title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"How exactly is it that a protein can catalyze a reaction with shape?"
] | [
false
] | I'm pretty sure I understand the basics, where two atoms\molecules can fit almost perfectly into a 'slot' that allows them to interact at a precise angle - I suppose what I'm asking is how is it possible for a protein to have a slot that holds the -exact- shape of an atom or molecule? What does it look like? From my un... | [
"I suppose what I'm asking is how is it possible for a protein to have a slot that holds the -exact- shape of an atom or molecule? What does it look like?",
"The combination of 20 amino acids can yield a startlingly large set of shapes, but it's not ",
" shape that matters, also the charges, hydrogen bonding et... | [
"This question really deserves a more in-depth answer, but I can't do it right this instant. I can mention the two major things I'm a bit surprised no one has mentioned....",
"The general notion is that enzyme function involves lowering the activation energy between reactant(s) and product(s). It does this by s... | [
"You have the correct basic idea. It is kind of hard to visualize, so ",
"here's a handy animation",
"! In that gif, a hemoglobin enzyme changes its entire configuration very slightly in order to bind an oxygen (O2) molecule. Proteins are composed of combinations of ~20 different types of amino acids (each with... |
[
"Is there anything in the universe that truly stands still?"
] | [
false
] | The moon moves around the earth moves around the sun...what does the sun move around? | [
"Yes and no. Any non-accelerating object could be said to be stationary in its inertial frame of reference. However no non-accelerating frame of reference is privileged over any other, so there is no absolute way to define a stationary object."
] | [
"Isn't the Cosmic Microwave Background Radiation used as the universal reference frame?"
] | [
"The sun moves around the black hole at the center of our galaxy. Whether or not our galaxy is moving depends on the reference frame it is viewed from. Velocity is relative, which means that there is no way to tell if something is \"moving\" or \"still\" other than to compare it's speed to the speed of other object... |
[
"If we could stop out telomeres from shortening, could we live forever?"
] | [
false
] | Could we? Why do they exist? And what role do they play in our bodies? | [
"No.",
"First off, humans do not run out of telomeres within a normal lifetime. We aren't meant to. Telomeres are there as an anti-cancer mechanism. If a cell line begins dividing very rapidly, telomeres ",
" run out and useful DNA would start to be lost for each generation.",
"And secondly, even if we had... | [
"Sadly not. ",
"Telomeres are like the \"aglets\" (the bits of plastic on your shoelaces) that stop your laces unraveling. They are part of your DNA that doesn't actually code for anything, no instructions are writen on this part of your DNA for anything.\n During DNA replication your DNA shortens slightly, at fi... | [
"Thanks for the info, I was hoping I that I could live forever... I guess not."
] |
[
"Is there an established way to deal with an invasive species? Is it better to intervene, or let nature take its course?"
] | [
false
] | I know that invasive species are often brought into a new environment, and they end up wreaking havoc on the ecosystem. I was wondering whether efforts by humans to "correct" the mistake end up actually working, or end up doing more harm than good. | [
"This is a more complex problem than this: Not all new species are actually invasive, and usually, it takes time to see whether they are. There are numerous species that are currently on the list of \"could be or become invasive\". Then, if a species turns out to be clearly invasive, something usually is done about... | [
"Very good explanation. Indeed what humans can do is currently not enough when a specie gets out of control. It is difficult if not impossible to control the relations each animal or plant have with each other.",
"A good way to at least relief the problem is to introduce specific parasites (usually against agricu... | [
"Well, a \"good\" way is relative. The problem with bacteria is that since they have short lifespans, are haploid, and can horizontally adopt genetics, they're likely to mutate. And try getting THOSE back in control afterwards. Not to mention, that usually, genetically modified bacteria is often resistent towards a... |
[
"Why do planets rotate in any particular direction?"
] | [
false
] | Somebody asked a question about planets orbiting the sun, but mine's actually about the direction of the planet's spin, which leads to the day-night cycle: why do planets rotate in any particular direction? Earth, for instance, rotates west-to-east. Why is this? My guess would be either something to do with conservatio... | [
"conservation of angular momentum, or simply as a further artefact of the Earth forming from the same accretion disk ",
"Bingo. Both are correct. Mass that's moving has a tendency to spin when it clumps into a mass like a planet, and since it maintains this momentum pretty much forever in space."
] | [
"You've already got a good deal of the answer figured out here...conservation of angular momentum of the initial debris disc from which the planets formed. ",
"The original large molecular cloud that formed our solar system had a very slight rotation to it. As it collapsed down to form the Sun and the debris disc... | [
"Venus actually rotates in the opposite direction from the other planets. Likely from one or many large collisions in its past changing its spin. Other theories include gravitational effects of its dense atmosphere from the sun.. etc.."
] |
[
"When a guy cums does it come from both testicles simultaneously?"
] | [
false
] | Or just one per ejaculation and they alternate? Or does one operate for so many years then retires? What happens if a testicle gets cancer and must be removed, how is ejaculation affected? | [
"When a guy has a correct vasectomy, the sperm stays with the testicles and whatever remains of vas deferens tubing yet connected to the testicles, dies there and is reabsorbed as waste. The testicles usually sense that there's a build-up of sperm and produces less going forward."
] | [
"Thanks for the detailed answer. ",
"So when a guy has a vasectomy, where does the semen \"go\"?"
] | [
"Thanks for the detailed answer. ",
"So when a guy has a vasectomy, where does the semen \"go\"?"
] |
[
"How much light is absorbed in the deepest part of the ocean?"
] | [
false
] | I just read about this new material and was wondering because i thought the deepsea was one of the darkest places on earth. | [
"It's dark because the water above it is kilometers thick, not because the water is inherently dark. If you were to turn on a (waterproof, pressure proof) flashlight down there, it would illuminate."
] | [
"Absolutely. In the open ocean light can penetrate further than at the coasts due to a lack of sediment, but the end of the euphotic zone (area with light) is around 200 meters."
] | [
"In addition, the red end of the spectrum gets absorbed (scattered) first and can't penetrate beyond the first 10 metres or so. If you ever go SCUBA diving, you will notice that the deeper you descend, the only colours that are visible from the sunlight penetrating the water are blues and greens. For this reason, u... |
[
"Is there a difference between electrical impulses sent to the brain by different sensory organs (say, between an impulse sent by the inner ear and one sent by the optic nerve)?"
] | [
false
] | Or are they the same type of electrical signal and the brain somehow differentiates between them to create different representations? | [
"Doctor here:",
"The signals are exactly the same electrical impulses, sent down the axon of the neurons, mediated by the sodium potassium pump and gated ion channels, but the signals can be sent up to 300 Hz (on average) or 300 electrical impulses per second, the nervous system does not waste energy sending more... | [
"On a tangent: it has been established that electrical signals pretty much propagate with the same speed all across your nervous system.",
"This means that for instance when you touch your toe with your finger, your brain receives the sensation from your toe several tens of milliseconds after it receives the sens... | [
"I edited my post to add everything after hope that helps! :-)"
] |
[
"Are there any homemade \"filters\" people can make so they can watch the solar eclipse on Sunday?"
] | [
false
] | First off, I hope this belongs here. I think it's more of an askscience question than an askreddit question. But I'd really like to watch as much of the solar eclipse as I can, but I obviously know enough to not look directly at it. So, are there any homemade lenses or filters we can try so we can look at it? If not, w... | [
"Welding glass (the bits that go in a welders mask) is a good option, and cheap as chips."
] | [
"You can make a camera obscura.",
"http://www.exploratorium.edu/eclipse/how.html"
] | [
"Check out ",
"NASA's page on Eye Safety During Solar Eclipses",
"It says \"The safest and most inexpensive of these methods (to view the eclipse) is by projection, in which a pinhole or small opening is used to cast the image of the Sun on a screen placed a half-meter or more beyond the opening. Projected imag... |
[
"What is physically happening in the eye that causes it to hurt when looking into bright light?"
] | [
false
] | null | [
"You are literally burning your eye.",
"Light or photons interact and transfer energy to receptors in your eyes. More light, brighter and concentrated means more higher energy photons that are more packed together are entering the eye. All that energy has to go somewhere, some is lost as heat energy, heating the ... | [
"There is an increase in temperature of the tissues leading to physical damage. Also, overstimulation of receptors and neural transmission has a detrimental effect, ya man bagit, dominate"
] | [
"Id presume it is the strain your iris undergoes as it contracts. Im not sure if the stimulation of your ganglion cells are linked to the sensory pain pathways, though my best guess is that they are not."
] |
[
"Why does 1/3 of the human population sneeze when they look at the sun? Why only 1/3 and not all of us? And why does it happen in the first place?"
] | [
false
] | Thank you guys for replying! I really appreciate the responses | [
"Nobody knows exactly. But \"photic sneeze reflex,\" which is what you're referring to, does not offer a significant evolutionary advantage or disadvantage to those who have it or don't, so there's no reason its prevalence would change significantly unless it was tied to another more important trait. It's like ea... | [
"Do you have a citation for this? "
] | [
"The 33% prevalence could be contested. Neurologist Louis Ptacek, one of the few scientists to study the phenomenon, says no one really knows the prevalence but he puts it at something like 10%.",
"http://www.diffusionradio.com/2010/08/photic_sneezing_and_a_naked_sc.html"
] |
[
"Question about cancer survival statistics relative to time of diagnosis"
] | [
false
] | Suppose that I am diagnosed with a brain tumor at a very early stage but that nonetheless it is incurable, and I forego treatment. Despite not being treated, my post-diagnosis lifespan will be lengthened due to the early detection; it will take longer than otherwise for the tumor to grow large and kill me. Is this sort... | [
"Unsurprisingly, the answer to your question is complicated and depends on the statistics that have been gathered for a particular condition. Also, your answer is likely to be different depending on whether you are talking to a statistician or a physician. ",
"The quick answer is that early detection will make it... | [
"This is an excellent question, and it makes the interpretation of cancer screening studies difficult. The problem is called lead-time bias. The best way to get information about whether a cancer screen is actually useful (prolongs life) is to do a randomized controlled trial, where you split people in to two group... | [
"Great answer, thanks!"
] |
[
"Why are there antibacterial medications but not antiviral medications (or are there)?"
] | [
false
] | I was sick this weekend and was on the phone with my doctor to get some medicine. He indicated that he would not be prescribing antibiotics because based on the symptoms it sounded like a viral infection, not bacterial and I would simply have to wait for it to subside. Are there antiviral medications for other sickne... | [
"As the others have said there are fundamental differences between bacteria and viruses the main being that bacteria are self-sustaining organisms where as viruses are completely dependent on a host. ",
"Antibiotics target specific parts of the bacterial life-cycle that are unique to the bacteria and not used in ... | [
"A bit ELI5:",
"Bacteria and virus (virii) are different problems. A bacteria is a functional cell, that has a metabolism, can duplicate on its own, eat and so on. A virus is just a piece of genetic material with a shell that let it infect one of your cells and use it to reproduce.",
"Having its own metabolism,... | [
"Just to tack on a (hopefully useful) bit.",
"Antiviral drugs do exist, and their goal is to help your body recognize viruses better while they're floating around, or to prevent them from binding to your cells and getting inside. One problem is that these antiviral methods work by targeting exterior proteins. The... |
[
"Does travelling faster than the speed of light create observational time travel?"
] | [
false
] | null | [
"Physics says you can't reach the speed of light, let alone go faster. You are asking what the laws of physics say would happen if you break the laws of physics. There is no meaningful answer to such a question."
] | [
"This is not a stupid question by any means, simply an unanswerable one with our current understanding.",
"The topic itself is fascinating, but all discussion on it is pure speculation and this subreddit does not allow such things."
] | [
"This is not a stupid question by any means, simply an unanswerable one with our current understanding.",
"The topic itself is fascinating, but all discussion on it is pure speculation and this subreddit does not allow such things."
] |
[
"Large Scale Renewable Energy Projects?"
] | [
false
] | I'm doing a project about large scale energy projects such as the Arizona Solar Tower, Iceland's use of geothermal energy, France's tidal power plant, etc. The project focuses on how there's no one "end all" solution to renewable energy. My question is, what other kinds of large scale renewable energy projects are bein... | [
"A significant amount of Brazil's transportation fuel is sugarcane ethanol."
] | [
"Germany",
" has a wind farm in the ocean "
] | [
"There's a slightly different type of solar thermal power project in Spain.\n",
"http://en.wikipedia.org/wiki/Andasol_Solar_Power_Station",
"Are you interested in the viability of these projects? "
] |
[
"Why did the Fukushima nuclear plant switch to using fresh water after the accident?"
] | [
false
] | I was reading about Operation Tomodachi and it mentioned that the US Navy provided 500,000 gallons of fresh water to cool the plant. That struck me as odd considering they could just use sea water. After doing some digging was all I could find. Apparently they using sea water but wanted to switch over to using fresh wa... | [
"Salt is corrosive. As water boils in the core, the salt concentrates, and you get deposits that impinge heat transfer. With enough salt you can eventually have molten salt which is harder to manage. If you had any intact fuel, the salt and sediment from raw water will plug the fuel inlet debris strainers, preventi... | [
"Spent fuel rods need about 10 years of cooling. Not sure about these since they weren’t “spent”, but not forever.",
"They will need to be sequestered/contained for many lifetimes however."
] | [
"Because generally they are still hot enough to heat water to hot, but not boil it to create pressurized steam that could power a turbine."
] |
[
"If we have two quantum entangled particles A and B, and we measure B's spin state does that collapse the superstate of particle A's spin?"
] | [
false
] | Suppose you had an infinite set of Quantumly Entangled particles, each set could be described as [A,B] and you decide an order, IE: 1[A.B], 2[A,B], 3[A,B]... etc etc. Now, we load all A particles into machine which can measure whether or not the particle’s spin is in a superstate or not (similar to the double slit expe... | [
"I understand your confusion. You need a slightly longer version of what entanglement is. A particle can have several properties, such as position and spin. When we say two particles are entangled, we really mean that one property of a particle is entangled with the property of another particle. So the spin of two ... | [
"could we not then use this system for faster than light communication by virtue of simply measuring whether or not particle 1A's spin is in a superstate?",
"You can't measure whether a particle is in a superposition state or not. So, no. "
] | [
"We both have two magic boxes that spit out 1 or 0, once a day, with 50% probability. Both our boxes appear to be random, but are actually linked: if we met up and compared notes we would find that both of our boxes always spit out opposite numbers. Despite this, there would be no aspect of observing an individual ... |
[
"Why is the air in the ozone layer so cold?"
] | [
false
] | [deleted] | [
"The ozone layer is found in the stratosphere, in fact it defines the stratosphere. Temperature increases with height in the stratosphere, because oxygen absorbs many kinds of UV light.",
"That's unusual, for the most part, the atmosphere is transparent to the light incoming from the sun. The ground absorbs this ... | [
"I dont think you fully answered my question, as i was thinking more in the proximity(+-10km) of the ozone layer, the temperature is way higher than the ozone layer itself."
] | [
"First of all, the ozone layer is in the stratosphere. And as described above one can say that the stratosphere is defined by the ozone layer based on the temperature profile.",
"It is possible that you are confusing the ozone layer with the tropopause? This is the height that separates troposphere and stratosphe... |
[
"Does the flow of traffic have any noticeable effect on wind patterns?"
] | [
false
] | I have read that jellyfish' pulsating movement has an impact on ocean current. There are tons of animals moving about the planets surface but none with as much energy as automobiles traveling at quick speeds in such predictable routes. So can we plot this impact or are predominating cells to large to be affected by thi... | [
"This is actually a really good research question. After a quick search I didn't come up with much on the topic. I would expect that if there is any effect it would be only on highways with both fairly heavy traffic and high flow speed. Other local conditions might dominate though, hard to say whether the traffic e... | [
"Some napkin math tells me the effect would get lost in the mix; I'm pretty sure:",
"(number of jellyfish * mass of water pushed per jellyfish per day) / (mass of the ocean)",
"is greater than",
"(number of cars * mass of air pushed per car per day) / (mass of the atmosphere)",
"I'm assuming that since jell... | [
"Cars contribute to ",
"Urban Heat Islands",
", which in turn affect the local wind patterns. So I think the answer would be affirmative, but the effect is (probably) relatively small compared to the other causes of urban heat islands."
] |
[
"How can we see light from the beginning/early universe?"
] | [
false
] | If we can observe the light, that would either mean that we 'beat' the light to our current location, or that the light somehow goes around the universe in circles. What am I missing here? Also, what is the earliest light we can see relative to the start of the universe? | [
"because the universe is expanding faster than light",
"That's not really a true statement. Some parts are expanding away from us faster than light, and other parts aren't. The expansion rate can't be described in terms of a speed, though.",
"The theoretical limit for how much universe we can see is about 13.7 ... | [
"The early universe was a time, not a place. It happened everywhere. So the light we see today from the early universe - particularly the ",
"cosmic microwave background",
" - originated many billions of light years away. Because the Universe is far, far larger than we can see, we'll continue receiving light fr... | [
"Absolutely. One of the most important things we've learned about the Universe is the ",
", that (on large scales) the Universe is uniform. There are no preferred or special places. So what would it mean to say the Big Bang happened here or there? It's more consistent with what we know to say that it happened ",
... |
[
"How do moles, and other animals that dig tunnels, keep their tunnels ventilated?"
] | [
false
] | I know that's a problem with human miners, but does that have more to do with coal dust and whatnot, or is carbon dioxide buildup just as bad? | [
"Some of them don't, they adapt to it. Naked mole rats are somewhat adapted to a higher CO2 level than surface air. "
] | [
"I can't answer the main question, but for human miners the problem is a compounded gas and particulate buildup. Gases of concern include CO2 and methane/ethane/natural gas of any kind, while particulates include any kind of aerosolized particles like coal or silica dust."
] | [
"Moles in particular, but digging animals in general, are often located up very close to the surface, especially when compared to human miners. It's a lot easier for air to diffuse through a few inches of soil than through a few hundred feet of rock. There's also a lot less distance between opening and animal, us... |
[
"What happens if a male takes birth control pills?"
] | [
false
] | If a male takes them daily like a female does, what chemical changes would he expect? How long would it take for the effects to be noticed? | [
"It depends on the amount taken. Some medications used in male-to-female hormone replacement therapy have the same active ingredients as birth control pills, but in different concentrations, so you would expect symptoms in the broad category of development of female secondary sex characteristics. One of the first s... | [
"And don't forget changes in mood and behavior due to hormonal imbalance"
] | [
"Would those symptoms persist even after stopping consumption of the pills? "
] |
[
"How do so many different languages have similar inflection patterns?"
] | [
false
] | For example, questions end in upward inflections and statements downward in so many varied languages. Why are such patterns so pervasive? | [
"You are talking about ",
", rather than inflection. Could you give examples of the \"so many different languages\" that you are thinking of? It will allow us to better get a sense of whether we are dealing with related or unrelated languages."
] | [
"But even among Romance and Germanic languages, patterns are different. For example, French and Spanish usually use a falling final intonation for questions, unless a question word (e.g. ",
", ",
") is absent from the sentence. The fact that you are able to 'often guess correctly' means that you are not able in... | [
"My girlfriend is Korean and I can often correctly guess correctly (as verified by her) whether her speech with other Koreans is a question, a statement of fact, patronizing sarcasm etc. That's a language that seems different enough from the Romance and Germanic languages I am used to hearing, and yet has similar i... |
[
"Why do scientists believe blood will boil if a human is exposed to the vacuum of space? Is this based on evidence?"
] | [
false
] | Aerospace/Electrical engineer here. I came across an article on BBC last night about Felix Baumgartner's attempt later this year to attempt a skydive at the highest altitude ever, 36.5km (120,000ft). The article states that his blood "will vaporize" if his suit loses pressure. I assume the reporter equates blood boi... | [
"Blood will boil but it will take a very long time. We have empirical data from accidents in vacuum environments. ",
"Soyuz 11",
" returned to Earth but in the process was depressurized resulting in the death of the cosmonauts on board. The bodies did not show substantial physical damage such as blood boiling o... | [
"Phil Plait PhD, aka the Bad Astronomer, recently posted a video about this. In summation, no the blood will not boil because we are a relatively closed system, so blood in our veins isn't immediately exposed to the vacuum of space.",
"http://blogs.discovermagazine.com/badastronomy/2012/01/31/qba-what-happens-if... | [
"The problem is with dissolved gasses in the bloodstream. It is similar to what is faced by scuba divers surfacing too quickly - a rapid downward change in pressure causes dissolved gasses in the blood to form bubbles, which can kill. If you have access to a vacuum chamber, put a glass of water into it and turn it ... |
[
"Help for a budding young scientist?"
] | [
false
] | null | [
"If you want organic chemistry, then Organic Chemistry by Clayden, Greeves, Warren and Wothers is really good, if a little expensive :/\nSource: I have a copy..."
] | [
"r/science",
" might have been better, but I will try answering nevertheless.",
"Disclaimer: I'm not American, so some of this may not apply there.",
"First, be absolutely sure that it is really what you want. Careers in science are pretty difficult to get, the competition is fierce, hours are long and the pa... | [
"Thank you for the well-articulated reply:",
"One: It's moreso a hobby-plus-one than a career, but I will look into it regardless. I'm actually enrolled for Renewable Energy!",
"Two: An excellent point that I definitely need to take into consideration. I suppose i'm trying to be too much of a 'Renaissance Man'.... |
[
"How does blackbody radiation work?"
] | [
false
] | I'm clearly stuck with some misconceptions about how blackbody radiation works, but am having trouble figuring out where my thinking is wrong. (This is not a question about uv catastrophe.) I'll try to trace my line of thinking below and would appreciate anybody pointing out my misunderstandings. When a blackbody abso... | [
"When a blackbody absorbs electromagnetic radiation how that energy gets absorbed depends entirely on the radiation's frequency. Some frequencies cause molecular vibrations, rotations, bending...other specific frequencies cause election excitation.",
"Yes, although the microscopic details of what kinds of excitat... | [
"Thank you! This helps immensely - I really appreciate your answer."
] | [
"Last thing -- when you have a lot of atoms close together, you don't have neat electron energy levels anymore, they separate out into a band."
] |
[
"Why doesn't air settle into its component gases?"
] | [
false
] | As air is composed of several different gases each with a different density, why doesn't air settle into layers of different gas? I understand winds mix them, but I would've thought over a long time they would settle out somewhat | [
"Yes wind and other meteorological effects mix the gases as you and other commenters have stated. But I don't think that truly answers the question, and an answer can be arrived at without even considering meteorological effects.",
"",
"When thinking about this are you picturing a layer of oil sitting on top o... | [
"Have you ever seen a boiling pot with rice, or small noodles or so, in it? The rice doesn't settle on the bottom because steam bubbles keep rising up and keep the rice and the water in motion.",
"It's similar in the atmosphere. The sun warms the ground. The ground heats up the air near the ground. Also moisture ... | [
"Something went wrong with your scale height values. Nitrogen should be very close to oxygen, while CO2 will be at ~2/3 of their value."
] |
[
"Why does salt \"bring out flavor\" in food, even sweet foods like cookies?"
] | [
false
] | null | [
"Check ",
"this",
" out if you got the time. From the coolest cooking show ever, they get all into the history and science every episode."
] | [
"You have different taste buds (sweet, sour, bitter, salty, umami) that have receptors for their respective tastants. The more of these taste buds that are stimulated in the passage of food, the greater the intensity of perceived favor. So by adding salt to a dessert, the cook, whether knowingly or not, is increasi... | [
"Here's all the segments of that episode. He gets into the flavor properties in the second segment.",
"S7E0P1",
"S7E0P2",
"S7E0P3",
"S7E0P4"
] |
[
"Does the absolute value of d(telomere length)/dt decrease with time as someone gets older?"
] | [
false
] | null | [
"The data is probably too noisy to measure that.",
"Here's",
" a graph of telomere length vs age for 299 healthy subjects. Original is ",
"here",
".",
"It looks to me that d(telomere length)/dt is constant with time, but this is measured in a population and not in a single individual."
] | [
"Theoretically, unless the cells become cancerous, telomere length decreases at a fairly constant rate. Hoewer, there are telomerases that reverse this process, the older we become the less active these telomerases become. ",
"So, I would say yes."
] | [
"Oh, well, I would expect that less telomerase would increase the absolute value of d(telomere length)/dt - since it would speed up the process of decay",
"The thing is - though - don't cells divide more slowly as their telomeres shorten? Telomere length is shortened when cells divide, but when cells take longer ... |
[
"How did Lance Armstrong pass hundreds of doping tests over a period of almost a decade?"
] | [
false
] | null | [
"Lot of informations about this can be found in the USADA report, but lets look first at the idea that he \"passed hundred of doping tests\".",
"Firstly he directly tested positive to cortisone in the TDF in 1999, but he got away with it with a backdated prescription. See USADA report page 32 ",
"http://cycling... | [
"Here is a very detailed Question and Answer with a Blood Passport panelist. If you read the entire thing you will understand how one can get away with it.",
"http://nyvelocity.com/content/interviews/2012/behind-scenes-contador-cas-hearing-michael-ashenden",
"Highly simplified you take a performance enhancing ... | [
"They do, and they did. Lance's old samples tested positive. ",
"http://usatoday30.usatoday.com/sports/cycling/2005-08-24-armstrong-samples-details_x.htm"
] |
[
"Family dispute over simple probability problem: please help solve! (X-post from r/learnmath)"
] | [
false
] | We were talking about this over dinner and I was told by my older brother that I am thinking "far too simplisticly" and that "math is much more complicated than I imagine." This is the problem: A garden tool is a certain years old. The only info you have is that it is at least 10 years old. I claimed that, with that in... | [
"Your brother's reasoning is, of course, wrong, as he would also be led to conclude that there is a 50% chance that it is at least 13 years old, a 50% chance that it is at least 14 years old, and a 50% chance that it is at least 100000 years old.",
"The actual probability of it being at least 12 years old depends... | [
"Your brother is using the ",
"Principle of Indifference",
". In this case it's used wrongly and comes up with a contradiction. In particular:",
"Applying the principle of indifference incorrectly can easily lead to nonsensical results, especially in the case of multivariate, continuous variables [e.g. the ... | [
"Squidfood and nicksauce have good answers here, but I'd like to point out a difficulty in talking about probability here.",
"What do we mean by \"probability\" in a situation like this? The tool has an exact age, so in a sense the probability of it being that age is 100%, and of all other ages 0%. However, bec... |
[
"Could someone tell if Venus rotated the 'wrong' way around without going into space?"
] | [
false
] | Could someone tell a planet's rotational direction without actually sending something to look at it? | [
"Yes",
". We knew about Venus' retrograde rotation in the 1950s, and we had good estimates of its rotation speed in the 60s."
] | [
"I believe astronomers can use the ",
"doppler effect",
" to gauge the rotational velocity of a body. Light reflected from the side of the planet \"approaching\" us will be blue shifted, and red shifted on the side receding."
] | [
"Radar, rather than visible light was used to determine this, but yes. Doppler shift and the echo time delay.",
"http://adsabs.harvard.edu/full/1967AJ.....72..351D"
] |
[
"Is it possible for a deck of cards to be shuffled accidentally into perfect order?"
] | [
false
] | Can one even calculate the probability of this event? | [
"The number of possible shuffles of a standard deck of cards (52 cards) is 52 * 51 * 50 * ... * 1, or otherwise written as 52!. This number is approximately 8 * 10",
" (an 8 followed by 67 0's).",
"To get an idea of how unimaginably large that number is, lets assume that we can create a billion different deck-o... | [
"Here's how it was explained to me once, to get an appreciation for it:",
"Imagine you shuffle a deck of cards once per second, every second. You shuffle 86400 times per day.",
"You start on the equator, facing due east. Every 24 hours (86400 shuffles), you take one step (one metre) forward. You keep shuffling,... | [
"That's the best way I've seen it be put. That's mind boggling how big that number is"
] |
[
"Do the nodes and the anti-nodes in a stationary wave have equal energy or is energy non uniformly distributed?"
] | [
false
] | null | [
"The nodes of a standing wave are the points that never move. They have zero energy density. The anti-nodes are the points that move the most. They have the most energy. It really depends on what kind of wave you are talking about (wave on a string, electromagnetic wave, sound wave, etc.). Typically, the energy den... | [
"Is there really no energy associated with the derivative of the field?"
] | [
"Thank you very much for answering."
] |
[
"Neutron Stars or Black Hole?"
] | [
false
] | I know the basics of supernovas, black holes and neutron stars. The thing i don't understand though is why a supernova leads to a black hole or neutron star? Is there a reason a supernova creates a black hole or a neutron star, or is it just a coincidence, or do we simply don't know? | [
"As far as I can tell, three solar masses is the mass of the largest neutron stars and the smallest black holes. The stars that gave birth to these compact objects, however, would have been much more massive, as most of the mass would have been blown off during the supernova."
] | [
"According to ",
"wiki",
", the limit is much higher than that: about 25 solar masses, depending on metallicity. Below 8 solar masses, a star would not go supernova, jst shed its outer layers leaving a white dwarf remnant."
] | [
"They both form when stars collapse due to its own gravity. But what determines that when a star collapses, would it become a black hole or a neutron star? The answer is mass. A star which has a mass of about three times of our sun will compact into a neutron star. And a star with mass greater than three solar mass... |
[
"Is it possible for a person to have both gigantism and dwarfism?"
] | [
false
] | null | [
"Yes. One dude. Ever."
] | [
"Picture in giant state",
"."
] | [
"Needs pics :("
] |
[
"Question about gravity and entropy"
] | [
false
] | Can gravitational forces stop entropy from increasing? i.e. billions of years from now, after the sun becomes a white dwarf and then a black dwarf and is no longer emitting radiation, how would its entropy still increase? Wouldn't gravity hold all of the molecules together? | [
"The relationship between gravity and entropy is somewhat complicated. I don't understand it well, but Brian Greene lays it out very well in \"The Fabric of the Cosmos\""
] | [
"Entropy is a measure of energy unavailable to do work. So as long as the sun is hotter than its surroundings, heat will leave the sun, increasing its entropy."
] | [
"The emitted radiation also factors into entropy. After it's emitted, it'll tend to be scattered, thus increasing entropy overall."
] |
[
"What is the most accurate graphical (visual) representation of a black hole you have come across?"
] | [
false
] | I've seen many 2-d interpretations that are misleading as well as those that show a simple black marble poking out of a soup of gas. I envision instead that a distant observer would see a highly luminous accretion "disk" which is not necessarily disk shaped, but is actually enveloping the black hole sphere along with ... | [
"This. It's more than special effects, it's the most current and accurate visualization of what nearing a black hole might be like that we've ever created. Of course the ",
" probably isn't a giant bookshelf though... "
] | [
"The black hole in the movie Interstellar was unique in that they hired a bunch of general relativity experts, including Kip Thorne, to compute what it would look like."
] | [
"It's a shame that they decided not to show gravitational redshift and blueshift"
] |
[
"What does the body do with all that extra keratin protein when someone goes bald?"
] | [
false
] | null | [
"Well when someone goes bald, usually the hair follicles end up shrinking and don't make any hair. Without any hair being made, the keratin protein is not synthesized in the first place, instead, the amino acids that would've made up the keratin protein are used for making other proteins around the body."
] | [
"So does that mean someone whose bald will have faster growing nails/hair in other places?"
] | [
"No. Your body needs what it needs. If you are actively trying to build muscle, then you will require a lot of protein to build both muscle and hair. If you become bald, you just don't need as much protein as before, a tiny amount less for hair, but you still need the same amount for muscles.",
"That is if you be... |
[
"Why does my shower curtain blow inwards while water is running?"
] | [
false
] | All I want to do is have a shower without the curtain constantly sticking to various body parts. | [
"See the aptly named ",
"shower curtain effect",
". There are a number of contributing factors and it likely is a combination of those at work."
] | [
"This isn't completely true, while the \"chimney effect\" does play a role, you can observe the curtain getting sucked inward with cold water as well.",
"The most famous explanation is the so called Bernoulli-Principle. The Bernoulli-Principle states that a change in velocity corresponds with a change in pressure... | [
"This explanation makes a lot of sense, but I am almost sure that I have observed the same effect with cold water.",
"I would add to the explanation the effect of (maybe) speeding the air close to the water stream, what would reduce its pressure by an effect similar to the Venturi effect, creating a pressure grad... |
[
"What would happen if you detonated a nuclear bomb in the Mariana Trench?"
] | [
false
] | null | [
"The pressure of nearly seven miles of ocean on top of it?"
] | [
"Much wittier than what I was going to say, but in the same regards.",
"Basically a Nuclear bomb would go off and some life would be disrupted. Perhaps depending on how close it was to the sea floor, a crater would also form."
] | [
"Much wittier than what I was going to say, but in the same regards.",
"Basically a Nuclear bomb would go off and some life would be disrupted. Perhaps depending on how close it was to the sea floor, a crater would also form."
] |
[
"When putting plastic over windows to prevent heat loss in the winter, is there an optimal distance between the plastic and the window?"
] | [
false
] | When searching online, it seems that people say <.25" is optimal. However, with the way my (old) windows are constructed, that isn't possible. Am I doing more harm than good by putting up plastic with a distance of 2-4"? | [
"As close as possible without touching is optimal, in order to disrupt the internal convection currents (the closer the surfaces are, the slower the air must move). But honestly, my gut feeling of the boundary layer thickness is that .25\" is no different from 2-4\" - that is, both spacings are much larger than 2x... | [
"Awesome, thank you so much for your answer! My instinct was also that any plastic at all will help, since the older windows are very drafty. I would love to have an infrared camera or something and test the different distances, but that might be for someone with more time and money."
] | [
"You certainly won't be doing any harm. You could try two different depths and tape a thermometer on the inside glass. Make measurements before sunrise. "
] |
[
"Why are female and male handwriting styles different?"
] | [
false
] | It's anecdotal, but from what I've seen, it appears that female handwriting is rounder and smoother than the more blocky and linear male handwriting. Is there any substantial truth to this apparent trend, and, if so, why? | [
"Your answer needs sources for the claim of increased fine dexterity in women versus men.",
"The reference to evolution is a nice story. However, like a lot of claims in evolutionary psychology, it is ultimately untestable and not science. You could also construct an argument that men needed to shape their tools ... | [
"Your answer needs sources for the claim of increased fine dexterity in women versus men.",
"The reference to evolution is a nice story. However, like a lot of claims in evolutionary psychology, it is ultimately untestable and not science. You could also construct an argument that men needed to shape their tools ... | [
"There are likely to be cultural and social factors. You'll have a hard time writing any Arabic without a lot of circular strokes. You can get away with writing Katakana without many at all.",
"The best way to look at this would be some kind of cross-cultural analysis. If women's handwriting is more likely to con... |
[
"How fast does antibiotic resistance spread? Will strategies such as reducing the days of antibiotic therapy reduce resistance spread?"
] | [
false
] | Some trials propose that antibiotic exposure can be reduced up to 3 days without jeopardizing the life of the patient. Their justification is to reduce antibiotic resistance. However, my question is, how fast does antibiotic resistance develop and spread? Do those 3 days of less antibiotics will actually make a differe... | [
"I'm not sure where you got this information so I can't speak for the trials that you read. However, from my study of biology it could actually do the opposite. It's fairly simple from an evolutionary stand point in that antibiotics will kill off weaker and less resistant bacteria first and then after the full cour... | [
"It's a misunderstanding that simply taking an antibiotic \"for the full course\" and not stopping early will always work to reduce antibiotic resistance. \"The full course\", by the way is always a number we kind of make up or guess. Many medical experts advocate stopping antibiotics early for certain infections."... | [
"We're still trying to figure this out. It's a very complex problem because it has to do more with the bacteria than the antibiotic. And bacterial species are ",
" different. As per basic microbiology, we would expect that bacterial species that replicate more frequently and faster would develop resistance more r... |
[
"10 years ago, athletes making full recoveries from major ligament tears was virtually unheard of. Today, it's par for the course (at least for the pros). What changed?"
] | [
false
] | null | [
"Advances in microsurgery techniques, in MRI imaging which can lead to more accurate diagnoses and treatment plans, and in physical therapy approaches."
] | [
"While I agree with the rehab and surgical procedures part, I have seen a few times where MRI shows no tear of the acl, but the dr wanted to scope just to make sure, and would find grade three ruptures of the ligament. MRI is useful, but it still should just be one of many tools used by an ortho."
] | [
"The health costs are generally related to the price inelasticity of medical care, and don't actually reflect the true costs of providing an MRI scan. For reference, MRI machines, while they involve a large up front cost, can be in service for nearly a decade - and on average pay themselves off within a single year... |
[
"Reddit, why does the bigger cyclist always (in my experience) descend a hill faster than the smaller rider? THIS MAKES NO SENSE!!"
] | [
false
] | So it's first-principle physics that all things on Earth will accelerate at the same rate (9.81 m/s2) regardless of mass right? I'm a cyclist reddit, and every time I go down a hill with a bigger person they ALWAYS accelerate more quickly!! Assuming the bicycles are the same, and the hill is roughly the same, what give... | [
"The force of damping from the atmosphere is proportional to velocity. The acceleration it causes depends on the force divided by the mass. The bigger the mass, the less the deleration caused by air resistance."
] | [
"Without air resistance the ",
"free body diagram",
" for a guy getting pulled down a hill is just m*g*sin(theta) = ma where theta is the angle of the hill. Here, of course, you can see that the m's cancel, so then you can say \"a = g*sin(theta)\" ",
"But once you add in air resistance, there is a second forc... | [
"Put perhaps more simply: Wind resistance is proportional to surface area, momentum is proportional to volume. Bigger people have a higher volume-to-surface-area ratio."
] |
[
"Why are there two bones in our forearms and shins? Does this feature serve some important function?"
] | [
false
] | null | [
"As someone who just has his radius head replaced by a prosthesis after a fall and is now working to try to regain his mobility I can answer :",
"the two bones structures alow for rotation in multiples axes.\nthe cubitus alow your arm to flex in and away from your upper arm.",
"the radius alow for your lower ar... | [
"This is why early tetrapods with them were able to out compete those without, but let's not confuse that with why ",
" have them. Evolution isn't capable of wholesale replacing major structures. We have radii and ulna in our arms, and fibula and tibia, because all land vertebrates do."
] | [
"I'm assuming cubitus is your languages word for the ulna? Regardless, this is a correct answer. Another good reason would be to split pressure while pushing into two bones, meaning less risk of fracture. It also provides more support for the carpals. "
] |
[
"Is the speed of gravity slower in a medium?"
] | [
false
] | null | [
"In the weak field limit, gravitational waves behave in a very similar fashion to electromagnetic waves. In fact the mathematics is nearly identical and if we consider a medium of point mass oscillators (say a thin gas because the math is easier) we can calculate what the \"refractive index\" of gravitational waves... | [
"So if you read the ",
"correct description",
" of why light slows down in a medium it seems pretty likely that something similar would happen with gravitational waves, i.e. gravitational waves passing through a medium would couple to vibrational modes and get an effective mass, slowing them down.",
"Note tha... | [
"You misunderstand, OP was talking about gravity fields/waves, which move at the speed of light."
] |
[
"What effect does time dilation have on electromagnetic waves?"
] | [
false
] | In the movie Interstellar, video recordings are transmitted from Earth to the crew of the Endurance. This made me wonder if the use of radio transmissions (or other forms of electromagnetic wave communication) could be used to overcome the effects of time dilation experienced by two individuals in drastically different... | [
"To keep within your example from Interstellar (spoiler warning!), some of the crew are sent to the surface of a planet orbiting close to a super-massive black hole, and experience time dilation relative to the mothership (Endurance) by a factor of ~60,000. Any signal the crew on the planet try to send back to the ... | [
"Wait a second, wouldn't frequency shift be detected on earth, and it be obvious that the \"ping\" signal is messed up, leading to obvious conclusion? How would it possible not to notice this?"
] | [
"Yep. You're right, they should have known about the time dilation from the frequency. "
] |
[
"Would A Binary System Of A Star (Preferable a yellow dwarf) And An Equally Sized Black Hole Be Stable?"
] | [
false
] | (This is for a sci-fi project of mine). What stars would be best for this binary system? Would it be habitable? Would it be possible to place the planet in between the two celestial bodies? Thanks in advance! | [
"Almost any system of two objects will be gravitationally stable. A black hole's gravity is just the same as any other object of the same mass. At long distances, all gravity looks like GM/r",
". It's just that a black hole is so small that you can get close enough that gravity gets strong enough that it stops be... | [
"Just to add a bit to what Astrokiwi said",
"Would it be habitable? Would it be possible to place the planet in between the two celestial bodies? Thanks in advance!",
"The system that will feel closest to this would be that the inhabitable planet orbits the black hole, and then the black hole and the star orbit... | [
"A binary system is never exactly stable, you always emit gravitational waves and the bodies eventually collide. However, this effect is usually extremely weak, and only becomes noticeable for very massive bodies orbiting very close to eachother. Just put the star a healthy distance away from the black hole and it'... |
[
"If I point randomly into the sky, how likely is it that I'm pointing at a star?"
] | [
false
] | Edit: phrased differently, If I extend a line from the tip of my finger to the edge of the observable universe, what's the probability that that line intersects with the body of a star? This was inspired by reading about or the "dark night sky paradox". | [
"If you take your finger hold it at arms length away from your body, you can block out the sun or the moon pretty easily. So I'm going to say that's your \"pointing\" That's around .5 degrees of the possible 360 degrees around earth. If you only could point along one axis, an imaginary straight line around Earth. T... | [
"Yes - a ray of zero width from your finger to the edge of the observable universe will almost certainly never intersect any star, thought it may possibly (but probably not) intersect a galaxy.",
"If half of these rays intersected a star, then the average brightness of the night sky would be the same as half the ... | [
"Depends on what accuracy you're talking about, but in actual reality, it's quite likely that you're pointing at multiple galaxies, never mind just a star. ",
"The Hubble Ultra Deep Field imaged some 10,000 galaxies, while looking at the darkest part of the sky. Those 10,000 galaxies were in an area that was just... |
[
"Two questions: False Vacuums, Vacuum Metastability events, and the Alcubierre Drive"
] | [
false
] | So, I'm writing a science fiction novel, and I'd prefer some rigour in the science bits. I've studied physics, but not near as much as I'd need to in order to speak with any authority (engineer here, hi!). (I understand my questions are insanely generalised and possibly horribly put, but I'll hone down to what I reall... | [
"Well, we'll get over the first paragraph of the answer, then :)",
"As far as the second paragraph goes, everything's fine, but I think we have a little disonnance at the last part. \nBy protected, what I meant is that if our part of the universe would be \"walled off\" if we were exist within a \"bubble\" of fal... | [
"No, no, the false definitely has the higher energy. That, I know. I'm just not being very articulate at the moment. I appreciate the time you're taking to try and help me clear this up, though :)",
"And I'm not exactly getting at that :(",
"I guess what I was saying was that I assumed the false vacuum is like ... | [
"There would be a significant difference between a VME and a big bang. Specifically, in the big bang all energy originated at a single point. A VME would have matter \"falling in\" to it from the edges. However, you are correct in that there could (theoretically) be some new sort of reality with different physi... |
[
"Would a 50g object traveling at 280,000m/s really possess the same kinetic energy as a megaton of TNT?"
] | [
false
] | Did a quick calculation, and a 50 gram weight traveling at 280,000km/s would have roughly 1.96 x 10 joules of kinetic energy. A megaton of TNT has 4.184 X 10 joules. Is my calculation correct? Would a 50g object traveling at relativistic speeds create an explosion comparable to a nuclear warhead if it were to collide w... | [
"In which case it's calculated by mc",
" x (sqrt(1/(1-v",
" /c",
" ))-1)",
"You can approximate this as 1/2 mv",
" + 3/8 mv",
" /c"
] | [
"KE is calculated through 0.5 x mv",
" I make it 1,960,000,000 Joules for a 50 g (0.05 kg) mass at 280,000 m/s.",
"But ultimately yes, a small mass travelling very quickly can impart a lot of energy."
] | [
"Sorry, meant km/s. Almost light speed."
] |
[
"At what size does gravity become nil/negligable?"
] | [
false
] | As the title says, I'm baisically want to know at what size gravity either stops being either detectable or becomes negligable enough to not be noticed? Edit: Thanks for all the answers guys and girls. I think I understand that everything has a gravitational pull but to varying degrees depending on distance and mass? S... | [
"Honestly, I think that's misstating it ",
" This is more about pedagogy than it is about physics, but indulge me for a moment.",
"I have here a coin. At present, it is heads-side-up. One might ask, ",
" is it heads-side-up? And were one to ask that, the answer might as well be, \"because the tails side is do... | [
"The best laboratory measurements of gravity are made by torsion pendulums. There's a group at the",
" University of Washington who does this",
".",
"I'm not 100% sure, because I don't have time to do the calculations, but I think that if you stood next to their torsion pendulum, they could detect your prese... | [
"If you're okay with saying a fundamental property of energy is that it ",
" ",
" a curvature of spacetime, then we know what causes gravity. If you're not okay with saying that, then, well.. we don't know.",
"edit: see below."
] |
[
"Are there any cognitive (or other) benefits I'm missing out on by listening to audiobooks rather than reading the book?"
] | [
false
] | [deleted] | [
"By not reading the words, you don't learn their spelling. "
] | [
"By not reading the words, you don't learn their spelling. "
] | [
"Well the most obvious thing would be spelling. "
] |
[
"If the Tibetan Plateau is so dry, how come it has so many lakes and is the source of so many rivers?"
] | [
false
] | The Tibetan plateau is generally accepted as being an incredibly cold and barren place, and its dryness is usually blamed for this. But not only does it have an abundance of lakes, it is also the source of the Yangtze and Mekong, among others. How is this possible? On a related note, if it does have water, why is it so... | [
"It has an abundance of lakes because of snow melt. It doesn't have many plants because of the altitude and the cold. "
] | [
"places that are cold are also dry. the lakes have water, but further away from the lakes, it is dry."
] | [
"Thanks for the response guys! I'm still a little confused though.",
"I thought that many of the lakes were saltwater. Wouldn't glacial runoff be fresh water? Also, does that mean that all the rivers coming off the plateau are caused by glacial melt?",
"Why, though, are there is there no vegetation AROUND the l... |
[
"Are visible atoms possible?"
] | [
false
] | Is it theoretically possible, given the existence of the commonly discussed "island of stability" in atoms with super-large nuclei, to synthesize an atom with a nucleus so large it would be visible to the naked eye? | [
"For an object to be visible by light it has to be larger than the light's diffraction limit, which is at most half it's wave length. For visible light that would be about 200 nm. The largest nuclei are about 15 fm. That's 13 million times smaller than what can be observed by light. \nTL;DR - No, nuclei are way too... | [
"I believe you're trying to refer to techniques like Scanning Tunnelling Microscopy (STM), which images the quantum wavefunction of an atom, and Atomic Force Microscopy (AFM) which images its charge density. In no way are these \"simulations\", they're direct experimental probes. ",
"This issue here is that \"l... | [
"I believe you're trying to refer to techniques like Scanning Tunnelling Microscopy (STM), which images the quantum wavefunction of an atom, and Atomic Force Microscopy (AFM) which images its charge density. In no way are these \"simulations\", they're direct experimental probes. ",
"This issue here is that \"l... |
[
"How does DNA recombination ensure the resulting chromatid is compatible?"
] | [
false
] | null | [
"Depends on what you mean by \"compatible\". Structurally, there should not be much difference in the DNA between alleles D and d, so the DNA just goes on in the recombined state. If the genes are involved in gamete function and a certain combination produces a non-functional gamete, then you get a non-functional g... | [
"Sometimes incompatable loci are evolved and used by plants to prevent self-fertilization. ",
"Ex."
] | [
"The evolutionary “goal” of crossing over/recombination during meiosis is to generate gametes that have a chance of having higher success. There’s also a chance that that they have lower success, or are “not compatible.” Not compatible could mean having too many recessive alleles, leading to poor “fitness” either... |
[
"What would you see if you were standing in the dead centre of a cylindrical mirror?"
] | [
false
] | Or if you were floating in the middle of a spherical mirror for that matter? | [
"i put this biped\n ",
"http://i.imgur.com/DLRwI.jpg",
"in a cylindrical mirror and got this",
"http://i.imgur.com/f3h1N.jpg"
] | [
"What did you use to model this? And thanks :) It's just one of those things that has always intrigued me but also annoyed me knowing that I'll never be able to physically construct it."
] | [
"i used 3ds max"
] |
[
"Is there something that determines if an animal can be domesticated?"
] | [
false
] | null | [
"A number of factors, not a single thing.",
"One is the animal's social structure in the wild. If for example they live in packs with a leader, then humans may be able to easily domesticate them by taking over that leader position. That's not absolute by any means, but it's one of the strongest factors.",
"The ... | [
"Theoretically, with enough time and patience, any* species could be domesticated, since domestication is just breeding for favorable traits over successive generations. (Gonna address that asterisk in a minute.) The real question becomes one of resources and risk vs. reward that faced our ancestors.",
"Spotted h... | [
"To expand on the eating point: The animal's diet also shouldn't be too specialised. It should be comfortable living off farm waste and table scraps. It's why we didn't domesticate anteaters.",
"Additional points:"
] |
[
"Evolution of viruses. Why kill the host?"
] | [
false
] | Forgive me if I sound overly ignorant here but I've recently come to accept that evolution is fact (long story: ex-JW). Anyway, I was thinking about how almost every species on this planet from bacteria to humans have evolved because of natural selection among other things. The point being that if a species survives it... | [
"Good question! You're right. It is generally not advantageous for a virus to kill its host. You'll find that the vast majority of viruses do not. Sequencing studies have shown most people have more viral particles in and on their body than they do human cells, and for the most part these cause little or no not... | [
"Since other answers have talked about this affects humans, keep in mind the situation is pretty different for killing cells (either in a multicellular organism's body or among a population of single-celled organisms) and for killing a multi-celled host. Viruses need a host cell's machinery for reproducing, and oft... | [
"Wow! That's really interesting. Never thought about the symptoms they cause also being a viable transmission system. "
] |
[
"Are there prisms and lenses for nonvisible wavelengths of the electromagnetic spectrum? What sort of things would they be used for?"
] | [
false
] | null | [
"Yes. There certainly exists a market for x-ray optical equipment, either to focus x-rays like you would need to do on the Chandra telescope (basically the Hubble telescope of the X-ray spectrum), or in x-ray spectrometers and microscopes. I would not be surprised if X-ray rated optical pieces would be what some sp... | [
"I do infrared spectroscopy, and there are all kinds of different optics for various infrared wavelengths. Metal mirrors are relatively straightforward, gold and aluminum have good reflectivity over a very broad region. Most often, people will use dielectric coated mirrors, which can be very highly reflective in ... | [
"Even so, very high quality & efficiency x-ray optics are notoriously difficult to make. There is a great demand for them to enable fine lithography for semiconductors, but so far that has been one of the barriers preventing introduction of such technology into manufacturing. We are stuck using \"deep UV\" and \"ex... |
[
"What is the study of genetic memory in animals called? For example elephants travelling vast distances knowing exactly where to go. And what evidence is there that animals are born with memories of past generations?"
] | [
false
] | null | [
"Geneticist here. I've never come across the term genetic memory before (in this context) and there is no evidence that animals are born with memories of their parents and ancestors. Animal migrations and movements are usually either learned from others of their species or instinctual. If you have a specific exampl... | [
"What's the biological basis of \"instinct?\" It's something often stated without explanation, that instinct drives an animal. I just don't know if it's neurological, hormonal, or what?"
] | [
"Some instincts are described as innate characteristics, as they can be explained by ",
"behavioral phenotypes",
".",
"See also ",
"Behavioral genetics"
] |
[
"Is there a maximum amount of energy that can be contained in a solar flare? Could the sun produce a solar flare beyond the X class?"
] | [
false
] | null | [
"I can't speak to the maximum energy of a solar flare, but the definition of the X class ( > 10",
" W/m",
" ) precludes there being a higher class. Within this class, there have been many examples of huge flares, like the X28 flare of 2003."
] | [
"Forgive me, but I don't actually know if the scale is logarithmic, but I'll throw out some values and let someone better with math explain the proper mathematical term for this.",
"A C1 flare has an intensity of .000001 W/m",
" . C2 would then be .000002, C3 is .000003, etc. M1 has an intensity of .00001 W/m... | [
"The scale is logarithmic, correct? Would a M10 solar flare be equivalent to an X1? ",
"If they have recorded solar flares that powerful in the past, wouldn't it make sense to use another letter for very large X category flares? Perhaps a \"Y\" scale? (Making the X28 flare a Y2.8 flare instead)."
] |
[
"Question about aerogel's electric properties."
] | [
false
] | Why aren't aerogels used as dielectric materials? | [
"Aerogel has a very low density and the majority of the volume is occupied by air. You could use it as a dielectric, but it would be very similar to using air as a dielectric."
] | [
"I've always been curious about aerogels. If there are experts in the room, here's some more aerogel questions:"
] | [
"Ah, that makes sense. I guess thats why aerogels have such a low level of thermal conductivity, because air does. Thanks"
] |
[
"Can you 'catch' a mental illness?"
] | [
false
] | [deleted] | [
"Yes and no...\nWe don't really know what causes it nor can we predict if it will be triggered. We can detect preliminary risks with fMRI scans but it is still limited to research (i.e. by comparing with controls (healthy) subjects, we can see brain differences between them and schizophrenic patients for example; b... | [
"Folie a deux",
" is a condition in which two or more people share delusions.",
"In Carl Sagan's book ",
", a gentleman by the pseudonym of Kirk Allen is brought up. Allegedly, he was a top-level physicist in the military who was referred to a psychologist. He told the psychologist that he could go into the f... | [
"What might trigger in some people and not other is the genetic predisposition to the mental illness in question.\nIf the family has a history of mental illness it means that the children have a risk/chance of having it too. Now whether it is dormant or not I do not know. If you have 2 children, there are chances t... |
[
"why don't companies like intel or amd just make their CPUs bigger with more nodes?"
] | [
false
] | null | [
"Conversely, this is one of the fundamental sources of instability when overclocking. It's possible that your processor will start giving you incorrect results before it starts overheating, and this means that you've found approximately how long it takes electrical signals to propagate through the longest paths in ... | [
"Conversely, this is one of the fundamental sources of instability when overclocking. It's possible that your processor will start giving you incorrect results before it starts overheating, and this means that you've found approximately how long it takes electrical signals to propagate through the longest paths in ... | [
"We past the \"propagation limit\" long ago. Modern CPUs do not work by having everything in lock-step of the clock. The clock signal propagates across the circuitry like a wave and the circuitry is designed around that propagation. In theory we could design larger chips and deal with the propagation, but the facto... |
[
"You live in an arctic igloo (with electricity). Will a refrigerator still be able to keep things at 40 degrees Fahrenheit?"
] | [
false
] | I once watched a documentary on an arctic outpost and the narrator said something like "the temperature here is 0 degrees. in this weather, you'd use a fridge to keep things WARM!". It was a bit cheesy, but makes me wonder whether a refrigerator DOES have heat capacity. | [
"I don't know where these other answers are coming from. ",
"Modern fridges have a complex mechanism to lower the interior temperature (that works better the colder the fridge's environment) and a different, very simple mechanism to briefly heat the interior to prevent frost buildup. I guess it might be possible ... | [
"Something that needs to be pointed out that most people here are getting wrong: assuming that igloos that are in use are at or below 0C inside. ",
"That's not the case",
". An in-use igloo can easily be >15C inside, purely from radiant body heat and an oil lamp.",
"Remember, when an Inuit person needs to ... | [
"What are you talking about? Fridges have to work a LOT less when the external temperature is lower. I mean not only are you gaining less heat through the case itself, but the colder the condenser coil the easier it is for the fridge to do its job."
] |
[
"Is there a relationship between droughts and the increased in carbon dioxide levels?"
] | [
false
] | i mean can it actually increase droughts in some parts of the world due to increase greenhouse gases? | [
"The short answer is \"Yes\". When people think of global warming, most people think of temperatures rising - which isn't surprising given the name! However, the temperature increase ",
" isn't actually the biggest problem. The real, major issues are the secondary effects that rising temperatures cause, such as c... | [
"Thanks kind stranger:)"
] | [
"If greenhouse gases act as an insulator shouldn't it increase temperatures in hot areas, but also decrease temperatures in cold areas?"
] |
[
"Has anyone ever used EEG to monitor their own mental activity and adjusted their behavior in response?"
] | [
false
] | [deleted] | [
"Are you asking if this has been done, or are you asking for anecdotes/personal experience?"
] | [
"Just google \"biofeedback EEG\".",
"If asking for anecdotes, this isn't really the subreddit for it."
] | [
"It's called ",
"http://en.wikipedia.org/wiki/Neurofeedback",
" "
] |
[
"Why doesn't eating stimulate our gag reflex?"
] | [
false
] | How is it that our body stops us from retching every time we try to eat? And why do we still mostly puke when trying to eat things not identified as 'food'? Guess this is my first front page post. W00t. | [
"The medical name for the gag reflex is the Pharyngeal reflex, if you haven't read it yet the ",
"wikipedia page",
" has more information on it and ",
"swallowing",
". There doesn't seem to be anything conclusive on what triggers the different variations of the gag and swallowing reflexes tho.",
"One inte... | [
"As for the second question, there is an area in the medulla called the area postrema that is responsible for detecting noxious substances and inducing vomiting through its connections to the nucleus and tractus solitarius. In addition, many poisonous substances have a bitter, unpleasant taste. For that reason we e... | [
"Potentially stupid question: Is it dangerous to not have a gag reflex? Like, is one at a higher risk of choking on their underchewed food due to a lack of gag reflex?"
] |
[
"Is it easier to fly inward to the inner planet, closer to the sun, than outwards to the outer planets, away from the sun?"
] | [
false
] | On how presentation on how gravity works there's a bowling ball in the center of a trampoline and marbles are spun around the blowing ball moving inwards slowly. Would flying a space craft to the sun be like driving down hill and flying away be like driving up hill? | [
"It can actually be harder to fly to the inner planets than to the outer planets, at least for simple orbits.",
"The main problem is that there's no drag in space, and we are orbiting the Sun at 30 km/s. Escape velocity from the Solar System is about 42 km/s. So we only need another 12 km/s to move out from Earth... | [
"Yup! A prime example of this is the Parker Solar Probe, launched in 2018 on the Delta 4 Heavy. It's a pretty small probe, but it needed the second biggest rocket we've got to give it enough push. Even that isn't enough to get the probe to the 8.5 solar diameter perihelion, so it is currently conducting a series of... | [
"What if I point my rocket to always accelerate the probe towards the sun (along the probe to sun radial vector)? On second thought, I think once the rocket runs out of gas it the probe will just move along an elliptical orbit. It's been a while since I studied physics so I can't compute just how close the closest ... |
[
"Ethanol vs. neutral grain spirit?"
] | [
false
] | My lab needs non-denatured alcohol (but we don't need anhydrous). Unfortunately, we're also poor. Is there any reason whatsoever that we couldn't go down to the store and buy it 750 mL at a time in Everclear form? It looks cheaper than buying nondenatured ethanol from lab suppliers. | [
"Run it through a brita filter."
] | [
"It's been a while since my ochem, but wouldn't charcoal absorb the alcohol (at least some of it)?"
] | [
"I think it would absorb the by-products of fermentation more than it would absorb alcohol. Things like aromatic hydrocarbons, un-fermented sugars, etc that stayed in the bottle."
] |
[
"Energy Distortion of Space-Time Similar To Matter"
] | [
false
] | I get that things with Mass distort/bend/warp Space-Time. However, given that matter and energy are essentially interchangeable via Special Relativity (as I understand it), would a massive energy source like a gamma ray burst also distort Space-Time? Or am I completely missing something here. Not a Physicist, but rath... | [
"Energy isn't a thing, really. It's a number. And energy has two principle forms. Energy of \"restful existence\", mass, or energy of motion (in the form of momentum). A system of massless particles (like photons all traveling in different directions) may have a mass themselves. Any time you can find a \"rest\" fra... | [
"Yeah. So this is in fact interesting and useful to us. For instance, we can choose a frame of reference in which the sun is at rest. And our orbit of that sun, at rest, is perfectly reasonable. ",
"But we can choose another frame of reference, where the sun is in motion, with some momentum. Now I ask you, do we ... | [
"To expand on shaveras answer; Yes, a massive gamma ray burst distorts space-time, as does a single photon. Also, a compressed spring distorts more than an uncompressed, as does a hot pot over cold, or a charged battery, or a strong magnet vs. weak. ",
"Also interesting to note that a large contribution to the ma... |
[
"How do scientists measure the mass of the earth?"
] | [
false
] | What method or formula do they use to calculate the total mass of the earth? Do They do one area and then use that as the baseline for the rest of the earth or what? | [
"We can measure the radius ",
" of Earth by various means. Then we can measure the gravitational force on an object at the surface by measuring the acceleration ",
" due to gravity. (Measuring ",
" is not as simple as it sounds since we have to account for the rotation of Earth and its effect on the effective... | [
"The accuracy of G is interesting, and you can read about it ",
"here",
". Measurements of G actually vary periodically with the rotation rate of Earth (about a 6-year period). The relative error in these measurements is 1 part in 10,000 (so about 4 decimal places), so not really too accurate. Like I said, G is... | [
"The Cavendish experiment he referred to earlier was done in 1798 and was 1% off (which gives you G and permits the calculations). The accuracy is pretty good. Here is an interesting read about how it's constantly changing: ",
"https://en.m.wikipedia.org/wiki/Earth_mass"
] |
[
"Is there a way to shift EM signal frequencies?"
] | [
false
] | Say can we shift IR to visible frequencies without receiving it on an IR sensor, reading it and reemitting it? | [
"Additionally to the non-linear effects that others mentioned in the thread small shifts in frequency can be realized by the use of ",
"acousto-optic modulator",
". It is very similar to optical non-linear interaction except one of the waves involved is made from phonons (so 'sound') instead of light."
] | [
"I don't believe there is a simple way, but one method would be to take advantage of ",
"non-linear optics",
", where the polarisation response of a material is non-linear to the applied electric field. This causes additional frequencies to be generated which can be separated from the incident light.",
"A com... | [
"without receiving it on an IR sensor, reading it and reemitting it?",
"It depends how abstract you mean by \"sensor\" and \"re-emission\". It's impossible to shift frequency without inputting or extracting energy, doing so would violate conservation of energy and momentum. However, one can have \"passive\" \"s... |
[
"Is \"Common Ancestor\" a Literal Concept of a Single Animal?"
] | [
false
] | We often see reference to our "common ancestor", particularly in genealogical "we're all related" type arguments, but it seems to me that life did not begin with a single organism and, esp., that evolutionary changes leading to populations created by sexual reproduction are not singular - i.e. there may have been 10 or... | [
"In evolutionary terms \"common ancestor\" is not used to represent an individual. The term defines a species from which two other species diverged. In the classical evolutionary tree schematic used to represent evolutionary history, a common ancestor is a point at which a branch forks. "
] | [
"Two people can trace their respective lineages back to a single common ancestor, which will be another person. This is limited by how well the two family lines have kept records. Two species can be traced back to their common ancestral species. This is most accurately accomplished through analysis of genetic simil... | [
"It makes more sense to think of a common ancestral population rather than individual. It is always a population issue, not just an individual."
] |
[
"Most people I know rave about naps, but they make me feel sick -- why?"
] | [
false
] | When I take a nap I always make sure I have at least 2 hours free with no disturbances because if I'm woken up before then (even if it is just 10 - 30 minutes) I feel nauseated, dizzy, and sort of heavy. I only get the "heavy" sensation if I nap. If I manage to get at least a 2 hour nap and wake up naturally from it, I... | [
"Are you taking these naps within 8 hours of your regular bedtime or once it is dark? If so I would suggest taking them earlier in the day. Try to not go over 45 minutes of sleep as that will usually put you into another sleep cycle which is correlated with that upset feeling "
] | [
"Not an answer to \"Why?\" but this may help. I get that sickly heavy feeling after a nap too. I have found that drinking a large glass of water as soon as I wake up helps immensely. "
] | [
"Not an expert, but between trying out ",
"polyphasic sleep",
" and ",
"lucid dreaming",
", I have some half-remembered tidbits that may apply.",
"From what I recall, waking up during deep sleep (that is, ",
"N3 phase sleep",
") is generally correlated with grogginess and unsatisfying sleep. If you lo... |
[
"How far under the ocean does the water extend? Or better yet, how far under the ocean before the ground is dry again?"
] | [
false
] | I know under ground there are water tables, is it the same under the ocean? do they extend deep? how far down under say the pacific ocean floor would you have to go before you were at dryness again? | [
"The oceanic lithosphere (crust and part of the upper mantle) has a layered structure that comprises of various igneous rock which are crystalline and impermeable in varying structures (massive peridotites, dolomitic dykes, pillow basalts etc). On top of these there is a layer of sediment that varies in thickness d... | [
"Correct the atlantic ocean is slowing becoming larger while the pacific is becoming smaller."
] | [
"What do you mean by closing and opening oceans? The continents are moving closer or farther apart? "
] |
[
"How will interstellar spacecraft deal with the extremely cold temperatures?"
] | [
false
] | We know that space is cold. Temperatures on Uranus have been measured as low as -224 degrees Celsius; and Uranus is still relatively close to the sun. During interstellar travel, there will be no stars nearby, so it will likely be even colder than on Uranus. How can we build a spaceship to withstand this extreme cold? | [
"Space is very cold indeed! However, it's also an excellent insulator, as there is nothing to conduct heat away. The only way to lose heat is by radiating it as photons. There's an equation that can tell you how much power you would radiate as a function of temperature and emissivity, the Stefan-Boltzmann law. You ... | [
"That is absolutely amazing. I never considered that the void of space would effectively be an insulator, sort of like a vacuum carafe. :)"
] | [
"If I remember correctly, they had significant problems with lack of power, so they turned everything off. However, the ship was still the same size as before, and therefore radiating as much energy as before. ",
"The ship was designed with all the heat-producing tech in mind. It had external heat radiators to re... |
[
"Can earthquakes be predicted?"
] | [
false
] | So can they? | [
"In short, no, and the feasibility of someday developing prediction capabilities depends on your definition of \"predict\". Will we be able to say \"a magnitude 5.2 earthquake will occur at this location, at this time\", no. What we're working towards and have the beginnings of is more like weather forecasts, but t... | [
"Short answer: No",
"Slightly longer answer: No, not to the extent that you could put a time frame on it that would be of much use. If enough data exists you could maybe put a range that would normally cover periods in which they could happen. However they could be delayed or sooner than you expected. There is no... | [
"No.",
"The ",
"2008 Sichuan",
" huge earthquake (M 7.9) started as a limited earthquake with the apparent potential to reach perhaps around M7. The rupture propagated towards the north-east and overcame 4 barriers, one after the other. In two segments, slip exceeded 10 meters. It eventually travelled for 200... |
[
"How does Saran Wrap work? Why is it that it sticks together? How does it not melt in a microwave?"
] | [
false
] | null | [
"Any polar molecule will heat up in the microwave. Not just water."
] | [
"Any polar molecule will heat up in the microwave. Not just water."
] | [
"Saran Wrap is Low Density Polyethylene (polyethylene is the most common type of plastic), which, because of the way the monomers chain together, is highly ductile and malleable (very strechy). This is obviously desirable when making something that is going to be, well, ",
" over something else. As for the sticky... |
[
"Why are we able to make vaccines for some viruses but not others?"
] | [
false
] | [deleted] | [
"Simply put, ",
"some viruses just change too fast",
". If a virus mutates enough, your immune system won't recognize it even if you've been previously infected with an older variety / inoculated with an older variety. HIV is notorious for mutating super quickly, which is why a successful HIV vaccine was never ... | [
"Is the seasonal flu just the same flu that keeps evolving? Or does a new virus emerge?"
] | [
"The most correct answer to this question is that seasonal flus are the same set of viruses, but primarily H3N2, that change slightly every year. Generally speaking the change from year to year is subtle enough that the viruses can still be considered the same species/strain (viruses are weird and so is their termi... |
[
"How do mammals deal with placenta and the umbilical cord?"
] | [
false
] | With humans, if the placenta is left in the woman it can cause harm so it is removed. However, animals can't do this. Similarly, whilst not life-threatening, the umbilical cord can still be a danger if left unattended. | [
"Pregnant/postpartum mammals can, and do, die because of retained placentas/products of conception, as well as incomplete miscarriages/retained fetal tissues after a miscarriage, and complications during birth. ",
"And neonatal animals can, and do, die due to umbilical infections. ",
"Wild pregnant mammals cann... | [
"If he really wanted to go natural, he would have chewed thru the cord with his teeth and offered the placenta to his wife raw as a way to replenish her strength after the ordeal of childbirth"
] | [
"Depends on the animal, but generally contractions continue until everything is out. The physiology is also a bit different here. Dogs for example have uterine \"horns\" so you basically have 2 tubes of puppies. Each fetus is in an individual sac with the amniotic fluid and placenta, so the placenta comes out with ... |
[
"Whats the relation of entropy in physics and entropy in information theory?"
] | [
false
] | In thermodynamics entropy seems to be a measurement of stored enery per volume(or mass? or per system?) and in infromation theroy entropy is a measurement of information density. Both formulas seem to be very similar(an intergal/sum of all posible states) but ive never bee able to make the connection in meaning. Therm... | [
"In thermodynamics entropy seems to be a measurement of stored enery per volume(or mass? or per system?) and in infromation theroy entropy is a measurement of information density. Both formulas seem to be very similar(an intergal/sum of all posible states) but ive never bee able to make the connection in meaning.",... | [
"This was an excellent explanation, thank you very much."
] | [
"Sort of. It is often described as the amount of disorder in a system, or a measure of how unavailable internal energy of the system is for doing work with, but these sorts of definitions are only approximate or subjective (for example I can think of systems that appear very ordered and predictable which are very ... |
[
"Could we breed animals to make them more intelligent?"
] | [
false
] | There are certain tasks that animals perform that they could do better if they were smarter. One that comes to mind is service dogs and other service animals. Could we breed them to reach fairly high levels of intelligence? What might the upper reaches of this be? Which useful animals would be the best candidates? What... | [
"With the dog example we've been breeding them for thousands of years already with goals in mind and you now have breeds which are specialized to do different tasks but it would be hard to argue that some are more intelligent than others. If you try to rank them based on what task they do we'd probably encounter th... | [
"Within the field of behavioral research what denotes intelligence is still up for debate so yes we can't use our current definitions on animals or at least we can't use one and apply it to them all. On the flip side there's obviously features which most people would agree denotes a higher level of intelligence suc... | [
"Yes, there is a range in the intelligence both within humans and within animal species. Whenever there is already variation in a population for selection to act on you can make relatively quick changes to a population with strong selection. But that doesnt mean being able to have a dog be able to do maths over a s... |
[
"Pounds weight or mass?"
] | [
false
] | null | [
"It's both. Most of the time, without qualification, pound means mass. To distinguish you can say pound-mass or pound-force. 1 pound-force is the weight of one pound-mass. "
] | [
"Thank you."
] | [
"Hi leogorg thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of the followi... |
[
"How do I know which color space is linear or non-linear ?"
] | [
false
] | The title says it all. How do I know which color space is linear or non linear ? Any recommendation (journal/paper) would be appreciated. | [
"The spec of the color space will define this somewhere. Usually with something called a \"transfer function\". The definition of \"transfer function\" is \"a mathematical function relating the output or response of a system such as a filter circuit to the input or stimulus.\", which is a fairly succinct descriptio... | [
"Depends on your definition of \"fun\". Thanks a lot !! also for articles recommendation. Actually, I'm working on image processing (in RGB) and trying to do color conversion for color deficiency, I'm yet to decide which colorspace will be the best option to go with so I do the conversion to all colorspaces and see... | [
"What's the question behind the question? What are you actually doing? Basically whether or not a color space is non linear is just part of the definition of the color space. So it seems like there's a broader question here about \"how do I figure out what sort of color space some particular image is in?\" or \... |
[
"Lunar Architecture"
] | [
false
] | Given the reduced gravity on the moon, just how high could you build a building? Also, is the gravity sufficient to make a fall fatal? | [
"Given enough time, any gravitational pull will accelerate you to speeds that would be fatal. Weaker gravity only changes how high you'd have to be for a fall to be fatal, not whether a fatal fall is possible at all."
] | [
"To expand and clarify, this is true only in a vacuum. If terminal velocity is limited by an atmosphere it is possible that you could fall from any height (within the atmosphere) and survive. ",
"For example, a fall on titan would probably not be fatal from any height, provided you are protected from the cold and... | [
"Thank-you!"
] |
[
"Please stop saying \"This is Probably a stupid question\" or \"I know I am dumb, but...\" Ask your question, we will be nice and answer it. The objective of this sub-reddit is to have questions you do not know the answer to answered."
] | [
false
] | [deleted] | [
"eh, I just think it's easy enough for people reading to ignore the statement. If it helps people overcome their fear of asking a question, then ask away. But this is just, like, my opinion man."
] | [
"This should be on the side bar or across the top!"
] | [
"Submit: Any self-post which asks a question for which it is appropriate that Science attempts to find a satisfactory answer.",
"This is probably a stupid comment, but you didn't ask a question."
] |
[
"Question about learning about history of science..."
] | [
false
] | Hi everyone. I know this isn't strictly a science question, but lately I've found myself really interested in the history of science. Specifically from the scientific revolution to the Victorian era. I have a few books and I'm trying to find online courses and blogs on this subject. Can anybody here interested in the s... | [
"The Discoverers by Daniel Boorstin."
] | [
"More on the \"human-interest\" side of things (i.e., not so much focus on the science itself), but nonetheless a good read (full of wonderful observations and interesting details) would be \"The Age of Wonder: How the Romantic Generation Discovered the Beauty and Terror of Science\" by Richard Holmes. "
] | [
"Thank you very much; this is right up my alley. It's downloading onto my kindle right now :)"
] |
[
"Would a wide mouth container fill faster than a narrow mouthed one when put out in the rain?"
] | [
false
] | null | [
"The rate of rain entering the container is dependent on the surface area of the opening, the rate at which the vessel fills is dependent on the incoming rate and the volume of the vessel. Everything else being equal the wider the mouth the better."
] | [
"So if both vessels are say, 1m deep, the wider mouthed vessels fills up slower (on account of having a larger vol)? But doesn't it have a larger incoming rate due to the wider mouth and therefore larger area? Both vessels are in the rain so receive equal amounts. "
] | [
"I think my previous post might be confusing because I wasn't talking about perfect cylinders, but things that could have wider or smaller openings than the rest of the container. What I meant by my last sentence is that if you have two different 1 L vessels but each has a different mouth size the bigger mouth fil... |
[
"Why do your eyes get puffy after waking up? What is going on near your eyes that causes this?"
] | [
false
] | null | [
"Sources?"
] | [
"oh wow; that makes sense\nthank you :)"
] | [
"When you sleep you lie down, this causes blood to move towards your head easier than it would while standing or sitting. This can cause puffy eyes and black eyes etc.",
"Try using extra pillows, my wife did this and it helped her black eyes."
] |
[
"How can we determine the curvature of the Universe while being inside of it?"
] | [
false
] | To describe the curvature of the Universe, wouldn't we need an external reference frame to compare with or something? That is, , I can only tell it is poorly drawn because of the regular, external pixel grid that supports it. Now if the pixel grid had the same shape as the triangle, I wouldn't be able to tell if the tr... | [
"You are confusing ",
" curvature and ",
" curvature. It is the latter that is always meant by the unmodified word \"curvature\" unless otherwise specified.",
"Extrinsic curvature is the curvature of a manifold when considered embedded in some other manifold. So a circle has positive curvature when considered... | [
"Thank you for this complete answer."
] | [
"Thank you very much, this makes a lot more sense. Excellent breakdown."
] |
[
"Why does it take longer to recall certain memories?"
] | [
false
] | Does it have to do with how the memories are stored? Is there a priority system to the recollection? | [
"Memory research is such a hot topic in Psychology/Neuroscience right now. There's so much research out there because it's so easily testable. ",
"There's 3 stages of memory, encoding, storage and retrieval and changes in any of these stages will affect how a memory is stored and subsequently how it is recalled.... | [
"In addition to ",
"/u/Mackerie",
"'s good summary, when you're remembering a memory you've remembered in the past, you're often recalling a memory of your memory, not the original memory. So if you've recalled something recently, even if the original episode happened a longer time ago than a more recent episod... | [
"That is all very interesting, I'm glad to see this subject is getting some interest among researchers. It always amazes me that my mind is so complex that it can't even fully understand itself yet. "
] |
[
"Does the observed state of a particle at a given time affect future evolutions in its wave function?"
] | [
false
] | I'm struggling to reconcile the physical and mathematical interpretations of the evolution of quantum particles. If an individual particle can be observed in a random (but predictable) state, does this observed state affect the probability of it being found in a given future state? If so, how can the properties of th... | [
"If you know the initial state of the particle and you allow it to undergo unitary time evolution, you can determine what its state will be at any subsequent time using the time-dependent Schrodinger equation.",
"The state at some time in the future will in general be different for different initial conditions."
... | [
"That's actually a really good question, and touches directly upon the measurement problem.",
"An undisturbed wave function will indeed evolve deterministically. But the act of a measurement and the collapse of the wave function is (in standard QM) an instantaneous effect. If you collapse the wave function, you w... | [
"Well it's a part of the measurement problem, in a way. If you take the simplified view that the observer and observation is somehow external to your system and need not be taken into account, then the wave function 'collapses' into an eigenstate of your observable. This is a non-unitary and (apparently) non-determ... |
[
"What phase is a flame?"
] | [
false
] | null | [
"Typically just a gas phase reaction. Some flames can get hot enough for plasma to form but need to be at a very high temperature. The wikipedia article may be helpful, and even has a nice pun in the intro. ",
"http://en.wikipedia.org/wiki/Flame"
] | [
"Right. The light is energy released as the bonds of CO2 are created (for the most part) and CO2 is a gas at room temperature, let alone after the heat gained in the reaction. Usually the particles are boiled into vapor during or just before ignition, also. "
] | [
"There are a few different answers and it depends on what field you ask.",
"\"From a physics point of view,\" says DARPA on their site, \"flames are cold plasmas comprising mobile electrons and slower positive ions.\" ",
"Source",
"A flame is the visible, gaseous part of a fire. ",
"Source",
"But this f... |
[
"How far back can you go before carbon dating becomes unreliable?"
] | [
false
] | Yesterday I was speaking with a friend who is a Jehovah's Witness, so obviously he believes in the flood, and that humans have only been on the earth for 6,000. He says he knows a lot about carbon dating, and that it's only accurate if you're dating something that's within the last 3,500 years, after that, it can be ve... | [
"How much of this is true?",
"To be blunt, virtually none of it (there is a sort of bastardization of one real thing, more on that in a minute). ",
"Wikipedia",
" has a pretty thorough and extensive discussion of radiocarbon dating, which I'd encourage you to look through along with our ",
"FAQ",
" on rad... | [
"Beta counting is no longer the preferred method, it has mostly been replaced by AMS. Some of the same considerations apply, but with AMS, the effective age range of the technique is dictated by there being such a small ratio of C",
" to C",
" that it can no longer be effectively measured for old samples."
] | [
"Hello, good answer here. I would like to add a bit about the probability of radioactive decay and radiation detection.",
"The reason there is a limit to carbon dating is essentially because:",
"1)Mathmatically, an exponential function such as a Half-Life would indicate that the quantity will never reach zero (... |
[
"Provided that you have 20/20 vision, if you wear someone else's glasses, can you really see the way they see without glasses?"
] | [
false
] | null | [
"Please correct me if I am wrong but I think you would move the focal point in the wrong direction. I think you would need the prescription with the signs changed to see the way the person that needs glasses does. ",
"To test this theory out, I just put my glasses on with my contacts in and it is not the same a... | [
"No, you will not. Take for example a simple case of someone who is myopic (Their eye's cornea and lens has too much power for their eye - you may know this as nearsighted). Their glasses have a negative lens element in order to compensate for this. A negative lens reduces the power of an optical system. So, if an ... | [
"This is not my topic at all but, seeing as glasses work by being either concave or convex (to varying degrees) - the glasses (flipped either way) will have the same effect."
] |
[
"How does one analyze the structure of a molecule?"
] | [
false
] | I'm a pretty visual guy, so analysis on the "meta" level escapes me quite often, no matter what the field is. Chemistry though is an extreme for me. I do have a middle-school idea about atoms, atomic bonds and how simple chemical reactions work. I do, however, have not the faintest clue about how a chemist identifies t... | [
"Much of it is empirically determined. For example, one can use chemical shift data from a ",
" simple molecule to learn how different bonds affect the NMR signal - and this will be applied to more complex molecules.",
"Take ethanol for example - given the molecular formula and the number of bonds each element ... | [
"Yet those are all pretty recent methods and often required \"I know this is in there\" knowledge beforehand.",
"No prior knowledge of the compound is needed. Mass spectroscopy can give you the molecular formula, and ",
" fragmentation information. IR can identify the type of functional groups. NMR can give you... | [
"Not my line of work, but I've been reading this book, ",
"Nature's Robots: A History of Proteins",
". Unfortunately for your question, I haven't gotten very far into it yet, but I find it fascinating that the first determinations of the size of large proteins came from just burning them and looking at the rati... |
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