title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Why do \"cold\" and \"hot\" burns feel the same to the touch of human skin?"
] | [
false
] | Burning is typically associated with heat or fire, but at times is also related to damage from extreme cold. What, why and how are the distinctions of extreme temp "burns" decided and what defines a "burn"? | [
"Because after a certain threshold, only neurons associated with pain are firing. The ones sensing hot and cold become irrelevant. So both sensations just feel like pain. And both hot and cold when extreme can cause tissue to die which may answer you burn question."
] | [
"Sorry for being a little off-topic but I thought it worth mentioning that this is true for any perceptions. Pain has its own neural network and associated pathways. Thermoreceptors, mechanoreceptors etc. are all separate and distinct and do not respond to noxious stimuli (i.e. things that cause you pain). Once a s... | [
"Having smashed my thumb a disproportionate number of times, why do crush injuries feel warm? Is it because hot/cold burns kill cells locally where as crushes are deforming the tissue and damaging cells over a more distributed area?"
] |
[
"Why is cyanide an anion, but carbocations cations?"
] | [
false
] | [deleted] | [
"They're real, and they're sometimes stable, too. The triphenylmethyl cation is probably the most famous example."
] | [
"Have you learned about formal charge? The difference between the two is that cyanide's carbon atom has a lone pair and the carbocation doesn't."
] | [
"Is a carbocation a real thing or just a theoretical placeholder for demonstrating a mechanism?"
] |
[
"Why do some antihistamines make you sleepy?"
] | [
true
] | [deleted] | [
"First generation antihistamines (i.e diphenhydramine) cross the blood-brain barrier, and thus can affect the brain directly. While we call them \"antihistamines\" because they affect histaminergic receptors (which are responsible for allergic reactions , among other things), they also have other effects, such as b... | [
"This. 1st generation antihistamines are full-blown psychoactive drugs, usually considered \"deleriants.\"",
"Eating 8-10+ Benadryl will get you high asf for 6 or so hours, but like... Not a good high: Itchy, confused, and sleepy but unable to sleep."
] | [
"To discourage the curious, benadryl is not to be messed with. People can die from overdosing. It’s rare but there have been cases of children taking 5 adult benadryl tablets and never waking up, usually due to negligence or ignorance from the caregiver."
] |
[
"How would you prove to a skeptic that the earth is round, not flat, using only instruments made from common household materials?"
] | [
false
] | null | [
"Such hypothetical / speculative / open-ended questions are better suited for our new-ish sister sub ",
"/r/asksciencediscussion",
". Please consider reposting there instead."
] | [
"You've misunderstood my question. It's not about whether the earth is flat. It's intended to elucidate fundamental facts and methods of astronomy, and also, possibly, the history of science and astronomy. I don't know the answer myself. I don't know if there is a good answer, but it seems an interesting question."... | [
"Sorry, my last response as the canned response I give to all questions that fall under one of the three question descriptions. In this case, the question is open-ended in that there is no one specific answer; it's really a discussion-based question. You're asking for people to come up with an experiment / demonstr... |
[
"My eyes see in different colors. Why?"
] | [
false
] | My left eye sees in hues of red and my right eye sees in hues of blue. Now, I still see in full color, but its like my eyes were ran in photoshop to add 5% color. Sometimes it is more noticeable than others and can make me a bit dizzy. Not sure if it is relevant but I have heterochromia. Why? | [
"I have the same thing. I never really even thought about why, I just always kinda accepted it. My left eye see's yellows and reds far better than my right, and my right sees blues and greens better. I've never been able to find an explanation. This sounds like it could definitely be a reason for it though."
] | [
"I have the same thing. I never really even thought about why, I just always kinda accepted it. My left eye see's yellows and reds far better than my right, and my right sees blues and greens better. I've never been able to find an explanation. This sounds like it could definitely be a reason for it though."
] | [
"I'm no expert, but I'm pretty sure everyone has a blue/red tint on opposite eyes. Go ahead a try it. Close one eye for a bit ( like 30 seconds) and look around with the other eye, then alternate open/closed eye. I've asked random people to do this (family, friends) and they all have the same experience. "
] |
[
"Can thunderstorms affect a wireless signal?"
] | [
false
] | [deleted] | [
"Wifi and cellular systems use microwave radiation (like your microwave oven, except far far less power). Microwave radiation rips absorbed quite readily by polar molecules like water and fats. (this is how microwave ovens cook food, imparting the energy of microwave radiation into kinetic energy of water and fat m... | [
"Rips=is. iPad typing, apologies. "
] | [
"Ah yes. My apologies, this is correct, fats are not polar. They do still absorb microwave radiation and convert it to atomic vibration though."
] |
[
"Ask Anything Wednesday - Engineering, Mathematics, Computer Science"
] | [
false
] | Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical post? No question is too big or small for AAW. In this thread you can ask any science-related question! Things like: "What would happen if...", "How will the future...", "If all the rules for 'X' were different...", "Why does my...". Please post your question as a top-level response to this, and our team of panellists will be here to answer and discuss your questions. The other topic areas will appear in future Ask Anything Wednesdays, so if you have other questions not covered by this weeks theme please either hold on to it until those topics come around, or go and post over in our sister subreddit , where every day is Ask Anything Wednesday! Off-theme questions in this post will be removed to try and keep the thread a manageable size for both our readers and panellists. Please only answer a posted question if you are an expert in the field. . In short, this is a moderated subreddit, and responses which do not meet our quality guidelines will be removed. Remember, peer reviewed sources are always appreciated, and anecdotes are absolutely not appropriate. In general if your answer begins with 'I think', or 'I've heard', then it's not suitable for . If you would like to become a member of the AskScience panel, . Past AskAnythingWednesday posts . Ask away! | [
"So I've been thinking about this one, there was this YA book I read a while back called Artemis Fowl and The Eternity Code",
"Basically it's an encryption system that is unbreakable because it creates a new language each time it does its thing. Is something like this possible?",
"I'm not sure if I'm even askin... | [
"Some expert can probably correct me/expand, but before all a precise definition of the cryto system is needed to evaluate it's security (security in the technical sense of computational hardness).",
"That said, for example say you and your friends generate create a language through some system, and use it for a ... | [
"I heard recently a new prime number was discovered. How was this possible? Was there a recent break through in mathematics or computing that led to it?"
] |
[
"Do operating theatres have to be a certain temperature in order to proceed with a surgery?"
] | [
false
] | null | [
"The room does not have to be a specific temperature, but the patient does. Remember, the patient is naked most of the time, and receiving chemical paralytic medications, so they can't shiver, and will quickly become hypothermic if left lying on a table in a 70-degree room. Being hypothermic will actually interfere... | [
"Off the bat, there is a common misconception that it prevents bacteria growth. Just feel in your fridge and it is a lot colder than any operating room. You also don't want the patients body temperature to drop so you can't expose them to the cold for very long. But it definitely isn't cold enough to prevent bacter... | [
"It also depends on the type of operation. I just finished a rotation in a burn ward. All operations are conducted in a room at 37 degrees (civilization units) and with a humidifier, as patients without skin coverage and repeated rinsing the operation are prone to hypothermia and dehydration from accumulated blood... |
[
"When a woman is pregnant does the baby follow the same sleeping patterns as the mother? Or can they have 2 separate sleeping patterns?"
] | [
false
] | null | [
"Fetuses are asleep almost all the time until third trimester, when they’re awake 2-3 hours per day. It’s unrelated to mom’s sleep, although people think it is because they notice their movement more when laying down and trying to sleep.",
"Edit - since this post became popular, I’ll add some info. ",
"Fetuses ... | [
"They burp and cough and yawn and chew on their hands and feet and roll around and do all sorts of stuff.... Well.. that's probably most of it."
] | [
"I just thought fetuses were in a suspended animation state while they are in the womb. I would have never thought. Now, when they are awake are their eyes open and such?"
] |
[
"May longitudinal eletric field oscillations be considered EM waves?"
] | [
false
] | EM waves must be transverse because of the way the oscillations on electric and magnetic fields perpetuate each other as they propagate from the source. However, even without this mechanism, imagine this: You have two eletrically charged spheres near each other, each one being held on their place by a spring that allows them to move in the direction in which they are aligned (see drawing below). (this would be the system in the equilibrium state)(sorry for being lazy to draw the electric fields) The electric field both produces is strong enough to cause the other to oscillate if you move one of them. And then, you pull one of them, making it oscillate and making both work as oscillators coupled by the electric field. In this scenario, the variation of the field (that corroborates with the motion) occurs in the same direction they oscillate. And as nothing can propagate instantaneously, this oscillations must propagate through the space between both. So, it's an oscilation in the electric field, that's propagating between them and transfering energy from one to other. Why can't it be considered as an wave? Even if in a small scale, as it decays rapdly as the distance increases, differently from an transverse EM wave (like the very-low energy transverse EM waves that they would be producing during this). Other scenario i could propose to simply talk about the longitudinal variation of electric field would be the field in the front of an flat charged surface (like a thin metal sqare) as you change it's charge, making it positively and then negatively charged. | [
"But this is considering that both spheres would oscillate in phase with each other, isn't it? ",
"I'm considering i'm starting the movement by pulling one of the spheres abruptly, and not moving both simmetrically out of the equilibrium point.",
"Doesn't really matter, the spheres do not actually interact at a... | [
"Are you moving the spheres, or do you assume they move as the effect of some phenomena, or...? Are they dynamical or \"on-rails\"?"
] | [
"But this is considering that both spheres would oscillate in phase with each other, isn't it? ",
"I'm considering i'm starting the movement by pulling one of the spheres abruptly, and not moving both simmetrically out of the equilibrium point.",
"Plus, if you had an similar system but now with an separation of... |
[
"Would a lead jacket compensate for bone loss due to low gravity on Mars?"
] | [
false
] | I would think that you would lose a lot of bone density on mars due to the low gravity. Would a weighted jacket help? | [
"Yep, probably. Weight lifting on earth has been shown to increase bone density, and astronauts on space stations use bungee cords to force them down onto treadmills. I think anything that adds extra stress to your bones increases their density, and a lead jacket would do that on mars."
] | [
"There are a few of reasons I do not think this would work/isn't a very feasible idea:\n1. The increased weight would only help to reduce decrease of BMD of lower body.\n2. The weighted jacket would change center of gravity of the body and would cause detrimental damages to bones during movement.\n3. Because weight... | [
"The weight experienced when standing versus jumping is always different. Look, it happens on Earth too and without a lead jacket. Amazing.",
"Due to a weighted jacket, this weight would be considerably more than our knees/bones could handle and again could cause damage to our skeleton.",
"He didn't say how hea... |
[
"Why do cells die from low oxygen?"
] | [
false
] | As far as found out from google, cells need oxygen to produce ATP , and necrose on low ATP levels. So why do cells do that? Why dont they just 'stand by' till they get more oxygen? | [
"There are certain processes that are required to maintain vitality and those consume ATP, some cells can't just switch off and on at will. On the other hand some bacteria create capsids when in unoptimal circumstances, this puts them in a \"low consumption state\" and they are known to survive low periods of time ... | [
"It's not true for all cells/organisms. But for mammalian cells, there are a number of biological and chemical gradients within the cell that must be actively maintained, on a permanent basis. Without an energy source (oxygen is the combustive of respiration) this homeostasis collapses",
"Eventually the proteins ... | [
"capsids",
"Do you mean spores?"
] |
[
"Are peripheral and central neurons structurally different?"
] | [
false
] | Do these neurons just serve different functions due to their location and connections, or is there something structurally different about them? I was reading about hot flatworms can remember things even after their brain is cut off and regrows, so I'm wondering if peripheral neurons could serve the same functions as CNS neurons, or if they are structurally different? | [
"So the thing with neurology and nerves are that generally speaking, everything is super specialised in their structure to aid in their functions, and there are many different types of nerves both in the periphery and in the CNS.",
"Let's look at peripheral nerves on their own, even before we bring central nerves... | [
"One day! I’m currently less than a year away from finishing my medical degree, and I have a real passion for teaching. I occasionally use Reddit for opportunities to explain stuff because it helps me consolidate my own knowledge as well. I’m really glad you found it useful, and thank you for the kind words. 🙂"
] | [
"You need to write textbooks. That explanation was much easier to understand than anything I have read about the subject. Thank you."
] |
[
"From what perspective do we look at the Milky Way?"
] | [
false
] | Take for example. It's hard for me to explain exactly what I mean in just text, but what I'm trying to say is when we see the Milky Way in the sky like in the linked pic, which part of it are we actually seeing? My own reasoning (which isn't backed by any form of astronomy) would be that we are looking parallel along the plane the galaxy lies on, which is why it almost appears more like a line than a spiral. But I have no expertise in this field, just awe and wonder. Thanks to whoever helps clarify this for me. | [
"We are part of teh Milky Way and are located on one of its spiral arms (about 2/3rds of the way out iirc). So yes, the reason the Milky Way appears as a line is that we are looking along its plane, as we are within that same plane. "
] | [
"The Milky Way is a flatish, spiral galaxy of which our solar system is a part of, on one of the outer arms. This is why it looks like a stream, or a \"Road of Milk\" going across the sky, because what you are seeing is some part of the plane of our galaxy. If you have access to a place with low light pollution, I ... | [
"Check out ",
"Stellarium.",
" This is probably one of the best tools out there for learning about constellations and such. "
] |
[
"Which planet has the best \"moonlight\"?"
] | [
false
] | Now I know most planets with satellites (in our solar system) are gas giants with no real atmosphere. So they are unlikely to have any "night sky" at all. But I just want to confirm this | [
"If you're asking which planet has the ",
" moonlight, that's something we can answer objectively. It comes down to (a) how big is/are the moon(s), (b) how far away they are, (c) what fraction of the Sun's light they reflect, and (d) how bright the Sun is at this distance (i.e. how much light there is available t... | [
"Thanks for the detailed answer. Yeah, I meant brightest"
] | [
"Came expecting \"brightest,\" was pleasantly surprised with the bonus fascinating \"biggest\" that I didn't even know I wanted the answer to"
] |
[
"What is happening to these rocks?"
] | [
false
] | Pics: They are placed in a south-facing window in the Pacific Northwest (ergo: it's humid). They've been there for a few months, behind a curtain. I just discovered them today—what is making them decompose? I believe we found them on the shore of Flathead Lake, in Montana. Edit: a couple more pictures: (this one you can clearly see the layered rock has decomposed on certain planes) | [
"That's because there are several minerals, which may be contained within those rocks, that crumble when exposed to light. Soda Niter is a good example (also called Nitratine). Orpiment is another great example, which crumbles when exposed to light (and is ALWAYS in the presence of Realgar). Changes in humidity, he... | [
"Physical weathering: specifically the interaction of heating in the window with high humidity levels infiltrating the porous material"
] | [
"Why would they 'perspire' their material. That is, presumably, why it looks so odd—the way the matter looks like it is being 'pushed' out of the rock."
] |
[
"How do I use a fair 6-sided die to generate a random number from 1 to 100, with each outcome occurring with the same probability?"
] | [
false
] | null | [
"One idea is to let the roll-1 be a digit in the base-6 expansion of a number. So if the roll is ",
", record the digit ",
"-1. All integers from 1 to 100 can be expressed with 3 base-6 digits. So you need to roll the die 3 times.",
"Now, of course, it's possible to get numbers that are greater than 100. Inde... | [
"How about this for outside the box.",
"Throw the die onto a 100 spaced roulette wheel. "
] | [
"I'm going to have to ask you to take a few steps back towards the box sir."
] |
[
"Gravity at the galactic scale"
] | [
false
] | We stars on the other side of the galaxy as they were 100,000 years ago. They should have rotated a fraction of a degree away from their perceived position in that time. Do we feel their gravity from their current position, or are we pulled in the direction of where they were in the distant past? | [
"That's not entirely accurate. While changes in the gravitational field do propagate at the speed of light, the field depends on both position ",
" momentum, with the net result being that the \"pull\" is toward their instantaneous, as opposed to retarded, position. So while we are \"feeling the gravity\" from wh... | [
" As far as we know, gravity propagates at the speed of light. "
] | [
"Well, I suspect it would assume ",
" motion, but really it's a hard question to answer: in talking about us being pulled toward them we're tacitly ignoring whatever might be causing them to not follow a straight-line path.",
"The only actual calculation I've ever seen on the matter is determining the path of a... |
[
"Will the vaccine help an infected organism to fight the disease?"
] | [
false
] | The vaccine is used to prevent a healthy organism from being infected. But can it be helpful in other cases? | [
"A vaccine is essentially just something that helps train your adaptive immune system. Most people think of prophylactic vaccines when they hear the word vaccine, but there are ",
"therapeutic vaccines",
" as well. ",
"That's not to say if you have an active infection that any old vaccine will help cure it, i... | [
"As others have said, vaccines are generally most effective when administered before exposure to an infectious agent, and they work by triggering an immune response which takes a few days to build up to a maximum and then provides long-term resistance (\"immunity\") to the true infection for months at least, and us... | [
"anyway this Covid-19 it’s going to stay forever, It will be like a flu, we just have to live with it",
"This is not at ALL obvious or a foregone conclusion. In fact, there's plenty of evidence that corona viruses have a type of genome repair mechanism despite that fact that they are ssRNA viruses, though it does... |
[
"Do blind dogs make better scent hounds?"
] | [
false
] | The other senses of the blind are known to be heightened. Does this apply to dogs as well? If so, do blind dogs make better scent hounds, or does their lack of vision make them worse. | [
"In theory they might have better sense of smell, but in dogs, so much of their brain is devoted to scent already. I think having a tracking dog tripping over everything and slowing you down might not be worth that extra little boost. For dogs, smelling is what vision is to us. They hear a noise, they turn towards ... | [
"Science and shit"
] | [
"In terms of sight, dogs (and cats for that matter) are biologically limited by their lack of a light absorbing retinal pigment epithelium (RPE). In humans RPE works to absorb all the light missed by photo receptors to prevent the light bouncing back and hitting another receptor (light would bounce at all kinds of ... |
[
"How much does personality really differ between sexes as compared to within-sex variation?"
] | [
false
] | I’m wondering about this because a common criticism of gay relationships is that men and women are complementary, but same-sex couples are not. However, it seems to me like sex is probably not a great predictor of complementarity. As far as personality goes, as long as there is significant overlap between the distribution of personalities for the sexes, it should be feasible to find complementary pairs both for homosexual and heterosexual couples. What I’m looking for is data that shows how much overlap there is between personalities for the sexes. Any related research would also be interesting :) Thank you! | [
"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3149680/",
"TLDR they are largely overlapping curves. Men and women are more alike than different with the extreme ends of the distribution leaning heavily to one gender or another. \nExample, most men and women can average out to similar levels of disagreeable-ness, ... | [
"Even worse when the quote is how men can't understand women. Yeah Bill, it's real hard to understand them when they are unconscious"
] | [
"It’s the statistical expression of the fact that humans aren’t very sexually dimorphic in the measured variable. There are some variables where the dimorphism is more pronounced. I believe forward cranking power (of the arm) is a good example of an instance where humans are actually pretty dimorphic (there is some... |
[
"Why do some aircraft, such as the F/A-18, feature canted tail fins, despite also having \"flat\" horizontal stabilisers?"
] | [
false
] | The F/A-18 Hornet, among other aircraft features canted fins, as well as traditional "flat" horizontal stabilisers. Why is this? Why do the fins need to be canted? Why not just have them pointing straight up, at right angles to the stabilisers, or just have a traditional v type tail? There must be a reason but I can't put my finger on it. Anyone? | [
"I can't speak for any aerodynamic reasons, but right-angles such as between traditional vertical/horizontal stabilizers have a very high radar cross-section. Essentially it acts somewhat like a corner-cube and reflects a large amount of radio waves back to the transmitter. Military aircraft tend to like lower cros... | [
"Another partial answer is redundancy. Canted rudders provide some pitch authority, which may be sufficient to recover the aircraft in case of a stabilator failure. I've heard of of one case where a Rhino with an aileron failure had enough roll authority using differential stabilator to successfully trap on a car... | [
"^ This. Also, I was curious about the anhedral geometry of the horizontal stabilator of the F4 Phantom.",
"\"After much wind-tunnel testing, it was found that the new McDonnell fighter would encounter severe stability problems at high speeds and would as a result probably be limited to speeds below Mach 2. In or... |
[
"Why do some people complain that their bones hurt when it rains?"
] | [
false
] | Usually It's people with old injuries. I've had broken bones, but I feel fine when the weather changes. | [
"Because the barometric pressure in the air drops, and the water in your bones can't equalize fast enough, they swell, and cause general achy-ness. ",
"Old injuries probably hurt more because when you break a bone, and it heals, it always heals a little more than it needs to to make it stronger in that area. So... | [
"Nurses know their shit and don't get enough credit. :P"
] | [
"Not a doctor, no. Just kind of a nerdy RN :)"
] |
[
"What do scientists think of the Harvard Landmark Study?"
] | [
false
] | null | [
"Like the other user said, it's a weird hypothesis that intelligence would lead to happiness. Even just from a purely statistical standpoint, a significantly above-average IQ puts you on the fringe of the population (due to the gaussian distribution of IQs). That marginalizes you and is unlikely to lead to happines... | [
"it's a weird hypothesis that intelligence would lead to happiness",
"It's like they were quite happy to completely ignore the idiom 'ignorance is bliss', which kind of breaks the irony meter."
] | [
"Why would IQ be a good predictor of overall happiness? We are first and foremost social creatures, it's our bonds with others that help us thrive. Intelligence can tell us why we are sick or injured but it won't care for us when we are. If anything it may be preventative and help us avoid some misfortune, but not... |
[
"When something becomes bleached from the sun, where does the colour go?"
] | [
false
] | null | [
"The color doesn't ",
" anywhere. The high energy ultraviolet radiation in sunlight simply destroys the molecules that give a particular object its color. Those molecules are colored because they interact with light, so they are naturally more susceptible to absorbing too much energy and having some or all of the... | [
"Interesting! Thanks so much!"
] | [
"Close.",
"Objects absorb electromagnetic radiation, \"darker\" objects absorb more EM radiation including more UV.",
"Objects have color because they absorb the wavelengths of visible light EXCEPT those we perceive as their color. The high energy UV changes the chemical composition and the object ends up refle... |
[
"Why does the sun look red as it nears the horizon?"
] | [
false
] | null | [
"Shorter wavelengths are blocked out the more atmosphere the sun has to travel through. ",
"This",
" graph is great for explaining the change in spectral response of the sun throughout the day. You can see that in the late afternoon (and of course at sunset) the solar spectrum is stronger in the reds (longer wa... | [
"Sunlight passing through the atmosphere scatters off molecules of gas and other small particles. Because the strength of ",
"Rayleigh scattering",
" is inversely proportional to the fourth power of wavelength, shorter wavelengths like violet and blue light scatter more than the longer wavelengths (yellow and ... | [
"It is not blocked, it is scattered. To me blocking implies absorption, which is negligible in the visible spectrum. "
] |
[
"Why does NADH and FADH2 give electrons at different points?"
] | [
false
] | So NADH donates its electrons at protein complex I but FADH2 donates its electrons at protein complex II. Why does this happen? Is it because FADH2 has less energy in its electrons and if so why does it have less energy even though it has the same amount of electrons as NADH. If NADH does have more energy how does it have more energy in its electrons then FADH2? | [
"Take a look at their structures: ",
"FAD, Wikipedia DE",
" and ",
"NAD+, Wikipedia EN",
"As you can see, there is a significant structural difference between those two cofactors - they would just not fit."
] | [
"The Wikipedia article for ",
"Complex II",
" says that FAD is actually covalently bound to one of the enzyme's subunits."
] | [
"What do you mean by protein complex I and II? Proteins have different binding sites for the specific cofactors they use meaning that they have specific physical pockets in their 3D structure where the appropriate cofactor can \"dock in\" and do its job. Also, usually, proteins do not receive electrons as they are ... |
[
"In the context of Astronomy, we often hear that space contains gases and dust. What is space dust and what is it made of?"
] | [
false
] | null | [
"There are different kinds of space dust. Within the solar system, the dust tends to made of similar stuff as planets: iron and silicon oxides. In interstellar space, it tends to be made of organic molecules (hydrocarbons) and ice. The grains in the solar system tend to be a few microns in size. ",
"Here's a pict... | [
"It absorbs light, making distant galaxies look redder and darker than they otherwise would. In the mid-20th century there was an apparent observation that the farther away a galaxy was, the bigger it was, which goes against everything we understand about the universe. Eventually it was realized the distance measur... | [
"I think it's based on spectroscopy done by cosmic microwave background experiments, e.g. ",
"https://iopscience.iop.org/article/10.1086/303568/meta"
] |
[
"How can a photon have a position?"
] | [
false
] | [deleted] | [
"Actually photons don't have a well defined position. We describe them as excitations of fields, which have a parameterized spatial and temporal dependance, and if you try and write down an operator that describes a single photon position it doesn't work out. Either the proposed operator doesn't transform as a ve... | [
"Warning: When you read answers in this thread, keep in mind that the word \"photon\" is heavily overloaded in both scientific and lay usage.",
"Ok, forget \"photons\" for a minute. Consider a rope where I hold one side and you hold the other. If I give the rope a swing on my end, a pulse will travel down the rop... | [
"Actually photons don't have a well defined position. We describe them as excitations of fields, which have a parameterized spatial and temporal dependance, and if you try and write down an operator that describes a single photon position it doesn't work out.",
"I would like to add to this because the answer migh... |
[
"How effective are plant seeds at sprouting?"
] | [
false
] | Given a certain plant that produces 100 seeds, how many would sprout into plants? Does this number change between families of plants, such as grasses and trees? | [
"This depends on a huge number of factors.",
"One thing you should take into account is the age of the seeds. seeds have a halflife and generally a certain percentage will die each year. This is a realy important factor for determining weed stress in agriculture.",
"To make stuff even more complicated you also ... | [
"Just to expand on the answers by ",
"/u/Fleur-de-lille",
" and ",
"/u/prettystupidstudent",
", germination rates can vary greatly even within families, orders, and genera (probably even within ecotype or subspecies). Dormancy is actually highly complex as a subject, and is hard to summarize in this kind of... | [
"It's actually quite hard to tell. I've germinated plants for experiments and normally I sow about 3 times as many as I need. One species will germinate at an 80% rate, while others would be more like 40%.",
"Germination rate, amount of seeds released and timing of seed release is totally dependant functional typ... |
[
"Does ISS have to increase speed after it's added more mass to remain in the same orbit?"
] | [
false
] | null | [
"No, mass can't be safely added to the ISS unless it has already matched orbits, so when a ship docks with it, they're already going the same velocity. The mass of the orbiting body doesn't enter into the equation when the mass is so small. "
] | [
"No, if it's orbiting at x velocity before the new module is docked then everything will still be at x after the docking is completed. The velocity required to maintain orbit depends only on the mass of the body you're orbiting (i.e. the Earth) and the shape/size of your orbit - not the mass of your satellite/space... | [
"No. The above assumptions are correct, it does not depend on the mass of the satellite, but ",
" when compared to the central attracting body.",
"The mass of the ISS is negligible when compared to Earth so you can keep adding modules or dock several Soyuz/ATV/Cygnus/whatever and leave orbital speed the same.",... |
[
"Why is LSD so powerful?"
] | [
false
] | [deleted] | [
"Not speaking to LSD specifically, but for a lot of drugs, a little bit goes a long way. Drug X, for example, might result in anti-depressant effects by reducing seratonin reuptake, but that doesn't mean the Drug X is causing that ",
". Drug X might be a ligand for Enzyme Y, which causes increased levels of hor... | [
"\"US scientists looked up close at an LSD molecule bound to a serotonin receptor from a human brain. As it turns out, when LSD latches onto a brain cell's serotonin receptor, the LSD molecule is locked into place because part of the receptor folds over the drug molecule like a lid, and sealing it inside.\"",
"ht... | [
"I've understood perfectly. Thanks for the answer! :)"
] |
[
"Why is \"gravity stronger in General Relativity than in Newtonian Mechanics\"? Is there an intuitive way to understand (at least as intuitive as relativity can be)?"
] | [
false
] | Specifically, for the Schwarzchild solution, the radial equation of motion for timelike geodesics looks like - A/r + B/r - C/r . I understand the A term is Newtonian gravity, the B term is some kind of centrifugal effect, but is there a physical way to interpret what the C term is? | [
"I think it’s much clearer if you look directly at the geodesic equation. From the point of view of a static observer (and pretending areal and proper distance are the same) then a purely radial motion looks just like Newtionian radial motion. ",
"That is the 1/r",
" term comes from the time dilation between th... | [
"Can you point me to what exactly you’re asking about? The Newtonian force goes like 1/r",
", not 1/r."
] | [
"Sorry I should have said what I wrote constitutes the effective potential (V(r)), which you get by doing something like this:",
"Taking the Lagrangian for the Schwarzchild solution to be L=g(dx/ds,dx/ds), with g as the Schwarzchild metric, then the Euler-Lagrange equation for the radial direction is (dr/ds)",
... |
[
"Are personal computers finite state machines?"
] | [
false
] | I Googled the question prior and got , however I don't fully understand everything past the first sentence. Why can a personal computer be considered more like a Turing machine then a FSM? | [
"A FSM is a machine with a finite amount of states, meaning that it can not represent infinity. This is true for your computer since it only contains a finite amount of data, whether that is 1 tb or a trillion tb, it is finite. Thus, a computer IS a finite state machine, it will run out of states given enough time.... | [
"Ok, so in response to your question (because the debate raging on in this thread is making my head hurt), yes, a computer is a finite state machine. ",
"In your link, the first answer discusses that your computer is a finite state machine in part due to the limits of it's computations before the end of the unive... | [
"Not quite. A linear bounded automaton is more powerful than a pushdown automaton, since they can decide context-sensitive languages."
] |
[
"Would the Stanford Prison Experiment yield similar results with people who have knowledge about the experiment?"
] | [
false
] | EDIT: I meant knowledge about the of the original experiment Of course this would be hard to answer, since as far as I know, there hasn't been an experiment conducted with these circumstances, although one could deduct from the results of other experiments in which the participants knew about the likely outcome of said experiment. | [
"I think he means the outcome, the experiment itself was conducted by participants that knew it was an experiment. But they didn't know the outcome at that time. A newer experiment would see different results, because the new participants know the outcome of the old experiment, so they might try to defy it."
] | [
"Do you mean knowledge that the experiment was happening or knowledge of the outcome of the original experiment?"
] | [
"This is what I was talking about, thank you for clarifying this for me. :)"
] |
[
"If most of conventional \"taste\" is actually smell, then why can something smell terrible but taste delicious?"
] | [
false
] | Specifically thinking about the durian fruit, which "tastes like vanilla pudding, but smells like the used underwear of someone you don't want to know". Knowing that taste is only composed of sweet, sour, salty, bitter, and umami, what accounts for the drastic difference between the experience of smelling versus tasting this fruit? Thanks! | [
"With the durian, in particular, it's more a case of ",
"a false smell",
" than a false flavor. Your tongue, with less complicated detectors, isn't affected and ignores the info from the nose. But your nose reacts more strongly, there are more than 50 different compounds that compose its scent... including 4 th... | [
"Wait what? There were 4 previously unknown chemical compounds that made up the smell of Durian?"
] | [
"According to that article anyway. Looking at the ",
"study",
" they cited I found: ",
"So I think the Smithsonian's writers either read more of the report than the blurb, or overstated the number of compounds by one. I'm also not sure whether these were compounds synthesized or identified in a lab before bei... |
[
"Why do we perceive three spatial dimensions?"
] | [
false
] | Is there a good reason for it? (I just read Flatland) | [
"I'm no string theorist, but I would venture to guess it is because we exist in a universe dominated by three spatial dimensions."
] | [
"Because that's the number of dimensions there are. There aren't any more or fewer non-compact spacelike dimensions.",
"Can we ",
" a manifold with more or fewer non-compact spacelike dimensions? Of course; it's not even hard. But just because we can imagine something doesn't mean what we imagine is related in ... | [
"I'm going to go ahead and quote ",
"Barrow & Tipler",
" as they have a very pertinent commentary",
"The fact that we perceive the world to have three spatial dimensions is something so familiar to our experience of its structure that we seldom pause to consider the direct influence this special property has ... |
[
"According to the graph inside, the temperature of Earth's atmosphere fluctuates back and forth as you increase in altitude, how come?"
] | [
false
] | This is the graph I am talking about Also, why does the atmosphere seem to change linearly in the Troposphere, but in the other regions it doesn't? | [
"Short answer: different layers of atmosphere interact and distribute solar radiation in different ways. ",
"Lower levels of atmosphere transfer energy primarily through thermal conduction, in which hotter particles impart heat through contact with cooler ones. The surface of the earth absorbs most of the solar r... | [
"Lower levels of atmosphere transfer energy primarily through thermal conduction, in which hotter particles impart heat through contact with cooler ones",
"This is false. Conduction is only important in a very small boundary layer (less than a meter) near the Earth's surface. Within the troposphere, energy is m... | [
"Temperature changes approximately linearly in the troposphere because it tracks the ",
"adiabatic",
" ",
"lapse rate",
" (the temperature change a parcel of gas will experience if it changes pressure and density without exchanging energy with its surroundings). In the troposphere energy is exchanged verti... |
[
"Does it require more battery power to stream music using a data plan vs. using WiFi?"
] | [
false
] | null | [
"Hi BlistersOnMySisters thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of... | [
"Computing"
] | [
"'Computing'"
] |
[
"If whales evolved from rat-like land mammals, how did their blow-holes develop and how did their size so substantially increase?"
] | [
false
] | This is a mammal I have difficulty in comprehending its evolution. Something so small affecting the emergence of something so large. | [
"First, we need to deal with a misconception. You say that there is an (apparent) lack of animals on a path to some major physical change, but here's the thing... how would you be able to tell?",
"If you take a snapshot of life on Earth at any given time, such as now, it won't look like many of the animals are on... | [
"Here's a fascinating tidbit from the Wikipedia blowhole article:",
"The blowhole of a sperm whale, a toothed whale, is located left of centre in the frontal area of the snout, and is actually its left nostril, while the right nostril lacks an opening to the surface despite the fact that its nasal passage is othe... | [
"Here is a wikipedia article and 2 discovery articles that will help you understand more about this topic. Although there are common rat-like ancestors, there are also better intermediate examples that were amphibious and maybe give a better resemblance.",
"\nOn the size thing, there are only speculations of cour... |
[
"If the universe was finite and there was an edge, what would happen if you went outside of it?"
] | [
false
] | null | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"It is hypothetical or speculative in nature. We do not allow hypothetical questions because questions that cannot be confidently answered with any available data often invite non-scientific speculation.... | [
"/r/asksciencediscussion",
" is a toxic pool of iamverysmarts"
] | [
"Well, it's too bad that you feel that way, because this question is not appropriate here."
] |
[
"When a supernova explode and collapse to a black hole, how much time does it takes from explosion to being a singularity ?"
] | [
false
] | Is the speed of the density increase constant, accelerated, decelerated ? In the time frame of a distant external observer | [
"The dying star doesn't really explode, it impodes. The singularity is formed as soon as the fusion power of the star can't stop the force of gravity from crushing the core. As the inner core shrinks and the singularity is formed it begins to eat the star but it can't handle the compression of the outer core. The o... | [
"As the inner core shrinks and the singularity is formed it begins to eat the star but it can't handle the compression of the outer core",
"What do you mean by 'not handle the compression'? Wouldn't the singularity eat anything pushing inward?"
] | [
"An accreting black hole does not eject anything from beyond its event horizon. The reason the accretion rate is not unlimited is that as matter falls onto the black hole, it heats up as it compresses and runs into itself. If enough matter tries to fall in all at once, it gets so hot that the pressure from its ow... |
[
"Is artificial gravity even theoretically possible?"
] | [
false
] | In nearly every sci-fi show or game or whatnot, the spaceship has an artificial gravity device on it that allows for everyone to walk around like normal. Even if we had some amazing technology with some kind of infinite power source, is it even possible to manipulate gravity like this? | [
"Yes. You can simulate gravity yourself with a simple experiment using centrifugal force. Get a bucket and fill it with water, make sure the top is open. Rotate your arm over your head and back to a resting position quickly making sure to move your arm in a fluid motion. ",
"Like this.",
"So what science is at ... | [
"If you've ever played Mass Effect you'd know what this guy is talking about. The Citadel simulates gravity by rotating, and it is a comfortable 1.02 standard G's on the Wards and a light 0.3 standard G's on the Presidium Ring."
] | [
"As far as we know...no. However, you can exert forces that would be perceived similarly to gravity (to different extents) in ",
"several ways",
". Though again, none are currently viable for actual use on a spacecraft."
] |
[
"Whenever I buy a lottery ticket I remind myself that 01-02-03-04-05-06 is just as likely to win as any other combination. But I can't bring myself to pick such a set of numbers as my mind just won't accept the fact that results will ever be so ordered. What is the science behind this misconception?"
] | [
false
] | null | [
"I'm not sure if there is a name for this heuristic, but is has to do with our ideas about randomness and what we think a \"typical\" set of random numbers or events looks like.",
"Another example of this occurs when you ask people to simulate flipping a coin 100 times. In the sequence of heads and tails that the... | [
"Gamblers fallacy. It's also to do with misunderstanding that each event is completely independent of any that came before and any that will come after which is why such a combination is statistically just as likely as any other. Our intuitive understanding of chance is such that, once something has occurred, it is... | [
"While it's true that 01-02-03-04-05-06 is just as likely to win as any other combination, you probably shouldn't choose that sequence, because it's likely that many other people have chosen the same sequence, and you'll have to split a top prize more ways if you win one. If you pick \"random looking\" numbers ins... |
[
"Does the moon have any legitimate effects on behavior?"
] | [
false
] | [deleted] | [
"If it did, the phase would be the main independent variable and the effects would cycle over a month. The distance pretty much has no effect besides making the moon look bigger right now. Female hormones vary across that length of time, but that's not directly caused by the moon."
] | [
"There's been ",
"some study",
" on this, both for human patients and animal patients. ",
"This study",
" seems to contradict you, saying that trauma rates were 2.1% lower than average on full moons (over a 36 year period).",
"It's got to be a tough thing to get confident results on, though, since you can... | [
"I've read that men have periodic fluctuations in hormone levels too, with about the same frequency. I was trying to find a reputable study, but Google Scholar is all about daily LH signals and Google is full of old wives' bullshit."
] |
[
"What are p-values? What would it mean to go from a p-value of 0.05 to 0.005?"
] | [
false
] | A month ago, made waves by publishing that the standard p-value should be changed from 0.05 to 0.005. If my intro to statistics covered p-values, I have completely forgotten, and the description in the commentary is abstract for me. (cross-poted to and ) | [
"EDIT for clarity: The proposal under consideration is about changing how we interpret p-values. So I need to go through what p-values are, then we can talk about the proposed change to a threshold called alpha that is used when we interpret p-values. ",
"The p-value is the likelihood of getting data at least ... | [
"I would add to this that lowering the alpha value (which is the cut-off for the p value; the point where you accept your hypothesis as true) from 0.05 to 0.005 not just only makes false positives less common (which is a good thing of course) but it also makes false negatives more common, where you conclude that yo... | [
"A p-value is the probability that the results achieved in the study were due to random chance. Usually p<0.05 is used as a threshold to determine if the study has significant results. This means practically that if the results the study showed have a higher than 5% chance of occurring randomly the study hasn't giv... |
[
"Is the world running out of chemical formulas to create new antibiotics?"
] | [
false
] | [deleted] | [
"Not really. The possible theoretical chemical space is so vast as to be infinite for practical purposes. The \"druggable\" part of that space is smaller, but certainly not even close to being fully explored.",
"The reason why we don't have more antibiotics is a simple economic one: antibiotics generally don't ... | [
"Thank you Ren, the exact answer and response I was hoping for, as it was a topic on debate between a workmate and myself. Is it so much so a problem, that if it were not for these philanthropic beings with the NIH, we would run out of viable combinations within a couple of generations, or do we have decades of sto... | [
"Profitability is a big issue, but largely for reasons other than what you mention here.",
"The way it typically works is Professor Smith at State Technical A&T University discovers new potential drug (smithidone) on his NIH grant. Prof Smith gets a patent and founds an emergent biotech (Smithtech) to get crackin... |
[
"When electrons jump from one atomic orbital to the next, how fast do they move?"
] | [
false
] | Electrons can only exist in defined energy levels, and cannot exist in an intermediate state. This seems to imply that the change is instantaneous. When an electron changes atomic orbitals, can it be said to have 'moved', and if so, how fast is that 'movement' if the jump is instantaneous? | [
"Good question. You may have heard of the Heisenberg uncertainty principle about how position and momentum of a particle have a bound, where the more precisely you know the location of a particle the less precisely you know the momentum. Well it turns out that energy and time also share an uncertainty relationship.... | [
"It's not instantaneous. Take a two-level system, with a particle starting in the excited state. The wavefunction of the particle will have time dependence in the form of",
"exp[(Γ/2 - iE)t/",
"].",
"When you evaluate the probability density, you take the modulus of this quantity. The imaginary part of the ex... | [
"Well, the premise is in principle wrong. Electrons can and do exist in states without a clearly defined energy level, and in intermediate states. Nevertheless, electrons do change atomic orbitals.",
"The mostly complete story of atomic orbital transitions:\nThe electron begins in an upper orbital A. Because that... |
[
"If an electron is 1/2000th the mass of a proton, how do they have the same magnetic force?"
] | [
false
] | null | [
"What do you mean by \"have the same magnetic force\"?"
] | [
"2 protons = 2 electrons they have the same attraction forces...unless I'm missing something."
] | [
"The proton and electron have equal and opposite electric charges. Their masses don't affect their electrostatic interaction."
] |
[
"How are atoms (which are made up of mostly space) affected if space is expanding faster than the speed of light?"
] | [
false
] | null | [
"The rate of expansion doesn't work like that. The units aren't km/s but km/s/Mpc. If you have two points at 1 Megaparsec distance, their apparent recession speed is 72 km/s (or something like that). So that speed is a factor of distance. That means no matter how how small that rate is, you can always find two poin... | [
"So what is it that's actually expanding?"
] | [
"Space is expanding."
] |
[
"Is there a difference between the \"space\" between planets in a solar system, between solar systems in a galaxy, and between galaxies in the universe?"
] | [
false
] | Sure the distances are much greater, but do we know of any other properties that make "space" distinct in different parts of the universe? | [
"The amount of gas in different parts of space is different. No space is an absolutely perfect vacuum, it's all varying shades of gray. There's the solar wind near Earth, particles blasting in our direction coming from the sun.",
"In between stars, the stellar winds are weak, and there's gas called the interstell... | [
"You might find ",
"this",
", ",
"this",
", and ",
"this",
" interesting. Dark matter (3rd link) is believed to be responsible for the large scale distribution of gas in the universe, including the interstellar medium (1st link)."
] | [
"Differences in gravity, which means differences in 'bending'. "
] |
[
"Why do older people's veins look squiggly? Do veins and other internal body parts sag like our skin does?"
] | [
false
] | null | [
"You are partially correct. In old age, the elasticity of blood vessels decreases just like our skin. Additionally, you will notice that these squiggly veins appear on lower extremities, where the back-pressure is great in an upright posture. There are valves inside veins to prevent backflow. Eventually these valve... | [
"I am a vascular technologist (meaning I use ultrasound to look at veins and arteries). I do a lot of vein mappings for people with varicose veins and this is a very good description of the physiology that occurs causing varicose veins."
] | [
"OP is not asking about varicosities. - ",
"EDIT: I musta misread that. OP is asking for older people, so maybe varicosities, maybe not. If not, then the answer in non-varicose veins (like arm veins, which do get 'squigglier') is that the tissue around the veins gets floppier, and stabilises them less, so the vei... |
[
"Imagine if the U.S. decided to divert 10%(72.13 billion) of the defense budget to science. What would be the most promising and necessary research, projects, and ideas they could effectively support?"
] | [
false
] | If we answered this and presented it as a worthwhile and necessary investment, we could use this to bring attention to the gross differences between defense vs. science expenditures. We could explain how one misuses resources and the other is an investment in the short-term and long-term future. Edit: Thank you all for your thoughts and discussion. | [
"Here's the problem: Just as 9 women can't make a baby in 1 month, throwing a ton of money at the problems won't make them magically be solved immediately. That said, if you want long-term, awesome and disruptive advancements, there are few better places to spend the money.",
"What I'd do with the money is establ... | [
"You want more science? Make sure as many people in the word are as free from disease and hunger as possible. Make sure education is available to everyone. Yes I'd love a few extra bucks for my detector or pet projects, but the real way to improve science is to improve the world we live in. Only when people are fre... | [
"Please note that the military does spend a lot of money on R&D, leading many fields of hard and soft sciences in the creation of what eventually becomes consumer technology. It's one of the reasons the budget is expensive, because they constantly push research and try to make it a reality, and that is very very e... |
[
"Mauna Loa not erupted since 1984; Kilauea has been erupting since 1983. Is it just a coincidence?"
] | [
false
] | Going by Wiki article on , it's currently in unusually long period of inactivity, while Kilauea is in unusually long period of activity. Are the two connected, or is that just a coincidence? | [
"Mauna Loa and Kilauea are thought to have a common magma source in the asthenosphere. Eruption activity on one volcano relieves pressure in the other, producing an alternating eruption pattern. Source: ",
"http://www.livescience.com/24262-kilauea-mauna-loa-linked.html"
] | [
"IIRC, the general theory is that it's a hotspot in the mantle. As the crust moves over it, the volcano that formed the last island tends to shut down, and a \"new\" one forms, and makes a new island.",
"Which is why Hawai'i is an island chain, in the middle of nowhere.",
"Both volcanoes are on the same island... | [
"Probably not unrelated. There's only so much magma coming up through Big Island, and the plumbing system below the south of the island is quite complicated. It's likely that the magma reaching Kilauea has been intercepted from the main Mauna Loa feeding system. This may well just be a short term thing."
] |
[
"Is seawater antiseptic? If not, at what salt/ mineral content is a liquid antiseptic,antiviral, etc?"
] | [
false
] | null | [
"My guess is those trace elements would be negligible. Let’s look at iodine first, one of the trace elements our body needs. You only need ",
"150ug of iodine a day.",
" In seawater, iodine is found at a concentration of ",
"0.05 parts per million.",
" This can be roughly converted to 0.05mg/L.",
"Doing s... | [
"So I just want to preface my answer by saying this isn’t really my field. Take it as you will",
"But different pathogens are going to have different tolerances to osmotic pressure. Gram-positive bacteria are more resistant to salt concentrations than gram-negative bacteria for example. And “naked” viruses are mo... | [
"Related question: I've heard that every drop of sea water contains a little of every naturally occurring element on earth. Wouldn't a few sips of sea water once in a while be good for you with all those trace elements to top you up?"
] |
[
"Have humans gained any traits over the past 2000 years through natural selection?"
] | [
false
] | Since natural selection is a constant thing, I was just curious if anything has happened to our species since year 0(AD). No matter how weird or worthless, I wanna hear anything! | [
"The taller and smarter changes have happened too fast for them to be attributable to natural selection. They likely were mostly due to better diet, health care, and education."
] | [
"We're getting taller and smarter than we were 2K years ago. It's hard to delineate those from improvements in medicine and diet though. Our skulls and brains are getting smaller and fewer people are growing wisdom teeth. Many populations have straighter hair and lighter skin due to being able to live in different ... | [
"Depends on how you define humans in that question. If you mean humans and their internalized biome, i would say that human gut bacteria have gained significant traits since the industrial revolution, learning to cope with rich modern diets in addition to countless drugs, toxins and chemical pollutants. All the whi... |
[
"Change in enthalpy for transition of carbon in the diamond form to carbon in the graphite form is apparently a negative number (-453.5 cal). According to this, graphite is more stable than diamond, how’s that possible? Isn’t diamond supposed to be stronger and more stable than any other material?"
] | [
false
] | null | [
"At standard conditions (1 atmosphere, 20 degrees celsius), graphite is a more stable form of carbon than diamond. However, the energy barrier to cross means that spontaneous reordering of diamond into graphite is essentially negligible. This doesn't affect the hardness or other physical properties of the material.... | [
"Graphite is layered, with a hexagonal, strong bonds in each layer. Weak bonds hold the layers together.\nThe c-c lattice which makes up the diamonds structure is made of identical bonds. The change in enthalpy being negative indicates the reaction is exothermic. "
] | [
"Mechanical strength doesn't necessarily correspond to phase stability. ",
"Another example is certain amorphous alloys. They're stronger than the corresponding crystalline structure because they don't allow easy dislocation glide, but they're also less stable than a crystal and need to be produced via extremely ... |
[
"Why have we not revisited the idea of nuclear aircraft?"
] | [
false
] | I was thinking about this because I recently found out how much carbon emissions are released by . It seems to me that the biggest problem with nuclear aircraft was radiation shielding, but newer technologies like could compensate for that, right? Add to that the size of proposed and the compactness with which we have created modern , it just seems more feasible than in the past. Is there something I am overlooking, or is the airline industry missing out on a huge new market? | [
"Power plant for aircraft require an extremely high power-to-weight ratio [",
"1",
"]. The Boeing 747-300 requires ~1400 W/kg (ibid.)",
"A nuclear power unit would require a thermodynamic cycle to extract thermal energy from the reactor and convert it either directly to motive force or (less efficiently) to e... | [
"Demron doesn't provide enough to shield against high energy neutrons or high energy gamma, which are the two main things that come out of a nuclear reactor. You need the equivalent of 4-6 feet of water to deal w/those, and thats extremely heavy to have on an aircraft."
] | [
"Its very simple: The idea of a nuclear powered aircraft was only interesting when you wanted to keep planes with nuclear weapons circling routes for weeks at a time. With the invention of ICBM's, all of this didn't matter anymore.",
"Otherwise, the safety and shielding risk was terrible. Pilots used to get lar... |
[
"Do spectral lines (emission or absorption) continue past the visible portion of light?"
] | [
false
] | I understand most of this topic I think. Quantized electron energy levels create shadows that you can see when you direct the light given off when the element is heated through a prism. But does it only correspond to visible light or are there more 'electron shadows' we can't see because its in the infrared or ultraviolet? | [
"Yes, there are spectral lines across the entire electromagnetic spectrum, and not just in the tiny region that is visible to humans. The existence of a \"visible\" portion of the EM spectrum is a result of the limitation of the human eye and not a fundamental aspect of EM waves in general. We can \"see\" the rest... | [
"So spectral lines are caused as these are the energies required to transition electrons between states. There is a maximum here, if you put in enough energy the elctron will escape the atom and become free. If I recall correctly for Hydrogen this is something like 13.6eV, which gives rise to the H-alpha spectral... | [
"Yes! Is is actually amazing that light visible to the human eye is only just a fraction of the whole electromagnetic spectrum!"
] |
[
"So we did this in my physics class and I don't understand why it worked"
] | [
false
] | We attached a cord to the cement at the bottom of a light pole, and hooked the other end to the back of my teacher's car. My teacher got several students to try and pull on the cord parallel to the ground and get the car to move. It didn't. Then he took one student and had them grab the cord and pull straight upwards (away from the ground), and lo and behold the car moved very easily. The car was in neutral the entire time. Why was it so much easier to move when pulling straight away from the ground as opposed to pulling straight away from the car? | [
"It's essentially leverage.",
"The students pulling on the car horizontally had to pull the rope one inch to make the car move one inch, but the student pushing the rope up had to move the rope further than an inch to make the car move one inch (exactly how far depends on the length of the rope). Look up an expla... | [
"Let's say the force F is needed (higher than the current tension in the rope) in order to pull the car.",
"If you pull it horizontally, you need to apply all of F which will be the tension in the rope then.",
"If you pull it vertically,you need to only apply T*sin(theta), where theta is the angle (close to zer... | [
"Did it look like this?"
] |
[
"What happens to the light/energy that's travelling faster than the universe is expanding?"
] | [
false
] | Energy can't be destroyed, the speed of light is 3,000,000m/s, and the universe is expanding at around 70,000m/s. Given those facts, light must constantly be travelling past the edge of the universe; what happens to it? | [
"Where did you get this number? The universe doesn't actually have a speed of expansion! What happens is that the velocity in which two points \"expand\" away from each other is proportional to the distance, and the proportionality factor is given by the Hubble parameter.",
"No matter how small the Hubble paramet... | [
"Can this also be scaled down, as in, is the distance between me and the other side of the room getting larger even by a minuscule ammount as time progresses? or is this only for body's seperated by a vacuum, or a set \"minimum\" distance?"
] | [
"It is only for bodies which are not bound to eachother by ",
" of the fundamental forces. Gravity is the only force that matters on the largest scales, so it basically applies only to galaxies that are not bound gravitationally. So, for example, the Milky Way, Andromeda, and the Triangulum galaxy along with se... |
[
"What exactly is, what I would call, \"leg bobbing\"?"
] | [
false
] | null | [
"Are we talking about a stereotyped movement that is ",
"? If that's the case, then it is very commonly used as a method of self-stimulation. Self-stimulatory behaviors are often seen (to a much, much worse degree than you're describing) in children with autism. However, what you're describing could just be indic... | [
"I've been very curious about this for awhile. Not sure if the OP is talking about conscious or not, but I know for me it definitely starts out as a unconscious act. Most often, it goes unnoticed for a long time (possibly an hour or more) before either I notice it, or my foot moves to where I'm tapping something th... | [
"I should have clarified. By conscious control I meant that you are able to stop it once you're aware that it's happening. Some people have tremors that they can't control due to various neurological disease processes (e.g., Michael J. Fox, who has Parkinson's disease), and that's a much different thing."
] |
[
"Is it dangerous to eat burnt foods?"
] | [
false
] | In this case, I had barbecued some chicken wings. The drippings caught fire and blackened the lot. The insides are cooked as normal, but the outside is blackened and tastes of char. Is this dangerous to eat? If so, why? | [
"First thing I found on google.",
"It's not dangerous the way speedballs or blindfolded skiing is dangerous. But it is unhealthy and harmful. "
] | [
"I was hoping to get a slightly more detailed answer than:",
"\"A: Maybe. Some chemicals in burnt toast have been linked to cancer.\"",
"While I understand that overcooking of food will cause carcinogenic compounds to form, I was wondering just how dangerous these compounds are. For example, after eating X amou... | [
"Potentially, but mostly if you ate it on a regular bases. Heat causes chemical reactions and some of those are carcinogens. These are present in any cooked food but the more cooked (I.e. The more charred) the more carcinogens there are. These can cause abnormalities such as tumors but these has really only been re... |
[
"Does taking notes actually help us understand the content we’re learning (lectures, reading, studying)?"
] | [
false
] | null | [
"I did a paper on this in college. There isn’t any evidence that taking notes by Itself helps people learn better. ",
"It should be noted that taking good notes and reviewing them within a couple of days after taking them does seem to help. ",
"The only source I remember using in that paper (you may not be able... | [
"I know for me, typing results in virtually zero retention. I can flow stuff through from my ears to my fingers easily. Actually handwriting and sketching results in far more retention."
] | [
"The very act of typing something makes it stick in your memory better. Also, by choosing what information to write down you're analyzing and processing that information as it comes in which improves you're understanding of it."
] |
[
"Disassociation of Salts in Water"
] | [
false
] | Through all my years in Chemistry I was always taught that when a salt such as NaCl is put in water it dissociates into Na+ and Cl-. I know water is such a great solvent because of the difference in electronegativity between O and H, and thus its ability to form H-bonds. I also learned that intramolecular forces (ie covelent/ionic) bonds are always stronger than intermolecular ones (ie Hydrogen dipole and London dispersion). How does water break the ionic bonds between Na+ and Cl- in order to disassociate the salt when it can only interact through H-bonds? Are my assumptions correct or am I looking over a critical point? | [
"Whether chemical reactions happen is determined by their free energy. For constant pressure processes, like a salt dissolving in water, the Gibbs free energy is used. ∆G=∆H-T∆S. When the Gibbs free energy, ∆G, is negative the process happens spontaneously. (Note that this does not give you information about how qu... | [
"In a sense. the term -T∆S is literally an energy change exerted by entropy. In this case with the salt and the water it is much more thermodynamically favorable to increase the entropy of the system by dissolution of the salt, than the unfavorability of breaking the strong ionic bonds."
] | [
"The ionic bond is breaking, check out this ",
"wiki",
" article. The first step of forming a solution is breaking the interactions in the solute. In the case of salts this would be lattice energy and the energy of the ionic bonds. Salts don't dissociate in the open because it is not energetically favorable. Th... |
[
"Will the Sun become tidally locked with Sagittarius A* in the future?"
] | [
false
] | [deleted] | [
"Thanks for making me check numbers, I was quoting from memory and totally wrong. Sgr A* is 4 million solar masses, which would be 0.0004% of the galaxy's mass (around 1 trillion solar masses). Which does make the \"insignifiant influence\" part way more obvious..."
] | [
"Sgr A* is much to far away to exert any sort of noticeable gravitational effect on our solar system. Tidal effects are required to cause tidal locking and they fall off even faster (1/r",
" than gravitational forces (1/r"
] | [
"The sun is orbiting the center of mass of the galaxy, Sgr A* just happens to be around there (and accounts for ",
" which is why it's considered as insignifiant for its gravitational influence on us)"
] |
[
"What do scientists mean by: X is the part of the brain responsible for Y?"
] | [
false
] | Where Y is a mental/psychological (as opposed to physiological) process. From what I can tell, they generally mean two things. (1) X is necessary for Y: based on the study of brain injury, it's clear that without X, the ability to Y is inhibited. And (2) activity in X corresponds with Y-activity: based on observing various neuro images, when a subject Ys, their X "lights up." To me this establishes (1) that X is a necessary condition for Y, and (2) that there's a robust correlation between activity in X and Y. I was just listening to Jonah Lehrer ( , ) on , who mentioned "the dorsolateral prefrontal cortex [...] which is closely associated with impulse control." And a basic google search turns up (Harvard Med School, emeritus) describing "the central importance" of the dorsolateral prefrontal cortex "in regulating many key aspects of consciousness, including attention, decision-making and voluntary action." I'm not sure how to interpret phrases like "X is closely associated with Y" (Lehrer), and "X is of central importance in regulating Y" (Hobson). I guess they sound to me like claims. But in other scientific disciplines, the standards for establishing causality seem to be much more stringent than (1) necessity and (2) correlation. For example, I know of Koch's postulates, required for establishing an etiological relationship between a microorganism and a pathology. In that case there is a more required than just necessity and correlation. Then again, maybe correlation is basically a first principle for neuroscience? If so, am I right that that makes it fundamentally different, methodology-wise, from other scientific fields? Anyway, I'm primarily interested in how actual investigators working in neuroscience fields think about such methodology/epistemology questions. Or is it just not something one thinks about all that much? | [
"I guess they sound to me like causal claims.",
"No and yesno. With current technologies and methodologies in the brain and behavioral sciences (e.g., fMRI, EEG, MEG, PET, SPECT) we can't infer too much causation. But, with appropriate experimental paradigms (i.e., setting up an experiment where you can manipulat... | [
"I hate to ask you to do sociological speculation, but... What do you think most neuro/cognitive scientists would say: in principle, could we \"build\" a DLPFC (the functional equivalent thereof), ",
"Nope. Too science fictiony. "
] | [
"I'll add a little something here as a neuroscientist who goes after a more direct but narrower analysis of brain function than the imaging/gross electrical studies mentioned by dearsomething. We're the electrophysiologists - we measure pretty directly the changes in electrical activity of small groups or even sing... |
[
"Why is the Earth's freshwater supply diminishing?"
] | [
false
] | If our potable water is considered a renewable resource, why are we taught to conserve water? Think about it: we use the water, it goes to the sewage cleaning facility, and then back to our water taps. So why is it so suddenly (within the last 10ish years) that there has been a movement to save, save, save water? What's happening to our fresh water? | [
"it goes to the sewage cleaning facility, and then back to our water taps. ",
"This isn't quite right, most of our treated sewage does not get sent back to the water supply as it's not fit for drinking and we either drain it into the ocean or use it for irrigation and other non-drinking uses. Most of our drinkin... | [
"The earth \"produces\" the same amount of freshwater that it always* has, what is changing is the amount of people that want to drink it and use it for bathing, cultivating land, etc.",
"more demand + same amount of water = shortages"
] | [
"As others have said - waste water is usually put straight our to sea.",
"One of the largest problems is that in large parts of the world, the freshwater supply is not drawn from the recharged water cycle, but from deep aquifers which are not recharged. This fossil water - once gone - will not be replenished.",
... |
[
"Why do volcanic hotspots create a chain of volcanoes instead of a continuous ridge?"
] | [
false
] | Why do volcanic hotspots create a chain of volcanoes like for example the hawaiian island chain instead of creating a single continuous ridge? | [
"There are a few things to consider. First, is that if we look trails of volcanoes formed by hotspots, in many cases they do form (at least in small parts) things like ridges, e.g. if we used the classic ",
"Hawaiian-Emperor seamount chain",
" as an example and consider the bathymetry, we can see sections where... | [
"Yes, that's an important contributor to the height (and areal extent) of Olympus Mons. Also important is the difference in flexural rigidity of the Martian lithopshere in the area under Olympus Mons compared to typical lithosphere on Earth, especially compared to oceanic lithosphere (i.e. the effective elastic thi... | [
"So volcanoes like Olympus Mons on Mars are so tall because Mars lacks plate tectonics and the magma pools generally in one place?"
] |
[
"What are the scientific theories behind why Saturn's north polar storm is shaped like a hexagon?"
] | [
false
] | [deleted] | [
"This",
" article from the planetary society is one I found a while ago. It explains the theory BlueStraggler outlined quite well, and shows some nice pictures of some experiments done at Oxford University in support of it. ",
"This",
" is the original paper, unfortunately it's behind a pay-wall."
] | [
"Some sort of oscillation in the weather patterns around that latitude that resembles a sine wave. North and south of that latitude the period of the wave doesn't sync, so it mixes and disappears. At the latitude where the period syncs, you get a standing wave, which happens to be 6 periods long in this case. Beyon... | [
"Here's an interesting article on the topic:",
"http://physicsbuzz.physicscentral.com/2010/06/secret-of-saturns-hexagon.html"
] |
[
"Why does a picture of a spider or a weird insect scare me, but a picture of a more dangerous lion or bear not scare me?"
] | [
false
] | [deleted] | [
"Phobias are generally thought to be learned associations to certain things. Put another way, you have probably learned to fear spiders from your experiences in your day to day life. Whilst lions and bears may in reality be more dangerous should you encounter them, because you have not encountered them in your expe... | [
"If I saw a larger-than-life size picture of a spider, I would most likely be even more terrified."
] | [
"If I saw a larger-than-life size picture of a spider, I would most likely be even more terrified."
] |
[
"Can we predict a double pendulum?"
] | [
false
] | null | [
"The double pendulum is a completely deterministic system, it just behaves chaotically, meaning that small deviations in initial conditions lead to large deviations in the motion. If you know the initial conditions perfectly, you can predict exactly what it will do forever. But if there's any uncertainty in your in... | [
"If you start identical double pendulums from exactly the same initial conditions, they will do exactly the same thing forever. But that's not possible to do in real life.",
"Where is the chaoticness?",
"Here:",
"But if there's any uncertainty in your initial conditions, eventually, your prediction of the mot... | [
"We can define them exactly mathematically. But experimentally, we can never reproduce the same initial conditions exactly."
] |
[
"How Accurate Is This Website?"
] | [
false
] | null | [
"About as accurate as saying that everyone should eat exactly 2000 calories a day. Everyone's body is a little different, with different requirements and strengths and weaknesses. Sleep is the same. Some people should aim for 9 hours, some people only need 6. "
] | [
"And a few lucky bastards who genetically need hardly any sleep at all."
] | [
"Not my field, but its saying you need 9 hours sleep (or any increment 1.5 less than that to have full sleep cycles) + 14 minutes of time to fall asleep. It seems to base this on your sleep cycle being 90 minutes=1.5 hours; hence 5-6 sleep cycles or 7.5 - 9 hours of sleep. Quick check on from ",
"NIH",
" say... |
[
"If I ignite the smoke of a candle it burns down but not up, why?"
] | [
false
] | So there is this to light a blown out candle by igniting its smoke. But the smoke only burns downwards, even if I try to ignite it at the very bottom. Anyone know why? | [
"But if there is enough vaporized wax in the smoke to burn, why does it not burn upwards too? At least until the concentration becomes to low to sustain the reaction?"
] | [
"But if there is enough vaporized wax in the smoke to burn, why does it not burn upwards too?",
"Best guess:",
"The heated air rises too fast pushing the vaporized wax & carbon too far out of the way to be used as fuel.",
"Get your camera. Set it too the maximum frames per second you can. Record yourself tr... | [
"I believe it's because the smoke isn't actually what is burning. Basically it is the vaporized wax that's catching so the fire is going to burn down towards the candle where the concentration of the vaporized wax is greatest."
] |
[
"Is space-time really just an aspect of the gravitational field ?"
] | [
false
] | null | [
"You've got it a little backwards. Gravitational fields are actually a derived aspect from the curvature field of space-time.",
"From this thread: ",
"http://www.reddit.com/r/askscience/comments/gpaha/what_causes_gravity/",
"Well it actually isn't really a force. It only looks like a force due to some really ... | [
"please feel free to ask for clarification. I'm just copypasting an old response. I'll try to write up in better detail after work."
] | [
"Sorry I forgot about this post earlier. The wiki on stress energy tensor is actually pretty neat and useful, imo.",
"Anyway my thoughts on the graviton are as follows:",
"Keep fresh in your mind that gravitation is ",
" a force. It is a fictitious force, a force that arises out of choosing a non-inertial ref... |
[
"why do the planets in the solar system have a mostly circular orbit but far objects like ceres have highly elliptical orbits?"
] | [
false
] | Edit: my bad I confunded sedna with ceres, I meant sedna | [
"Ceres has an eccentricity of 0.075. That's not much more than Earths eccentricity. I think you are mistaking Ceres for a kuiper belt object, such as Pluto? Ceres is located in the asteroid belt between Mars and Jupiter. ",
"Anyway it is true that many trans-neptunian objects have quite large eccentricities compa... | [
"Ceres is the largest object in the asteroid belt. I think OP might have confused it with something else, maybe Pluto? But it is definitely part of the solar system and has always been. We know very few interstellar objects, actually ''Oumuamua' is the first and only confirmed interstellar object. Although there ar... | [
"I'm not expert but I believe it would be caused by a collision. I'm fairly certain that Ceres is also believed to have originated somewhere other than our solar system. However a collision with another object can/would change the orbit of said object. Pluto would be similar with charon and their elliptical orbit. ... |
[
"Could many dead languages be resurrected 'as is' -- with just terms for new discoveries added -- and still be as practical as any modern language?"
] | [
false
] | null | [
"I think you mean \"the early years of the last century\". Hebrew has certainly been in use as a modern language for more than 14 years."
] | [
"I think you mean \"the early years of the last century\". Hebrew has certainly been in use as a modern language for more than 14 years."
] | [
"That's really interesting. I did not know Hebrew had been revived so recently."
] |
[
"Is the string in a canter-leaver under tension or compression? - Teacher disagrees with the class can someone please explain"
] | [
false
] | Our physics teacher spent todays lesson trying to rationalize that the string in a canter-leaver is under compression while the class disagreed saying that if the string was supporting the beam from above then the string would be under tension not compression. Bellow are 2 diagrams showing the forces that the teacher stated where acting on the object and the workings that she tried to use to explain her reasoning. Can someone please explain why or why not the string is under compression. Links to images for reference Edit: thank you for all your responses, it has realy cleared up my understanding. | [
"Because that's the convention that mechanical engineers use",
"No it's not. My undergrad training is in mechanical engineering, I've worked as a mechanical engineer, and I've taught mechanics of materials classes. It's flat incorrect to say \"The string is under compression because it is being pulled apart at th... | [
"Oh wait, I think I figured it out.",
"The question you're asking is ",
" \"why is diagram 1 correct and not diagram 2\".",
"What looks like is being done is a combination of a free-body diagram with the picture of the object. If we look at picture 3, we see that diagram 1 is on the board, and immediately bel... | [
"The string is under tension: outside forces are pulling its ends apart. The arrows in the first diagram are a bit confusing: they indicate the force ",
", not the forces applied to the string. The string is pulling the tip of the beam up and to the left.",
"At the tip of the beam, the string is pulling up an... |
[
"Have we ever whitnessed an impact of a non artificial object on the moon?"
] | [
false
] | null | [
"Yes, an impact was observed during the last eclipse",
"http://www.astronomy.com/news/2019/01/impact-on-the-moon-during-the-total-lunar-eclipse"
] | [
"Many of them. There are many cameras pointed at the Moon to spot these events.",
"55 events found by ESA here",
"54 from a NASA program a while ago",
"A NASA follow-up program is at 435 candidates",
"and many more"
] | [
"Wow, thank you!"
] |
[
"Aquagenic urticaria: Is it a real condition or media-hoax?"
] | [
false
] | [deleted] | [
"It's real, and a pain in the butt. I've had it since I was born. It's not simply water, in my case the problem is hot water. For example, every time I take a shower, all these red spots appear and it gets really itchy. Swimming is fine, as long as I don't move a lot, as sweat also makes it \"happen\". I'm 22 today... | [
"My aunt has it. Though not as bad as the girl from the last link."
] | [
"How is this possible? You're allergic to water? The substance that all of your cells are made out of and require for sustained life?",
"I could imagine something IN the water reacting, maybe salts or fluoride or something. I have a REALLY hard time believing that pure distilled H2O would cause a reaction."
] |
[
"When your body is 'burning fat', (during exercise) what fat does it burn first?"
] | [
false
] | As in is the fat burnt localised to the muscles that require the energy? Also how is the fat 'burnt'? An oxidation process? | [
"You can NOT target fat loss.",
" For example doing lots of ab crunches will not make you lose more belly fat than doing something else (e.g. bicep curls). Genetics alone will determine which fat is burned off faster.",
"Furthermore your body will actually burn your ",
"glycogen",
" stores first while those... | [
"This means it's important not to consume carbohydrates before working out, and you should also reduce your carbohydrate intake significantly at all other times too.",
"this is partially opposite to what people who are already in ketosis are doing ( the TKD diet ). they increase their carbohydrate intake (compare... | [
"Dogs4life's post is incredibly biased. It is far healthier for the vast majority of the population (basically anybody but epileptics) to eat at least a moderate carb diet.",
"It is best to eat some high glycemic carbs (such as an apple) about 45 minutes before a workout.",
"Fad diets like the ketogenesis don'... |
[
"Humans have huge brains. It's that the only thing we have going for us?"
] | [
false
] | I am always fascinated by the feats some animals can do, their amazing senses and evolution and adaptations. So... Besides our brains, do humans have any other kick-ass things that other animals would be jealous of? | [
"We sweat! This gives us very impressive endurance compared to most of the animal kingdom."
] | [
"opposable thumbs, though some other animals have this as well. "
] | [
"Bipedal motion and the ability to sweat makes us the best long distance runners.",
"Relevant: ",
"http://en.wikipedia.org/wiki/Persistence_hunting"
] |
[
"Massive space station's centrifugal \"gravity's\" effects on plants"
] | [
false
] | So, I hope this doesn't sound too sci fi, but, if a massive tubular space station were to be built (something along the lines of the spindle in William Gibson's Neuromancer; a long band of artificial sun in the middle, the ability to see straight across to the opposite interior surface) and there were big forests and such, would the trees growth be effected by the "spin gravity?" if the trees were big enough, and the tops grew closer to the center of the "spindle" space station, would they experience a different "gravitational" pull than the bases of the trees? would trees grow crazy in a gravity free environment for that matter? I know this is a bit of a muddled question, but any thoughts/insights are welcome. | [
"We are of course talking about angular motion.",
"For an object in uniform angular motion there is a constant angular velocity (radians per second).",
"--acceleration = radius x angular velocity",
"Say you built a giant cylinder with a radius of 1kilometre at \"ground\" level where there was a centripetal ac... | [
"He's asking about a hypothetical centrifugal space station probably of the order of at least 1 kilometre across. "
] | [
"Considering how easily trees can break apart rocks and damage metal structures with their roots, it would be a phenomenally bad idea to grow them in a spaceship. If you think they're bad when they get into your sewer pipes, imagine what it would be like if it breached the ship's hull halfway to Jupiter.",
"I don... |
[
"How will the James Web Space Telescope orbit AROUND L2 lagrange point?"
] | [
false
] | I've been reading up on the James Web Space Telescope and how it will orbit around the L2 point. I'm familiar with lagrange points and the balance of gravity which allows objects to be stable or meta-stable to have the same orbital speed around the sun as the Earth does while being in a different orbit "elevation", but how will the telescope orbit around the L2 point when there's not actually any attractor there? As I understand it, the L1, L2, and L3 points are the meta-stable ones, akin to a bowling ball being able to sit on top of a very small plateau on top of a peak. Move too far from the L plateau, and the ball will roll down the mountain into the nearest gravity well. The JWST orbiting around the L2 at a distance seems to me like it would be circling the mountain at a constant elevation contour line below the level of the plateau, without ever rolling down hill. In contrast, the L4 and L5 points, being stable points, would be more like a saddle bowl on the side of the mountain with a small lake in it. The bowling ball could orbit around those lakes in the bowl with centripetal force keeping them at a stable elevation, ignoring friction. Is it the same phenomenon with the L2 point? Is it actually a lake at the top of the mountain with its own little bowl? I suppose that would look more like a volcanic crater, but I digress. In such a case the ball would be rolling around the rim of the crater, but would not have to stay in the center of a small plateau. But being that case, how would the L2 be meta-stable and any different from the stable L4 and L5? Can anyone explain or point me to a good source? I've not been able to find anything Googling, but having the right term for the phenomenon might help. Thanks! | [
"If you look at the individual coordinates then the point is unstable in the radial direction but stable in the other two. Overall that makes the point unstable but it gives a plane where you can orbit.",
"https://en.wikipedia.org/wiki/Lissajous_orbit"
] | [
"Have a look at ",
"halo",
" and ",
"lissajous",
" orbits. JWST will use a halo orbit. "
] | [
"Excellent. That at least gives me the right term to use for Googling to get a better grasp. Thank you."
] |
[
"Water boils at about 7 degrees in .01 atmospheres. Could you cook instant ramen in this boiling water?"
] | [
false
] | This question was inspired by . | [
"The process of cooking food works through the application of heat. Therefore, temperature is what matters. Whether or not the water boils is not very important. If water boils at 7 degrees, then the food won't heat up beyond the temperature of a fridge and it will not be cooked.",
"This is why people bring press... | [
"This is an experiment you can conduct yourself. The fact that the water is \"boiling\" at 0.01atm is irrelevant. Take some instant noodles, put them in cold water, and put that in your refrigerator and see what happens."
] | [
"The denaturing of proteins requires heat. Putting them in water at 7 degrees under atmospheric pressure would be no different than putting them in water at 7 degrees at 0.01 atmospheres. Cooking of any kind requires heat, not pressure."
] |
[
"I may sound stupid asking this, but how come we can see massively coloured and detailed pictures of objects in deep space (galaxies etc.) But not of certain objects in our own solar system? (Sedna for example)"
] | [
false
] | null | [
"Galaxies are huge. Sedna is small.",
"Not only in physical size, but in angular size as well: they actually appear much, much larger in the sky than Sedna does. The Andromeda galaxy is as large as the Moon in the sky, while Sedna is so small as to be barely resolvable.",
"In other words, galaxies, compared to ... | [
"Ah that actually makes sense. Is that just because telescopes enhance the light that we can already see? And if we can't see the light from the smaller objects we wouldn't be able to see them at all? "
] | [
"Well telescopes focuses light from a huge area onto a small one, in order to capture more light and details; that's just how they work. Keep in mind the distant galaxies we are imaging are producing their own light (and it's alot of it, from billions and billions of stars, some thousands of times brighter than ou... |
[
"Are hex-shaped pixels better than square-shaped? Are they viable?"
] | [
false
] | null | [
"The answer is, for the most part, no. Here's an easy way to see why. This is how you draw a rectangle and a circle in a square grid:",
"X X X X X X _ _ X X _ _\nX _ _ _ _ X _ X _ _ X _\nX _ _ _ _ X X _ _ _ _ X\nX _ _ _ _ X _ X _ _ X _\nX X X X X X _ _ X X _ _\n",
"This is how you draw a rectangl... | [
"Actually, hexagonal grids are square grids with odd and even rows offset by half a cell. So they're trivial to index and store. Interpolating the values isn't a huge deal, this is basic sampling and filtering theory. Both square and hexagonal pixel grids are ",
"voronoi diagrams",
", so linear approaches still... | [
"With a bit of knowledge of how to write device drivers, you can, indeed, hack your monitor to use hexagonal pixels. Then watch as every program ever written tries to draw rectangular pixels and then go crazy as your eyes tries to piece together the squiggly horror that results."
] |
[
"What happens to the large object orbiting the black hole?"
] | [
false
] | Let's imagine the space station with its center of mass having sufficient distance and velocity, so it can orbit a black hole. However, station is very large, and some parts of the station are below the event horizon. What happens to them? Do they get torn apart? If not, does it mean that people can go below the event horizon, and then get back up? (I am absolutely sure that they do not, it however seems to be possible from classical point of view(gravitational force is not fully balanced by centrifugal force, but it is with additional station elasticity force/ floor reaction force)) | [
"However, station is very large, and some parts of the station are below the event horizon.",
"No, they aren't. To an observer who's not actually falling toward the black hole, the event horizon is an impenetrable barrier. Nothing ever crosses a black-hole event horizon.",
"Do they get torn apart?",
"Say you ... | [
"…\"particles that eventually smack into the singularity\".",
"There aren't any."
] | [
"The surface area of a black hole is proportional to its entropy. So as the entropy of a black hole increases, due to scattering interactions with matter and fields, its surface area also grows. When the entropy decreases, due to thermodynamic changes over time, the surface area gets smaller."
] |
[
"Can we ever know the exact position of a photon."
] | [
false
] | Ok, so I've only ever had an introductory physics course. According to Heisenberg's uncertainty principle, the uncertainty of the position of a particle times the uncertainty of its momentum is a constant yes? But according to relativity a photon can only travel at c. So our uncertainty with regards to it's momentum must be zero. Wouldn't that imply that we have zero certainty about it's position? I feel like I'm conflating and/or abusing concepts here. Can anyone enlighten me? | [
"The momentum of a photon isn't mass times velocity, but rather its frequency times Planck's constant divided by its speed. You can't measure the frequency with absolute accuracy."
] | [
"Two things:",
"A photon's momentum is related to its wavelength according to p = h/λ, where λ is the wavelength and h is Planck's constant. Thus there is uncertainty in the photon's momentum since there is uncertainty in its wavelength.",
"We can't know ",
" quantity exactly. If you wanted to exactly know ... | [
"The uncertainty principle applies to photons in the same way that it does to regular particles. In this case, as already pointed out, frequency takes the place of momentum.",
"What this means is that light generally exists in little wave packets. A wave packet is a set of frequencies of light mixed together, and... |
[
"Why do flies rub their limbs together?"
] | [
false
] | Sometimes when flies land I can see them apparently rubbing their front and back limbs together. Is this some type of self grooming? | [
"Please keep this kind of material out of AskScience. "
] | [
"On-topic humor is the best kind of humor. Try to limit the rest of it",
"And above that is says:",
"focus on giving scientific answers to the question at hand."
] | [
"To the side, it says \"On-topic humor is the best kind of humor. Try to limit the rest of it\" pretty on-topic, considering they look like evil monsters rubbing their hands together menacingly.",
"A quick google search of ",
"\"Why do flies rub their legs together\"",
" confirms the OP's suspicion on self... |
[
"Can the stomach of an obese person hold more than the stomach of a regular person?"
] | [
false
] | [deleted] | [
"Yes. Its the same situation as people who get their stomach stapled. If they continue to eat the way they used to, it can stretch right back to almost normal size again."
] | [
"For the most part, yes, but mainly because obese people are almost always obese because they eat a lot more than necessary and thus expand their stomach capacity that way. The bigger stomach essentially causes obesity (indirectly) rather than the other way around. If you were to somehow become obese without overea... | [
"Interestingly while obese people are likely used to eating larger amounts than normal people, lean people are more able to greatly exceed their normal food intake. This is because the fat buildup around the midsection acts to restrict the expansion of the stomach.",
"So while an obese person will likely have a m... |
[
"If the flu adapts around the vaccine every year, why don't we let everyone catch the flu once and be done with it?"
] | [
false
] | null | [
"There's a few reasons: \n1) because it also adapts around whatever individuals in the population have had previously,\n2) there are lots of different strains of flu,\n3) immunity wanes, and\n4) flu kills a lot of people every year, and that's WITH flu vaccination in place.",
"Basically at all times there are loa... | [
"Great answer. Thanks!"
] | [
"You're welcome!"
] |
[
"Some genetic mutations cause disease when inherited from the mother, but not the father. What is going on?"
] | [
false
] | Some genetic mutations cause disease when inherited from the mother, but the same exact gene sequences do not cause disease when inherited from the father. What causes this? I am guessing it has to do with genetic imprinting, and maybe epigenetics. Point me in the direction of the relevant Wikipedia articles, please. What happens if the mutation is sporadic? Is that the right term? Inherited from mother -> disease. Inherited from father -> healthy. What about the case where neither parent had the mutation, and this is a newly emerging mutation that first appeared in the child. Is sporadic mutation the right term for this? Is there another term? Can you link to any mutations which have this trait? Namely, can you list some mutations that are more likely to cause disease if inherited from one parent based on the parent's gender. Thank you. EDIT: I am only talking about autosomal dominant mutations, not sex chromosome mutations or recessive mutations. You can deduce this from my original post. For instance, you can deduce that I am talking about dominant diseases, not recessive diseases, because I say that the mutation causes a disease when it is inherited from only a single parent. | [
"Epigenetics and imprinting are at play in the case where different diseases are caused by inheritance from different parents. There are also diseases that are only inherited from fathers. The other post here so far describes X-linked inheritance, which is a different scenario than what you are trying to describe... | [
"This is exactly the answer I was looking for, thank you."
] | [
"Epigenetics, as sasky_81 already explained well, certainly answer your conditions. There is another option, which you might not be expecting. Maternal effects (",
"Wiki",
") cause offspring to have the same phenotype as the mother, no matter what the father's phenotype is. This is because the egg/oocyte is ... |
[
"If I placed a cold pot into a cold oven, then turned the oven onto 350 degrees. Will the pot reach 350 degrees at the same time the oven does?"
] | [
false
] | null | [
"The heating element will heat up first, then the heat will radiate from there. It takes a lot of energy to heat a pot of water, so that will probably take longer to heat than the air in the oven."
] | [
"Wait a minute. You could heat a metal pan much faster with a radiant element. Think of the sun heating your car. The surface will be much hotter than the air ever is."
] | [
"Depends how technical you want to be. If you hear the air very slowly, they will stay almost the same temp the whole time. ",
"Technically though it's a no. Since the pot is being heated by convection, the air would have to be hotter than the pot to give heat to it. So the air would have to be slightly hotte... |
[
"Are there ideas or knowledge about anything that would release more energy than nuclear fusion?"
] | [
false
] | null | [
"Matter-antimatter annihilation."
] | [
"Matter-antimatter annihilation is a direct and ",
" conversion of mass into energy, so you can't get more energy out of a reaction than that unless you discover some even more exotic type of matter that interacts via a mechanism we haven't discovered yet.",
"I don't know about any steps in-between fusion and a... | [
"Is that where it ends? And is there something between Matter-antimatter annihilation and nuclear fusion?"
] |
[
"How did domestication actually happen?"
] | [
false
] | [deleted] | [
"I cannot give you a general answer, but one that I found convincing in the case of wolves/dogs:",
"Wolves might have fed on human leftovers, at least the ones that were not too shy to go near human settlements. And the ones that were aggressive towards humans were more likely to be killed than the tame ones. So ... | [
"Sometimes referred to as \"self-domestication\"."
] | [
"Russian scientists experimented with ",
"creating a domestic fox",
"."
] |
[
"Why does tapping a beer bottle on its top result in foam, but a standard 'cheers' tap doesn't do anything?"
] | [
false
] | I've seen this happen a few times: someone takes the bottom of their beer bottle and taps it on the top of another one, causing the beer to foam violently. Why doesn't this happen with a clink from the side? I would guess it has something to do with the vibration propagating down the sides, agitating the liquid enough to cause nucleation points to form. But if that was the case it seems like a clink from the side would do the same thing. | [
"I thought something like this too;",
"The glass is pushed down, the liquid lags behind \"in freefall\", pressure thusly drops, the glass jerks back up, and the pressure increases again.",
"Edit: On the other hand, this happens fine when victimized glass is placed firmly on a table as well. And it's seemingly a... | [
"I was skeptical of this as well.",
"I was talking with a buddy at a bar, and the best we could come up with is that the vibration from the top moves down the sides of the bottle at the same speed on all sides, meets at the bottom of the bottle, and then returns in the opposite direction with weaker energy. Possi... | [
"I was skeptical of this as well.",
"I was talking with a buddy at a bar, and the best we could come up with is that the vibration from the top moves down the sides of the bottle at the same speed on all sides, meets at the bottom of the bottle, and then returns in the opposite direction with weaker energy. Possi... |
[
"If not even light can escape form a blackhole, how does radiation and energy leak out?"
] | [
false
] | [deleted] | [
"There are two things you might be thinking of... Neither of them is really radiation the way you might expect.",
"Radiation can be emitted when things slam into each other on their way around or into the black hole... That's what we often see as a jet of particles or radiation streaming outwards from the hole...... | [
"You'll hear a lot of answers - you have already - talking about particle-antiparticle pair production near the event horizon, and how one falls into the black hole and the other escapes. Those are decent answers because they're very intuitive, but the problem is they aren't exactly correct. Even Hawking (who uses ... | [
"The black hole has to repay the debt with its own mass of the escaped particle that came into existence."
] |
[
"My girlfriend asked me, and I told her to /r/askscience instead. So here: Why have animals shrunken over the course of evolution?"
] | [
false
] | [deleted] | [
"My understanding is that a number of factors are at play, including:\n1. Most recently, human predation has selected against large size in animals because of their high desirability in hunting. (see stellar's sea cow, the largest fish in the ocean, the buffalos, etc.)\n2. The largest animals have always had to be ... | [
"can you be a bit more specific about which animals?"
] | [
"That's not true."
] |
[
"When a person severs a body part like a finger , or part of foot and doctors are able to stitch it back on do the severed nerve endings and blood vessels reconnect? Or do they form new nerve endings,and blood vessels?"
] | [
false
] | [deleted] | [
"I have assisted at microsurgery for limb reattachment. Larger blood vessels and nerves are relatively easily brought together, but the nerve bundles within a nerve sheath can’t always be directed to the muscles they originally supplied. Many tiny blood vessels and nerves are sewn together with suture material so t... | [
"They're stitched back together with very fine suture. Unfortunately that doesn't stop the downstream axons from dying, it primarily functions to leave a tract of support cells for the neurons to use as they slowly regrow."
] | [
"Individual nerve cells are hair thin, they're organized into bundles though. It's the thicker connective tissue that holds all the individual cells together that can be stitched together."
] |
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