like being in a bath of neutrinos. This would probably be a good time to point out that we are in fact in a bath of neutrinos, with 65 billion per square centimeter or thereabouts.",
"So yeah, it'll just fly right through you without you noticing. Which kinda puts a damper on the whole bucket... | [
"Neutrinos are what's called ",
" yes."
] |
[
"To my understanding, things don't have a choice, why are living beings different, if at all?"
] | [
false
] | null | [
"Perhaps I didn't explain well what I meant. ",
"Consider the atoms and molecules that make us up. Those molecules form muscles and other tissues that work thanks to energy that we assimilate. So far so good.",
"A muscle simply moves because an electric signal that comes from the brain tells it to move, then th... | [
"Personally, I believe that the result of dice thrown is only deemed random for lack of sufficient information.",
"This would be true classically, but if quantum effect truly randomize the result of each action, then it becomes impossible to predict the result (Given that you try the action in the exact same cond... | [
"Only answering because it is unanswered. I have to technical info to offer but thoughts. We are a product of \"random\" mutations. I use quotes because of new studies showing that environment perhaps has more of an impact on mutations than previously thought. Anyways, the adult human body is made up of about 37 tr... |
[
"If there was an ideal environment (such as no predators and unlimited food/habitat resources), would evolution still take place?"
] | [
false
] | [deleted] | [
"I disagree. Competition is an important factor in evolution, but not a necessary one. Even assuming infinite food/resources/space etc., no competition and no predation, allele frequencies would still change over time. Some genotypes would lead to higher fecundity than others, and they would gradually become more c... | [
"For hypothetical purposes, evolution would not be necessary, but it could happen through a mutation that “ups the game” and makes one of the animals more attractive to a mate. ",
"I imagine a good example would be a cockroach. They can survive in what feels like anything, and they really haven’t changed much rel... | [
"Humans are continuing to evolve. Recent and ongoing changes include the ability to digest lactose as adults, loss of wisdom teeth, malaria resistance, and many more."
] |
[
"[Psychology] Can a healthy and mentally sound adult develop Anti-Social Personality Disorder?"
] | [
false
] | I know that ASPD is usually considered hereditary and appears to be expressed at a very young age, but could someone in a healthy environment and in good health develop it? | [
"ASPD (and other personality disorders) are theorized to be caused by a combination of genetic, social, and environmental factors. ASPD is entirely possible despite a \"good\" life. You can have a healthy social environment, for example, but if you have a large number of genetic/biological or environmental vulnerab... | [
"Well put and well written. Thank you!"
] | [
"Thank you!"
] |
[
"When the moon is in the sky during daytime, does it increase brightness on earth due to reflecting light, even if just by a fraction?"
] | [
false
] | Or does the brightness of the sun overwhelm it too much to measure? | [
"Yes. The moon contributes 400,000 times less light, which is too small to measure (from the ground, anyway).",
"https://en.wikipedia.org/wiki/Apparent_magnitude#Example:_Sun_and_Moon"
] | [
"The short answer is yes. Anything that you can see is reflecting light at you. However there is a massive difference between a full moon at night and broad daylight. I would be surprised if the increase in brightness from the moon is more than 1%. I would guess it's a fraction of a percent. You would need some ver... | [
"It would increase the amount of light hitting the Earth by some amount. I don't know how much, but I would guess it would be measurable. The closer the Moon is to full, the more light it would reflect to the Earth."
] |
[
"If the Graviton is discovered, could we use it to create artificial gravity in an other way than centripetal force?"
] | [
false
] | I have been searching the Internet lately for artificial gravity, but the only way right now to create that is a rotating rigid body. If we could somehow manage to detect the graviton and use it (just like we can use electrons), could we create artificial gravity with it? | [
"Not really. The graviton would allow us to unify quantum mechanics with gravity, but we still expect the macroscopic behavior of gravity to be exactly what general relativity predicts. It is similar to the way QED still gives rise to Maxwell's equations."
] | [
"Two things:",
"1) there is basically zero chance the graviton will be discovered in the lifetime of anybody alive today (we haven't even found classical gravitational waves yet).",
"2) if you use gravitons to produce a gravitational effect that is a real gravitational field- not something which mimics it."
] | [
"Thanks. I may have been wrong in the choice of the word 'artificial'. By that I meant gravity that isn't 'created' by an attracting mass, but a man-made gravitational field."
] |
[
"How far \"back through time\" can we see using telescopes?"
] | [
false
] | Assuming we had a telescope of infinite resolution (eg we could see molecules on Mars), and we focussed it as far away as possible (past early galaxies ect), what would we see? Would we see anything special, or is it just darkness all the way to infinity? | [
"The furthest back we can see with photons would be right after the ",
"recombination",
". That's what the cosmic microwave background is, the light given off by as the Universe cooled (albeit highly red shifted, which is why it is made of microwaves). This happened about 380,000 years after the Big Bang."
] | [
"how much further if we can eventually build good neutrino telescopes? Is there anyway to see further than that?"
] | [
"That is an interesting question. What would you be seeing? We are essentially able to see the light from the big bang cloud. We can not see any further because photos could not travel through the cloud. My understanding of the event would mean that there would not be any neutrinos. But even if there were there... |
[
"Would repeated exposure to varying scary experiences desensitize one to the feeling of fear (conditioning) or would it cause long term psychological harm?"
] | [
false
] | null | [
"The ",
"Little Albert experiment",
" would seem to indicate that, at least at a young age, this can cause long term harm. On the other hand, a lot of training occurs for people who need to deal with dangerous situations (firefighting, police, soldiers), which to me (I am no expert) would suggest that there is... | [
"Don't know much about PTSD, but is it a fear response paired with \"turning on\" of previous combat training/experience? If that's the case, then is it possible for a civilian, for example, to continuously watch/read/play horror stories which may elicit an initial fear response but, after a while, they may become... | [
"Don't know much about PTSD, but is it a fear response paired with \"turning on\" of previous combat training/experience? If that's the case, then is it possible for a civilian, for example, to continuously watch/read/play horror stories which may elicit an initial fear response but, after a while, they may become... |
[
"If a valve is broken in the left ventricle of the human heart, what impact does it have on the blood moving around the body?"
] | [
false
] | null | [
"The left ventricle is the larger of the two, and has the less enviable job of ejecting blood into the systemic circulation (brain, little toe, taint, etc). It interacts with two valves, the Mitral (named after a bishop's hat for its shape) which interfaces with the left atrium, and the aortic, which separates the ... | [
"You just clarified something I didn't realize was important. Thanks.",
"Didn't know about the iron depostion in the lungs.",
"Knew about pressure effects on Monday he lungs ans the effects f regurgitation though. Bernoulli applied to echos and calculating pressure deltas is a neat application. But the iro... | [
"To expand a little on what you said:",
"MS: A rare disease in the developed world these days. The majority of MS results as a post-infectious complications from streptococcal infection (rheumatic fever). With reasonable access to antibiotics this disease becomes very rare. It is still seen fairly commonly in the... |
[
"I read somewhere that the engine noise on airplanes diminishes our sense of taste, making food seem less salty. Biologically, what's going on that makes this so?"
] | [
false
] | null | [
"I understood that it was changes in cabin pressure and humidity that had a greater impact on our sense of taste than the noise."
] | [
"The lower air pressure affects our sense of smell, which is much more important to our ability to taste than most people realize. Humidity can act as a transport for some chemicals, but not for others."
] | [
"This is the only thing I've found with that suggestion",
", but it cites a 48 person \"study\" that seemed pretty far from scientific."
] |
[
"How do humans get accustomed to the temperatures of the places they live?"
] | [
false
] | For example Eskimos can handle the cold very well and Aborigines do well in the heat. Also as simple as someone from Minnesota will be wearing shorts when it's 30 degrees but someone from Miami will be shivering while bundled up in layers. | [
"The body has a temperature regulation system controlled by the hypothalamus. When in colder weather, it signals the pituitary gland to produce more thyroid stimulating hormone to increase metabolism and create more heat. It doesn't happen as much today due to air conditioning and heat, but in older times people's ... | [
"People who live in cold climates DO acclimate to the winter via increased thyroid hormones, just nowhere near the extent that we would if we were exposed to the elements. For example, in the winter, people commonly wear very different clothes around the house (fleece pants/sweatpants vs a t-shirt and shorts in the... | [
"So I have a follow up some question:",
"Since our we don't need to increase our metabolisms in the winter time due to heating, does our bodies know we don't have to eat as much too? That is, is winter weight gain is biological or just a cultural phenomenon due to fall and winter holidays (Thanksgiving and Chris... |
[
"What is coefficient of friction on Velcro?"
] | [
false
] | Learning about the effects of friction between one object and another. I would like to know what the approximate static and kinetic friction between a marble and a strip of Velcro would be. Note that its the soft part of Velcro, not the hooks. Also it is nylon Velcro, and I do understand that there is very little information given. The marble is an average glass marble. The information doesn't have to be super accurate, just ballpark. | [
"Wouldn't the better question be: \"How would I calculate ",
" on velcro? Or, perhaps, if you feel more physically inclined, \"how would I ",
" coefficient of friction on velcro\"? ",
"In this way, we encourage a reader to perform an experiment. "
] | [
"Could one consider velcro a meta-material with a coefficient of friction greater than 1?"
] | [
"One way might be, to adhere velcro on a tiltable plane, and try to slide stationary objects along it by precisely manipulating the tilt. Friction coefficient could be measured by the degree of tilt between different materials."
] |
[
"is the Pythagorean theorem appropriate for figuring out how far apart two stars are?"
] | [
false
] | null | [
"It's not appropriate to apply the Pythagorean theorem there, since you don't have a right triangle."
] | [
"Do you know what is?"
] | [
"The ",
"law of cosines",
", but you additionally need to know the angle between the two stars."
] |
[
"If you traveled underwater faster than the speed of sound (in water), would you get a sonic boom?"
] | [
false
] | And if so, how would it manifest? Would there be a bubble of air or something like that? I assume it would be quite a bit different from how sonic booms work in air. | [
"There are a few problems with this. The speed of sound in water is much higher than in air: 343 m/s in air, and 1481 m/s in water",
"1",
" Technically, the friction at work here depends on the shape of the object we're talking about- but at these speeds, I bet there would be ",
"problems",
" with any shape... | [
"According to ",
"this",
" page, creating a large enough cavitation bubble to encompass the object in question would lead to reduced drag in comparison to a small or non-existent bubble. "
] | [
"The speed of the object would super-pressurize water in front of it",
"Um.. how would it do this? Pressure waves cannot travel faster than the speed of sound...",
"Does anyone have a tank (the kind with a giant gun on it), a tank (the kind that holds water), and a really really fast camera? :-)",
"https://en... |
[
"What is the smallest object we can see with our naked eye without the aid of any instruments?"
] | [
false
] | I've recently read Ergroilnin's thread on what is the smallest object we can see with the aid of instruments. That got me think what about the smallest object without instruments? | [
"This is an extremely interesting question, which deserves a full answer. Unfortunately, I have to run, so will just say a few words and release it from the modqueue.",
"The two key points to kick off with are that both 'smallest object' and 'see' are surprisingly malleable terms. In terms of smallest object, we ... | [
"Thanks for your comment, it was an interesting read. How about we standardize it to an average young adult with a 20/20 eyesight. And for the object, it should be something that we can instantly recognize when we see it at high magnification."
] | [
"degrees-visual-angle is a distant-invariant metric of size. It describes the size of the image in terms of its size on the retina. It is is computed as:",
"y_deg = rad2deg(2*atan(x_cm/(viewingDist_cm*2)));\n",
"so if x_cm is the width of a single white stripe, and a cycle is made up of one white and one black ... |
[
"Can an object be accelerated to (almost) the speed of light arbitrarily fast?"
] | [
false
] | Or is there a physical limit to acceleration as well as speed? Thank you. | [
"There’s no fundamental limit to the acceleration as there is for the speed. But there are “engineering limits” to how fast people or things can accelerate without being killed/damaged."
] | [
"It's interesting to note that the only reason such limitations exist is because most forces are surface forces. This means they are applied to the surface of the object only (your chair transfers the force of acceleration from the car to your body). Because of this the loads must be transferred through the structu... | [
"Excellent point. Just to illustrate, when you free fall, you are being accelerated but you don't feel that acceleration."
] |
[
"Watching Cosmos...questions about light...brain hurts!"
] | [
false
] | [deleted] | [
"I can elaborate on 1). I'm going to lay a small amount of groundwork, so bear with me if you know this already.",
"First: Visible light is one tiny part of the ",
"electromagnetic spectrum",
". The only way it differs from the other parts of that diagram (x-ray, infrared, etc.) is in its wavelength. Gamma ra... | [
"You only perceive the light that hits your eyes. You can't see the other trajectories because they aren't hitting your eyes, and they aren't bouncing off anything. For instance, if you look at a person in front of you and a tree to their left, you can see light from them and light from the tree, and you know tha... | [
"You only perceive the light that hits your eyes. You can't see the other trajectories because they aren't hitting your eyes, and they aren't bouncing off anything. For instance, if you look at a person in front of you and a tree to their left, you can see light from them and light from the tree, and you know tha... |
[
"How do electrons never collide with the nuclei of atoms?"
] | [
false
] | I am aware of the concept of centripetal acceleration and orbit and all that, but it seems statistically impossible that no electron, after being manipulated by another electron or proton, would ever wobble out of orbit and strike the nucleus of an atom. If there is such attractive force between protons and electrons, why are there not vast quantities of electrons stuck to nuclei everywhere? And what would be the consequence of an electron/proton collision? | [
"That'd be the planetary model of the atom, which is incorrect. Actual electrons don't 'orbit' at a fixed distance from the nuclei. They 'move' quantum-mechanically, which means they don't have a definite position and velocity; all we can say is the probability of finding the electron(s) at various points surroundi... | [
"Electrons exist in certain orbitals because it is at those positions that the wavelength of the electron forms a standing wave. If you take a rope that is connected to a wall, and oscillate it with your hand to form a standing wave, you will notice that you can only form a standing wave at certain frequencies and... | [
"They do, ",
"sometimes",
"."
] |
[
"Question about traveling at light speed."
] | [
false
] | I read this : "It is interesting to observe that a real particle, in our universe, subject to all the laws of physics we understand, is a rather better interstellar voyager than the best fielded in the 24th century by the United Federation of Planets. Their much-vaunted Galaxy Class starships are capable of speeds slightly in excess of Warp Factor 9, an apparent velocity of 1516 cochranes (or 1516 times the speed of light).[4] At a velocity of 1516 c, traveling to the centre of the galaxy would take, as perceived by the life forms on board, a little more than 21 years. By contrast, an observer on board the Oh-My-God particle would arrive at the nucleus of the Milky Way, according to his clock, just about 3 seconds after leaving Starbase Terra. That's more than 9,700,000 times faster than the starship. In the time the starship spends vacuum-whooshing and rumbling its way to the nearby star Aldebaran, the particle could travel to the edge of the visible universe." on this website: " " Maybe I'm not getting something, but wouldn't a starship traveling at 1500+ times the speed of light get somewhere much faster than a particle travelling at 0.99999... times the speed of light? Thanks for your help! | [
"Star Trek warp speeds ignore relativity."
] | [
"And everything occurs in the same reference frame."
] | [
"Basically the speed of light is the speed limit of the universe (as far as we know) so travelling faster than c doesn't make physical sense (sorry to be mean.) ",
"The reason the OMG particle takes 3 seconds is due to a relativistic phenomena called time dilation. For someone observing the particle who is for al... |
[
"TIL ISS gradually loses altitude while it's orbiting earth. Why doesn't this happen to the moon?"
] | [
false
] | null | [
"The ISS is losing altitude because it gets slowed down by the atmosphere.",
"The moon is much farther away than the ISS and doesn't have this problem."
] | [
"The migration of the Moon away from the Earth is mainly due to the action of the Earth's tides.",
"The Moon is kept in orbit by the gravitational force that the Earth exerts on it, but the Moon also exerts a gravitational force on our planet and this causes the movement of the Earth's oceans to form a tidal bulg... | [
"Contrary to what common sense would dictate, the moon is actually GAINING altitude as its orbit decays. It is a very slow rate, however the reason it is gaining is that it is taking the angular momentum of the earth's rotation. As the earth spins, it transfers a small amount of its momentum to the moon. Back when ... |
[
"Why can we breathe out more air than we breathe in?"
] | [
false
] | null | [
"Because you don't empty your lungs all the way during a normal breathing cycle. We call the amount you can breathe out beyond what is breathed out during a normal respiratory cycle the expiratory reserve volume. "
] | [
"In terms of weight, you do breathe out \"more\" air. As for volume, I have no idea what the density for CO2 is at these temperatures."
] | [
"What makes you think you can breathe more out??"
] |
[
"Can a rotating non-expanding universe explain Hubble's red-shift data?"
] | [
false
] | Could the angular velocity/acceleration be perceived as velocity "away" from us? | [
"No. Rotation has poles. The redshift data do not. "
] | [
"It's an interesting idea. It doesn't work but it's fun to imagine. The issue is that the Hubble velocity field is isotropic: wherever you look, galaxies are moving away faster as they are far away. If the universe was somehow behaving as a sphere rotating around an axis you could see the direction of the axis as g... | [
"What if it was rotating on an axis through a higher dimension?"
] |
[
"Is it possible for a virus to infect a bacteria or a parasite?"
] | [
false
] | null | [
"Yes, absolutely.",
"While I can't say concretely that there is not a single cell in the world that cannot be infected by a virus, it's very likely.",
"There are known examples of viruses capable of infecting bacteria, archaea and eukaryotes (plants, animals, fungi and protozoans).",
"Viruses that specificall... | [
"There is phage therapy.\nBut human testing isn't allowed in many countries. "
] | [
"Are there any studies on using bacteriophages to fight bacterial infections in humans or animals? "
] |
[
"How many more \"new\" stars become visible each year?"
] | [
false
] | In other words, how many stars join the observable universe each year? | [
"The edge of the visible universe is where we see light from 380,000 years after the big bang, when the universe became transparent. If there were stars back then (and we had telescopes orders of magnitude more powerful) we'd see them emerge. But there weren't any, so all we see is empty space emerging. Stars didn'... | [
"I'm going to start with a disclaimer that I'm not exactly an expert on this but I think I can help find some kind of an answer for you. Someone please correct me if anything is inaccurate below.",
"Pretty much every individual star visible from Earth is astronomically very close to us in our galaxy. The average ... | [
"This is right. Also, we can only resolve galaxies (not individual stars) at that distance and they are very strongly red shifted, making detection difficult. The current record holder is ",
"GN-z11",
", and that is 32 billion light years away from us and we are seeing it as it appeared when the universe was 40... |
[
"How can a black hole, which can't have light escape, emit the more light than anything else when it gamma ray bursts or forms into a quasar?"
] | [
false
] | Basically, how can a black hole, which nothing can escape from emit so much? Also can multiple gamma ray bursts occur, or does it only happen soon after a hypernova? | [
"hmmm...I think what we're seeing (via satellites and telescopes) are the effects of a black hole on matter adjacent to it. Gravity attracts gas, gas is compressed and heats up. If the gas gets hot enough it is ionized and becomes a plasma. Plasma interacts with local magnetic fields and all kinds of crazy phenomen... | [
"Yep. ",
"What we're seeing",
" is either the matter in the accretion disk, heating up and emitting light as it spirals in; or matter flung out along the poles before it quite reached the black hole. (Or neutron star or other really dense object; black holes aren't the only things that generate accretion disks.... | [
"Tests of the constancy of the fundamental constants are a continuing enterprise. So far, there is no significant evidence for their variation at the 10",
" level. See ",
"this",
". I can provide more references, if you're interested."
] |
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