title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"How is quantum entanglement achieved in real world practice?"
] | [
false
] | From what i think know, you take two particles at one location, magically entangle them(this magic is the core of my question), then separate the particles and measure. Is it a synchronization of say their magnetic fields or some other energy that makes them deterministic after being separated? Do they have to be "ide... | [
"Well one common way is to use non-linear crystalls for ",
"Spontaneous parametric down-conversion",
". Basically, the crystal splits an incoming photon into two new photons. But since there are conservation laws, like conservation of energy and momentum, those two new particles can't be arbitrary and basically... | [
"Thank you for the answer.",
"\nThe second link was actually a Forbes neuroscience article about Kate Fehlhaber."
] | [
"Xeno's answer is a good one but I thought I'd add that entanglement is a relation between pieces of quantum information and not, necessarily, between two particles (identical or not).",
"A fun example of this is that if you have a particle which carries multiple pieces of quantum information then you can entangl... |
[
"Are there any examples of animals keeping other animals as pets?"
] | [
false
] | null | [
"It was baboons in Saudi Arabia. This was written about it in 2012 when the author researched the veracity of a video that went viral: ",
"https://www.huffpost.com/entry/a-scientific-mystery-do-w_b_1714600",
"The place, baboons, and dogs are real. The question whether the dogs are pets remains."
] | [
"It was baboons in Saudi Arabia. This was written about it in 2012 when the author researched the veracity of a video that went viral: ",
"https://www.huffpost.com/entry/a-scientific-mystery-do-w_b_1714600",
"The place, baboons, and dogs are real. The question whether the dogs are pets remains."
] | [
"Not an expert, but it really depends on what you mean by \"pets\". There are 2 big reasons why the answer is mostly \"no\"; ",
"1) modern humans provide our pets with food. The vast majority of animals can't afford to waste excess energy getting food for an animal of another species. If the pet eats the same st... |
[
"What is the minimum area in which rain can occur?"
] | [
false
] | What I mean is a constant, normal rainfall, however brief. Not scattered droplets. What is the least area that it is possible to be limited to, without our interference? | [
"Your own definition has doomed your question. When you say \"I don't mean scattered droplets\", well, what exactly are you asking? Technically one drop is the minimum amount of rain that can fall from a single cloud (and yes, this is completely possible). Technically a stream of drops could fall in single file, ma... | [
"I'm not an atmospheric scientist, but couldn't a frigid breeze cause nearly any amount to condense? In which case hypothetically you'd need as much as it takes to cause a drop?",
"First we need to define \"rain\". Is 1 drop rain? 2? 2000?"
] | [
"How about just an order of magnitude? If you had a 1 cm",
" cube could it form rain? 1 m",
" ? 1 km ",
" ?"
] |
[
"Phobias. What causes them and why is it that some are more \"powerful\" than others?"
] | [
false
] | Are they purely physiological in nature (like they originate from past traumas) or is there some other factor that plays into them, like chemical imbalances or some other kind of thing. | [
"Fascinating. Thank you."
] | [
"There are basically 3 ways its developed. Through classical conditioning, vicarious acquisition, and and informational acquisition.",
"Classical: think of this as fear caused from something else negative. Say you have someone in a room. You shock them with a taser. Naturally, they will fear the shock, but if you... | [
"About the second part--why some are more \"powerful\"--there is some evidence suggesting we are predisposed to fear some things. Monkeys raised in laboratories and never exposed to the jungle are more easily conditioned to fear a plastic snake than some other objects. I think there's reason to suspect that thing... |
[
"Why does squinting make my vision clearer?"
] | [
false
] | null | [
"First of all, realize that this only works for people who have vision problems due to incorrect focusing of the light. For our eyes to work properly, incoming light must be focused down to the retina. When this does not happen, either because light is focused in front of the retina (a condition called myopia or ne... | [
"Just adding a little something.. there's actually something called ",
"Pinhole Glasses",
" that make use of this effect. Growing up, I had a friend who had a pair of these and it really was pretty amazing how sharp they made things. I doubt they do anything to improve vision long term as they're often market... | [
"Awesome answer, thanks! "
] |
[
"How far along are studies that connect obesity with not having a sufficient flora of \"good\" bacteria in the gut? Also, does holding your poop in for an extra day or two, instead of defecating at first urge, affect this?"
] | [
true
] | [deleted] | [
"I recently saw Dr. Ley give a presentation on this topic, which she just published here: ",
"www.ncbi.nlm.nih.gov/pubmed/22863002",
". ",
"She compares the change in microbiota of pregnant women at different trimesters to those of individuals with metabolic syndrome, i.e. increased adipose deposits, high BP... | [
"It's not that obese people have a \"bad\" microbiota (microbiota is the term used to describe all the microbes associated with a host) but that there's is different. We aren't 100% sure why obese people have a different microbiota, nor how this difference arises. We aren't use if obese people have a different mi... | [
"I wouldn't really think of feces as breeding grounds for bacteria, but more as a bunch of \"extra\" and \"waste\" bacteria that get pushed out with the rest of the waste (along with any bacteria that couldn't adhere itself to something to keep it in place). ",
"The issue with fecal transplants, at least as I un... |
[
"The sun is travelling at 800,000k/h. Could earth ever transfer orbit to another passing star at these speeds without getting obliterated?"
] | [
false
] | null | [
"Such hypothetical / speculative / open-ended questions are better suited for our newish sistersub ",
"/r/asksciencediscussion",
". Please post there instead."
] | [
"Fair cop. I got this last time and that sub didn't exist last time, so I got pointed to a dead sub where no-one answered.",
"It's just that I saw a question about lifeforms existing outside of the temperature zone we live in, and it seemed based on hypotheticals about what kind of life could exist outside that b... | [
"Perhaps a more general phrasing would work; something like \"could a planet change orbits from one star to another?\" Or \"can a planet be captured by a passing massive body?\""
] |
[
"If both sound and temperature are both vibrations in a medium, why can't we hear heat or feel heat from sound? What separates the 2?"
] | [
false
] | [deleted] | [
"Sound is an oscillation of pressure in a medium (think of a ripple created from a pebble dropped in a pool), whereas heat is a vibration of molecules (think about playing with a paddle ball). ",
"We can't hear heat because the vibrations associated with heat are at the atomic level. There's no way those tiny ato... | [
"You hit upon some import points and your discussion of sonicators is interesting. However, there are some subtleties which should be addressed.",
"The thermal motion of particles (what we measure as heat) and the motion of particles due to sound waves are different because the first is random and the second is c... | [
"Thanks, this explains a lot!"
] |
[
"Why is my beard hair different than my head hair?"
] | [
false
] | My head hair is very curly | [
"The growth and the distribution of hair are under the influence of the sex hormones. At and following puberty, longer, coarser, more heavily pigmented hair, called terminal hair, develops in the armpits, genital regions, and, in males, on the face and sometimes on parts of the trunk and limbs. The hair of the scal... | [
"Androgenic hair, the growth of which is regulated by androgens (male hormones), is the terminal hair that develops on the human body during and after puberty, so essentially they are the same kinds of hair. What makes them different is their location."
] | [
"Androgenic hair, the growth of which is regulated by androgens (male hormones), is the terminal hair that develops on the human body during and after puberty, so essentially they are the same kinds of hair. What makes them different is their location."
] |
[
"How does seeing things far in the past work (with a telescope)?"
] | [
false
] | null | [
"Telescopes detect light. It takes time for light to travel from one place to another. If a star is 10 light years away from the telescope that means that it would take light ten years to reach the telescope. So when you are looking through the telescope, you are receiving photons that were emitted 10 years ago bec... | [
"But if you looked at light from the beginning of the universe (assuming there is one), it would be really far away (perhaps billions of light years) but could our current planet actually be part of that star matter (and could we see it?)"
] | [
"I don't understand what \"that star matter\" is referring to. Can you try rephrasing your question?"
] |
[
"What limits the range of artillery?"
] | [
false
] | Current (non-propelled) artillery systems are limited to a few dozens of kilometers. What physical phenomenon is limiting their range? | [
"Air resistance, mainly. Drag for high speed projectiles depends on the square of the velocity. Secondly is gravity: for a certain velocity, there is a limit to how far you can go. ",
"Both of those things can be overcome by building bigger guns and using more propellant, but you need a pretty big gun and the eng... | [
"Thanks for your answer!"
] | [
"Do you have a link to that project?",
"The purpose of my question is that I'd like to understand why there have been no major advances in artillery range since WW1."
] |
[
"Read a really strange article that says we need bacteria (p. Syringae) to make rain and it was full of microbiologist quotes. Is this a commonly accepted theory?"
] | [
false
] | Heres the place I read it. Still can't believe I've never heard this before. | [
"I was also a bit surprised about it. I researched a bit (5 minutes) and this is what I found so far: \nThe Verge wrote a sensasionalist piece of crap, full of out-of-context quotes by a bunch of laser-physicists that don't know anything about atmospheric science, but I guess were happy with the attention. ",
"Ho... | [
"I agree with ",
"/u/vonBeche",
". To me, the most head-scratching part of the article in TheVerge was the quote towards the end, from ",
"Russell Schnell of the NOAA",
", in which he claims \"To make rain, your clouds have to form first an ice crystal\", which according to TheVerge then will \"turn into r... | [
"(and, yes, that is an invitation to educate me, if you have sources to back up this claim)",
"In the process of ",
"educating myself now",
", but feel free to help!"
] |
[
"What differentiates edible gold from the gold in my computer or a ring?"
] | [
false
] | I've been watching a Youtube series called "Most Expensivest Sh*t". And in it the rapper Two Chainz basically reviews super expensive versions of everyday items. In one episode he tries a 5 dollar kernel of popcorn covered in "edible gold", what makes this gold edible and the gold you normally see inedible? | [
"Gold leaf used in food is just gold that has been pounded into a very thin sheet, usually only a few micrometers.",
"Metal leaf (called varak when used on food) is commonly used to ",
"garnish sweets",
" in South Asia (with silver being more common than gold). The amount used is very miniscule, and so it doe... | [
"There's no difference. You could swallow a gold ring and you'd be fine; it would pass straight through your digestive system. Gold is inert and won't be affected by digestion. ",
"The gold used on food is ",
"gold leaf",
". It's just regular gold beat into ",
" thin sheets - around 400 atoms thick. ",
"I... | [
"Edible gold is exactly the same as regular gold, except that it's generally been reduced to powder or foil so you don't hurt a tooth on it or choke on it. But you could swallow a (small) ring if you wanted to and be unharmed. ",
"Gold is biologically inert (which is why they used it for teeth in the first place... |
[
"When I wash my hands in a public bathroom and grab the door handle with a paper towel, does the paper towel actually prevent germs from getting on my freshly washed hands?"
] | [
false
] | [deleted] | [
"Even without the paper towels, your hands are perfectly safe. When I took my microbiology class, near the end of the semester we all decided to take swabs of random things/places and culture whatever we swabbed. The two groups that swabbed the bathroom handles, expecting them to be dirty, didn't get anything. Bact... | [
"This is only related, not directly answering your question, certain metal surfaces like copper and brass are very good at killing bacteria. That's often why you'll see metal handles on the side you pull and a metal plate on whatever side you push.",
"Metallic Copper as an Antimicrobial Surface",
"Antimicrobial... | [
"What about just material? Dead bacteria, their toxins, fecal matter....etc",
"Is a piece of paper towel a sufficient barrier?"
] |
[
"Do plants of the same size give off the same amount of oxygen?"
] | [
false
] | Are there any plants that give off a higher percentage of oxygen per centimeter of (plant space?) than other compatible plants? What would be the best house plant for good fresh air? | [
"Oxygen is a waste product of photosynthesis. Different plants can have different maximum photosynthesis rates. Mechanism like ",
"photorespiration",
" and ",
"non-photochemical quenching",
" can reduce photosynthesis rates. At higher lighting levels plants are going to be CO2 limited as to their maximum ph... | [
"I would look at plants that grow at different rates. The other byproduct of photosynthesis (sugar -> cellulose) has to go somewhere. I’d guess the faster a plant grows, the more O2 it’s producing."
] | [
"Air is more than just oxygen, it's mostly nitrogen. \"Fresh air\" is probably air with less pollution. So you would probably want to look into plants or filters that absorb more pollution than plants that produce more oxygen."
] |
[
"Science fiction gives us many examples of human-habitable Single-Biome Planets. Would anything like these be possible in reality?"
] | [
false
] | To give examples from , Tatooine is entirely desert, Hoth is entirely ice, Dagobah is entirely swamps. All of these have breathable atmospheres and temperatures that are (if uncomfortable) within human tolerances. Would anything like these planets be possible in reality? | [
"Mars can be thought of as being one big desert, and Europa is a big ball of ice. Granted, these worlds do not have breathable atmospheres but I don't think it's to off to say they could. One of the biggest things that affect our weather patterns on earth is differential heating between land and ocean, so I think i... | [
"Though it might be fixed by having an atmosphere (I don't know, do you?) Mars doesn't quite fit the bill because of the extreme variation in temperature across day and night (and latitudinally?)"
] | [
"Deserts don't really have to do with temperature - just lack of moisture."
] |
[
"If you were to drive in a car at the same speed as a bullet and shoot backwards, would the bullet hang in mid-air? If so, how long?"
] | [
false
] | [deleted] | [
"As far as the bullet is concerned, this scenario would be effectively identical to a person standing still (with respect to the ground) and simply dropping the bullet. This example is a straightforward application of the principle of relativity (specifically ",
"Galilean relativity",
"). This principle tells u... | [
"I would like to add that technically it doesn't \"hang in mid air\". It immediately starts falling to the ground just like if you dropped a bullet.",
"The horizontal velocity would be zero but the gravity would still act upon the bullet. "
] | [
"Ignoring air resistance [EDIT: and the curvature of the earth, you pickypantses], it would fall with ",
" the same vertical acceleration regardless of its horizontal speed. The only difference is how far it moves horizontally before its vertical acceleration brings it down to the ground."
] |
[
"If you had unlimited money, what is the fastest way to get rid of a cold?"
] | [
false
] | Are there medical procedures out there average people cannot afford that would eradicate a cold in a day/a few hours? | [
"I'm going to go and overcomplicated the answer.",
"150 healthy men and women (aged 18–51 years) were randomly assigned to 1 of 3 groups: intranasal interferon (IFN)–α2b (6×106 U every 12 h × 3) plus oral chlorpheniramine (12 mg extended release) and ibuprofen (400 mg) every 12 h for 4.5 days (n=59 subjects); [..... | [
"I like the article, their results look quite convincing. Note, though, that one doesn't \"get rid of the cold\", but only",
" suppresses the symptoms.",
"*) I admit, of course, that efficient relief is close enough to a cure for most people."
] | [
"Its kind of a mixed thing. The interferon will increase your body's response to the cold, helping kill it off, where the other two would just mask the symptoms."
] |
[
"As a hospital security dispatcher, I see a lot of elderly patients who come into the ER for rectal bleeding. Why is this so common in the elderly population?"
] | [
false
] | To clarify. I work in the dispatch office which is directly across from the ED triage. I have access to a program which displays all ER patients info and their issues. I have no direct contact with the patients or staff and it would be distasteful to ask the staff in person. Any ideas? | [
"Elderly patients often have poor diets(no fiber), little fluid intake, and are usually immobile/static(no abd muscle flexion to help the intestines). They also have decreased smooth muscle tone in the intestines(just like any other muscle in the body), and are more prone to tears due to the age and fragility of th... | [
"Wow. Thank you so much for your thorough answer. I always want to use this subreddit for medical issues I don't understand. Google usually suffices, but it is nice to have a specific answer to a specific question. Also, I am now super motivated to take special care of my body and tubes when I am elderly. "
] | [
"this is the one thing I stress the most with my patients. take care of yourself NOW, and you'll reap the benefits later. overweight but don't have diabetes or hypertension? start exercising asap! 90% of americas medical problems are due to lifestyle choices(smoking, sitting on our ass, poor diet, drinking). Fiber ... |
[
"Is it possible to stop a reaction midway to study an intermediate?"
] | [
false
] | For example, in a synthesis of an inorganic compound (so enzymes will not necessarily be involved), is there a practical means of halting the progress of a reaction to study intermediates? | [
"Most of the time in chemistry if we refer to an intermediate we are usually talking about an unstable species that once formed very quickly reacts to form either the next intermediate or final product. In cases like these, it is not possible to stop the reaction or isolate the intermediate as it is so unstable tha... | [
"Thank you for your input. To be clear, I was asking about the stable intermediates. Are there any examples of practical means of studying these, perhaps by making the rate-limiting step so slow that the reaction stops altogether?"
] | [
"If you are interested in stopping a reaction part way through, there are several common methods that are used, but what will work is very dependent on the reaction that is taking place.",
"One method is cooling the reaction down. In general, all reactions are slower at lower temperatures and some reactions can b... |
[
"Are there any examples of two animal species that both regularly hunt/kill each other?"
] | [
false
] | Basically they could be could be each others' prey or predator. | [
"Last year I watched a huntsman spider and a gecko run at each other presumably to attack. As they got closer they both sort of paused, had some sort of mexican stand-off, then realised they'd sized the whole thing up wrong before noping out of there to find something smaller for both."
] | [
"There are a lot of examples, but they tend to be at different ends of their lifespan, so it might not be what you're looking for. IE lots of predators eat the offspring of other predators. Snakes and birds, birds and other birds, amphibians and insects, mustilidae(weasels, etc.) and rodents, many many animals. "... | [
"before we evolved out of it",
"I don't think there's anything in our genetics that prevents cannibalism. It's more of social pressure that stems it."
] |
[
"Do all salts taste like table salt?"
] | [
false
] | null | [
"They do not. A salt is just two groups of opposite-charged ions (there is a more complex acid-base definition that I'm not entirely confident on. Hopefully another Redditor can provide it). Table salt, NaCl is a 1:1 ratio of positive sodium (Na) and negative chloride (Cl) ions.",
"But there are lots of other sal... | [
"To take a different tack, \"the taste of salt\" isn't a property inherent to a specific chemical formula--it's a perception, so it's all about your nervous system. The taste of salt is a specific pattern of neuronal responses that you've learned, over time, is because of the presence of salt in your food (or in yo... | [
"The acid-base definition is simply that when you make a proportional mix between an acid and a base, you get water plus some byproduct, and that byproduct is defined as a salt. This reaction between an acid and a base is called \"neutralization\". ",
"Table salt for example is created from:",
"NaOH + HCl -> H2... |
[
"How is this cardboard guitar able to withstand the 200+ lbs of tension applied by the strings?"
] | [
false
] | As seen here: | [
"Incredible. OK, after watching the video here are some thoughts:",
"The cardboard stock they use is very high quality, this is not some discarded packaging.",
"The orientation of the honeycomb structure is crucial.",
"If you check 1:30 you see that the fingerboard has a clear layer on top, which also helps ... | [
"I would say the truss rod is the only real 'body' a guitar needs. The string vibration can be picked up on the neck or even on the nut. The entire pickup (front body) area is optional.",
"Also, this puts to rest the notion of material having a major effect on electric guitar sound. ",
" on sustain, but I doubt... | [
"The tension runs from the bridge to the tuning pegs, so you need a little more than that. That said, the 'pick guard' may also be acting as a compressive structural element, so the cardboard would only have to act in tension (which would make it pretty strong.)",
"Electric guitars really only need to be stiff.... |
[
"If our bodies are most comfortable at 98.6° F (or some approximation of that), why is air of the same temperature during the summer so uncomfortable for us?"
] | [
false
] | null | [
"Our bodies constantly produce heat (at a rate of about 100 W averaged over the entire day) and one of the main ways of getting rid of this heat is through heat conduction to the surrounding air. The rate at which this heat transfer occurs is proportional to the difference in temperature between our body and the ai... | [
"I don't know if that's a question that has an answer, our bodies are too adaptable for that. It's why people in hot and cold climates disagree on what a hot day is"
] | [
"at a rate of about 100 W averaged over the entire day",
"Which is also about 2000 calories per day."
] |
[
"Yet another backhole question..."
] | [
false
] | Let's first discard some stuff as realistically as possible: 1. I'm an AI on a sufficiently small device such that tidal forces won't affect me. 2. I have enough power on me that I can dive into a BH perpendicular to its surface (as opposed to going in spiral). Let's say I tell my friend Herpina to stay at a finite dis... | [
"in short, in theory, yes. But science is about predicting observations. And the predicted observation for \"Herpina\" would be that you are stuck on the event horizon. Although she could equally predict",
" your observations as you fell through. ",
"note 1: There's no way to confirm her predictions however. In... | [
"I don't understand where the idea that you reach the speed of light upon reaching the black hole comes from. I think that's the misconception we're facing here.",
"Let's treat gravity as a \"force\" for instance. A force can increase your momentum (as viewed from an outside observer). But momentum is defined to ... | [
"Ah. Are you implying that you exceed the speed of light when entering a black hole? That wouldn't be the case I'm pretty sure. See you of course would only ever measure yourself as being at rest. And the external frame will always see you frozen on the event horizon, so your speed in any frame in the universe outs... |
[
"Is it possible for flatulence to transmit pathogenic organisms or other disease? If not, why not?"
] | [
false
] | null | [
"Relevant info: ",
"http://www.thenakedscientists.com/HTML/content/interviews/interview/917/"
] | [
"Yes, it can be transmitted through gas?"
] | [
"Yes, it can be transmitted through gas?"
] |
[
"I have never heard a satisfactory explanation for the active camouflage of some octopi and chameleon's to mimic their surroundings down to the details."
] | [
false
] | We've all seen it- nature shows where an octopus changes in a moment to blend in seamlessly with a multi-colored seafloor below, down to the pebbles and grains of sand. How do they do this? Do they mentally take stock of their surroundings and imitate it? How do they do it so fast? What chemical reaction is taking pl... | [
"It's not a chemical reacation, it's their chromatophores changing size/shape.",
"Last thing I read about how they match patterns, especially those behind them (they can't see it) was \"we don't know\". Presumably they get a look at it at some point or see what's on their left/right and produce a blending patter... | [
"This same question came up about a month ago and someone showed me a study where the octopuses.octopods.octopi produced changes in skin appearance when they couldn't see the environment. "
] | [
"there is some evidence that their skin itself has some visual capabilities. They have a very decentralized nervous system."
] |
[
"How do twisted pair wires reduce electromagnetic interference?"
] | [
false
] | I've scoured the web and I just keep finding sources that elaborate what a twisted pair is or their history. I cannot find anything that explains how twisting 2 wires around each other insulates them and prevents magnetic fields affecting them. Are they creating their own protective magnetic field? What is happening? E... | [
"The signals are transmitted over both wires in opposing polarity, but the EM interference picked up will have the same polarity. When both signals reach the other end, one is inverted and the signals are summed. What you end up with is “noise cancellation” of the interference. This happens because both wires will ... | [
"And the reason they’re twisted instead of just side by side is so that both wires are on average the same distance from the noise source, which better allows for the cancellation to occur."
] | [
"This image might help visually describe what’s happening\n",
"https://upload.wikimedia.org/wikipedia/commons/e/e7/DiffSignaling.png"
] |
[
"What are the factors that determine the lifespan of an animal?"
] | [
false
] | null | [
"Evolution is blind, it doesn't care how fast it goes. There is no such thing as \"better\" evolution. \nAlso, the working unit of evolution is the individual, and there is no advantage to the individual of going \"through many more generations faster\" or to \"adapt faster\". It is not the individual that is adapt... | [
"This is a fundamental misunderstanding of the way that evolution works.",
"I suggest you read a basic introduction to the subject (maybe The Selfish Gene?) Or this ",
"Khan Academy video",
"Nevertheless, I will try to explain in a nutshell:",
"1) individuals vary;",
"2) their traits are inherited by thei... | [
"Telomeres",
" determine how many times cells can reproduce.",
"They protect the DNA of the creature and set a hard limit for maximum possible life expectancy. All other factors controlling a creatures lifespan work only to cut down the longevity of the creature."
] |
[
"Why are some surfaces reflective and others not?"
] | [
false
] | Okay so I understand the fact that light bounces off of mirrors and other reflective surfaces and hit our eyes and produces an image and stuff, but why can't we see those images in other surfaces? I know that they absorb most colors and reflect the ones we see, but what makes mirrors so special? Is it the color? Someth... | [
"Surfaces are reflective when they're smooth. Most surfaces aren't reflective because on a microscopic level, they're quite bumpy and so when light hits them, the light rays are reflected all over the place. Meanwhile, mirrors are really smooth so the light bouncing off of them are all uniform, so the image is clea... | [
"It does! Thank you very much 😁"
] | [
"Haha! Something that is perfectly up my alley as an optical coating engineer (hopefully I don't make a fool of myself).",
"Mirrors are mainly created by coating some substrate (typically silica SiO2) with a highly reflective material at the wavelength band of interest. A mirror as you're probably used to (like o... |
[
"Do trees die of old age?"
] | [
false
] | If a tree lives in the same place, with the same environmental conditions, why does it die eventually? | [
"Interesting thoughts.",
"would it go on, and on, and on, or would it just die eventually, like a well cared for human being? ",
"Theortically yes.",
"But a tree was/is never meant to singular. The reason why giant oaks or maples are sometimes out in field or park, or an ancient yew in a churchyard, on thier ... | [
"I specialize in tropical forest ecology/ and molecular ecology. ",
"The main reason why trees die is not due to age but other factors like wind, rot caused by saprotrophic fungi, herbivory damage at younger ages, pest damage, competition with other trees and in some biomes fire.",
"If none of these agents are ... | [
"Interesting.\nI have recently seen a Quercus robur estimated to be over 600 years old. Its physical condition is very poor - basically falling apart and has to be kept together with human help, but it is still alive.",
"I'd like to know if there is a table somewhere, someone madr, showing the 'cause if death' fo... |
[
"What does it mean to have a mass of 0?"
] | [
false
] | I've frequently heard that the reason light is the fastest thing in our universe was because the photons that are apart of it have a mass of 0. So I was wondering if there was a way to visualize/understand that in layman's terms. | [
"Photons never accelerate to light speed. They move at the speed of light constantly. There is no transition from zero velocity to the speed of light. As soon as a photon exists, it is moving at the speed of light."
] | [
"Photons never accelerate to light speed. They move at the speed of light constantly. There is no transition from zero velocity to the speed of light. As soon as a photon exists, it is moving at the speed of light."
] | [
"Consider how light would behave if the mass was really low. As it approaches zero, light behaves like that. This allows you to work out how it behaves using equations in special and general relativity that don't quite work for m = 0."
] |
[
"How can we explain raising a number to an exponent?"
] | [
false
] | When I was in school, I was told that raising a power to an exponent, n, is that same as multiplying the number by itself n times. So, for example, 2 = 2 x 2 x 2 = 8. But that doesn't account for exponents < 1. So, for example, how could we explain 2 or 2 | [
"You're right, it doesn't. How do you get from \"Exponentiation is Repeated Multiplication\" to \"2",
"\" or \"2",
"\" or something? You can't multiply something by itself 0.22 times or pi times. To do this, we need to come up with, that is, invent, a new way to do exponentiation that allows us to do these new ... | [
"It's funny how many people I tutor never got a proper explanation of exponentiation in high school, I have to go through this process with them every time, and it always makes people think. I think part of the problem with math pedagogy is that we never work through why mathematicians defined things the way they a... | [
"I know this is a very late reply, but how do we get from x",
" - 2",
" = 0 to x = 1.165? "
] |
[
"Assuming we had a spaceship that was built in a space station (meaning there is no need for it to ever enter or exit a planet's atmosphere), would there be any need for it to be aerodynamic?"
] | [
false
] | null | [
"No, for example google a picture of the international space station, it was assembled in space and is not at all aerodynamic "
] | [
"So long as it never went through the atmosphere, staying in high orbit and using secondary shuttles to get people/resources back and forth sure.",
"There ",
" a very little bit of interplanetary dust, hydrogen, and all the rest of that good stuff that makes up our universe out there, but not enough to consider... | [
"The lunar lander was designed in such a way, that's why it looked so bizarre. \nThis is an awesome documentary about the design process.\n",
"http://www.youtube.com/watch?v=cwrXcuK4LgY"
] |
[
"Why do people spasm as they fall asleep?"
] | [
false
] | I wake myself up every once in a while because of this but figured they were random occurrences. However, my girlfriend tells me that my whole body spasms several times every night as I'm falling asleep. What causes this? Is it harmful or indicative of any medical issues I may have/develop? | [
"http://en.wikipedia.org/wiki/Hypnic_jerk",
"\"",
"When we drift of into sleep, the body undergoes changes in temperature, breathing and muscle relaxation. The hypnic jerk may be a result of the muscles relaxing. The brain misinterprets this as a sign of falling and signals our limbs to wake up; hence the jerki... | [
"Dug around for some peer-reviwed/clinical stuff. NOT TO GIVE MEDICAL ADVICE but most people report these jerky movements (known as 'hypnic jerks' or 'sleep starts') from time to time and it's harmless. There's no really satisfying explanation for the benign forms, though stress seems to be a factor. Have a read of... | [
"This sounds like calcified speculation to me."
] |
[
"Could Hubble Track Voyager 1, and What Would it Look Like?"
] | [
false
] | Is Hubble capable of looking at Voyager 1? If so, do we have any idea what it would look like? Would it be dusty? Frozen? | [
"I can't answer your question about what it would currently look like, but I can answer for you, that no- Hubble could not see Voyager 1. ",
"One of the things about Hubble is, it doesn't get all of the great pictures it gets because it has such a great zoom, it get's the pictures it gets because it collects a lo... | [
"Here's a ",
"recent Astronomy Picture of the Day",
" illustrating the angular size difference between the Moon and Andromeda."
] | [
"I found ",
"this",
" but I know it's not what you're looking for. I also know that google sky maps SKeye are two really cool android apps that can give you an amazing view and understanding of the night sky."
] |
[
"If a spacecraft was launched from the Moon, would the smaller and quicker rotation of the moon's orbit produce a more efficient slingshot effect than the earth?"
] | [
false
] | I just read an article that there may be sufficient water on the Moon to support a human base and got to thinking: if we were able to build a launchpad from there to visit other planets in our Solar System would it require less fuel to launch? I understand getting fuel there would be another issue, I am asking hypothet... | [
"Astronomer, but not an actual rocket scientist (orbital dynamics)",
"I'm inclined to agree with JasoTheArtisan. The primary benefit would be the lower escape velocity. This would only be realized if you could make rocket fuel using lunar resources. ",
"Generally yes, Gravity assist is a fly by method. ",
"... | [
"By the way, for anyone who is interested in space flight and orbital mechanics, this is a great simulator:",
"http://orbit.medphys.ucl.ac.uk/"
] | [
"layman here:",
"I would imagine that the only real beneficial aspect of launching from the moon would be a lower escape velocity than from earth. ",
"as far as the slingshot technique is concerned--and I haven't played with the maths--I think that's more of a fly-by while en-route technique. "
] |
[
"I'm reading this book on digital photography and I cannot get past one of the things I read...[quote inside]"
] | [
false
] | When comparing cameras to buy, you're likely to find moderately priced compact point-and-shoot models with the same number of megapixels as larger prosumer and SLR models that are more expensive. The big difference is image quality. Because the pixels themselves are bigger in size on the image sensors in larger-size ca... | [
"Yes the problem is that they have used the pixel in a relative way. The Pixel they are talking about here is the pixel density of the CCD sensor. see a close up of pixels in a CCD sensor in the ccd section of this page ",
"http://www.scss.com.au/family/andrew/camera/inside/",
"The problem with today's digital ... | [
"Their statement doesn't mix up usages at all. The pixels ",
" larger if the sensor is larger. Larger pixels = more light per pixel = better quality images. OP is simply confused about what resolution is."
] | [
"when they say large pixels they mean something different than what you're thinking.",
"The cheaper cameras have smaller light sensors in them. So an area on the sensor that is designated as the area for a pixel is smaller. The sensors on expensive cameras are bigger, so the area on them corresponding to a pixe... |
[
"How does power come out of a Tokamak or other fusion reactor?"
] | [
false
] | As I understand, fission reactors work on the same mechanism as any other steam power system - a lot of head is generated, this drives some water through a turbine, which spins a magnet and a wire, and electrical power comes out (nuclear/chemical -> mechanical -> electrical). From diagrams I have seen of fusion systems... | [
"At the moment it doesn't. Current reactors are experimental and do not generate power.",
"Extracting energy could seem like a problem with the very magnetic fields that you use to keep your plasma contained preventing it from touching anything to conduct it's heat away.but we are blessed with some good fortune."... | [
"Beryllium / Tungsten panels",
"No, the blanket would be outside the walls. You will have plasma facing components, in the case of JET and the plan for ITER they are Be+W,that the neutrons just pass through then a tank of something, heavy water/lithium etc that you heat up with the neutrons.",
"Presumably ITER ... | [
"So the Beryllium / Tungsten panels, seen ",
"here",
", are heated by the neutrons and conduct heat to a conventional turbine system? Presumably ITER will be the first to make use of that? And you imply that JET has not hooked up to an output system, but only measured the output neutron energy to get their 20MW... |
[
"Are there any deep sea explorations happening right now?"
] | [
false
] | Isn't there a lot of unexplored territory down there? I can't seem to find any explorations that are happening currently... (no pun intended) | [
"Well, what do you mean by \"unexplored territory\"? We have a vague idea what the bottom topography is.",
"Check this out: ",
"NOAA's ",
"This is the only full-time (well, mostly full-time) ship that the government devotes to ocean exploration.",
"In addition, there are constantly scientists working on ex... | [
"http://en.wikipedia.org/wiki/MIR_(submersible)"
] | [
"I'd also recommend checking out this Woods Hole site: ",
"http://www.whoi.edu/page.do?pid=7400",
" The Woods Hole Deep Ocean Exploration Institute is doing some pretty exciting stuff. For example, researchers there are investigating the deep ocean biosphere and geodynamic processes in the ocean floor (e.g., s... |
[
"Is it possible to estimate the density of a body based on the time it takes to sink through 1m of water?"
] | [
false
] | With only a video of an object sinking into 1m of water from which the time of descent can be measured can an accurate estimate of the density of the object be derived or is more information needed? | [
"You also need to know its size, shape and surface properties.",
"A smooth iron sphere of 1m diameter will not sink at the same rate as a smooth iron sphere of 1mm diameter."
] | [
"You could get started here ",
"http://en.wikipedia.org/wiki/Terminal_velocity#Terminal_velocity_in_the_presence_of_buoyancy_force",
"Maybe you'll even find a drag coefficient for humans in water, that would make things easier."
] | [
"It is, but not only with the premise in your title.",
"To calculate the drag coefficient you usually also need the density.",
"You can get around it but you need more information."
] |
[
"Would it be possible for a telescope to take HD photographing of Betelgeuse? If so, what would it take?"
] | [
false
] | Asking because I was kind of thinking about it and how it would be impractical to send a probe given it would take at least like 1500 years to receive data | [
"So, the angular size of Betelgeuse is about 47 milliarcseconds. A milliarcsecond is 1/100ths of an arcsecond, which is 1/60th of an arcminute, which is 1/60th of a degree, which is 1/360th of a circle. So it's very small in apparent size. By comparison, the Moon is about 30 arc",
" across. Pluto is about 60-110 ... | [
"That was a really interesting read, thank you for the answer! It’s kind of insane how good interferometry is and how good our pictures are even now (I mean it’s very blurry but I was expecting much much worse). So it seems like it definitely is possible, some day, which is really cool,\nI’ve heard about the ELT bu... | [
"Huh, so Pluto appears “only” about double the size of Betelgeuse in the sky. I would’ve guessed Betelgeuse would appear far smaller than that. ",
"And indeed, the pic you linked of Betelgeuse appears to have very similar detail to the best pic we had of Pluto, before the New Horizons probe arrived there."
] |
[
"Why is the amount of energy of 7 terra-electronvolts produced at CERN's LHC considered huge if it's a lot under 1 Joule (2.2 microJoules) ?"
] | [
false
] | [deleted] | [
"because that's the energy given to EACH PARTICLE they accelerate (well, technically its 3.5 TeV right now, not 7, but you get the idea). Imagine a speck of dust that hit you as hard as that bag of potatoes. That's gotta be moving fast. And a proton is much, much smaller than that fleck of dust.",
"edit: also,... | [
"When I run, I have about 1 kJ of kinetic energy, which is less than a quadrillionth my rest energy. When a proton moves with 7 TeV, its kinetic energy is 7000 times its rest energy."
] | [
"7 TeV's on a single proton is why. And protons are tiny.",
"Using k = mv",
" (incorrect for this application), using 1 TeV = 1.607 ^ -7 J, and one proton = 1.67*10",
" we get 25,888,323,855 m/s.",
"As it gets closer to the speed of light, though, it takes more energy to make it move, say 5 m/s faster. The ... |
[
"Is it possible to have a form of electricity other than AC or DC?"
] | [
false
] | null | [
"mostly semantics, but there is pulsed dc, variable frequency ac (trap or sine), polyphase ac, some motors even run on polyphase pulsed dc. And if you have a dc motor/generator, is it \"AC\" when the current reverses direction (but the voltage doesn't)? Plus probably lots of things I'm not considering.",
"edit,... | [
"i.e. what would you consider a cathode ray tube",
"Essentially an electron gun shooting a one-way stream of electrons onto a phosphor surface, wiggled from side to side by an alternating magnetic field, in order to paint a series of dots across the screen.",
"\"One-way\" is the essential thing. The electrons a... | [
"Surprisingly complicated question. It's important how you are defining electricity. I believe you are talking about the stuff that powers our machines which is basically us manipulating the electromagnetic force in clever ways. Two of those main ways are AC and DC which both deal with the direction of the flow of ... |
[
"What would happen if you shot a bullet through a high-powered laser beam?"
] | [
false
] | Standard 9mm? Airsoft? Super-soaker? As I understand it, the lasers we use for cutting materials require time and repetition. Would it be possible to cut a bullet in half with a laser, and if so what conditions would that require? | [
"I'm inferring the real question here is:\n\"How powerful a laser beam is required to cut through a bullet?\"",
"Let's do a little thermo.\n",
"This page",
" actually has a quite-good dimensioned drawing of a 9mm bullet, along with some numbers regarding mass and velocity in common stock. We can see from the... | [
"That's maximally 240MW, which is getting to the need an entire power station to yourself range. If such a laser existed there would be serious engineering concerns like, say, keeping it from vaporizing its own parts when turned on, and not setting fire to the surrounding countryside.",
"Bullshit.",
"Shooting a... | [
"I'm pretty sure there are complications to this problem beyond just pumping enough energy into the laser. Even if there's not enough time for heat transfer from the affected areas, vaporizing the metal is going to amount to a small explosion along the surface and interior of the bullet. I don't have the math or ... |
[
"What are the crests and troughs of light waves on an oscilloscope?"
] | [
false
] | Alternating current has both positive and negative voltage (travelling in both directions), represented on an oscilloscope as crests and troughs, with a line along the middle being zero energy. Does this mean that light can be both positive and negative? What have I misinterpreted? | [
"When measuring something with your oscilloscope you are measuring with respect to some reference (ground). Remember voltage is a scalar quantity and its value is relative to what you measure it to. What the positive/negative means in this case is that the voltage is either above/below ground. If the voltage is neg... | [
"The plots you often see where they depict light as a sine curve (wavey), are plotting the magnitude of the electric field. That is, at some points on the wave, the electric field is strong (a crest on the wave) and at some points it's weak (a trough on the wave). The strength of the electric field varies as a si... | [
"How do you \"observe light waves\" on an oscilloscope? Somehow you have to convert the light wave into an electric signal to display, and there are several methods to do this. If you can be a bit more specific, I'm sure that we can clear up your confusion."
] |
[
"Did Top Gear really find the source of the Nile and are they the first?"
] | [
false
] | Reddit seem to be fairly avid watchers of Top Gear so I assume most people know that in their end of season special they attempted to find the 'true' source of the Nile in £1500 estate cars. They claimed that no one had truly found the source and that some explorers have claimed to have found it but that this was not t... | [
"One definition of a river's source is the tributary starting farthest from the river's mouth. Using the point where the Nile empties into the Mediterranean as its mouth the possible sources of the Nile are on the west side of Lake Victoria.",
"For the Top gear special they redefined the mouth of the Nile from it... | [
"So that their amusing antic filled trip around the heart of Africa could have a driving purpose.",
"The idea was that since the Nile flows into the Mediterranean and the Mediterranean in turn flows into the Atlantic that you could view the Strait of Gibraltar as the true terminus of the Nile. It doesn't make a l... | [
"So that their amusing antic filled trip around the heart of Africa could have a driving purpose.",
"The idea was that since the Nile flows into the Mediterranean and the Mediterranean in turn flows into the Atlantic that you could view the Strait of Gibraltar as the true terminus of the Nile. It doesn't make a l... |
[
"How does a nerve gas mask differ from other gas mask?"
] | [
false
] | WWI mask were tested against chlorine , phosgene and mustard gas. What would be the necessary modifications to be effective against nerve gases, such as tabun and sarin? | [
"So i actually do this for a living, and the other comments have partially correct info but not the whole story. Firstly, nerve agents are not the only threat, they do however have alot of notoriety. There are other things to also consider such as blister, blood, and choking agents and biological agents (like anthr... | [
"While there are a lot of factors involved in your question, the short answer is in an open field, if you have been exposed to the primary source of contamination, youre probably going to die without immediate (like within minutes) treatment. Some stuff to think about though, exposure can happen through a many diff... | [
"CBRN trained. There is no difference between any gas mask used by armed forces. There are filters that differ in effectiveness, but The Armed Forces use only a filter that will filter all known agents. There would not be a situation where a lesser filter would be used as it would not be mission effective. Gas ... |
[
"Does staring at a computer monitor for prolonged periods in the dark damage your eyesight?"
] | [
false
] | I've recently read about how reading a book in the dark only causes temporary eyestrain rather than permanent eye damage. Also, I've read it's similar for staring at a computer monitor for long periods generally. But what about sitting in a dark environment and staring at a computer monitor? | [
"This was asked before, and I believe the conclusion was that it infact can't, and only cause strain but no lasting damage whatsoever. I'll try to find the post."
] | [
"Get ",
"F.lux",
", it adjusts screen color and brightness when it's dark. My night setting is at 4000K (daytime at 6500K) and it's a lot more comforting on the eyes when it's dark around."
] | [
"Seriously? Do you have any sources? I'd love to read more."
] |
[
"What has been/will be the eventual fate of all our space probes?"
] | [
false
] | This includes probes both in space or on planets/moons themselves. | [
"Either they will collide with a celestial object or they will evaporate.",
"Probes in orbits around other planets are, wherever possible, deliberately crashed at end of life. We just did this to the MESSENGER probe at Mercury.",
"This has the dual benefit of only contaminating the planets we want contaminated,... | [
"We could, a probe might be discovered in trillions of years. But what then?",
"Also, space is big. Really big. The chance of a probe being discovered is so small that increasing this chance by a million doesn't really change anything.",
"Don't get me wrong, I'm all for exploring space and sending probes, I jus... | [
"What technology we have now it still awfully slow. Voyager is currently leaving the solar system, and it was launched in 77. At this rate, it won't enter another star system for a few centuries, and (but we're leaving the reality of pure science to enter the realm of science fiction here) at this rate it's more li... |
[
"Why is it that leptons can exist individually but quarks cannot?"
] | [
false
] | [deleted] | [
"The strong force has a property called ",
". It means that by far, the lowest energy state is one where the net color charge of an object sums to white. In other words, the quarks are ",
" together in configurations that have zero net color. Nature prefers low energy, so this is the only kind of state found in... | [
"The reason is their interactions. Leptons do not interact through the strong force, whereas quarks do."
] | [
"The ",
"strong interaction",
" is responsible for binding quarks together into composite particles.",
"Since leptons do not carry the charge of the strong interaction (called \"color charge\", in analogy with electric charge), they do not get bound together. Quarks, on the other hand, ",
" carry color cha... |
[
"How is it possible that the solubility of a solid increases with temperature, but the solubility of a gas decreases with temperature?"
] | [
false
] | null | [
"The spontaneity of a particular process is given by ",
"Gibbs free energy",
":",
"ΔG = ΔH - TΔS",
"A negative ΔG means a process is spontaneous; a positive ΔG means the reverse process is spontaneous, and ΔG = 0 means the process is in equilibrium. From this relationship, you can see at what temperatures a... | [
"...a higher temp will make the liquid expand which leaves more room for the solid to slip between molecules of the liquid.",
"That's not what dictates how a solid dissolves into solution."
] | [
"It's a very easy way for people to understand it. More heat means more energy in the liquid, which can break apart the forces of the solute easier. "
] |
[
"Do plant roots excrete solid or liquid waste?"
] | [
false
] | null | [
"Plant roots can ",
"exude",
" many substances in liquid form, and these serve many different functions. Much of this is \n",
"root mucilage",
" made of polysaccharides (polymers of sugar in the same class as starch and cellulose). Root exudates are not quite like animal waste excretion, though. (They are c... | [
"I work in a vegetal biology lab and we work a lot on this question. A lot of plant exude different molecule such as mucilage but also extra cellular DNA and even some cells. All this things form a protection barrier against pathogen that we call RET (Root extra cellular trap)."
] | [
"it's only because of the process of evolution that we adapted lungs to breathe it",
"Aerobic microorganisms evolved well before anything even remotely resembling lungs existed. All higher life is oxygen-respiring."
] |
[
"A friend of mine doesn't recycle because (he claims) it takes more energy to recycle and thus is more harmful to the environment than the harm in simply throwing recyclables, e.g. glass bottles, in the trash, and recycling is largely tokenism capitalized. Is this true???"
] | [
false
] | I may have worded this wrong... Let me know if you're confused. I was gonna say that he thinks recycling is a scam, but I don't know if he thinks that or not... He is a very knowledgable person and I respect him greatly but this claim seems a little off... | [
"Recycling some materials does take more effort than other materials, but overall the energy you expend recycling something requires less energy than producing it from raw materials. ",
"Here's",
" a good article from the Economist that discusses the vice and virtue of recycling."
] | [
"For glass, most manufacturers try to purchase back as much cullet (essentially shards of recycled glass) as they can find. This is because adding the already melted glass to the furnace while making new glass can ",
"reduce energy consumption",
" by up to 25%. Because of the cost savings, manufacturers tend to... | [
"I'm guessing the economist article covers the recycling stuff, so I'll add that a better strategy is reduction- aka, if you buy less in the first place, a whole lot energy gets saved when you don't have to have it produced and don't have to have it recycled.",
"Of course, this leads to things like reusable shopp... |
[
"In Classical Physics, why does an accelerating charge give off radiation but not an accelerating mass?"
] | [
false
] | I mean I know in GR there are gravity waves which is what LIGO is set up for but just a curiosity. | [
"It may be best to look at classical mechanics as the limit of GR where masses are small enough and speeds are slow enough that you can ignore the crazy GR effects. In this limit, gravitational waves from an accelerating mass is one of those things you can ignore.",
"However, when you've taken this limit in GR, ... | [
"In classical physics, gravity propagates at infinite speed, so the information that the field has changed doesn't have a wave of propagation like the electric field does."
] | [
"Neat. Thanks so much."
] |
[
"Are scientist currently trying to find out the cause of the current explosion in the number of Dementia/Alzheimer's cases, similar to how scientist where able to successfully trace back exactly how AIDS originally started, and what eventually led up to the massive outbreak in the 1980's and 90's?"
] | [
false
] | null | [
"What's your question? "
] | [
"THE TITLE - Are scientist currently trying to find out the cause of the current explosion in the number of Dementia/Alzheimer's cases, similar to how scientist where able to successfully trace back exactly how AIDS originally started, and what eventually led up to the massive outbreak in the 1980's and 90's?"
] | [
"yes."
] |
[
"Why do all electrons have the same mass?"
] | [
false
] | null | [
"I was going to say that the best answer is that, experimentally, we have never found electrons with a different mass. (You can construct your theoretical models of the universe as ",
"/u/corpuscle634",
" indicates in his last paragraph, but in the end you have to validate those models with experiment. By ass... | [
"Because there's only ",
"one electron in the universe",
".",
"More seriously, there's a number of laws, theories, and principles that we can't explain the world without that rely entirely on every electron being identical (and thus having the same mass). I think anyone who's studied a decent amount of physic... | [
"He's not talking about mass.... but size (volume)."
] |
[
"In Conway's Game of life, is there a seed that doesn't end in a periodically repeating cycle of states?"
] | [
false
] | Many starting combinations in Game of life end in still life that repeats after a few cycles. Is there a starting position that results in a endless chaos that perpetuates itself? I guess this question makes sense only in Game of life variant with unlimited space because on a finite number of cells there is a finite nu... | [
"Conway’s Game of Life is ",
"Turing complete",
", and there exist ",
"recursively enumerable",
" calculations which result in a state of infinite length and no repeating pattern (for example, calculating the decimal expansion of pi), so the answer is yes. "
] | [
"Depends on if the board is infinite. If the board is finite, then there are a fixed number of possible combinations of states. If the process does not terminate then it must eventually repeat a state. Since the process is deterministic this must create a loop.",
"For infinite boards, GoL is Turing complete so it... | [
"It isn't repeating, though. You recognize it as repeating, but the fact that the plane is infinite means that no iteration will ever be exactly the same as any previous iteration. The only reason you consider that as repeating is an assumption based on intuition.",
"I mean, with just a single glider, at least yo... |
[
"What happens to motor and sensory region neurons after a limb is amputated?"
] | [
false
] | [deleted] | [
"They recirculate themselves and doesn't take very long to do so.",
"There is a interesting procedure that answers this. \n",
"https://www.youtube.com/watch?v=QQVAHbAV8QM",
"If the leg is amputated above the knee, there is a procedure that can allow your foot to be attached (backwards) at the amputation point... | [
"cortical neurons getting recruited for contralateral limb would be impossible since those are represented in opposite hemispheres; a slight shift in the representation (e.g. from one finger to the next, or up or down a limb a bit) is possible and has been shown in monkeys.",
"there's a big limitation on this pla... | [
"Thanks a lot. What would happen if you were born without the arm? Would a residual limb be overrepresented on the cortex instead of what would normally be neurons in charge of hands and fingers?"
] |
[
"Alright zoologists (or ornithologists), why do birds stand on one leg so often?"
] | [
false
] | Also, when I see a grackle doing a funny dance where it kicks back its wings and opens its beak and starts chasing another one around, is the grackle attempting to mate or scare off the invader? | [
"It regulates heat loss. See: ",
"rete mirabile",
". I don't know what the Grackle is doing."
] | [
"For the grackle, yes, that is a mating dance. It is always the larger black male who is courting a lighter colored brownish smaller female. Sometimes there are multiple males competing at the same time. You can also notice them puffing their feathers out to make themselves seem bigger. Grackle stuff ",
"gene... | [
"TIL Grackle calls are more colorful in ultraviolet light."
] |
[
"How (if at all) do architects of large buildings deal with the Earth's curvature?"
] | [
false
] | If I designed a big mall in a CAD program the foundation should be completely flat. But when I build it it needs to wrap around the earth. Is this ever a problem in real life or is the curvature so small that you can neglect it? | [
"I imagine the local terrain would be a much larger factor than the curvature of the earth though right?"
] | [
"I imagine the local terrain would be a much larger factor than the curvature of the earth though right?"
] | [
"Right now, I'm at \"the straightest object in the world\". The SLAC National Accelerator Lab. As others have mentioned, the curvature of the Earth is something like \"8 inches a mile\". Well our linac is 2 miles long and we need it to be actually straight and not follow the curvature of the earth. Otherwise the el... |
[
"How good were our ancestors at keeping track of time in previous centuries? Is it definitely 2011?"
] | [
false
] | [deleted] | [
"There's actually a theory called the Phantom Time hypothesis that the dark ages never happened, and that we're actually in the 1700s now. This theory is totally, completely bonkers, but I suspect that if you track down some of the debunking articles on it you will get a good start on the evidence for the current d... | [
"then again it is only 2004 in Ethiopia... ",
"clickkk"
] | [
"We've been using the Gregorian calendar since the late 1580's, when Pope Gregory XIII introduced a calendar system to replace the Julian calendar that had been in place since 58 BC when Julius Caesar implemented it. The Julian calendar was replaced because while it assumed that the year was 365.25 days long, the ... |
[
"What keeps the ISS stable when a craft docks with it?"
] | [
false
] | When a craft docks with the ISS how does it compensate for the force exerted on it by the other craft docking. Why is it able to maintain its stability and not spin out of control. | [
"Both craft are orbiting together in the same orbit. Just before docking they are almost stationary with respect to each other. Once docked they ",
" stationary with respect to each other. Tidal forces are too low to complicate their docking."
] | [
"Tidal forces are too low to complicate their docking.",
"They don't complicate the docking but they are important afterwards. The ISS flies in an unstable equilibrium, gyroscopes constantly have to fine-tune its orientation and spin rate. That balance changes based on the crafts docked to the station. The stable... | [
"Thank you!"
] |
[
"Glaciers have been melting for decades now. What conditions would need to happen for them to reform?"
] | [
false
] | And on a different note, can they even reform? Would the glaciers be new and would they settle in a different place compared to where they were before? Or would they grow from existing ones? | [
"What conditions would need to happen for them to reform?",
"Colder average temperatures. There is certainly a good deal of nuance in terms of needed changes in temperature (e.g., are average melt season temperatures more important than average freezing season temperatures, etc) or radiation balance that one coul... | [
"Very simple answer:",
"Glaciers are fed by snowfall. Glaciers melt when temperatures are above freezing. If snowfall amounts meet or exceed the melt amount, the glacier stays the same or grows, and vice versa.",
"A glacier can form anywhere there is sufficient snowfall to make ice, and the ice starts flowing. ... | [
"A large-scale caldera eruption could produce short term cooling (e.g., ",
"Jones et al., 2005",
"), that could lead to some amount of glacial advance, but as highlighted by climatic effects from past large-scale eruptions, global effects can be quite diverse, e.g., the variability in responses regionally to th... |
[
"Why do we start to feel sick (or even throw up) when we go beyond our limits while sporting?"
] | [
false
] | I know so many people who had the feeling to throw up, after they were pushing their limits in a condition training (swimming, running) or power training, i have even experienced this myself sometimes. An example is someone trying to lift weights, but because they are putting so much force they start to throw up. Im t... | [
"Blood flow is shunted away from the digestive system, in order to improve oxygen delivery to muscles. Diminished blood flow to digestive organs means that digestive organs are unable to transfer nutrients from food to blood at the usual rate, which means that your body has more food than it is able to process. The... | [
"Is there a source for that claim? When I was in the army, we would run in the morning before breakfast, and people would frequently puke. We were always told it was due to a lactic acid build up in our system."
] | [
"That statement (about lactic acid) is not entirely false — the way that lactic acid gets removed is through improved circulation, so a buildup of lactic acid will, indeed, cause shunting of circulation away from digestive tract and towards skeletal muscles, which will ultimately lead to vomiting.",
"I could not ... |
[
"On a physical level, is there a difference between PTSD and extreme anxiety that does not stem from a traumatic event?"
] | [
false
] | I know that where the anxiety comes from and how someone might work through it will differ between these two types of anxiety but I'm curious if they're functionally the same as far as the body is concerned. As an example: there is someone who has been violently mugged and they have developed severe PTSD due to it and ... | [
"Therapy would be very similar. Acute stress disorder becomes PTSD after three months if the person is still experiencing symptoms such as flashback, intrusive thoughts, avoiding, nightmares, and somatic symptoms. Medicine for anxiety and depression can be used for ASD, PTSD, and anxiety. Anxiety is mostly an over ... | [
"How our bodies handle certain psychological disorders, it doesn't really care what is causing the symptoms. PTSD and non-PTSD anxiety is still anxiety. (I believe PTSD is classified as an ",
" disorder as is) It reminds me of addiction, how addiction to gambling triggers the same part in the brain as when addict... | [
"The main difference is that cortisol levels are lower in sufferers of PTSD.",
"This is the only anxiety disorder where this happens. Usually cortisol levels would be higher than average.",
"Cortisol helps shut down the stress response via a negative feedback loop, so there was a theory that the low levels of c... |
[
"Does an octopus favor a tentacle in the same way that a human favors a hand?"
] | [
false
] | null | [
"Probably not, or at least not the same way as in humans. What causes it for us is specialisation of hemispheres, which makes them better or worse at controlling motor activity if their respective limb.",
"Unlike humans, octopuses don't have a \"specific limb\" controlled by a specific part of the brain, nor do t... | [
"That was one of the many things in the book “Other Minds” that blew me away. They basically have 8 sub-brains in their arms, which appear to work in unison with their brain-brain. \nIt’s an amazing book about cephalopod intelligence, and we’ll worth a read. ",
"https://www.amazon.co.uk/Other-Minds-Octopus-Origin... | [
"They don't work with unison, they are controlled by the brain. The difference is that human brain controls both decision making and actual motor movement. And octopuses only have the motor movement part located in the actual limb. I know it's less exciting when I put it this way, but that's science for ya. I mean,... |
[
"what would have a better chance of survival, a breeding population of polar bears dropped off in Antarctica, or a breeding population of penguins dropped off near the north pole?"
] | [
false
] | [deleted] | [
"Found this in a quick search: ",
"http://earthsky.org/biodiversity/penguins-north-pole",
"It basically confirmed what i thought. The Polar bears would probably do fine in antarctica mainly because they would be the only land predator and feed on the vulnerable Penguins. Where as penguins would be transporte... | [
"The ",
"Great Auk",
" is a penguin-like bird that used to live in the northern hemisphere. ",
"Edit:I guess you'd need to drop it off near open water, though."
] | [
"The great auk is very informative, actually. They had somewhat limited range of places where they could breed successfully, because of the much higher prevalence of terrestrial predators in the arctic. So penguins could survive in the arctic, certainly, but could only breed in on isolated islands and rock spires... |
[
"Why was the Coronavirus (SARS-CoV-1) outbreak of 2002-2004 not worse?"
] | [
false
] | I'm curious why that Coronavirus outbreak didn't become worse/affect greater numbers. From reading about it, it doesn't seem as though the early reaction to it was much different than the early reaction to SARS-Cov-2 (Covid 19). Was it less contagious? Was it just luck? | [
"One reason: ",
"It’s much harder to contain SARS-Cov-2 because there are so many asymptomatic people and people with minor symptoms spreading the virus. ",
"SARS-Cov-1 was easier to contain because if you had it, you were likely pretty sick. Plus, you had to be showing some symptoms to spread it. You didn’t ha... | [
"Yep. In addition, what made COVID such a killer is that it’s nowhere near as lethal as SARS despite being a very close relative. A good parasite doesn’t kill its host, because it won’t be able to survive without one. SARS was more easily contained because of the number of people who died from it before it could sp... | [
"SARS-CoV-1 featured:",
"Shorter incubation period.",
"Shedding only occurred during visible symptoms.",
"Consistency in presentation. We could take a temperature of a person and reliably find infected people.",
"When you don't need testing, just eyeballs, to find people who are spreading, as opposed to ja... |
[
"Given time to decompress slowly, could a human survive in a Martian summer with just a oxygen mask?"
] | [
false
] | I was reading this comment threat about the upcoming Martian announcement. got me wondering. If you were in a decompression chamber and gradually decompressed (to avoid the bends), could you walk out onto the Martian surface with just an oxygen tank, provided that the surface was experiencing those balmy summer tempera... | [
" No. Exposure to vacuum or near vacuum is not well understood because it hasn't happened to many people, and while we're fairly sure it will kill you no one really knows what will get you first... but we do have a few ideas.",
" You know how liquid water freezes at 0 C and boils at 100 C? That's a lie - it only ... | [
"bubbles",
"Right. It's just a liquid to gas phase transition. "
] | [
"Yes. Boiling is the phase transition, it just happens at cooking temperature where we live. "
] |
[
"What is the most valuable program/programming language for correcting, analyzing and expressing experimental data as a grad student in the sciences?"
] | [
false
] | null | [
"I come from a different background as my flair says, but I expect my experience will be the same as most scientists. When you're using a manufacturers GUI, you often only have limited options in how you can save your data. Often you'll be able to save data in something that is basically raw text/CSV, but not alway... | [
"I can recommend Mathematica. I've used it for all kinds of things during my physics degree. It can handle complicated maths problems and has a huge range of inbuilt plotting and data manipulation functions, which have been very useful for doing experimental analysis. ",
"It's not so much a programming language, ... | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"It is not a science question. Questions about education and careers in science are welcome in ",
"/r/AskScienceDiscussion",
"If you disagree with this decision, please send a message to the moderato... |
[
"Merthiolate 'antidote' of eggs, milk, and mustard?"
] | [
false
] | My office was cleaning out some old supplies when we came across several first aid kits that must have been from at least the 1960's. Inside them were several snake bite kits and boxes of 'Tincture Merthiolate'. I know merthiolate was used as an antiseptic for some time but also has a dangerous amount of mercury, and t... | [
"The relevant part is probably the \"mustard emetic\". An emetic is a substance that induces vomiting, used in this case to empty an overdose of the drug out of the stomach. Large amounts of mustard in water is probably just the thing most people might have on hand that works as an emetic. Conjecturing here, but th... | [
"The mercury gets attached to the egg white protein. A process call ",
"denaturation",
".",
"Heavy metals may also disrupt disulfide bonds because of their\nhigh affinity and attraction for sulfur and will also lead to the\ndenaturation of proteins.",
"This will slow the absorption by the stomach and intest... | [
"Isn't the sulfur bound up in proteins? Would it still react with the mercury?"
] |
[
"Why is a normal curve shaped like it is?"
] | [
false
] | null | [
"https://en.wikipedia.org/wiki/Central_limit_theorem"
] | [
"Are you asking why f(x) = exp[-x",
"] is shaped the way it is, or why lots of random variables in nature seem to be distributed like Gaussians?"
] | [
"In order to really understand this, you need to understand the mathematical operation of \"convolution\".",
"Given two functions f(x) and g(x) on the real numbers, the convolution of f and g, denoted f * g(x), is the integral of f(x - t)g(t) with respect to t. In plain English, we sort of \"add up\" the product ... |
[
"Why is environmentalism lost and then re-discovered in the development of a society/culture/country?"
] | [
false
] | I've been reading about environmental history a lot lately and have been thinking about the cycle of environmentalism in places. To use extremes to illustrate what I mean, I would compare 3 types of societies (I'm not a social scientist or a social science student, so bear with my terminology): first-world developed i.... | [
"I don't think it's quite right to say that preindustrial peoples are some bastion of environmentalism. Humans even in the stone-age have definitely obliterated species across all sorts of islands and probably were instrumental in killing off much of the continental Pleistocene megafauna. They altered whole envir... | [
"First world countries are not always that environmentally enlightened. Many of them just manage to externalize the negative environmental effects of industry to other countries. In other words, they're rich enough that they can pay to have the smog spewing river polluting factories that make all their stuff in Chi... | [
"It's not that it's lost and rediscovered, more that people pollute as much as they can get away with as pollution is generally a negative ",
"externality",
" that doesn't effect the polluter directly, so outside government regulation they lack an incentive to reduce it.",
"The poorest countries simply don't ... |
[
"Is the universe an Isolated system?"
] | [
false
] | The definition in the Wikipedia suggests that 'Truly isolated systems cannot exist in nature, other than possibly the universe itself,' An isolated system does not permit exchange of matter or energy. If the universe has an energy, what type of energy would it have, and how are they conserved? | [
"I doubt that this question has a definitive answer yet. Mainly because in general relativity there is no conservation of energy in the thermodynamic sense. Rather some derivative of the energy-momentum tensor is conserved...\nHowever, you might want to look into this hypothesis: ",
"http://en.wikipedia.org/wiki/... | [
"I think the \"possibly\" may be there due to using the term \"universe\" differently from how the dictionary defines it.",
"There seems to be a school of thought that \"the universe\" should be defined in terms of what you might call \"our spacetime,\" or in more technical terms, the manifold on which the matter... | [
"I don't think he means derivative in the calculus sense. He means a tensor thats derived from the energy momentum tensor of GR."
] |
[
"How can records store photos?"
] | [
false
] | I was reading about the on Wikipedia and apparently it contained images, but the wiki article doesn't really go into how that works. So I ask, how does that work? I thought records could only have sound on them-the whole bumps in the groove=vibrations thing. How can vibrations turn into images? | [
"According to NASA/JPL \"The 115 images are encoded in analog form.\"",
"http://voyager.jpl.nasa.gov/spacecraft/goldenrec.html",
"I'm still looking for details."
] | [
"possibly using binary information. But I think they just have actual images, not encoded at all?"
] | [
"This site",
" provides a decent explanation.",
"Scroll down a bit to",
"These waveform representations of the picture signal recorded in the groove provide an explanation for how the images are to be constructed."
] |
[
"Nostril breathing impact on nervous system- yoga school topic"
] | [
false
] | Talked about alternate nostril breathing in yoga school tonight and how little research is done on breathing's impact on the nervous system. Can anyone provide some insight about the dominance of the nostrils and how the body body switches dominance every 90 minutes or so? Also interested in how yoga teacher mentioned ... | [
"This is another point he brought up- that little to NO research on breathing and its effect on the nervous system. Welp, let's go reddit! What's the hold up?"
] | [
"Please read the FAQ before posting."
] | [
"My guess about research about yoga is this:",
"Modern science is yet not focussing on physical and functional subsystems with respect to yoga/meditation.",
"For example certain practices in yoga produce certain effects on multiple systems by tweaking their functioning gradually and subtly.",
"These tweaks ar... |
[
"Is there any possibility that meteorites/asteroids have some new material? Like a new metal that doesn't exist in earth?"
] | [
false
] | (I'm not sure if that's the best flair) | [
"This depends what you mean by \"material\". ",
"If you mean element, probably not, as the majority of elements have been discovered and those that haven't have been theorised (i.e the periodic table). ",
"However a unique alloy or composition of elements with a unique structure that we haven't seen before is d... | [
"An element is just a matter of how many protons combine to create an atom. With our current understanding of physics, there's an upper limit to how many protons will bind together before falling apart.",
"With that knowledge we're pretty certain about how many elements can exist. Especially natural elements beca... | [
"Might I add, however, that there is whispers and speculation of the possibility of \"supermassive\" heavy elements beyond the ones at the end of the table today, ones that stabilize under their (relatively) huge mass."
] |
[
"What is déjà vu?"
] | [
false
] | I want to know the scientific explanation behind the idea of déjà vu. | [
"Something to do with your hippocampus trying to differentiate between memories with similar qualities or details, I believe there was an article about this in PopSci a couple years ago. Basically when you experience deja vu, all that's happening is that your brain believes is has witnessed something before and is ... | [
"Since no one knows, one theory is that it's a problem with your brain getting confused and thinks that a new memory is also an old memory. ",
"Basically your brain has a mini (simple-partial) seizure in the hippocampus. The hippocampus is the most fragile part of the brain, and it's main function is to control ... | [
"I tried to go and find the ",
"referenced article",
"."
] |
[
"Are there any stars travelling around their galaxy at relativistic speeds?"
] | [
false
] | If that's possible what kinds of effects would that have on the star and any planets orbiting it. | [
"The SO-2 star near the supermassive black hole in our galaxy, ",
"trajectory seen here with error bars",
" orbits at up to 2% the speed of light. To my knowledge this is the fastest \"macroscopic\" object relative to some reasonable rest frame. Neutron stars can rotate much faster about their axis."
] | [
"In order for speed to be a thing at all, you have to pick a reference frame and then speed is the magnitude of velocity in that frame. You can always pick a frame in which that velocity is zero. Therfore there is no such thing as absolute speed. Kinetic energy of an objects centre of mass cannot cause it to grav... | [
"Is there a limit (lower than the speed of light of course) that a \"macroscopic\" object such as a star or planet can actually travel at? Would it's kinetic energy eventually cause it to gravitationally unbind itself?"
] |
[
"Is it possible to view anything that was left on the moon by humans, with a telescope from earth?"
] | [
false
] | I cannot help myself thinking that the moon hoax discussions are a lot of fun. But I am sure that we once did walk on the moon. Seeing some physical evidence should be able to put my mind to rest about this and go on with my normal life. Can anyone help? | [
"The Apollo astronauts left mirrors known as retroreflectors on the moon, and we ",
"regularly bounce lasers off them",
". Every time we do so we prove the moon landings."
] | [
"Unless every single person who has ever done that is in on it."
] | [
"Not with a telescope from Earth, but there are images from the Lunar Reconnaissance Orbiter. ",
"It's also known as the LRO."
] |
[
"It seems like all cutting-edge research in physics is about subatomic particles. Is there anything interesting happening in other branches?"
] | [
false
] | null | [
"A good home for this question is ",
"/r/AskScienceDiscussion",
".",
"Please see our ",
"FAQ."
] | [
"Nope, no need to remove. The discussion subreddit is really growing and I believe you should get some really good answers. Also, we are looking to do more AMAs and I will add one about new research in other areas of physics. Keep an eye out for it. :D"
] | [
"I'll post it there too. Do you want me to remove it?"
] |
[
"Does the sun's fusion of Hydrogen into Helium occur at a constant rate or does it become exponentially faster as time goes on?"
] | [
false
] | So I understand that the fusion of Hydrogen into Helium is done through a massive chain reaction, which implies that the speed at which hydrogen is fused to make helium should increase exponentially. Is this the case or do other factors influence how fast Hydrogen is used up? If I was right in thinking it increases exp... | [
"A star like the sun is getting brighter! Really, chain reaction ideas and thing like that break down at this scale. Imagine that you make helium, then it will sink to the center because it's heavier right? Well that's now you have an inert helium core, and the \"shell\" of hydrogen combustion is getting bigger and... | [
"It does, sort of, occur through a chain reaction, but the speed of the reaction depends on the available fuel, the temperature and the pressure involved. Firstly, as the amount of available hydrogen goes down, the reaction will clearly slow down. It does not increase exponentially.",
"Secondly, the reaction is n... | [
"It isn't a chain reaction in the nuclear bomb sense, but rather a \"chain of reactions\". I assume you're talking about the ",
"Proton-Proton Chain",
" which isn't a chain reaction in the sense of one reaction triggering many others, but is rather a chain in the sense that it is a series of reactions that proc... |
[
"Did the US successfully land a spacecraft on the moon, then return to Earth, before the manned Apollo missions?"
] | [
false
] | null | [
"No, there was no successful sample return prior to Apollo 11"
] | [
"I looked there and it wasn't clear from the wikipedia page whether missions returned or not. There were plenty of missions before the manned missions, but it is unclear if there were any return missions before manned missions."
] | [
"You can find the basic answer with a simple Google search / on wiki. Please start there and come back with a more specific question."
] |
[
"Exactly how does depression/anxiety cause insomnia?"
] | [
false
] | [deleted] | [
"On my phone but I'll take a stab...\nIt's a bit chicken and egg-ish once the pattern is established. Normal sleep is a restorative state and important for memory (particularly the emotional valence in memories) consolidation. However, when sleep is inadequate, it leads to increased anxiety and irritability. Pair t... | [
"I'm curious too because after a bad panic attack I often get a lot of symptoms associated with stimulant use such as sweating, jaw clenching, energy (obviously), etc... I've often heard it explained as our evolutionary \"fight or flight mode\" basically our body preparing for extreme situations by dilating blood v... | [
"A synthetic panic attack... i am sure a hit of crack or meth has a very similar effect to the brain and body as a “panic attack. That is why stimulants are so bad for people. It forces the brain to “rev up” for a flight or fight response making sleep difficult because of “vary basically” fear that keeps your br... |
[
"Why do we feel a need to sleep with a blanket? Is it biological or cultural?"
] | [
false
] | null | [
"Biological; it's due to your body's thermoregulation during sleep. Your body's core (thoracic, head, abdomen) and shell (skin, muscles, appendages) temperatures ",
"vary over a 24 hr period",
". As you can see your body loses much of its heat during normal sleeping hours, and people actually sleep better and l... | [
"This is speculation so I'll piggyback a top level response, but in addition to the issue of temperature do you think it'd be fair to note the presence of a physical barrier? I know that if I'm trying to fall asleep without a blanket, a local wisp of wind is about enough for me to alert to that visceral sense of, \... | [
"That's more subjective, but it ties into what I said about the microclimate in the blankets. Variations like a breeze from a window or vents in your house can definitely disrupt sleep by cooling your exposed skin faster so a physical barrier definitely protects from this, yes."
] |
[
"Which planet in our solar system is the oldest/youngest?"
] | [
false
] | null | [
"Jupiter is often thought of as the oldest, though the following classical explanation is complicated by recent exoplanet discoveries that don't always conform to the model. ",
"In the classical model of the formation of the solar system, the protoplanetary disk from which the planets accumulated only had water a... | [
"The obvious answer is that Jupiter is the youngest by virtue of its gravitational time dilation.",
"Based on what I know about the formation of the solar system, all of the planetary bodies were accreted from many smaller colliding planetessimals in a very turbulent and dramatic period of solar system history. I... | [
"Depending on how you think of these things, the Earth - Moon system could be considered the youngest considering that the current Earth is the result of the older Earth being struck by a Mars sized object and taking on some of its mass. "
] |
[
"How do viruses become resistant to antivirals if they're not really \"alive\"?"
] | [
false
] | [deleted] | [
"As best I understand it (supplemented by the Wikipedia page for ",
"enzyme inhibitors",
"), an inhibitor targets something in the chemical structure of the reverse transcriptase and/or the molecules to which reverse transcriptase binds.",
"If the reverse transcriptase has a different chemical structure but i... | [
"Technically, a thing doesn't need to meet our definition of \"alive\" to evolve. It just needs to reproduce and mutate, which viruses do.",
"Let's say a certain antiviral agent kills 99% of a certain virus within 5 days, but 1% of viral population has a mutation that allows it to survive for 10 days. It isn't ... | [
"a thing doesn't need to meet our definition of \"alive\" to evolve. It just needs to reproduce and mutate",
"Just to add to this -",
"genetic algorithms",
" and ",
"evolutionary computation",
": ",
"Pieces of computer code that \"evolve\" to find answers or optimal solutions, and they ar... |
[
"My theory on what dark matter/energy is, what do you think?"
] | [
false
] | null | [
"We don't vet personal theories on this sub."
] | [
"But I'm asking a question? There also isn't a rule against it"
] | [
"Under the Asking Askscience section of the wiki:",
"Posts about personal theories are discouraged."
] |
[
"Is it possible to gain more weight than the weight of the food you eat?"
] | [
false
] | e.g. if you ate 1kg of energy dense food like chocolate, could you put on more than 1kg in weight assuming you ate or drank nothing else? | [
"seems impossible"
] | [
"Hmm, I don't think so. Where would the heat come from if not from your own body, and therefore resulting in no net change?"
] | [
"For all practical intents and purposes, weight gain or loss can be described by this equation. ",
"(Mass of food and drink you intake)+(Mass of O2 and other gasses inhaled)-(Mass of waste products suck as urine, feces, and sweat excreted)-(Mass of CO2 and other gasses exhaled)=Accumulation of mass in the body. "... |
[
"Why does it hurt when you eat something spicy followed by drinking something hot in temperature?"
] | [
false
] | Every time I eat something spicy and immediately drink something hot in temperature it feels almost too painful to drink anymore until the spiciness clears. Any science behind this? Also, I'm guessing this is the same reason food that is hot in temperature and spicy tastes much hotter than the same food when it is cool... | [
"Capsaicin irritates the same nerve receptors that sense actual heat. It tricks the nerves into thinking they have actually been burned. The increased sensitivity to heat afterwards is an evolved response that is designed to protect us from worsening the burn through additional exposure. ",
"http://en.wikipedia.o... | [
"Well what happened was I was eating a piece of spicy italian sausage for breakfast and was drinking some coffee. I know, my diet's fucked up, but I like italian sausage and I like coffee. ",
"Also I was eating really hot wings and drank some hot tea."
] | [
"I know milk coats your tongue, so it limits the spice that gets to your tongue. Never actually tried it, so I don't know if milk relieves spice if you drink it after the fact."
] |
[
"Attempted to dissolve Ricola cough drops in 60% alcohol..."
] | [
false
] | [deleted] | [
"It seems like the majority of each cough drop would be made of isomalt, aspartame and acesulfame-k. None of which are very soluble in ethanol. In addition, aspartame isn't very soluble in water either. So what happened was that the 60% alcohol solution dissolved what it could left the insoluble portions behind, re... | [
"It'd be speculative, but it seems like a reasonable supposition."
] | [
"so the alcohol mixture is the actual medicinal ingredients?"
] |
[
"What liquids can we distill?"
] | [
false
] | [deleted] | [
"I think the correct answer is probably that any liquids that can be mixed, and have different boiling points, can be distilled. ",
"So for example liquid silver and liquid zinc are miscable. They have different boiling points. Therefore you could distill zinc from a silver/zinc alloy. "
] | [
"I think the correct answer is probably that any liquids that can be mixed, and have different boiling points, can be distilled.",
"They also shouldn't decompose or react with each other before they boil."
] | [
"Depends what you mean for distill everything can be turned into gas at the right conditions and condensed back into a solid or liquid, its just that we are acostumated to earth is conditions so it limits our capabilities but i would say every single element in the periodic table is distillable"
] |
[
"What is the Michelson-Morley experiment, and what does it mean?"
] | [
false
] | I wanted to put this in ELI5, but that's probably not realistic, so could you explain it to me like I'm 15? Response from thegreatunclean that somehow got lost in reddit's servers. The Michelson-Morley interferometer experiment was designed to show that a beam of light would take longer to travel some given distance in... | [
"I made a rather long post and submitted it, now it isn't showing up but it says there's 1 comment. Not showing up in my list of posts either.",
"If it doesn't pop up in the next 20 min and nobody else has answered I'll type up another."
] | [
"Send it back to thegreatunclean so he can repost it then."
] | [
"Send it back to thegreatunclean so he can repost it then."
] |
[
"Has the Copernican Principle been proven, or is it simply unquestionably obvious?"
] | [
false
] | This is a dangerous question to ask on askscience, so please hear me out. Let me be first and foremost clear: I am NOT asking where the center of the universe is, as gets asked every 12 minutes here. I've searched and searched for my question and found once user rmxz tried to ask a similar question to mine 2 years ag... | [
"One way to answer this would be to consider the large-scale distribution of superclusters, as shown in large-scale sky surveys*. If there were a violation of the Copernican principle, there may be a point whose region of local smoothness is much larger than expected. From what we see, beyond the local \"end of gre... | [
"Have there been any observations that show that the Copernican Principle cannot be wrong?",
"There's no way to demonstrate that. Maybe there's a little bit of the universe that's somehow a privileged space but outside our lightcone; no possible observation here on Earth could detect it and would be indistinguis... | [
"Isn't that just a prediction of the Friedman solution to general relativity? Our cosmology can be wrong without our gravitational framework being wrong."
] |
[
"What are the medical effects of a long distance, commercial flight on an average human being?"
] | [
false
] | I was told today (by a non-doctor friend) that half of the probiotic "good" bacteria found in one's digestive system dies off in a single long distance flight. I found this to be incredibly interesting/scary, considering I intend to travel a lot in the coming years, and was wondering if there was any truth to it. Als... | [
"Deep vein thrombosis is associated with sitting in the same position for prolonged periods of time. "
] | [
"Jetlag?"
] | [
"slight irradiation from being at such an altitude, I think. "
] |
[
"How does a computer know how to do math?"
] | [
false
] | I've been searching for for an answer to this question, but I haven't gotten an answer. I know that a computer receives an instruction from memory, converts the instruction into numbers, then into binary 1s and 0s, and only does math as the base for everything, but how does it every rule of math and how to solve math p... | [
"Inside a computer are tiny structures called transistors that (simplifying hugely) connect two different wires if their input wire is a certain voltage. For instance, you can take two transistor and tie an input wire to both of them. One ties the output to low if its input is high. The other ties it high if the... | [
"AND and OR are not ",
"functionally complete",
" which means using only AND and OR you can't build all functions that you'd want. For example using only AND and OR you can't build NAND. No matter how you combine AND and OR your output will always be 1 if both your inputs are 1. But the output of NAND is 0 if b... | [
"Outputs have to maintain their output voltage \"no matter what\" (in an ideal circuit). If you connect two outputs together that are in different states (trying to make \"0 or 1\") then one will force the voltage to be low while the other will force the voltage to be high. You get a short circuit.",
"If you conn... |
[
"How does heat and humidity affect sound travel?"
] | [
false
] | The reason I'm asking is that there is a particular amusement park (go-carts, mini-golf, batting cages, etc.) that pumps music through a new sound system across the river from my house. (roughly 1500 feet) During the summer months, my family and I like to have dinner on the back porch and we are generally unhappy about... | [
"Some textbooks mistakenly state that the speed of sound increases with increasing density. This is usually illustrated by presenting data for three materials, such as air, water and steel, which also have vastly different compressibilities which more than make up for the density differences. An illustrative exampl... | [
"In outdoor sound, the two big things that matter are how the sound propagates and how much attenuation is caused by the air. In the 500 feet from the amusement park to your porch, attenuation will likely be a small factor, so let's consider propagation.",
"Let's imagine those speakers putting out rays of sound i... | [
"Always happy to see people interested in acoustics. There aren't enough of us to go around.",
"To your question, though, understanding the effects of humidity on the gradient is a big question. If the river causes a downward gradient in the summer, it's because the water has a large heat capacity and it's colder... |
[
"Why is the image of a photocopied mirror black?"
] | [
false
] | Photocopied mirror: | [
"The photocopier has a light source shining on the paper, and a lens collecting light reflected from the paper. The light source and lens are not mounted such that light would be specularly reflected from the light source to the lens. This does not matter in the case of a paper, since the reflections are diffuse.... | [
"the photocopier is shining light at the mirror, and it is reflecting back and missing the scanning element. The white background is scattering the light in al directions so this part is hitting the scanning sensor."
] | [
"So essentially, the lens of the photocopier that collects the light is slightly off the point where the specularly reflected light would be, so as to reduce glare, and it is because of this positioning that the mirror appears black? "
] |
[
"Is the universe neutrally charged? i.e. would the sum of the charges of all the particles in the universe be 0?"
] | [
false
] | null | [
"Yes. Our current understanding is that the total net charge in the universe is 0. There are a few reasons for this. ",
"From a theoretical perspective, we know that charge is a conserved quantity, i.e. you cannot create net charge. Any process that creates a negative charge (like an electron) must also create a ... | [
"In nature (below the QCD deconfinement scale), quarks are only found bound in hadrons, and all known hadrons have integer charges."
] | [
"The proton is +1 charge, but it is made up of 3 quarks, some of which have goofy 2/3 charges. How do we know the sum of the charges of all 10",
" particles in the 'verse doesn't come out with a 1/3 remainder? Is it possible that somewhere out in the black there's 2 quarks, bound together with great big dreams?"... |
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