title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Do robotic prosthetic limbs work on a two-way or one-way communication system with the brain?"
] | [
false
] | [deleted] | [
"The journal Nature has this (free) and relatively jargon-free ",
"feature on neuroprosthetics",
".",
"As you'll read in that link, the current neuroprosthetics are all one-way. They read what is happening from the brain to decode what hand movements to make. There is no feedback from the prosthetic hand itse... | [
"I will add that visual feedback remains, meaning that individuals can see, for example, if they are applying too much or too little pressure to pick up a water bottle"
] | [
"I will add that visual feedback remains, meaning that individuals can see, for example, if they are applying too much or too little pressure to pick up a water bottle"
] |
[
"Is there a natural bias in favor of even numbers in mathematics?"
] | [
false
] | For example: An odd number multiplied by an odd number equals an odd number. An even number multiplied by an even number equals an even number. But an odd number multiplied by an even number equals an even number. Is this just a coincidence, an strange quirk in math, some sign that the universe chooses order over chaos... | [
"An odd number divided by an odd number (assuming the numbers are divisible) gives an odd number. An even number divided by an even number can equal an odd number. ",
"Multiplication of natural numbers produces more even than uneven numbers. However, this is not a general result or trend in mathematics.",
"Edit... | [
"Remember that a number is \"even\" if it has at least one 2 in its prime factorization. Multiplying two integers together just combines their factors and never destroys any, so any product of a multiple of 2 with another integer must be a multiple of 2. In the same way, any product of a multiple of 17 with another... | [
"You can apply maths for many useful purposes such as Physics or Informatics.",
"However, properties inherent in Maths built on a specific set of axioms do not reflect properties of the universe.",
"You can only use math to make predictions about the universe after linking formulas to properties.",
"edit: I a... |
[
"Can we make pairwise genome-wide association studies? Have any been done?"
] | [
false
] | I'm pretty sure that some genes work best in synergy with each other, and it would be interesting to see if we could do that on the IQ phenotype - as described at | [
"Tes, that stuff is done in GWAS. But, for GWAS it's too hard to say that there are interactions. We can note how a SNP of one gene marker and a SNP of another gene marker ",
" contribute to a phenotype but this only tells us about the alleles.",
"To really know if they are working together you need expression ... | [
"Can you provide more detail in your question regarding pairwise? Do you replicability across GWAS or literally pairwise comparisons of the SNPs between people (basically sequence alignment...)?",
"Are you curious about the work in GWAS to include more phenotypes or other markers?",
"Something else?"
] | [
"Like - basically - interactions between genes.",
"It could be possible that there's little effect between two individual genes - say - DRD2 and MAO genes, but that they have a significant effect when expressed together (if they were expressed as the DRD2:MAO term)"
] |
[
"How can asymptomatic cases cause long-COVID? Doesn't that stem from the damage caused by the initial symptoms?"
] | [
false
] | null | [
"Typically, most symptoms aren't caused by the actual infection but the immune response to it afterwards.",
"Someone could feasibly have a weakened immune system and have little of the normal symptoms of infection but still have a pretty widespread infection of the body."
] | [
"There are both good and bad sides to a weakened immune response.",
"Sometimes, when people have an overactive immune response the vast majority of the damage to the body is actually caused by the inflammation and controlled cell death of the immune response. On the other hand, having a weakened immune system can... | [
"There are both good and bad sides to a weakened immune response.",
"Sometimes, when people have an overactive immune response the vast majority of the damage to the body is actually caused by the inflammation and controlled cell death of the immune response. On the other hand, having a weakened immune system can... |
[
"9/11 - One question no one ever seemed to ask..."
] | [
false
] | null | [
"There's not really a solution for that. Maybe if they could all get to the roof and rescue helicopters got to them. Other than that I don't believe there is a realistic way to rescue people."
] | [
"Actually there are several patents for systems out there (google escape elevator systems) These tend to have a high economic cost so they would not be plausible for use in normal high rises."
] | [
"Yeah... let's just say we know some crazy mofo who works in Canary Wharf that keeps base jumping equipment in their office..."
] |
[
"Why is gravity not a violation of the second law of thermodynamics?"
] | [
false
] | Note: I come from a chemistry background and this is an astronomy question, so I may be off on some of my assumptions. This is a question I've struggled with for a long time and haven't been able to get a clear answer from my previous professors: The second law of thermodynamics states that the total entropy of a syste... | [
"Something similar was asked about attracting magnets recently. The answer is the same: When the things come together due to an attracting force, the potential energy that's equivalent to that force has to go ",
" (First law of thermo!). ",
"If two asteroids attract each other, they'll accelerate towards each o... | [
"How about some ",
"Entropic Gravity",
"?",
"Here's an interesting paper entitled: ",
"Can Gravity Decrease Entropy?",
" -",
"In the calculation I just did, it's a bit hard to see exactly why the entropy of the gas cloud goes down as it shrinks. As the gas cloud shrinks, each atom roams around a smaller... | [
"GUAH, ANOTHER CHEMICAL ENGINEER. ",
"/ontopic/\nYeah, you'd initially think that gravity would essentially reverse entropy, but the heat generated by the release of the potential energy when the objects come together offsets that and keeps the second law of thermodynamics alive :P"
] |
[
"Which country spends more? A cold one keeping warm, or a warm one cooling down?"
] | [
false
] | null | [
"Know a little about cold weather engineering although it is not my area. I'll explain what I can.",
"In most cases it is cheaper to heat than to cool.",
"Air conditioning compresses a gas like freon, or nowdays R-22 into a liquid, then when it goes through the phase change back to gas it pulls heat. At this po... | [
"It's a loaded question, unfortunately. There are far too many factors that exist with heating and cooling a building. These include climate (how cold is cold, how got is hot?), humidity, tolerance of occupants (80 degrees versus 70 degrees means a big difference) , energy rates, etc. To generalize, heating is ... | [
"The other factor to consider is thermodynamics, whose laws we obey in this house, young lady.",
"Any electrical devices you have will produce waste heat, and speaking for one house, all year, in the winter, this heat contributes to warming the house (raising the temperature isn't doing work) , but in the summer,... |
[
"How much bigger is the universe than the \"observable\" universe?"
] | [
false
] | We can only see billions of years in any direction. Has new stuff formed further out than that? | [
"The size of the Universe is unknown; it may be infinite. It depends on how big the large scale curvature of space is. According to the current measurements universe is either flat and infinite or very nearly flat. It is estimated that universe is at least 250 times the size of observable universe. ",
"sources:... | [
"And that is just the estimate for the minimum possible size. "
] | [
"The term 'flat' does not mean a piece of paper laid out on a table, like the Earth was one envisioned to be. It is a topological term that means the curvature of our 3-dimensional universe is 0. ",
"Read this",
" to enlighten yourself. There have been many observations made that very strongly suggest that the ... |
[
"How does magnetic tape/magnetic disk storage work?"
] | [
false
] | null | [
"The surface has a magnetic dust embedded in it.",
"The write head can magnetise parts of it as it moves, this is done by making the head an electromagnet and having the surface move below the head.",
"To read the data the head moves through the magnetic field of the tape and this creates a small current.",
"... | [
"I can answer this one, I'll be using layman's terms but I'll try to be thorough. We'll start with magnetic tape as it's slightly simpler, and then I'll explain how disk storage works differently. There is a third form of magnetic storage that was very widely used until the 1960s which is magnetic-core storage, bu... | [
"Thanks, great explanation!"
] |
[
"What should you do if parents comes into a clinic and says they doesn't want their children to be vaccinated?"
] | [
false
] | null | [
"Consider it identical to any other refusal of treatment, because that's all it is.",
"You need to first find out ",
" they object to vaccination. A lot of the time it's \"I read once on this website it makes them autistic.\" You can then offer information about the correlations (that most of us have accepted... | [
"Oh okay, I see. Thank you!"
] | [
"In the US, each state has it's own laws about the subject. Washington recently changed their laws, so that might be a good starting place."
] |
[
"How is quantum tunnelling the reason our sun shines ?"
] | [
false
] | My daughter shared video ted talk by Jim Al-Khalili titled "How Quantum Biology Might Explain Life’s Biggest Questions ". I understand the basic concept of quantum tunnelling but not how it applies to our sun. | [
"There are nuclear reactions occurring in the sun that involve particles tunneling through each others Coulomb barriers. Nuclei repel because they’re positively charged, but even if they have a low relative kinetic energy, they can still tunnel in order to react with each other."
] | [
"The important thing about quantum tunneling is that barriers that cannot be overcome classically with the amount of energy typically available, can be overcome with some chance quantum mechanically. That's all there is to it. So processes that are classically impossible or unlikely will happen with a higher freque... | [
"The sun is made up of nuclei (protons and neutrons) which undergo nuclear fusion.",
"The protons repel each other because they have the same electronic charge, but still fuse due to the tunneling effect.",
"The energy emitted from the fusion is done so as light."
] |
[
"Why does a wet dog smell?"
] | [
false
] | null | [
"From ",
"this",
":",
"\"Molecules have to leave the smelly objects and get to your nose through the air and that means that these molecules must be very small and volatile. That's to say they must be easily evaporated. The chemicals that make dogs smell are mostly what we call volatile organic acids and th... | [
"So how might that change when it’s wet? Well, if the organic acids are dissolved in water on the fur of the wet dog, as the water evaporates, the concentration of those smelly acids increases, so they'll evaporate more, so there are more molecules in the air for us to smell.\"",
"But wouldn't the highest absolut... | [
"You're not smelling the acids on the dog. The water gets on the dog, the acids get in the water, the water evaporates and takes the acids into the atmosphere, you inhale some atmosphere through your nose, the acids are sensed, and you smell them. ",
"Dogs don't sweat all over the way humans do, so there isn't u... |
[
"What would happen if a sun, larger than a black hole, went into the black hole?"
] | [
false
] | [deleted] | [
"I think what the OP is asking is whether the black hole can tear a hole through the inside of the star in a direct collision (not merely a close orbit). Since the black hole's radius will be a small fraction of the diameter of the star, it takes a \"bite\" out of the core. And repeat this process as the star's now... | [
"Here's a computer simulation of what would happen: ",
"https://www.youtube.com/watch?v=thkKrW23vNU"
] | [
"\"Larger\" has to be defined in this context as well.",
"Are we referring to net mass, or measurable size? Of the singularity, or of the total amount of mass spiraling towards the event horizon?"
] |
[
"Why haven't humans adapted to their environment in the same way animals have?"
] | [
false
] | null | [
"If you take a polar bear to that country it would have quite a difficult time. Likewise if you take a desert creature to the arctic it may have some difficulty. "
] | [
"I think you may have misinterpreted my question, I'm asking: ",
"\"Why humans haven't developed similar traits as animals to cope in extreme climates?\""
] | [
"Unfortunately, the general answer to \"why hasn't something evolved\" is \"because it hasn't been selected for\". Although there are plenty of changes that we might point to if we are looking at our local environments, for example differences in amount of hair or skin tone or even type of ",
"earwax",
" depend... |
[
"How can I calculate the magnetic field strength required to stop a metal projectile such as a bullet?"
] | [
false
] | null | [
"For context I'm a student and I'm writing a theoretical research paper on the possibility of doing this.",
"I'm a little lost on where to begin. I understand the concept of eddy currents but I'm not sure how to link kinetic energy of the bullet to the magnetic field strength,conductivity of the bullet(assumed to... | [
"Please post calculation requests to ",
"/r/estimation",
" or ",
"/r/theydidthemath",
"."
] | [
"Alright thank you!Apologies "
] |
[
"Do short-lived species, such as fruit flies, evolve/adapt quicker because of shorter, more frequent generations?"
] | [
false
] | On paper you would think so right? since the driving force behind evolution is the variations of traits passed from generation to generation. An example I can think of would maybe be cats with thumbs, isn't that a relatively new common mutation? | [
"It's just polydactyly",
" (i.e. an extra digit).",
"I don't really know why the OP thinks cats area good example of a short generation time though. Cats have generations times on the order of multiple years, which is a long time in the world of biology. A better example for the OP is the evolution of antibiot... | [
"Where are you finding cats with thumbs?"
] | [
"All else being equal (a big assumption), evolution will proceed faster on the per year scale in populations with shorter generation times, yes.",
"Can you clarify where cats with thumbs comes into this?"
] |
[
"Are canker sores (apthous ulcers) contagious? If so/not, could you please show me the peer-reviewed article showing this?"
] | [
false
] | [deleted] | [
"Here's",
" the mayo Clinic's basic health information page on canker sores (not cold sores, those are different, but often confused.)",
"It says that they are not contagious."
] | [
"Thank you, I found that one, but it doesn't link to a scientific article that shows the information to be researched."
] | [
"Here's",
" an article about the recurrent form, I did not get a chance to read the whole thing, but it doesn't mention direct transfer as one of the standard causes.",
"The references might be a good place to start looking for more in-depth information."
] |
[
"Pharaoh's Snake: Can someone please explain what is happening here?"
] | [
false
] | Is this actually solid mass? What happens next? Does it disintegrate? What is left behind? What does it smell like? | [
"It's not a solid mass, it's a very porous light sponge-like material, it will crumble to dust if you crushed it and you could ultimately reduce it back to a powder about the size of what they started with. "
] | [
"I'm more annoyed at the ridiculous use of a rattlesnake sound effect."
] | [
"was a minute and 20 secs off him dumping the powder really necessary?"
] |
[
"Why do I faint after flu shots?"
] | [
false
] | null | [
"We can't really comment on isolated incidents / personal anecdotes without resorting to speculation."
] | [
"Speculation is fine. I am curious to hear if anyone has had a similar situation and knows what it is or if there's any doctors that have experience with this."
] | [
"We don't allow that on this sub."
] |
[
"What is the speed of gravity? I.e. If the sun just disappeared in a moment, how long would it take for earth to go out from its orbit?"
] | [
false
] | [deleted] | [
"There is no such thing as instantaneously in this universe. The earth would fall out of orbit in 8 minutes, the speed of light "
] | [
"Dude, you are completely 100% wrong. I don't know where you read that, or if you just came up with it on your own, but you heard wrong, completely wrong.",
"The speed of information aka the speed of light aka the speed of gluons aka the speed of gravity is all the same. All massless things (such as gravity) trav... | [
"Gravity is said to travel or \"ripple through space-time\" at the speed of light. ",
"Prior to Einstein's Theory of Relativity, we thought (as did Isaac Newton) that if the sun disappeared, the Earth would immediately cease its orbit and continue off into space along a tangent to the point in orbit.",
"Einste... |
[
"How can a single speaker cone vibrating reproduce the sound of all the individual instruments of an entire orchestra at once?"
] | [
false
] | I imagine the cellos causing the speaker to vibrate, then I imagine adding in the violins, and then the percussion, and then the woodwind etc. and how their vibrations would all interact with each other. How can this all be reproduced accurately on one speaker cone? | [
"Riding a sine wave on a sine wave. ",
"Say you had a high freq sound wave going steady, and then you played a low wave at the same time. You would actually be able to observe that as the low wave caused the cone to move back and forth slowly, it would at the same time be vibrating quickly along the low freq wave... | [
"Here are some graphs I made to help",
"Edit: made frequencies further apart"
] | [
"Sound is a pressure wave in time. Objects in the world move, and bump the air molecules around them. These molecules then bump into molecules farther away, and so on and so forth until finally the air molecules bump your ear drum and your sensory system interprets the bump as sound.",
"Music, and individual note... |
[
"Are giant space animals possible?"
] | [
false
] | null | [
"You'll need an astrobiologist for this one. On top of that, this question will pretty much yield only speculative answers as we haven't found any life in the dead of space yet. May I suggest reposting this instead to ",
"/r/asksciencediscussion",
" ?"
] | [
"I would agree.",
"I'll just post my standard astrobiology answer -",
"Yes, we can imagine any kind of animal that could for example feed on interstellar hydrogen as it swam through space. ",
"But doing so is completely incompatible with life as we understand it. Doesn't mean it's impossible, but according to... | [
"Energy? Check.",
"Materials? Sort of check.",
"Water? No.",
"There is abundant sunlight for a solar-powered creature. Raw materials like carbon and nitrogen are available in comets and asteroids, but these are ",
" widely distributed. Spacewhales might benefit from low-fuel propulsion options like solar sa... |
[
"Historically many fields of science have been quite dogmatic about certain theories and wound up being wrong. To the scientists on this board: Is there anything you personally believe that would be considered outside the mainstream of your field, perhaps even heretical?"
] | [
false
] | null | [
"I'm not going to answer your question (because I don't have anything that fits) - but I am going to address your comment.",
"Science is indeed very often wrong, or misled, by experimental results. But that is the nature of science. Each answer we obtain adds or subtracts from the weight of an observation. Very... | [
"Yep: P = NP. But I'm no where near as educated about the subject as the professors who taught me. Very much so considering one of them is Stephen Cook."
] | [
"I'm a respectable materials scientist, but I still think the jury is out on what happens when you load lots of deuterium into palladium (you can take palladium metal and make the D to Pd ratio nearly 1:1). An experiment on this subject led to the cold fusion controversy, which killed all research on the topic. If ... |
[
"Is there something in our body that gives a clue about our [species, not individual] approximate lifespan?"
] | [
false
] | For instance, if an alien species abduct a single human, would they be able to find out that we're supposed to live a maximum of 80 to 100 years? And if it's possible, how young could that person be so that prediction is still accurate enough? (All of this using known, earth science, obviously) | [
"There are some ways to do this; you can pretty cleanly draw correlations between resting heart rate and life expectancy (slower heart, longer life) and between body mass and life expectancy (bigger body, longer life)",
"That said, we ",
" supposed to live this long. Humans are an incredible outlier in both of... | [
"No. At this point we aren't even close to a biological model of aging in humans nor can we tell if there's a hard limit to how old humans can get. The only reason we can make reasonable estimates of max age is because we can analyse people throughout their lifecycle, something I assume the aliens can't.",
"Even ... | [
"Are you aware of anyone who has put together a regression of those correlations? I’d love to see what they suggest about the “natural” human lifespan.",
"Edit: based on the averages in this paper (",
"https://pubmed.ncbi.nlm.nih.gov/9316546/",
"), human lifespan should be less than 20 years, assuming resting... |
[
"Can space reach the point where it can't become any smaller?"
] | [
false
] | [deleted] | [
"No. There are speculative theories that space might be discretized like this, but none of them have evidence going for them (and some have evidence going against them). ",
"We have every reason to believe that arbitrarily small volumes in space are meaningful; we don't quite know how to describe things once you ... | [
"It's important to note that the Planck length is the smallest length we can \"describe and still make sense of because our current theories break down there, not necessarily because space itself can't \"get any smaller.\""
] | [
"Someone with more expertise in this area will likely have a better explanation than me, but ",
"this article",
" on the Planck Length might interest you. From what I understand (not an expert, just a curious layman) this is about as small as we can really describe and still make sense of, which I feel is what... |
[
"Can I \"integrate\" special relativity (stepping between nearby IRFs) to get GR?"
] | [
false
] | I've always seen SR described in terms of inertial reference frames, not really "dealing with" acceleration. Well, what if I compute forces on an object during some small time interval "taking SR into account," move the object into a new inertial reference frame based on those forces, and repeat? If I make the time i... | [
"This is an interesting question! I hope it doesn't get overlooked by the panelists, but if it does, it might be worth posting in ",
"r/askphysics",
" as there is likely to be at least one person with experience in numerical relativity who could help you out.",
"GR is a bit outside my comfort zone, but I do k... | [
"This is actually an exercise in Goldstein's ",
":",
"Show that the relativistic motion of a particle in an attractive inverse-square law of force is a precessing ellipse. Compute the precession of the perihelion of Mercury resulting from this effect. (The answer, about 7'' per century, is much smaller than th... | [
"Thanks for the reply and the links to Classical Mechanics and Bertrand's Theorem. I guess I shouldn't be surprised that the integration trick doesn't work. If that was all it took to go from SR to GR then GR would be taught as a little appendix on top of SR instead of a whole new topic.",
"You said that the ge... |
[
"When I heat up water in the microwave and then pour it into a bowl, it always clings to the side of the container I'm pouring from and spills all over the place, spout or not. Why?"
] | [
false
] | [deleted] | [
"If you look though the side of a glass of water you can see the water is not flat across but actually curves up the side a bit. I believe this has to do with the interaction between the glass, the water and the water's surface tension. I don't know how this interaction exactly works. But I'm pretty sure that wh... | [
"What you're talking about is capillarity. It comes from the difference in attraction of liquid molecules to each other vs. to the container. In the case of water and glass, the glass tends to be charged, so water molecules are more attracted to it and thus \"climb up\" the walls (opposed by gravity). Surface te... | [
"Have you tried with cold water too? Maybe make 2 videos with cold and hot water? Because regardless of the container heating up too, the decreased surface tension of the hot water should actually have the opposite effet and let it disconnect from the container more easily.",
"But maybe I'm just an idiot and the ... |
[
"How is testicual cancer (or any cancer in less than vital organs like cervix, breasts etc.) potentially lethal?"
] | [
false
] | Of course, I am going under the assumption that such a cancer will, untreated, ultimately lead to death. I am, however, not exactly sure how. What I am thinking is that, as organs like the testicles, ovaries, and breasts are (seemingly) not vital to staying alive, it is not that cancer in itself that will cause death. ... | [
"Shorter: Cancer can ",
" - tumors can spread - they are not confined to where they start. ",
"Some cancers may be considered more dangerous than others due to the ways they commonly metastasize. Breast cancer, for example, can result in a spread of tumors to the bones, brain, lungs, and liver (among other loca... | [
"Shorter: Cancer can ",
" - tumors can spread - they are not confined to where they start. ",
"Some cancers may be considered more dangerous than others due to the ways they commonly metastasize. Breast cancer, for example, can result in a spread of tumors to the bones, brain, lungs, and liver (among other loca... | [
"Yes, you are thinking about it the correct way. Either the cancer kills you by infiltrating more vital organs, think liver, lungs, brain and shutting them down or it does it by something called paraneoplastic syndrome. That's when the cancer cells start behaving in a way that disturbs the rest of the body without ... |
[
"What happens to magnetic field when a north pole is near a south pole?"
] | [
false
] | I'm trying to understand magnetism currently and had this question: Let's say I have a line of u-shaped magnets all facing the same way (north poles next to north poles and vice versa). What happens if I switch one of these magnets? My theory is that it would reduce the strength of the magnetic field, but I can't find ... | [
"I'm not sure what your scenario is, can you draw it? ",
"If you have the same poles facing each other, the magnetic field between them would be weaker. If you have different poles, it would be stronger. "
] | [
"My theory is that it would reduce the strength of the magnetic field, but I can't find any sources on this. ",
"You're right. When there are two magnets next to eachother, their magnetic fields add together. That means:",
"0.001 Tesla in the \"left\" direction + 0.002 Tesla in the \"right\" direction = 0.001 T... | [
"Magnetic fields follow the principle of superposition just like electric fields do (E total= E1 + E2 + E3 +... where these are all vectors. So B total = B1+B2+B3+...). So if you have two magnets facing where the South people of one magnet touches the North pole of the other (end on end) the total magnetic field wo... |
[
"What evidence do we have for an early hot universe - or: Are there alternative theories for matter generation and the cosmic microwave background?"
] | [
false
] | Hi, answering in another post got me thinking; AFAIK we deduce from redshift that space is expanding as time increases, and from the CMB we deduce that the younger the universe was, the higher its energy density. My question: How certain are we that these assumptions are correct? Are there alternative theories out ther... | [
"Well, to be specific let's say what the current model is. We know everything is expanding, so if we trace back in time, we assume (with other data along the way) that there existed some time in which everything was packed very densely together. Infinitely dense perhaps. Now let's play that tape forward and for the... | [
"Conservation of energy is pretty darned axiomatic."
] | [
"It wouldn't have been a stupid question ",
" To the contrary, the energy-time uncertainty relation is a very important aspect of quantum theory.",
"I wish I were sufficiently educated to explain it.",
"Or even fully understand it."
] |
[
"Why does xenon an inert gas interact with flourine?"
] | [
false
] | Isn't it accepted in science that inert gases do not chemically interact to form molecules with other elements? Why is xenon different from the other inert gases? | [
"\"Xenon reacts directly with fluorine because fluorine is a very powerful oxidizing agent (hence it gets reduced and it gains an electron from Xenon). Xenon has larger radii; therefore the electron attraction to the nucleus is weaker in comparison to the smaller noble gases. Fluorine on the other hand is very tiny... | [
"I'm going to add on to this with a mini-lecture on chemical reactions in general. Despite the mystique many people attribute to chemical reactions, they generally fall into only a few categories of reactions which are in reality the same thing - redox or, Reduction-Oxidation. ",
"The reason this is true isn't ... | [
"The noble gases, inc. Xenon, are commonly said to be inert. In fact they're just unusually stable, not totally inert under all circumstances.",
"A simple way of looking at it is that Fluorine's 'reactiveness' is just bigger than Xenon's 'unreactiveness'."
] |
[
"Has there ever been an animal with visual acuity based on movement?"
] | [
false
] | Watching Jurassic Park for the millionth time. I know that the idea of T-Rex only being able to see you if you moved has been debunked, but it got me wondering. Has there been an animal that this could have been based around? Or was this just some crazy idea? | [
"Theoretically it would be pointless because they could just move their head to see everything. ",
"But the line from the movie came from the sex-changing frog they used in the film to splice in DNA. The frogs had poor eyesight and only identified prey and predators based on movement patterns. So at the time we t... | [
"I'm not aware of this applying to the entire visual field of any animal, but most animals have something like this for at least a part of their visual field, including you! Take your left index finger, hold it up in front of your face (about 10 inches away), point to the right (so that your hand /arm is parallel t... | [
"But the line comes from a paleontologist, and he's talking about T-rex, not frogs. That's some sloppy writing, then, I suppose. "
] |
[
"How can chemists predict the resulting products of alkane cracking?"
] | [
false
] | For example - if we break down decane we can produce propane + heptane or perhaps pentane + hexane, etc. How can we dictate the result and choose between what we want the product to be? | [
"Ah okay, that definitely makes sufficient sense. I sort of figured that perhaps we'd just want one or two specific products from such reactions, but thinking about it now I realize that it'd be kind of inefficient and a bit of a waste of time.",
"Thanks for your answer!"
] | [
"Ah okay, that definitely makes sufficient sense. I sort of figured that perhaps we'd just want one or two specific products from such reactions, but thinking about it now I realize that it'd be kind of inefficient and a bit of a waste of time.",
"Thanks for your answer!"
] | [
"I see. Thanks again! ",
"May I ask though, why are chiral molecules useless?"
] |
[
"How does a black hole consume matter?"
] | [
false
] | What I'm wondering is: If we could open a tiny black hole by/in a rock, for the short amount of time it would take to consume a part of the rock, would the rock break into pieces? Or would it be sort of smeared (couldn't find a better word) into the hole? What got me thinking was this picture: I'm just using a rock as ... | [
"An object near the surface of a black hole experience massive tidal forces because one end feels a stronger gravitational field then the other, so it gets stretched."
] | [
"Thank you!"
] | [
"If we could open a tiny black hole",
"This isn't really an answer to your question, but based on your wording, it looks like you're under a mistaken assumption. Please feel free to ignore this if I'm wrong.",
"Anyway, a black hole is not a hole, and isn't something that \"opens\". A black hole is a massive b... |
[
"Which is denser; Tungsten or Gold?"
] | [
false
] | null | [
"I'm not going to let this out because the answer can easily be found on google.",
"The density of tungsten is 15.63 grams/cc and the density of gold is 19.3 grams/cc. I hope that helps"
] | [
"Fair enough. I looked did a bit of searching, but even wiki (which should be a good source for something like this) had contradictory results.",
"Here",
" is a listing of tungsten at 17.6 g/cm",
" and gold at 17.31 g/cm",
" . My CRC (64th) lists W at 17.6 and gold at 17.28, but that's liquid state. Everywh... | [
"The website you gave me lists Gold at 19.3 and tungsten at 19.25 which is closer than I put it but the order stays the same. "
] |
[
"Medical Physics: what is it?"
] | [
false
] | I read the Wikipedia article, and I'm still not clear. It seems related to diagnostic imaging and whatnot, and I knew that already, so I have a few questions: 1) How is it different from an engineering discipline? It seems very focused on devices like MRIs and whatnot. 2) Is someone in medical physics a physicist prope... | [
"Medical physics student here. Depending on your definition, there's around 3 broad specializations for the field: Health physicists, imaging physicists and radiotherapy physicists.",
"Health physicists are mostly concerned with radiation protection and shielding. They're a bit more rare than the other two in the... | [
"From what I know, Medical Physicists work mainly in radiation therapy and nuclear medicine.",
"Radiation therapy uses highly energetic beams (photons, electrons, protons or ions) to destroy tumors. These beams are deadly but invisible. The physisicst's work is to insure the correct dose gets delivered to the cor... | [
"I am finishing my PhD in medical physics hopefully before new years. My research and experience is in functional CT imaging and intensity modulated radiotherapy of cancer, but I have been around for a while so I have had my hands in a bit if nuclear medicine, MRI, ultrasound and other things.",
"The majority of ... |
[
"If two identical twins produced an offspring (gross), would the offspring be some kind of genetic clone?"
] | [
false
] | null | [
"This wouldn’t be possible since identical twins would be the same gender."
] | [
"If this was possible (other people have mentioned the same-sex thing) then the child would not be a clone of the parent(s). ",
"Any genes where the parent was homozygous would still be homozygous. However, only 50% of the genes where there is heterozygosity would still be heterozygous. The others would become ... | [
"Actually, it is possible for identical twins (twins born through a process where a single fertilized egg splits into two) to be born with different genders in the presence of genetic defects. If the gene determining gender is xxy, when the egg splits it is possible to have one xx and one xy egg after the fact.",
... |
[
"Does cupping your ear with your hand improve your hearing significantly? How about in terms of sound quality?"
] | [
false
] | [deleted] | [
"As DrWurm pointed out, you are forming a reflector with your hand, and directing more acoustic energy into your ear. It is worth noting, however, that you are preferentially increasing high frequency sounds. This is because for low frequency waves the wavelength can be on the order of ten meters long, and your han... | [
"I agree with this. I will add that cupping a hand behind the ear adds 6-8 dB to high frequencies (some at frequencies >1000 Hz, more >4000 Hz)"
] | [
"Cupping your hand over your ear creates a sort of directional parabolic receiver around your ear. You're bouncing in more sound energy than would have otherwise made it into your ear. ",
"Parabolic microphones are basically the same concept",
"."
] |
[
"In case it hasn't been brought to your attention, there's a new subreddit, \"Explain Like I'm Five\" that might do well to have some of our scientists checking it out."
] | [
false
] | null | [
"RULES:",
"No science questions. Those belong in ",
"r/askscience",
"."
] | [
"Seems reasonable to me. There's already a subreddit for science questions, this one, so it makes sense to keep those questions here.",
"Also, I'm not sure I see how this is any different from ",
"r/answers",
"..."
] | [
"Whoa, didn't notice that. Seems a little much to me. :/ Maybe they'll change that."
] |
[
"If 2 people with walkie talkie's fell past the event horizon of a super massive black hole, would they be able to talk to each other with their walkie talkies?"
] | [
false
] | null | [
"I thought the basic geometric description of inside the event horizon was basically \"all directions point to the singularity\", in that case one-way communication would be possible if one person was \"in the way\" of the others path to the singularity, but two way would not be possible."
] | [
"The standard view is that in a basic non-rotating super massive black hole the gravitational gradients just inside the event horizon can be low enough that you not have to worry about spaghettification for several hours, and that there is no local measurement that you can make that would tell you that you have pas... | [
"Pretty sure OP is asking about two people being able to communicate if both are inside the event horizon. Is the answer still no? Could you elaborate?",
"/r/AskScience",
" should be more than one word answers."
] |
[
"Why does mixing mustard and honey together make a compound that is far runnier than either one by themselves?"
] | [
false
] | I poured out some mustard and it was pretty thick. It didn't move. Honey slowly poured down the side of the plate. However, when I mix them, it becomes quite liquid, almost like a thick soup. Why is this? | [
"In ",
"/r/askscience",
", it's considered bad form to guess or speculate, especially in top-level posts.",
"But you should definitely consider that mustard is thick because of the presence of a natural emulsifier, called mucilage. That's why a bit of mustard allows you to mix oil and vinegar. The emulsifier ... | [
"In ",
"/r/askscience",
", it's considered bad form to guess or speculate, especially in top-level posts.",
"But you should definitely consider that mustard is thick because of the presence of a natural emulsifier, called mucilage. That's why a bit of mustard allows you to mix oil and vinegar. The emulsifier ... | [
"I don't really know for certain, but I do know that the viscosity of honey is very sensitive to temperature. Mixing two viscous substances together will add some heat and may be enough to explain the increased fluidity that you observed.",
"Maybe you could set some honey, some mustard, and a mixture of the two a... |
[
"Why is pykrete so strong?"
] | [
false
] | [deleted] | [
"Drop a crystal from the second floor vs. a piece of wood. There are several different material properties contributing to what would be colloquially called strength. Hardness, tensile strength, compressive strength, shear strength are all different and independent properties that one might call \"strong\". In the ... | [
"Because the stresses used to define them are very different and thus different molecular structures react differently.",
"To pick some macroscopic examples, picture a rope vs. a stack of bricks. The stack of bricks will have excellent compressive strength, whereas the rope doesn't. If you put something on top of... | [
"Because the stresses used to define them are very different and thus different molecular structures react differently.",
"To pick some macroscopic examples, picture a rope vs. a stack of bricks. The stack of bricks will have excellent compressive strength, whereas the rope doesn't. If you put something on top of... |
[
"What happened with the Black Death? Is it still around? Can it come back?"
] | [
false
] | null | [
"What happened is that it ",
"killed a lot of people",
". ",
"Yes, ",
"it is still around",
".",
"A future major outbreak is unlikely unless it mutates or is used as a bioweapon, because it is preventable (through sanitation) and treatable (with antibiotics). "
] | [
"The Black Death is an appearance of Yersenia pestis that presents itself by swelling the lymphnodes to ungodly sizes. Yersenia pestis also presents itself as pneumonic and septisemic plague which each cause their own, deadly problems. Originally carried by fleas on the backs of Rattus rattus, the black rat, on mer... | [
"For one, the rapidity of the transmission of the virus ",
"Note: ",
" is a bacterium, not a virus."
] |
[
"Does the location of a mosquito bite have any impact on the itchiness or swelling at all?"
] | [
false
] | I recently received a ton of bites, some of which swelled up much more than others. I realize that a possible/ most likely answer is that I was bitten by different types of bugs. But still: if I received a bite closer to a large vein, or in a particular area, would it itch or swell more? | [
"its about the concentration of blood vessels and tissue in the area. More of either or both = more swelling, redness and yes itching."
] | [
"Anecdotally I've had bites on my face, which seem to itch and swell quite a bit less than other places. "
] | [
"Do you have any evidence of this?"
] |
[
"What kills you when you burn to death?"
] | [
false
] | Ok so the title sounds a bit silly but my question is, What exactly is shutting down or ceasing to function when one burns to death? Obviously burning skin probably wouldn't you (not quickly anyway) and pain cant kill people AFAIK So what is the fire doing to your body that causes you to die? is it heatstroke? does the... | [
"Obviously burning skin probably wouldn't kill you (not quickly anyway)",
"If your skin is burned deeply enough and widely enough, it can compromise circulation and also breathing as the skin tightens and blood vessels are compressed and the chest is unable to expand. In such circumstances an escharotomy can be p... | [
"Seriously don't Google this. This looks just like my pork belly, but people."
] | [
"how is a heart attack stimulated (sorry can't think of a better word) when in a fire? as in, what is causing the blockage of the artery? Is it any different due to the fire? "
] |
[
"What causes the entire sky to turn a deep red?"
] | [
false
] | About 5-7 years ago, I recall having a large thunderstorm where I live (Vancouver Canada). One thing that stood out about this thunderstorm was that afterwards, the sky was red. That's a picture I took after the rain subsided. It was shortly after sunset, and I asked several friends who live between 5-10km away about i... | [
"The sun is white light (all colours - or at least enough to serve as an approximation). As light enters the atmosphere, short wavelength light gets scattered, whereas longer wavelengths are able to \"make it around\" particles in the sky (water molecules - clouds, etc). Once the shorter (blue) wavelengths are scat... | [
"Just a minor correction: while individual molecules in our atmosphere (nitrogen and oxygen) cause blue-heavy Rayleigh scattering, water vapor and clouds cause Mie scattering, which is not wavelength dependent. This is why on very humid days the sky appears more white, while very blue skies are usually only seen in... | [
"Is there any reason it never happens inbetween and produces a green sky?"
] |
[
"Is the movement of tectonic plates ever going to stop?"
] | [
false
] | So I'm not a physicist or geologist. But I am a well-read amateur in physics, and I took a few geology courses in college. Doesn't thermodynamics require that the earth eventually bleeds off enough energy that it cools even further and eventually becomes more solid; which is to say, won't the tectonic plates eventually... | [
"Eventually, yes. But the heat inside the Earth is supplemented by radioactive decay, slowing the internal heat loss down. In addition to this, some of the plate tectonic processes at work don't require convective motion to continue functioning, such as ridge push and slab pull. "
] | [
"So is it basically one of those questions where the answer is, \"Yes, but the Sun will expand and envelop us before it happens\"?",
"Edit: typo"
] | [
"Pretty much. The core of the planet is hotter than the surface of the sun, and you may note that precious little of that heat reaches us here. It'll take a long, looong time for it to cool down to background levels."
] |
[
"Our bones repair themselves, why don't our teeth?"
] | [
false
] | null | [
"The evolutionary need to maintain or keep this trait never developed. If this were a problem that significantly inhibited reproduction, we'd have a different tooth setup today. ",
"I would love to grow more teeth, but my ancestors were able to stay alive long enough to reproduce despite their potential loss of ... | [
"For most of human history, the key reproductive years would have been just about the same time that you were completing the move from deciduous (baby) teeth to permanent teeth; i.e. in your teens. ",
"Evolutionarily speaking, there wouldn't really have been much selective pressure for anything at all that happen... | [
"The move to permanent teeth completes roughly around age 20 with the arrival of wisdom teeth. ",
"The peak age for hormonally-induced sexual lust is in the teens. ",
"Both boys and girls acquire their secondary sexual characteristics and the ability to reproduce in their early teens.",
"All through recorded ... |
[
"How does a spinning black hole differ from a stationary black hole? Also, can we tell the difference between the two just by looking at their gravitational signatures?"
] | [
false
] | null | [
"A spinning black hole is ",
"stationary",
". Which is distinct from ",
"static",
".",
"The difference between a spinning black hole and a static one is the spinning. There ",
"can't",
" be anything else.",
"And yes you can, in principle, extract these numbers (modulo any degeneracy, I've not though... | [
"To add to ",
"/u/Para199x",
", here are a few key differences:",
"Regarding your second question, yes, and astrophysicists do this measurement in a clever way by observing the spectral lines of ions in the accretion disk near the black hole. These spectral lines are affected in a way that depends on the rota... | [
"A spinning black hole has two event horizons, one inside the other.",
"Does this mean that events that are in between the two horizons can have causal relationships, but events between the horizons and events within the inner event horizon cannot?"
] |
[
"If I were the size of an atom, how long would it take to walk across the tip of a sewing needle?"
] | [
false
] | null | [
"From ",
"this scanning electron microscope image",
", one can generously estimate the point of a sewing needle to have a diameter of 50µm. You would therefore have to walk approximately (π/2)·50µm ≈ 80µm to get across. The diameter of an atom is in the range ",
"0.06 nm (for Helium) to 0.5 nm (for Francium... | [
"Wow, that's a great way to put in perspective how tiny atoms really are. Thank you!"
] | [
"The point of the needle is (approximately) in the shape of a hemisphere, so to get to the other side, OP would only need to traverse ",
" a circumference."
] |
[
"Why isn't ECMO / Bypass used for resuscitation in Cardiac Arrest?"
] | [
false
] | If someone is in Cardiac Arrest, they're dying due to lack of ventilation and circulation due to their heart not pumping. Lets say a huge MI caused the onset of arrest. Why can't they hook them up to ECMO or bypass and allow them to live that way until they can fix the MI that threw off electrical conduction in their h... | [
"I am an ECMO specialist and have been for 15 years. ECMO for cardiac arrest is already in use in the form of ECPR, which stands for Extracorporeal CPR. It isn't widely used because it can only be reasonably instituted in a hospital that has an active bypass team in place, and physicians (usually surgeons) who are ... | [
"I am not a doctor and I don't play one on TV (I am an EMT, but that doesn't qualify me to say much) but here is what I know about reactionary ECMO.",
"As a field therapy, it is probably not indicated. A lot of cardiac arrests happen outside of a hospital and it would be prohibitively expensive and difficult to h... | [
"True, but the amount of evidence for this particular application of ECMO indicates to me at least that it is new for this application. So the technology is not new, the technique of using it on sudden cardiac arrest victims in a hospital setting is (or at least seems to be, im not an expert x.x)"
] |
[
"How do spacecraft take off from the Lunar surface?"
] | [
false
] | [deleted] | [
"Like so",
". It is much easier to get to orbit on Moon, for several reasons.",
"First the gravity on the surface is low so you only need low thrust to lift anything. That means that you need less powerful and less massive engines. Also all the supporting structures of the spacecraft can be much lighter.",
"T... | [
"This xkcd",
" gives a good visual representation of the amount of energy required to escape earth compared to the moon. The short answer is yes, it does take much less energy to escape the moon than it does to get there from earth."
] | [
"The Apollo Lunar module consisted of two parts, the descent and ascent stage, as you can see in ",
"this illustration",
". The descent stage was left on the moon and used as a platform for take-off.",
"According to ",
"\"Apollo Experience Report - Mission Planning for Lunar Module Descent and Ascent\"",
... |
[
"How did aircraft navigation systems work before GPS?"
] | [
false
] | I always wondered how things like ATC or autopilot navigations worked before the days of GPS. Certainly it wasn't all map-based, was it? How could a pilot land in foggy conditions without an exact positioning system? | [
"There is a system of radio beacons on the ground that aircraft can detect and track with specially tuned equipment on-board (VOR, NDB). These stations broadcast a signal on a known frequency, and all the pilot has to do is tune the navigational radio to that frequency, and if it's in range, you can track yourself... | [
"There are a bunch of really interesting navigation systems that were used - many of them are still in use.",
"One simple system is ",
"VOR",
". Scattered throughout the country are various radio towers. The plane has a receiver that tells which direction (relative to the plane) the signal is arriving from. ... | [
"Inertial navigation",
" which is still used as a backup.",
"before gps we had ",
"LORAN",
"and before either of those, there was of course ",
"dead reckonig"
] |
[
"How random is random?"
] | [
false
] | How difficult is it to make something entirely random? What methods can be used to ensure truly random number generation? Is it even possible? And which, if any, applications require these methods? | [
"It is impossible to generate truly random numbers using a compter.",
"Nah, it's not. Look up Lavarand, an R&D thing that came out of Silicon Graphics in the 90s. What you meant to say there is \"It's impossible to generate truly random numbers purely algorithmically.\" Generating true random numbers using a comp... | [
"It is impossible to generate truly random numbers using a compter.",
"Nah, it's not. Look up Lavarand, an R&D thing that came out of Silicon Graphics in the 90s. What you meant to say there is \"It's impossible to generate truly random numbers purely algorithmically.\" Generating true random numbers using a comp... | [
"It is best to define what we mean by random. First, we can only define randomness for a sequence of symbols (numbers). There are two different, but similar, criteria for if a sequence is random or not. One is if it has a positive ",
"entropy rate",
". A positive entropy rate would mean that if you were watchin... |
[
"If light always moves at the same speed in a vacuum, does that mean we can use it to find a stationary point in the universe?"
] | [
false
] | Say light is coming at you from the front at 1.1 light speed, and from the rear at 0.9 light speed. Would that mean you are moving away from a stationary point in the universe at 0.1 light speed? Is this a method used? If not, what ways do scientists do it? | [
"Say light is coming at you from the front at 1.1 light speed, and from the rear at 0.9 light speed.",
"Light will be coming at you from the front at light speed and from the rear at light speed as well.",
"The speed of light is independent of your reference frame. So if I'm on a hypothetical spaceship travelin... | [
"They would measure your ship at 0.5 c and the beam from your headlights at 1 c.",
"You (on board the ship) would measure the planet passing by at 0.5 c compared to your rocket. You would also measure the speed of the beam from your headlights at 1 c.",
"The speed of light is the same in every reference frame, ... | [
"Unfortunately, this viewpoint is incorrect. First, there is nothing such as a \"stationary point\" or \"center of the universe\". The big bang did not happen \"somewhere\" (as in \"somewhere in this universe\") because the big bang IS the universe. I think the first concept to forget is that this big bang is like ... |
[
"How much would the distance grow between two atoms near the colliding black holes due to the gravitational waves?"
] | [
false
] | null | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"Gravitational Wave Megathread",
"If you disagree with this decision, please send a message to the moderators."
] | [
"Well, it doesn't! Should I submit it again?"
] | [
"I did a rough calculation for you. The strain amplitude A is proportional to 1/D for gravitational waves (D=distance). The strain is the fractional length change (change in length divided by the total length). For a distance of 410 megaparsecs (1 parsec = 3.26 lightyears), we measured a strain of 10",
" So that ... |
[
"Which vitamins and supplements are scientifically proven and witch are just new age?"
] | [
false
] | The guy in the office next to mine offered me a free "biophotonic" scan: I simply held my hand on a machine to get some kind of number to prove my over all health. He also sells a combo-pack of vitamins and supplements, and even do my brain screamed "you're being scammed", i bought one to keep the office peace. So my q... | [
"On a side note: Biophoton scans, and the whole concept of \"biophotons\" are ",
"utter bullshit."
] | [
"Pretty much all vitamin supplements are unnecessary. Only in the rarest of cases will someone actually develop a vitamin deficiency. Starvation (not the diet-starvation type, but the two grains of rice a day for extended periods of time type of starvation) or gastrointestinal diseases (Crohn's) for example.",
"P... | [
"Vitamins and micronutrients have been well studied by serious labs. Some are anti-oxidants that will help to prevent mutations (and therefore cancer), some are co-enzymes that are necessary for metabolic activity. Think about iron in the hemoglobin (blood), for example. If you're lacking iron, you'll be anemic.... |
[
"When you train yourself to hold your breath longer, what exactly is it that you improve?"
] | [
false
] | null | [
"=======",
"Vital capacity (how much air your lungs can hold) is increased in competitive divers, but that may be misleading. Most competitive divers use a technique called \"lung packing\", in which they basically force more air into their lungs using their pharynx. This could cause changes in lung structure. Th... | [
"hi there ",
"/u/bloonail",
", could you please indicate your sources? i'm genuinely interested, but i would like to be confident about these facts in case i need to cite them in future. thanks."
] | [
"hi there ",
"/u/bloonail",
", could you please indicate your sources? i'm genuinely interested, but i would like to be confident about these facts in case i need to cite them in future. thanks."
] |
[
"Would Earth be detectable from the perspective of Alpha Centauri with current exo-planet detection methods?"
] | [
false
] | Assuming a terrestrial planet in orbit around Alpha Centauri A with inhabitants that have identical detection methods to those we currently have. What would they find when they point their equipment at Sol? | [
"Depends on how you're looking.",
"Easiest way is the way the Kepler spacecraft uses, looking for dips in a star's light as a planet moves in front of it. I believe looking at Sol from Alpha Centauri, none of the planets move across the disc of the sun, so they wouldn't be detectable by this method.",
"The har... | [
"What about our communications? We're leaking tons of signals that could be used to detect Earth."
] | [
"We couldn't detect normal TV and radio transmissions from that distance. If we beamed a powerful signal right at Alpha Centauri with something like Arecibo, and there was another Arecibo over there listening to our solar system at the time the signal arrived, then it could be detected."
] |
[
"Is this accurate? Do we move in a forward motion in space?"
] | [
false
] | null | [
"It's not terrible. The scale of the planets is entirely wrong - they're much smaller in reality, but that's forgivable because it actually makes it possible to see what's going on. The periods of their orbits seem plausible too- Mercury looks to be whizzing around in the middle with the gas giants taking far far l... | [
"Thanks will read."
] | [
"This is a list of other stars nearest to our own: ",
"https://en.wikipedia.org/wiki/List_of_nearest_stars_and_brown_dwarfs",
"The nearest one is about 4 light years and generally all stars in a certain region are moving in the same direction, so relative to each other they are moving at a small fraction of th... |
[
"Health concerns when using zinc as a catalyst. (Zinc oxide and you.)"
] | [
false
] | null | [
"Unfortunately this qualifies as asking for ",
"medical advice",
", which is not allowed under Reddit's user agreement. Sorry!"
] | [
"I am seriously worried that you are working with chemicals yet appear to have no clue how to obtain safety information. ",
"Here is a ",
"material safety data sheet",
" for zinc oxide in powdered form. Read it. Do the same for every other chemical you work with."
] | [
"I have amended the post to reflect an interest in chemical stability. Will this suffice?"
] |
[
"How do we take images of our own Milky Way Galaxy when we are INSIDE of the galaxy itself?"
] | [
false
] | [deleted] | [
"Any picture you will ever see of the Milky Way that looks like it was taken from the outside looking in, is either an artist's impression or actually a picture of another galaxy (albeit maybe a galaxy that was selected due to its similarity to the Milky Way). There are also plenty of real images of the galaxy whic... | [
"This is possible, but our knowledge of the specific locations of stars, nebulae, etc diminishes greatly as you cross to the opposite side of the galaxy. So unfortunately, we don't have the ability to map the galaxy in great detail across the entire surface"
] | [
"Interesting. I had assumed the answer was going to be that they're projections based on what we can see from where we are now. A 3d panorama stitched together and then rotated so that we're looking at it from outside."
] |
[
"How do electrons move through a coil?"
] | [
false
] | I know that electricity running through a coil creates a magnetic field, because the charged particles moving in circles create a magnetic field from one end of the coil to the other. The question I am asking is "Why don't the electrons move straight through the coil, when the turns in the coil are wound tightly up nex... | [
"Insulation. Even if a coil is copper coloured, the cord has a thin layer of transulent insulation."
] | [
"Specifically, coils are wound using ",
"magnet wire",
", which is coated with (usually multiple layers of) polymer film insulation. "
] | [
"The magnetic field resulting from the acceleration of the electrons is something we can quantify, ( Michael Faraday ) but may never understand. ",
"I'm not sure what you mean by this. Both electromagnetism (which explains the magnetic field) and electronics (which explains the motion of electrons in the wire) ar... |
[
"Why are reptiles and amphibians grouped together in the field of herpetology?"
] | [
false
] | It's always seemed very arbitrary to me that reptiles and amphibians are grouped together when (as far as I know) they aren't particularly closely related. Aren't birds more closely related to reptiles than amphibians are? | [
"It's not just a word, it's professional societies, their conferences, and scientific journals that run herpetology. So in North America there is the CNAH, SSAR, Herpetologists League, ASIH and they publish journals like Journal of Herpetology, Copeia, Herpetological Monographs and meet every year all together with... | [
"http://en.wikipedia.org/wiki/Herpetology",
"From the wiki basically it's an old term that just kinda stuck. Reptiles and amphibians when looked at broadly have some similarities that led to the thought of them being related and therefore grouped together, and once a term has persisted for so long it's kinda hard... | [
"There is a similar situation with Mycology. There are many things such as slime molds and Oomycetes which we used to think were fungi. Well, we got DNA sequences and turns out neither group are Fungi: the Oomycetes are more closely related to plants than Fungi and the slime molds fall out better with amoebas. T... |
[
"How powerful would a laser have to be to penetrate Earth atmosphere? Specifically in relationship to whether or not it could blow up a spaceship too."
] | [
false
] | [deleted] | [
"It depends on the weather, your location, and the angle of the laser.",
"At sea level, at the equator, with an angle of 45 degrees into the sky, on a clear day, about 75% of the photons released in a laser escape into deep space.",
"So take however much power you need, multiply it by 1.33, and that's your answ... | [
"It depends on the wavelength of your laser. The middle graph ",
"here",
" seems to answer the question - for visual light, most of the laser would make it through (assuming your laser can stay coherent at those distances). Looks like less than 20% is scattered or absorbed.",
"Water vapour is a major componen... | [
"So how much heat would a laser need to generate to penetrate clouds, and how much energy would that require?"
] |
[
"What's the human body tolerance for sustained lateral acceleration?"
] | [
false
] | Hello reddit. I was wondering what the limit is for lateral acceleration for the human body. I'm interested in sustained acceleration, like from cornering at high speed, not in peak acceleration, like from a crash. I would also be interested in repeated short periods of acceleration, so, again, like a car driving aroun... | [
"Are you just interested in the force being applied to a different side of the body? There's a reason those sustained forces are applied to the back and not the side. You would need to put someone in a centrifuge sideways and intentionally injure them to find out."
] | [
"You're right. That's probably why most of the research I found was from the 60s, not so many ethics questions when we're talking about the space race."
] | [
"Testing this would be pretty unethical whether it's done on human or animal studies so hopefully the only real answer out there is that no one knows. I'd imagine it also matters a lot on age, risk factors, body habitus, safety equipment, etc."
] |
[
"Is it possible to die of \"old age\"? Absolute perfect health"
] | [
false
] | null | [
"Age alone does not kill you, but it does lead to ",
"senescence",
". This senescence probably causes you to become susceptible to ",
"age-related illnesses",
".",
"However, \"old age\" is not a cause of death.",
" There is always a biological reason. However, in many cases an autopsy to determine pr... | [
"I think the question is better if simplified:",
"Can organic matter stay \"living\" forever if it is left uninfluenced from outside harmful variables.",
"I would assume it is impossible for a human being to survive the kind of sterile environment without outside contact in order to sustain itself in this manne... | [
"Is it possible to die of \"old age\"? Absolute perfect health",
"Superficially \"perfect health\" still has problems: calcified and sclerotic arteries, decreasing tone from both sides of the autonomic nervous system, sporadic \"senior moments\" from the tail end of a gracefully decaying brain's lifespan.",
"Th... |
[
"How exactly does a black hole's gravity create particle-antiparticle pairs in the form of Hawking radiation?"
] | [
false
] | So on the it says that this radiation is the "result of virtual particles being "boosted" by the black hole's gravitation into becoming real particles." Can anyone explain how gravity can do this? | [
"Unruh radiation is blackbody produced in accelerating reference frames. From a reference frame with significant acceleration, the vacuum is not empty: it contains a non-zero number of particles and antiparticles. One way of visualizing the Unruh effect is that the normal vacuum particle/antiparticle fluctuations a... | [
"This is not correct, an antiparticle has positive mass and positive energy. An antiparticle falling into a black hole would increase its mass. In the virtual particle description of Hawking radiation, the in falling particle must have negative energy in order to reduce the mass of the black hole.",
"I believe th... | [
"When an antiparticle collides with a particle, energy is conserved and must be transferred to the products of the reaction (typically photons). If this process were to occur inside a black hole the energy would still be trapped within the black hole, increasing its mass."
] |
[
"Are there any other useful gauge choices apart from the Lorentz and Coulomb Gauges?"
] | [
false
] | Gauge invariance allows a great amount of freedom regarding the choice of gauge used in EM theory, however all Griffiths and my EM II course only concern themselves with the Coulomb and Lorentz gauges. Are there any other gauges that are useful and practical in EM (or QED) and in what situations? | [
"I always like to mention this: it's actually Ludwig Lorenz, not Hendrik Lorentz, who developed the gauge condition in 1867. Griffiths even mentions this in a footnote (and Jackson consistently uses Lorenz). Since Lorentz was a giant in physics and electromagnetism, and since the Lorenz gauge is Lorentz invariant, ... | [
"The unitary gauge in which charge and current density are set to zero in the electroweak theory and spontaneous symmetry breaking is one example."
] | [
"Interesting. Do you know why it's preferable to set charge to zero? I was under the impression that which W exchange boson mediates the interaction is dictated by charge conservation."
] |
[
"Why did we use MRNA?"
] | [
false
] | null | [
"Everything you claim here is wrong."
] | [
"I got your mod message."
] | [
"Yeah, I got your mod message"
] |
[
"When a fingertip regenerates after trauma, does the new fingerprint match the old one?"
] | [
false
] | null | [
"No. \nDepending on the type trauma there would be varying levels of scar tissue which would permanently alter the appearance of the fingerprint; even though the stem cells present near the fingertip can regenerate said fingertip, they can't prevent scarring from occuring. The fingerprint would remain similar, albe... | [
"So if I used my fingerprint as a password, lets say for an iPhone, and I cut my finger there would be a possibility that I would never be able to access it again?"
] | [
"You have bacteria living all over your body. The species vary from place to place. Your fingertip bacteria are different from those behind your knees, for example. You have around 20 types on your fingertips, and the combination is generally different for different people. In theory, they could take bacteria from ... |
[
"Do arteries unclog eventually? Or is plaque build up permanent?"
] | [
false
] | Is there anything in the body that breaks down the plaque? | [
"HDL participates in a process called ",
"reverse cholesterol transport",
" that can remove ",
" cholesterol from peripheral tissue. As qxrt points out, this might not remove the plaque itself."
] | [
"HDL carries lipids back to the liver and can reduce the rate of the plaque-forming process through reduction of inflammation and sequestering of cholesterol, but once the actual plaque forms, it becomes calcified, and it's relatively permanent. I only say relatively since it's likely that there are some processes ... | [
"You're referring to an embolus, which can be caused by thrombosis, which is a blood clot that forms inside the blood vessels. A thrombus is composed of fibrin and platelets and other coagulation factors and is different from an atherosclerotic plaque. Risk factors for thrombosis include hypercoagulability (includi... |
[
"What would happen to a stack of paper if compressed with an obscene amount of weight?"
] | [
false
] | Assume a simple stack of printer paper. What would happen if you were to apply an obscene amount of weight to the paper? I imagine it would undergo compression and likely become incredibly brittle, but past that, I have no idea what would happen. | [
"Wood fibres are hugely resistant to compression. Imagine how much pressure rests on the wood at the base of a redwood tree without damage. And wood fibres are not brittle under compression (except for very dry or damaged wood fibres).",
"Basically, the paper would flatten (as the air between layers was squeezed ... | [
" amount of compression",
"With an obscene enough amount of compression, the electrons in the atoms will merge with the nucleus and form ",
"neutronium",
" - a substance never yet seen on Earth. With even more obscene compression, the Pauli exclusion principles which prevents subatomic particles like electro... | [
" amount of compression",
"With an obscene enough amount of compression, the electrons in the atoms will merge with the nucleus and form ",
"neutronium",
" - a substance never yet seen on Earth. With even more obscene compression, the Pauli exclusion principles which prevents subatomic particles like electro... |
[
"When developing a new measuring device more accurate than anything that existed before, how is it calibrated?"
] | [
false
] | [deleted] | [
"Determining accuracy is tricky, and essentially depends on testing your results via some well-established physical theory. ",
"Precision is what people usually talk about when they're developing new measuring devices, though, and that can be determined through statistical tests. Even a relatively imprecise ins... | [
"Accuracy: of a measurement system is the degree of closeness of measurements of a quantity to that quantity's actual (true) value",
"Precision: of a measurement system, also called reproducibility or repeatability, is the degree to which repeated measurements under unchanged conditions show the same results"
] | [
"I'm not at all an expert in this area, but I once saw an interesting talk on metrology - did you know there are ",
"government bodies",
" whose role it is to determine calibration standards? I had no idea, despite taking measurements in nanometres for years... But anyway, I'll try to share what I know!",
"Th... |
[
"how powerful a laser would be needed to melt metal powder, eg aluminium or steel?"
] | [
false
] | null | [
"Are you looking for a theoretical minimum laser power? or do you want a practical answer?",
"If you want the theoretical answer, then I would highly suggest you amend your question to be \"What is the theoretical minimum laser power required to melt metal powders together?\" or something similar, and then resubm... | [
"Thank you very much for tge time you toom putting into your answer, i was looking at using a laser beem to melt powder togeather layer by layer. What sort of diffrences in properties could i expect from diffrent techniques?"
] | [
"Depends heavily on the actual material. You might actually influence phase stability. For example, when I deposited a certain material, I could make it be pure fcc or pure bcc depending on my laser scanning speed.",
"Low powers might be sufficient to melt the particles together, but maybe not fully melt them. Hi... |
[
"What's the deal with Helicobacter pylori?"
] | [
false
] | H. pylori has been my favourite bacteria for a while, mostly because I love things that seem to defy an easy conclusion. My knowledge of it only extends about this far: H. pylori can cause ulcers. H. pylori produces a compound that can cause stomach cancer. There have been studies done showing a correlation between a l... | [
"Here's the best part about H. pylori. The guy who proved it caused ulcers won the Nobel, and no one believed him because it didn't cause ulcers in rats, so he drank a bunch of it himself and gave himself ulcers. Baller status of the scientific community.",
"It's very likely that it offers benefits, however the... | [
"There's even some evidence that eradicated h. pylori will increase platelet counts for those with ITP and other disorders."
] | [
"no prob"
] |
[
"How do birds actually find worms in the ground?"
] | [
false
] | We had a hard rain here, and when I look out the window there are many blackbirds seemingly prodding into the ground at random places and 25% of the time pulling up a worm. How do they (or any bird hunting for a worm) know which spaces in the ground to pick? and furthermore once they have found a worm, how do they kno... | [
"The actual answer is that they can hear the worms. Birds use primarily visual or auditory cues to locate the subterranean prey, but perform best with both of those senses. When deprived of any vibratory input, their performance is unaffected. When they can't smell the food, they can still find it. But if their hea... | [
"After a hard rain, worms will surface from the ground so they don't drown.",
"My guess is that birds are pecking at exposed worms or worms just peeking out of a wormhole.",
"Also, with flooded ground, the concentration of worms near the surface will be much higher than normal. Even taking random stabs is going... | [
"I have no clue about the factual accuracy of what I'm about to say, but I've heard that birds sometimes stamp the ground for a few minutes to imitate the feeling of rain underground to trick the worms into going near the surface. "
] |
[
"Can someone explain thermal conductivity units?"
] | [
false
] | I mostly understand thermal conductivity. What really confuses me, is the unit for it, watts per meter per kelvin (W/(m·K)). In general, derived units seem to make some kind of intuitive sense. One meter per second is a speed at which an object travels one meter in one second. One meter per second per second (1 m/s is... | [
"The units are simplified which makes them hard to understand. These are the non-simplified units:",
"Thermal conductivity = (J*m)/(m^2*s*K)\n",
"Here is a sentence copy/pasted from wikipedia that explains it well:",
"It is defined as the quantity of heat, ΔQ, transmitted during time Δt through a thickness x,... | [
"You could think of it as a diffusion distance of a watt per unit kelvin.",
"To put it in to more usable terms: a watt put into a \"good\" thermal conductor will distribute over a distance easily, while a watt put into \"poor\" thermal conductor will stay localized and not conduct outwards as easily."
] | [
"Good dimensional analysis skills are key to figuring out how to solve problems that don't fit exactly in place with textbook examples. Even if you aren't sure of the exact equation, understanding the units, and what needs to cancel where is the first step to understanding a complex issue.",
"Solving the problem ... |
[
"Will the curvature of my spoon's edge always be able to match the side of my yogurt cup so I get a clean scrape?"
] | [
false
] | null | [
"If the yogurt cup is a truncated cone (classic Yoplait cups come to mind), then all you need to scrape the sides is a straight edge. That is, you don't even need a spoon. A fork or knife will do just fine.",
"A more interesting question is \"what shape of yogurt cup allow for scraping of the sides with only a st... | [
"Yes, as long as the radius of curvature of the spoon (at some point on its edge) is larger than the cup's. When you tilt the spoon towards the vertical relative to the cup, it presents a smaller and smaller radius. At some point, it will match the local radius of the cup and you get maximum coverage. If you hav... | [
"If your spoon is (a part of) an ellipse, then the ",
"curvature",
" of its edge is non-constant, varying from a maximum value (at the tip) to a minimum (on the sides). As long as the curvature of your cup is between these bounds, you will always be able to find a part of the spoon that ",
" matches the cup. ... |
[
"People always say that the scissors never actually touch the paper ( atoms repelling and such ), so what would happen if two atoms actually did contact?"
] | [
false
] | The answer could be "Nothing at all". Just curious! | [
"In order to understand this you have to first understand that atoms do not have well defined boundaries. You may have learned that matter is made up of little \"particles\" like protons and electrons which form larger particles called atoms. In reality though, these things aren't really little hard balls. Particle... | [
"It depends on how you define \"contact.\" In our every day experience, we say objects contact each other when their electron's fields repel each other. That IS what contact is. ",
"If you want to talk about what happens when atoms overcome this repulsion, then you are talking about fusion. Inside of the sun and ... | [
"Thank you for such a wonderful response. I've been trying to figure out how to explain things like this (should I ever need to, I doubt it though, I'm just a sucker for information). You did it wonderfully without being too complex."
] |
[
"Firing a gun in space; does rifling matter? Or could a smooth bore be just as effective?"
] | [
false
] | null | [
"Your cartridge is already air-tight - the powder contains its own oxidizer and does not require atmospheric oxygen to ignite."
] | [
"There would be no difference. Riffling causes the bullet to spin, it acts like a gyroscope, giving it extra stability that keeps it from tumbling randomly and deviating from its intended target due to variable wind drag.",
"But there's no air in space, no wind drag, so whether a bullet tumbles or not, it will st... | [
"The rifling would help to ensure that the bullet's trajectory when it leaves the muzzle is precisely in line with the barrel - and thus potentially increase accuracy.",
"With a smoothbore, there is a chance that the vector of the bullet is slightly off from the straight line and there will some deviation in aim.... |
[
"What’s the difference between clinical depression and regular unhappiness?"
] | [
false
] | null | [
"Clinical depression is characterized by a prolonged and enduring sense of dissatisfaction, unhappiness or feeling or similar low mood. It's beyond simply having a bad day. It's a pervasive experience, one that doesn't change like... Well, a mood. An important feature beyond the unhappiness is that patients often f... | [
"Depression isn't just being sad for fleeting periods of time. ",
"It does involve sadness, but also lack of motivation, fatigue, too much sleep or insomnia, weight gain or weight loss, lack of ability to find enjoyment, suicidal thoughts, feelings of worthlessness, often times anxiety, etc. To be clinically diag... | [
"2 weeks actually. You’d need at least 5 of the symptoms you mentioned to last for 2 weeks or more in order to be diagnosed "
] |
[
"Is this article on female/male brain differences accurate?"
] | [
false
] | The article: It makes a lot of claims about anatomical differences in male and female brains that I haven't seen sources for anywhere else. On a side note, how much is transgenderism related to these or other anatomical/biological differences between male and female brains? Paring it down: the differences, TL;DRed (the... | [
"I'm a neuroscientist and I study sex differences in the brain. I can answer this but in order to do your question justice, can you pare it down a little bit? I don't really have the mental energy to address all 9 thoroughly and with citations -- or maybe I can take a few and someone else can jump in with the rest.... | [
"Ok, I'll start with 2 and make new comments for the others as I get to them (if I get to them).",
"This statement is true for specific kinds of language processing:",
"During phonological tasks, brain activation in males is lateralized to the left inferior frontal gyrus regions; in females the pattern of activ... | [
"Just jumping in to make one brief comment, which is that the way all 9 statements are phrased makes it sound as if ",
" men have the 9 differences compared to ",
" women. It's really important to keep in mind that every single one of the differences described is only apparent when you look at population averag... |
[
"No fapping connection to muscle growth?"
] | [
false
] | null | [
"There was a single study that has not been replicated that showed testosterone levels rose up to around 147% of baseline value on day 7 of not touching your trouser snake.",
"This bitch",
" is the study from China that is hard as hell to access and nobody seems to ever speak of the full text; just the number i... | [
"0.5nm more testosterone",
"That a typo?"
] | [
"Yup"
] |
[
"Where are we on fusion power? How clean would it be? How long can we see fusion power in grid?"
] | [
false
] | According to wikipedia, On March 15, 2012, the NIF's array of 192 lasers fired a shaped pulse of energy that generated 411 trillion watts of peak power - 1,000 times more than whole of the United States uses at any one moment. [56] The total energy created as the pulse was generated, was calculated to be 2.03 million j... | [
"NIF has yet to reach ignition. That is to gain more power from the fuel than was used to generate the laser pulse. If NIF cannot reach this mark, it would represent an awesome laser experiment and materials shock wave physics testing platform but would not be suitable for a power source. Even if ignition were to b... | [
"We cannot sustain fusion without enormous energy usage. We cannot produce any energy from fusion yet.",
"It will probably be a long time before it's used for commercial power production."
] | [
"We are about ten years out. Same as last year. And the year before that. And the year before that."
] |
[
"Water freezing out of freezer"
] | [
false
] | [deleted] | [
"Related: What low temperature would you have to drink Vodka (or other spirits) at to cause physical injury to yourself? ",
"I heard a story about a soldier stationed in Korea who took a chug of vodka at -40C without thinking and ended up in the hospital for it. Wondering how true this would be and what a \"dange... | [
"The process of lowering the temperature of a liquid or a gas below its freezing point without it becoming a solid is referred as supercooling also known as undercooling. The process of going from liquid to solid is exothermic. This means that as a liquid changes into solid, heat is released.",
"Water normally fr... | [
"The internal heat generated by your body would melt the ice. You could theoretically choke to death on ice, but it would be very difficult."
] |
[
"How do people develop fetishes?"
] | [
true
] | It seems weird how many different things turn people on. I always wondered how people have so many different fetishes. | [
"There are 2 basic groups here. ",
" Looks like the jury is out on this idea, but we do know that neural crosstalk is real, and it is studied in several specialties, like pain management (",
"example paper",
"). The other type is an acquired fetish. This can come about in many ways, and there are several mode... | [
"Various neurologists pointed out that fetishism could be the result of neuronal cross links between neighboring regions in the human brain. For example, in 2002 Vilayanur S. Ramachandran stated that the region processing sensory input from the feet lies immediately next to the region processing sexual stimulation.... | [
"Several experts saying something ",
" is not evidence of anything."
] |
[
"Is it ever possible to experience the full effects of time in the Spacetime equation?"
] | [
false
] | After reading post it got me thinking about this question. If for example you are sitting at your desk right now, it seems that you're not moving at all, but in reality; the earth is spinning on it's axis, the earth is orbiting the sun, our solar system is orbiting our galaxy, and all galaxies are moving away or toward... | [
"From your perspective, you are only traveling through time. So yes? It is an odd question.",
"By the way, you are always moving is some reference frame, and always standing still in another."
] | [
"Nope, you would no more be standing still than you are now. There is no place or reference frame where you are only standing still or only moving. There is no such thing as absolute speed."
] | [
"What he's saying is that you always have a velocity of zero in some frame, and a nonzero velocity in other frames, and no particular frame is objectively \"better\" (i.e. THIS FRAME IS THE UNIVERSE FRAME) than any other."
] |
[
"Do all planets rotate around the same plane/ axis ?"
] | [
false
] | This is hard for me to formulate but bare with me. So since outer space is a 3 dimensional space. Consider you're at the north pole of the sun looking to the sky, do all planets rotate at a single level as if they are aligned. is there even the slightest off possibilty that all planets align causing a solar system ecli... | [
"For a solar system we can calculate something called the ",
". This is the unique plane that passes through the centre of mass and is at right-angles to the angular momentum vector. It's a sort of weighted average of all the spins and orbits of all the planets (so bigger planets contribute more).",
"In our own... | [
"Relative to Earth Mercury's orbit is tilted by seven degrees, Mars's orbit is tilted by just under two degrees, ",
"etc.",
" They're all very close to being on the same plane but do not seem to have been placed by someone with OCD.",
"That's not luck. All the planets and the sun condensed from the same swirl... | [
"Before exoplanets with highly eccentric orbits were observed, a polar orbit was deemed impossible. That was because of the accretion hypothesis.",
"It was more because we didn't really have much to go on besides the current snapshot of our own solar system and modeling complex systems with multiple bodies is di... |
[
"Why do oil stains on paper appear clear, while water spots don't?"
] | [
false
] | I know that water and various non-polar substances reflect light differently, as in the instance of oil slicks reflecting 'rainbows' and lenses atop the surface of water...but I cannot explain why an oil stain on paper would be partially see-through while a water spot is hardly so. Anyone? | [
"Well, my daughter and I were interested in this so we ran an experiment with various fluids available to us here, just a moment ago. ",
"Here are the results. Now, if someone could explain the why's, that'd be awesome!\n",
"http://i.imgur.com/HJRp1mc.jpg",
" & ",
"http://i.imgur.com/I78HTDR.jpg",
"The fi... | [
"Refractive index matching. The opacity of paper relies heavily on light scattering. Water doesn't match the refractive index of paper fibre, but oils are a lot closer."
] | [
"Paper is made from wood pulp, which is basically cellulose; so this is a good refractive index reference, ",
"n = about 1.47",
" for paper. ",
"Oil has a refractive index that is ",
"about the same",
"Water is ",
"n=1.33",
"So from the refractive index matching part it certainly checks out [and is al... |
[
"How does alcohol affect vision?"
] | [
false
] | null | [
"It doesn't it affects the volume and composition of the fluid in your inner ear which regulates your equilibrioception.",
"This in turn affects your ability to determine which way is up and this makes you dizzy and your eyes rely on your equilibrioception to focus correctly.",
"If you look in a mirror at your ... | [
"Great answer, I knew about the fluid but I didn’t know it affected the eyes.",
"Is this fluid a standard amount between people with different size? Or is this part of the reason that some people are affected faster from alcohol (by having less fluid or a different composition)?"
] | [
"Multiple factors but all falls to blood alcohol percentage, the water in your ear is not like the water in the blood or brain it takes longer to dissipate so you may have sobered up slightly but still br dizzy or even sick later on.",
"Factors:",
"Body size is a big one ratio of alcohol to consume is greater t... |
[
"How would the earths orbit be effected by an increase in mass?"
] | [
false
] | The subject of near earth asteroid mining popped up in , and it got me wondering about the effects of mass on orbit distances. Will a change in mass cause a change to the speed of orbit or the distance at which it orbits. In my head I cant help thinking it would maintain its speed and gain momentum pushing the orbit fu... | [
"It depends on how the mass is added to the earth. If the earth just spontaneously gains a bunch of mass by magic, but maintains its speed, nothing will change. While the total momentum has gone up, so has the mass, so the specific angular momentum (angular momentum per unit mass) stays the same. In the same way, i... | [
"It depends on how the mass is added to the earth. If the earth just spontaneously gains a bunch of mass by magic, but maintains its speed, nothing will change.",
"In two body orbital mechanics, that would be true. In multi-body, it would shift the centre of mass of the solar system and could result in some signi... | [
"Sure, but again, a change of mass of that scale is ridiculously beyond anything you'll ever get from asteroid mining. In fact, the total mass of the asteroid belt is only around 0.1% that of earth. Also, the only planets that could possibly affect are Venus and Mercury, since from the point of view of everything o... |
[
"Do male enhancement products actually do anything? If so, what?"
] | [
false
] | null | [
"This is a question which can be answered with peer reviewed science and expertise, which is and remains the standard for askscience questions. Please stick to these sources for answering. "
] | [
"Found a paper by Ted Manny and coworkers in 2011 with the title \"Penile Sclerosing Lipogranulomas and Disfigurement from Use of '1Super Extenze' among Laotian Immigrants\"",
"No link because you have to have a subscription to Journal of Sexual Medicine to see it and i dont feel like breaking any copyright laws.... | [
"There was a study published in the British Journal of Urology that showed that a penis stretching device was able to increase the length by a third (32%) in men with below average penis size. ",
"http://www.livescience.com/3381-penile-extenders-work-doctors.html",
"This penis traction device was used for 6 hou... |
[
"Can a routine blood test (CBC) detect a blood clot or pulmonary embolism?"
] | [
false
] | null | [
"I wish this was true but unfortunately not. Ddimer is used to help classify risk. A negative ddimer does not rule out a clot. In general ddimer should be used when a physicians suspicion is relatively low for the presence of a clot. If a physician thinks it’s unlikely to be a clot and has a negative ddimer then th... | [
"Not really, typically a D-dimer blood test is done to look for fragments of a clot as well as imaging of the areas where a clot is suspected. A CBC only shows the cells/components of the blood, it can identify a clotting disorder but it is not a good method of detecting clots."
] | [
"This is correct. If a PE or clot is suspected a d- dinner test is run to rule it out. If it's negative there is no clot. If elevated, they will do further tests since it just indicates elevated clotting of any form. I.e. a bruise will elevate it etc. So only a negative will rule it out.",
"After an elevated d di... |
[
"Is Sigmund Freud's work valid? Does it stand up to more modern research? [Psychology]"
] | [
false
] | I ask because I hear mention of Freud around Reddit a lot, usually jokingly. But, is there any legitimacy in his research/conclusions? | [
"As a starting point, have a look at the ",
"legacy section of Wikipedia's Freud article",
". Your question has also been asked a lot, so ",
"there are quite a few answers on AskScience already",
".",
"When looking at contemporary psychological research, you're going to have a hard time finding any influe... | [
"fear of spiders and snakes is there for a reason and nearly universal. A spider or a snake is just a symbol for the pain and death they can cause if treated without respect.",
"If fear of spiders and snakes is indeed prepared, then this is very little to do with treating them with respect and much more to do wit... | [
"Luckily there was an ",
"AskScience question exactly on this",
", so I don't have to waste any more time on Scholar today. Oh wait, I'm meant to be researching review articles. Back to Scholar!"
] |
[
"Humanity's dominant sense is vision - why then does a significant proportion of the population have poor eyesight?"
] | [
false
] | null | [
"The book \"Why we get sick\" by Nesse and Williams discusses this in one of the chapters. Natural selection selects for genes that increase an organism's ability to pass on their own genes (reproduce and make sure your offspring reproduce), regardless of whether or not the individual desires the trait associated ... | [
"optometrist here: one of the theories for the increase in myopia is that an increased amount of near-work increases myopia. so for instance, studying in school have been shown to make you more nearsighted. There has also been shown to be a genetic component for refractive error. Since glasses can correct for refra... | [
"I think it's a leap to say that Huntington's disease is kept around by some selective pressure. As you point out, a disease that only affects individuals after the time period where they would typically reproduce can not be selected against. But that doesn't imply any selective advantage in the mutation--just that... |
[
"Is it bad to eat entire sunflower seeds?"
] | [
false
] | I mean including the shell. If so, why? | [
"Aha, yes that what I was looking for. For some reason (not an expert) I had imagine the opposite, that the shells would act like fiber. Thanks for the link."
] | [
"Aha, yes that what I was looking for. For some reason (not an expert) I had imagine the opposite, that the shells would act like fiber. Thanks for the link."
] | [
"Every few years or so I'll forget that eating sunflower seeds with shells is a bad idea. I'll eat a whole bunch and then end up shitting razors the next day. There will be blood. "
] |
[
"If I try to lift up an object I cannot lift, where does all the energy go? My arms get tired from the exertion, but I haven't transferred any \"energy\" as I know it (kinetic/potential/chemical) so where does it go?"
] | [
false
] | [deleted] | [
"It becomes heat. ",
"The mechanics of muscle contraction are pretty hairy, but basically if the muscle contracts but cannot shorten some of the energy in the actinomyosin thingy has to be dissippated to compensate. This can become a vibration in the arm, or simply produce heat by the decomposition of high-energy... | [
"The reason you don't notice the heat output is that thermodynamics operates on a whole different energy scale than you're used to: heat, under standard conditions on Earth, requires a shitload of energy.",
"To put this in perspective, imagine you heat a cold pint of beer from freezing to room temperature. A pint... | [
"If the object is on a rigid surface and does not move no potential energy will be transferred to it. Work is done only when a force acts along a distance. The main source of energy loss here is in the mechanics of muscle contraction. ",
"Are you referring to the elasticity of seemingly rigid objects acting as a ... |
[
"Does the eye color gene follow simple Mendelian genetics?"
] | [
false
] | Briefly, my neuroscience teacher said this once, and I was wondering if it is true, or if there is ever a possibility where it doesn't follow? Thus, could a blue eyed person and a green eyed person make a brown eyed baby? Arent both blue eyes and green eyes recessive to brown, thus the parents would be homozygous reces... | [
"It isn't simple Mendelian Genetics, because that would be 1 gene with 2 alleles (2 forms of the gene). There are many traits that are controlled by a single gene with 2 alleles. BTW, the alleles are located on separate chromosomes. You get 1 set of chromosomes from Mom, and the other set from Dad. This gives you 2... | [
"http://en.wikipedia.org/wiki/Eye_color#Genetic_determination",
"\nIt's pretty complicated."
] | [
"No, its not, eye color is polygenic, same as skin color, height, weight, gut morphology, eyelash length...etc..."
] |
[
"Which others diseases have we discovered to have a heterozygote advantage? (besides sickle-cell, tay-sachs, and cystic fibrosis)"
] | [
false
] | null | [
"That would be a decided disadvantage... I think he is asking about diseases where being a heterozygote carrier of a deleterious mutation is actually beneficial. Getting retinal cancer isnt beneficial"
] | [
"Familial retinoblastoma."
] | [
"Can you be more specific? Which disease is disadvantaged by Familial retinoblastoma?"
] |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.