title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"During the first nuclear bomb test, how did they know how far away to observe the blast? Did they already know how many tons of TNT (or TJ) it was?"
] | [
false
] | I tried some google-fu, but nothing showed up. How did the scientists that made the bomb know where to place their observation cameras and bunkers? From what I've seen they were fairly close enough to the blast to see it without using binoculars or other things. There were bunkers 10,000 yards away and observation things 20 miles away. I also read that there was a betting pool as to how many tons of TNT or TJ the blast would be. Is there a way to figure this out mathematically? (the TJ and distance of the blast wave) | [
"The question of how large a nuclear blast can be is a function of the total energy release possible multiplied by the expected efficiency of the weapon. ",
"So in the case of the first nuclear weapon, they knew that it contained 6.2 kg of plutonium. 1 kg of plutonium, completely fissioned, releases 18 kt or so o... | [
"They had blown up a test explosion of 100 tons of TNT earlier in the month, to help calibrate the effects. They did not have good reliable understanding of what thousands of tons of TNT would do, though — that's a ",
" of TNT. But they could guess for some aspects of it, like how the shock wave would work. A lot... | [
"Castle bravo - the reason bikini atoll is ",
"missing a chunk",
"Apparently it has been deemed 'habitable' again, long before half lives would lead us to expect which is rather interesting."
] |
[
"Why do the same voltages appear frequently?"
] | [
false
] | 3.3v, 5v, 9v, 12v and so on. Is there something inherently advantageous about these numbers or are they just somewhat evenly spaced out arbitrary numbers to try to keep things standardized? | [
"As far as batteries go you are limited to using multiples of the cell voltage of the system used in the battery. For example alkaline batteries are around 1.5V/cell, so AAA, A, C and D batteries use a single cell. 6V and 9V batteries use 4 and 6 1.5V cell in series. Other cells produce different voltages that you ... | [
"In regards to digital electronic circuits, which it kind of sounds like what you are referring to, the voltages are determined to suit the ",
"logic family",
" or the communication protocol being used in the design. These standardized logic families were created so that chips and circuits could more easily in... | [
"There are some good answers here. To embellish, I'd imagine part of the reason there is such a drive to lower operating voltages on ICs has to do with ramp up and fall off delays for high speed digital circuits. ",
"No node voltage can instantaneously change from 0 volts to X volts or from X volts to 0 volts. ... |
[
"If your brain releases melatonin when it gets dark, is it the opposite for nocturnal animals, and it releases when it's light?"
] | [
false
] | null | [
"The answer is: melatonin is released during the night in both diurnal and nocturnal species, but it is not sleep-promoting in nocturnal species.",
"In both diurnal and nocturnal species, there is a daily rhythm in the firing of neurons in the central circadian clock, the suprachiasmatic nucleus (SCN). The neuron... | [
"No. Melatonin is released from the pineal gland into the blood during darkness, regardless if the animal is diurnal or nocturnal. "
] | [
"Then what is the primary regulator of the sleep-wake cycle in diurnal and nocturnal animals?"
] |
[
"Why aren't we growing square trees?"
] | [
false
] | The article says that the original scientist moved onto other things because "inertia and distractions delayed implementation." Still though, this seems like a hugely beneficial idea given that only 50-60% of trees are actually used for lumber - the rest goes to pulp, paper or waste. So what gives? | [
"The method discussed appears to promote a specific growth pattern via an artificial scarring response. Perfecting the method, training a workforce and artificially maintaining millions of trees throughout their long lifetime would be labor intensive and wouldn't reap any potential benefits for decades. Given lumbe... | [
"Sure - but it seems that they had the process down where you basically cut the tree down like grass. Cut off the top 3/4 and the tree regrows itself. I'm guessing it probably has to do with the already low-cost of lumber. It's a shame though, less forest cutting seems like a pretty good idea. "
] | [
"Indeed; I personally find it fascinating. Unfortunately migrating between large-scale systems involves an inherent cost of time, money and risk that is often not justifiable until the existing system becomes unviable."
] |
[
"Why are we carbon based?"
] | [
false
] | [deleted] | [
"Carbon is in group 14 of the periodic table. It has 4 valence electrons, and so can form 4 bonds, allowing for very complex large molecules. 4 is also halfway between 0 and 8, both of which form a stable octet of valence electrons, so carbon can bond easily with nearly any atom, regardless of electronegativity. Ca... | [
"A little background, first: in general, the properties of all matter around us, from living things to rocks, are determined by the outer, or valence, electrons in the atoms making up those things. It is these valence electrons (their number and how they're arranged) that determine how atoms bond and interact with ... | [
"As mentioned elsewhere, Carbon is very versatile when it comes to forming chemical bonds. It can bond to form stable molecules with many different atoms including other carbon atoms. This allows it to form the long chains and polymers that are vital for something as complex as living organisms. ",
"Another point... |
[
"Could an audio speaker demolish a large structure (like a bridge or building) via sonic resonance?"
] | [
false
] | Imagine the following system: Would that even work? I've seen old videos of bridges torn apart by resonance, and I've had neighbors crank their car stereos up loud enough to rattle the floor in my apartment. I'd like to think it wouldn't actually be that easy to take down a building, though. | [
"In order to get the structure to fall apart, you would need to generate a big enough wave inside the structure to overcome the structural integrity. In theory, there's no reason you couldn't do that. However, wave propagation through any medium is always a little bit lossy (sometimes a lot lossy). That means that ... | [
"The resonant frequencies of buildings are generally too low for speakers to reach, well below the human hearing range, so it would be a difficult technological feat to build a speaker capable of accomplishing this.",
"Edit: Relevant ",
"Myth-buster's test of Tesla's Oscillator"
] | [
"Yeah, the issue is power. Finding the right frequency is the same as asking what's the minimum power I need to make speakers that can knock down a building, but that minimum might be really big."
] |
[
"What does radioactive decay actually look like? If you had a gram of an element with a short half-life (maybe an hour or so) what would you observe?"
] | [
false
] | [deleted] | [
"If you had a gram of an element with a short half-life (maybe an hour or so) what would you observe?",
"Typical decay energy is on the order of tens of thousands to a million electron volts per decay. To put this in perspective, ",
"the burning of sodium in chlorine gas",
" to form table salt, releases a pun... | [
"Nuclei are really, really small. The smallest feature a microscope can see is ",
"slightly less than half",
" the wavelength of the light it focuses.",
"Visible photons have a wavelength of 400-700 nanometers, and are much too \"big\" to image a uranium nucleus - which is about 266 million times smaller than... | [
"Yup, it'll be warm to the touch. If you insulate it— so that the heat it generates doesn't escape— it'll get hotter and hotter.",
"A blob of plutonium and some thermocouples and a heat sink makes a fairly long-lived power source, a \"nuclear battery\" which is very simple and reliable. These are used in deep-spa... |
[
"What is it exactly that makes your throat hurt?"
] | [
false
] | Bonus question, why does it dry out so quickly when you swallow or take a drink? | [
"I assume you are asking about sore throats during infections. When viruses or bacteria infect your throat, your immune system responds by inducing a localized inflammation. This is primarily mediated by ",
"granulocytes",
" and the cytokines/chemokines they release. One of the effects of inflammation is pain a... | [
"Great reply. On a side note, if you're experiencing inflammatory pain and you take an anti-inflammatory like ibuprofen to reduce it, does that also lessen your immune response to the infection? And so, would taking anti-inflammatories actually cause you to recover more slowly?"
] | [
"This is a question I occasionally wonder about too. Off the top of my head, I can't think of any studies that addressed this directly but I would imagine that taking NSAIDs or immunosuppressants does affect the immune response against pathogens although the extent of the effect will probably depend on a wide varie... |
[
"Is it possible for a human being to condition themselves to hibernate throughout the entire winter like other animals and insects do?"
] | [
false
] | null | [
"Sort of",
"http://www.nytimes.com/2007/11/25/opinion/25robb.html",
"They aren't hibernating, of course. But then, neither are bears."
] | [
"We could certainly adjust our metabolic rate to use less energy and require less food, but we wouldn't be able to hibernate. The biggest problem with hibernation is warming the body rapidly upon waking. Animals that can truely hibernate have large stores of brown adipose tissue to produce a large amount of heat qu... | [
"You would really have condition yourself to deal with the tappen too. (the fecal plug that builds up and prevents a bear from soiling itself, very painful poop upon waking)"
] |
[
"Why can i not see the exhaust from a bus, but i can see its shadow"
] | [
false
] | The bus i take to school everyday has the exhaust pipe on the back of the bus, when i look at it, i see nothing(except the occasional puff if black), so why can i see the shadow of this invisible gas? | [
"Its a ",
"shadowgraph",
" caused by the difference in index of refraction between the hot exhaust and cold air."
] | [
"The reason is really because the light casting the shadow is collimated. I.E. it is all coming from the same direction. However, when you are simply looking at the exhaust, light is coming from multiple directions, so it hides the distortion. If you look closely, the exhaust will still blur whatever it is in front... | [
"The refractory index of the exhaust is markedly different to the surrounding air. "
] |
[
"Is baldness more prevalent now than it was years ago?"
] | [
false
] | null | [
"Yes, it's much more prevalent today than it was in the past.",
"Androgen hormones, the cause of male pattern baldness, are elevated in hyperinsulinemia, the pre-cursor to type II diabetes. Formerly called \"adult onset diabetes\" until it started appearing more and more commonly in younger people. (sources: ",
... | [
"Androgen hormones, the cause of male pattern baldness, ",
"Only if they carry the allele for male-pattern baldness. Androgens by themselves will not cause male-pattern baldness.",
"Balding is not unknown among tribal populations, but it is quite rare and usually limited to a receding hairline. (source: observ... | [
"Well, ancient and medieval art depicts tons of bald men. And since we lack any sort of epidemiological records for the bulk of human history, I'd say \"We don't know, but probably not.\""
] |
[
"Is there a name for when you review a mental list and you almost always forget 1-2 items?"
] | [
false
] | null | [
"Hi Papapadopoulos 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 ... | [
"‘Psychology’ "
] | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"listed in our wiki!",
"If you disagree with this decision, please send a ",
"message to the moderators."
] |
[
"What do they mean when they say that electromagnetism, the strong nuclear and weak nuclear forces all unify into one force at high temperatures? Is it one force or three forces?"
] | [
false
] | null | [
"Yeah, sorry about that. It’s quite a technical subject and I don’t know of anything to point you to"
] | [
"The fundamental forces all arise from symmetries. There is a lot of mathematics I don’t think I can cover here but basically there two types of symmetry:",
"a trivial kind where you do nothing to everything and a non-trivial kind which does something to multiple things such that the effect cancels out.",
"For ... | [
"Hmm this is still sort of hard to grasp",
"Are there any videos you'd recommend to make things easier?"
] |
[
"I'm trying to get into illustrating extinct mammals. Is my drawing of Hyenadon gigas anywhere near accurate?"
] | [
false
] | Hey, Askscience! I'm a concept artist and thought it would be fun to try my hand at illustrating extinct critters, but I'm not entirely sure how to go about doing it accurately. I thought I'd draw a hyenadon first, so I went ahead and drew it over a picture of a skeleton I found while looking at lots of reference of modern hyenas and previous hyenadon illustrations. According to Wikipedia, Hyenadon gigas, one species of hyenadon, was 10 feet high! I added in the human silhouette and it was absolutely dwarfed and didn't seem right at all, so I shrank the hyenadon down a little to perhaps reflect hyenadons in general or a younger hyenadon gigas. Does this seem OK? Also, could any of you recommend any good blogs or resources that I could look at to get better estimates of the metrics of extinct critters in the future? | [
"Edit - Your last statement is bogus - extinct critters in the future...",
"You misread OP. They were asking for resources where they can, at a later date, find references for the body dimensions of extinct animals. They were not asking about extinct animals in the future, but rather their future studies of ext... | [
"He means look at in the future. . . "
] | [
"Hi! This is not my field of expertise, but since no one gave you any kind of answer I'll just try to help. I believe 10 feet is probably not how high they were, but the end of the tail to tip of nose measure. Usually when talking about sizes of similar animals that measure is used (alongside weight). 10 feet high ... |
[
"Do airline crews suffer a higher ratio of radiation illnesses?"
] | [
false
] | It seems to me that even a marginal exposure, over a large number that work in the business would result in a higher incidents of cancer or other illnesses vs the average population. | [
"The amount of radiation received by airline crews is small roughly 2 mSv per year. It's not known with certainty whether these levels are harmful or not. According to the linear no-threshold model, any amount of radiation increases the risk of cancer, however, according to the radiation hormesis hypothesis, small ... | [
"Does 5% mean if you had a 1% chance of developing brain cancer, you now have a 1.05% chance? Or does it mean you now have a 6% chance?",
"Whenever I see results of studies given in that form, I'm never sure what is meant. Is there a grammatical standard or way to tell?"
] | [
"Ideally, you should say that 1% to 1.05% is a 5% increase, 1% to 6% is a 5 percentage-point increase. Wikipedia says:",
"the incidence of cancers due to ionizing radiation can be modeled as increasing linearly with effective dose at a rate of 5.5% per sievert.",
"I take that to mean that it's a 5.5 percentage-... |
[
"Why are homosapiens the only organisms still alive in the homo... ehh I forgot the word. Family? Also, how would life be different today if the population was a mix of homo species?"
] | [
false
] | Edit: it was genus! Genus, right? Genus and species make up the name? I remembered this right after I submitted. | [
"Yes, Homo is the genus name. The homo genus arose about 2.3 mya with ",
", humans evolved 200,000 years ago. We are the only living representatives of this genus. Not so long ago 3 species co-exsisted: ",
"neanderthals",
" and ",
"floresiensis",
". The other species like erectus, or habilis were extinct ... | [
"Is there? I have never heard this before at all. Infact, Austalopithecines appeared after the pan/homo lineage split so you would have to include all Australopith precursor species such as ardipithicus and the other handful of species who's names escape me in Homo too."
] | [
"Some argue that neanderthals were not a separate species, but rather a subspecies of human and should be therefore classified as H. sapiens neaderthalensis. We could get into a lengthly discussion about speciation and what a species is, but the long and short of it is - not every case is a species defined by the a... |
[
"Reinterpreting the Drake equation, I call it 'Edens Everywhere'. Could it hold up?"
] | [
false
] | Every time I see someone go through the steps of the Drake Equation, they get to the part where they put in the number for how long a civilization exists they use ourselves as an example, and put in between 2000 and 40 years. The result is that there should be very very very few civs at our level. However, life has been on this planet for 500M years. If you use that number, there should be a crapload of planets with complex life (monkeys / dinosaurs... whatever). Everywhere, there should be planets with 'jungles', 'oceans', and rich biomes. Edens everywhere. Is there any reason this cant be the case, and would it maybe explain why we have found no signals from ET? | [
"Actually life is believed to have been on earth for up to about ",
"3.8 billion years now",
". ",
"edit: apparently even longer, read the comment below"
] | [
"I took the \"up to\" to mean that is the earliest estimate (I apologize if I misunderstood), but that number comes from direct fossil evidence, and so is the latest estimate. It is very possible based on what we now know that life had existed on earth for up to 4.2 billion years, assuming the various conditions th... | [
"Thanks for the reply, I was siding with caution on the dates given that it is very much not my area but I knew the OPs 500 million was way off."
] |
[
"Why are batteries arrays made with cylindrical batteries rather than square prisms so they can pack even better?"
] | [
false
] | null | [
"First of all, some packs are made with prismatic cells. The pros and cons of cylindrical vs prismatic cells themselves are more important than packing efficiency. Notably, cylindrical manufacturing is more mature, and cylindrical cells tend to be better (in energy density and cost per kWh) at lower capacities, whi... | [
"Mostly historical now.",
"Originally many mass-manufactured batteries were made by rolling flat sheets of material, inserting a rod, and filling the space with an electrolyte. It made for a fairly simple method of manufacture and was pretty reliable. By rolling a sheet around a tube you easily got a known size w... | [
"Another thing to note is pressure. Cylinders are more able to withstand overpressure, and batteries tend to produce hydrogen (which is catalytically recombined and/or diffuses out).",
"Additionally, packing of cylinders in a hexagonal lattice is pretty close to packing of hexagons, so the gains are relatively mi... |
[
"What is an anaerobic environment?"
] | [
false
] | [deleted] | [
"An anaerobic environment is one in which there is little to no breathable oxygen. The Earth is mostly made of aerobic environments and features few anaerobic areas. Perhaps unsurprisingly, most of the life on Earth inhabits aerobic environments while avoiding anaerobic anomalies. However, anaerobic environments ar... | [
"Nope. Much of the seafloor and deeper ocean has low enough concentrations of dissolved oxygen to be considered anaerobic. And that's to say nothing of anoxic lakes and other freshwater features."
] | [
"Nope. Much of the seafloor and deeper ocean has low enough concentrations of dissolved oxygen to be considered anaerobic. And that's to say nothing of anoxic lakes and other freshwater features."
] |
[
"Is there an electronic component that can change its resistance based on the current that flowed trough it? A bit like air ionization just more permanently."
] | [
false
] | Basically satisfying the following equation: R(q) = C * sum(q) where R is the resistance, C is an arbitrary constant and q is the charge that traveled trough the device with a negative and a positive direction. | [
"Sounds like a \"",
"memristor",
"\" - its resistance varies depending on how much charge has flowed through it previously, and in which direction.",
"It doesn't satisfy your equation though, because a memristor's characteristics are non-linear; you can't vary the resistance all the way from zero to infinity ... | [
"Thermistors are sometimes used this way, exploiting the fact that when current flows through them, the power dissipated causes them to heat up and change resistance with either a positive or negative temperature coefficient.",
"Positive coefficient (PTC) types are sometimes used as current limiting devices.",
... | [
"Within its range and a range of currents, (if my shallow understanding hasn’t betrayed me) a thermistor between power source and load would also vary resistance depending on how much its own resistance heated it. Again, not a linear variation."
] |
[
"I take a sheet of plastic and rip it. What's happening at the chemical level?"
] | [
false
] | Is it mostly just disrupting some type of intermolecular force holding the separate molecules together? Or does the force actually break the covalent bonds within the polymers? If covalent bonds are breaking, what happens to the electrons that were once in those bonds? Any interesting analogues to other substances (paper, skin, graphite, etc) would also be appreciated. | [
"It's not favored energetically. You can use bond dissociation energies to determine this."
] | [
"I don't believe it would be intramolecular forces that are being broken, but intermolecular forces. Intermolecular forces (hydrogen bonding, London dispersion, etc) are bonds that hold a paper molecule to another paper molecule. "
] | [
"Sorry, I mixed the two up. But why can't you easily recreate the bonds by pressing the torn sheets together? From my understanding of it, the proximity could set up the system again, 'reforming' the paper."
] |
[
"Could someone please explain (like I'm 23) how the rotational motion of a turbine shaft produces electricity?"
] | [
false
] | [deleted] | [
"suppose you have a magnetic field passing through a loop of metal wire. When you change how much field passes through that loop, the wire responds by creating a current that would generate a magnetic field that opposes that change. So at the end of this shaft is a magnet, which as it rotates near coils of wire, ge... | [
"A conductor and a magnetic field in relative motion create an electric current in the conductor. Properly arranging magnets and coiled wire, you can make a generator which converts rotational motion into electricity."
] | [
"The turbine doesn't produce the electricity, it converts the water, steam, wind, whatever to rotational mechanical energy.",
"Then we connect that rotational mechanical energy (via a shaft or pulleys or whatever) to a generator, and ",
" produces the electricity. ",
"- ",
"http://en.wikipedia.org/wiki/Ele... |
[
"Intuition of Wave Function"
] | [
false
] | According to Wikipedia, the wave function describing a particle in one dimension is Ae . Why does it take this form? Why is there a need for a complex valued function? I understand Euler's formula and that it is cos(kx-omega*t) + isin(kx-omega*t), but why does it need a cosine and sine term, and why is the sine term imaginary? Is it just the way the math works out, or is there an intuitive way to understand this? Thank you. | [
"The only good answer to the \"why\" is due to symmetry arguments. If you get higher into physics and learn some group theory, you learn how to approach a physics problem from scratch.",
"We assume that we are looking at a particular type of field/particle and we try to find it's governing set of equations. (If y... | [
"I'll vouch for the technical correctness of this answer, but I have a few problems with it.",
"1) Who decides what the Lagrangian is supposed to be, and how? This is at some point an ",
" choice, and all the fanciness with symmetry is just about keeping the set of assumptions to a minimum.",
"2) The free par... | [
"quantum mechanics is, in some as yet poorly understood way, the square-root of probability theory.",
"I don't know if it's that poorly understood. As Scott Aaronson points out, it can be thought that as straight forward generalization of probability theory: ",
"This is from nice lecture where Aaronson teaches ... |
[
"Do all blue eyes really come from ONE person? See description for more."
] | [
false
] | [deleted] | [
"Yeah, two people had to carry the gene to make a blue eyed baby. Those two people were descended from that original ONE person with the blue eyed mutation.",
"(This is purely hypothetical, assuming easy stats with no bernoulli trials, etc...)",
"Let's say the guy/gal was particularly successful, and had 6 kids... | [
"So it only spread due to inbreeding?"
] | [
"Sure, if you want to call it inbreeding. The parents who made the first blue-eyed baby would both be able to trace themselves back to this original individual at some point. It could've been one generation ago or twenty."
] |
[
"Newton's Third Law of Physics - Why does anything move at all if there is an equal reactionary force?"
] | [
false
] | So the rule to my understanding and Googling is that for every action there is an equal and opposite reaction. What I can't wrap my head around, is that if I'm playing pool, and I knock the white ball into another ball, why is the white ball not knocked backwards an equal amount to the ball it knocked into? I can understand in a lot of cases gravity or other forces diminish the reactionary force, but in this case.. when one ball rolls into another the energy transfers to the other ball without an equal reaction visually. This video you can see him applying force to the ball, but no matter what way it hits the yellow ball.. at least visually to me there doesn't seem to be an equal reaction of speed from the white ball. Is it a case of diminishing returns? That the white ball after it transfers all energy to the yellow ball, the reactionary force from the contact is only so big as to move it a little bit? Where as the yellow ball has the energy from the cue plus the reactionary force from the white ball that gives it the greater speed? | [
"If the white ball transfers some of its momentum to the yellow ball, the yellow ball will speed up and the white ball will slow down. That is what you see in the video."
] | [
"What Newton's third axiom says is, that the center of mass of a closed system cannot be accelerated.",
"That means, if you are in space, you cannot accelerate in any direction without emitting mass into the opposite direction (technically anything with momentum, so shining a flashlight in the opposite direction ... | [
"The white ball is indeed knocked backward an equal amount. Think of it in terms of the overall momentum. Before the collision you had one ball moving forward and one ball at rest. After the collision you have one ball moving forward and one ball at rest. ",
"The white ball was moving forward at we'll say 1 m/s. ... |
[
"Why does a protoplanetary disc not stay?"
] | [
false
] | From my understanding, a protoplanetary disc is a disc of dense gas and material orbiting a newly formed star. My question is the disc only around young stars? I presume the matter falls into the star, but why? Does it not have enough speed? IF anyone could give me some insight into what happens it would be much appreciated! | [
"It's called a protoplanetary disk because it forms into planets. Material that collides and sticks together will create a gravity field, pulling more debris into itself."
] | [
"Here is a quick article that talks about Micro-gravity and how planet building gets started",
"The disc is the gas that wasnt close enough (also Pushed away by stellar winds from the new star) to fall into the star during its formation. As far as I know if a old star was to orbit into a gas cloud it would be pus... | [
"The ",
"Wikipedia article on accretion disks",
" discusses the process of matter falling into the star. Matter in the orbiting disk must lose angular momentum in order to spiral inwards towards the star. Angular momentum is conserved, so it has to be transferred from one portion of the disk to another in ord... |
[
"Is there anywhere in the universe where energy is being converted to matter?"
] | [
false
] | In my Introductory Astronomy class, the professor said that the large amounts of energy produced by stars is the result of nuclear fusion converting some matter into energy. Is there anywhere that energy is converted back into matter or is the net amount of matter slowly diminishing? I guess a different approach to asking this is "Is it possible to convert energy to matter, and what are the conditions required?" Additionally, what form would this new matter take? Edit: Just to clarify, I am asking about matter, not mass. I understand that energy has a relativistic mass. | [
"The Large Hadron Collider converts the kinetic energy of protons into a series of massive particles.",
"The expression \"energy converted into matter\" doesn't quite make sense, because energy is a quantity and matter is a description of something. But there are examples (like the one above) where things with en... | [
"Particles, e.g fermions and hadrons, are formed whenever enough energy is available. So two 511kEv Gamma rays could collide and form an electron-positron pair. This however leads to a big unsolved conundrum of the big bang theory, why does their appear to be so much more matter than antimatter.\nWhat I think you a... | [
"In the CNO cycle and pp-chains some positrons are emitted by nuclei in beta decay, which then annihilate with electrons. This is not the dominant part of the energy output, but it is significant.",
"Edit: Also, beta decay in general can be seen as turning energy (nuclear binding energy) into matter (electrons ... |
[
"Commutators (QM)! How do they work?"
] | [
false
] | Saying two things, A and B, commute ([A,B] = AB - BA =0) always struck me as a totally arbitrary operation. Where did the idea for a commutator come from, and why is that relation special/what does it tell us? When two observables don't commute, they can't be measured at the same time (x & p, Lx & Ly, etc.), but why is this determined by their commutators? | [
"The way I think of it is that it doesn't matter which ",
" you make the associated measurement with. Say you measure x and momentum in the y direction. These operators commute so you can measure x first then y or y first then x and get the same result. But something like x px will give a different result than px... | [
"In the cause of angular momentum the commutators generate the algebra. So from the idea of group structure angular momentum is closed under this operation. IE [L_i,L_j] will always give you another element of the group. In particular these groups are called Lie Groups and the Algebra, Lie Algebra."
] | [
"Touching on the Lie Algebra of angular momentum, considering certain operators as the infinitesimal generators of motions (J for rotation, p for translation) it becomes obvious why certain observables would fail to commute. NOTE: I've ignored the factors of -i when considering the momentum operator in the position... |
[
"Do women with big boobs have more estrogen?"
] | [
false
] | null | [
"I have no idea why the top comments here are all people idly speculating about it when real answers exist one google search away. Breast development and size is a complex interaction between genetics and ",
"several different hormones",
" which includes the steroid hormones, estrogen and progesterone, growth h... | [
"When taking estrogen based birth control pills these are the side effects to watch out for. You are messing with your hormones and can end up with higher than intended estrogen levels."
] | [
"I don't know about breast size, but facial features are correlated:",
"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1560017/"
] |
[
"If an object with mass is moving near the speed of light towards me. Does the light reflected from that object \"blue shift\" into dangerous gamma rays?"
] | [
false
] | So it is my understanding that the light coming from objects moving toward an observer is "blue shifted" and the wavelengths compressed. If this is true can the light be so shifted that it is harmful to an observer? For example, if say "the flash" was holding a flashlight and running toward me at relativistic speeds, does the light get compressed to gamma rays? | [
"If this is true can the light be so shifted that it is harmful to an observer?",
"Yes, it can be.",
"For example, if say \"the flash\" was holding a flashlight and running toward me at relativistic speeds, does the light get compressed to gamma rays?",
"If he's running fast enough, yes."
] | [
"And not only that, but thanks to relativistic beaming, the light will be focused into a narrow beam ahead of the object, so not only will you be hit by higher energy radiation, you'll also be hit by more of it."
] | [
"/u/RobusEtCeleritas",
" is right, the answer is yes. But the gamma rays from The Flash's flashlight are the least dangerous thing in this scenario. To blueshift from visible light to gamma radiation, The Flash would need to be moving at at least 99.99999992% the speed of light. At this speed, his relativistic... |
[
"How can exchange of photons generate attractive force?"
] | [
false
] | So I read that electromagnetic interactions are carried out by exchange of photons, but I can't understand how can that generate attractive force between electron and proton for example. | [
"Static forces are brought about by an exchange of ",
" particles. Virtual particles are not really particles (hence the name), but are mathematical pieces of the overall equation describing the fields. Static forces are brought about physically by static fields. The \"photon\" does not describe every possible el... | [
"There's a good description of it ",
"here."
] | [
"\"Exchange of photons\" and \"exchange of virtual particles\" in general is a terrible term in my opinion. In my opinion, it's people mistakenly thinking of a mathematical approximation scheme as a physical process, just because it can be formulated in terms of Feynman diagrams (",
"http://en.wikipedia.org/wiki... |
[
"What's the best thing to say to someone when you're talking about evolution and they bring up the missing link?"
] | [
false
] | null | [
"Then we best wait for an expert to come along if I’m to be responsible :)"
] | [
"I won’t directly answer because it is not my field but in general you have to really ask yourself if it is worth engaging with this kind of thing. If somebody is educated in science and says something like this they are being wilfully ignorant and no actual ",
" will change their mind."
] | [
"She wasn't really that educated in science though. I'm pretty sure the only reason they hired her was because she had a teaching degree. She mostly just showed videos and gave worksheets. Now got the school year is over though I probably won't see her again I just want to know what to say if I ever hear that argum... |
[
"Why does the Earth have an axial tilt?"
] | [
false
] | null | [
"No one is sure! The most frequent theory that I have heard is that during the formation of Earth, it was struck by a very large object, such as another planet, at an angle. This would have caused Earth's rotation to have been altered. This theory is often coupled with theories about the formation of the Moon. See... | [
"The Chicxulub impact did not produce enough force to give the earth an axial tilt. Like the other commenter said, it's thought to be a product of the moon formation impact. Also the moon stabilizes our axial tilt! Without such a large moon, the axis would sway more and seasons would be very unstable over the years... | [
"could it have been the Chicxulub asteroid? or do we have reason to believe the earth has been tilted for longer. ",
"Also is earth unique in its axial tilt?"
] |
[
"Is it theoretically possible to have a set of entangled photons to interact with each other, even if one part is in a black hole?"
] | [
false
] | If you entangled a set of photons and sent one part into the hole, is it theoretically possible to have the entanglement survive the forces of the black hole and still interact with the other pair? Like, would one theoretically be able to entangle a pair, keep one in a sensor and send the other into a black hole and observe the interaction between the black hole one and the one in the sensor, thus getting data from inside a black hole? | [
"Imagine four playing cards: two Aces and two Kings. You select two cards at random; these are placed in envelopes, the envelopes placed in boxes, and one of the boxes is chosen at random and mailed to your cousin in Ontario. The remaining undrawn cards are destroyed. Now, you and your cousin each have a card, and ... | [
"You place the two in envelopes, send one of them on their way",
"To anyone else reading this, it's an analogy. In quantum entanglement, there are no local hidden variables and the quantum states are not pre-determined."
] | [
"That is orthogonal to what I was trying to illustrate, but it is a very important point; I couldn't think of a way to incorporate that in a simple analogy. Thanks for clarifying."
] |
[
"What are the oldest species that we could (in theory) bring back from extinction, given the half-life of DNA?"
] | [
false
] | null | [
"I do not believe that we are capable of truly bringing any species back. With out a parental cell then even if a \" \" was cloned, by using using an egg from a common ancestor, it would be a hybrid and not a pure \" \". DNA is not the blueprint of a creature, it is more like the library of information, of ... | [
"It's not the half-life of DNA that's the real concern. DNA needs to preserved, and most DNA will not preserve well enough to even approach it's half-life. Some study specimens that have been preserved in alcohol for hundred of years provide viable DNA, but that's only a few hundred years we're talking about. Th... | [
"There's the ",
"ice age flowers",
" (that's the first search result i got, if someone has a better article I would be interested in seeing it.)",
"If you're talking about animals, every few years I hear talk of resurrecting mammoths using elephant DNA to fill in the gaps like in Jurassic Park, but haven't he... |
[
"Do antibiotics kill all healthy gut bacteria and if so how does the body return to normal after treatment?"
] | [
false
] | null | [
"They certainly deplete the gut microbiome and in fact stomach issues are common with abx. Some bacteria escape due to a combination of factors, some are replenished from the appendix (turns out it is now thought to be a reservoir), and food. In bad enough cases some doctors even tell people have to eat probiotics ... | [
"Depends on the antibiotics. For most of them, no they don't kill ALL gut bacteria, but still result in dysbiosis. You would need a very high dose of a very powerful antibiotics to delete all your microbiote. The body returns to normal through the alimentation."
] | [
"It's real. Most common right now is with people that have had C-diff infections that keep recurring and need good bacteria to re-colonize and cure their infection when antibiotic treatment isn't effective."
] |
[
"Using acceleration to achieve artificial gravity on spacecrafts?"
] | [
false
] | As the feeling of gravity is created if a spaceship is accelerating or spinning around in a centrifuge á la 2001: a space odyssey, one could achieve the feeling of gravity in a micro gravity environment. How fast does the spaceship have to accelerate in order to achieve near-earth values though? Is it 9.82 m/s And then would this method be useful for any sort of missions or would there be too big a energy demand so that we're better of with a centrifuge? | [
"To calculate the \"centrifuge-style\" acceleration, the formula to use is ",
". This formula is also equivalent to ",
"You can plug in your own figures into this - ",
" would be 9.81 in your example. If you are imagining a spaceship rotating end over end, then ",
" is the distance between the centre of m... | [
"The \"less nice\" thing about rotating to produce gravity is that if your rotating section is small (think Discovery from 2001 sized) the acceleration on your head will be a lot less than the acceleration on your feet. Not sure what this would do to your circulation over time!",
"Plus, huge coriolis effects when... | [
"Forces aren't particularly useful at relativistic energies. This thread has a good talk through of the ideas. \n",
"http://www.physicsforums.com/showthread.php?t=552219"
] |
[
"If someone was born blind and suddenly gained their vision 20 years later could anything bad happen?"
] | [
false
] | null | [
"This does happen with individuals who born with congenital cataracts and who live in places without easy access to surgery. Project Prakash is an oeganization that does this in India and there are a number of research articles published on the vision of such people post surgery. I'm not sure what you have in mind ... | [
"Any type of sensory overload or anything like that"
] | [
"Yes in the sense that things are brighter. But they continue to have poor visual acuity for a while and only slowly gain visual function."
] |
[
"What is happening when my nose clogs up?"
] | [
false
] | So, it's allergy season again, and it seems my sinuses have clogged up completely. It also seems no matter how much I blow my nose or rinse out, there's more to come. What is going on, and why does it seem to never end? | [
"The reason your nasal congestion \"never seems to end\" has more to do with the swelling and inflammation in your sinuses than with mucus production.",
"The allergic reactions you're having cause your sinuses swell, thus blocking the airways. Blowing your nose can help remove mucus, but it does nothing to decrea... | [
"You're nasal passages get inflamed due to the irritants in the air, whether they be smoke, pollen, or animal dander. The mucus built up is to protect your sinuses from coming in contact with the irritants. Blowing your nose can help relieve some pressure but if you blow to much you can cause your sinuses to come i... | [
"Netipotting has always helped for me. What you do is take a pot (in my case I always used a syringe without the needle as it was easier) and place it in one nostril and make sure it is a near 100% seal and pour water into the nose. This will cause the water to either run down your throat or out your other nose whi... |
[
"What happens to all the random particles that are inhaled into our lungs?"
] | [
false
] | I'm thinking particles of sand, dust, bugs or any other random particle. Do we just cough them out over the course of a day? Do they get lodged in there? Like that guy who had a pine tree growing in one of his lungs! From a seed!... | [
"what the.....",
"\n",
"http://www.mosnews.com/weird/2009/04/13/firtree/",
" ",
"I've never seen anything like that!"
] | [
"Stores of energy in the seed?"
] | [
"Similarily, ",
"a guy had a pea plant growing in his lung."
] |
[
"Are there any naturally occurring lasers?"
] | [
false
] | Either organically or in places like stars or small scales minerals? Where do materials lase without man? | [
"There are masers (microwave lasers) in galactic centers. "
] | [
"Well, the \"a\" is for \"amplification\". The coherency is due to the \"se\"."
] | [
"Certain star and planet atmospheres contain masers. The CO2 atmospheres of Mars and Venus in particular do. Not sure why that wasn't mentioned. I don't know if any solid state material has been found to naturally lase, but it's entirely conceivable to me that a particularly pure crystalline mineral of some sort on... |
[
"What is the mechanism behind optical fresnel losses?"
] | [
false
] | Even a perfectly polished glass surface can exhibit ~4% loss per surface when bombarded by orthogonal incident rays. I understand that optical coatings form layers of increased density, therefore decreasing the "step density" between air and glass, but I don't understand the actual mechanism behind the Fresnel less. In a vacuum would the effect become more pronounced? | [
"The backreflection arises from an impedance mismatch between the two media. In this case the impedance is related to the electrical permittivity, which exhibits a discontinuity at the interface. The permittivity of air is very close to that of vacuum, so there wouldn't be a significant difference between air and a... | [
"Index matching is common with fibers however AR coatings for optics normal work by interference (like a DBR in reverse), by having a layer on the substrate that is quarter of the wavelength thick and a refractive index that is the sqrt of that of the substrates you can eliminate the reflections at that wavelength.... | [
"Different materials have different refractive indices (optical densities). As we move from one material to another, some component of light is reflected and some component is transmitted (the remainder is absorbed, but that's not really relevant to Fresnel loss). The Fresnel loss is the fraction reflected from the... |
[
"What would happen if a living brain was exposed to light?"
] | [
false
] | Please humor my silly hypothetical. What if you could twist off the upper portion of your skull and replace it with a transparent, temperature-controlled dome. Would light have ANY effect on the brain? Positive effects? Negative effects? or would it only get a sexy tan just in time for swimsuit season? | [
"The brain has no melanin, so it wouldn't get a tan. As to the effects, I can't imagine UV radiation having a terrific effect on it. It has no natural defenses to it, the way your skin does (see the aforementioned melanin). I'm betting you're looking at cancer, one way or another."
] | [
"Only you wouldn't feel the inevitable burn as the brain doesn't have any nerves. Thinking about it, it could be a really deep question due to the brains nack for adjusting itself, would the brain in question be able to compensate for the \"cooked\" parts of the lobes?\nEdit: assuming of course that the light ment... | [
"What if you could twist off the upper portion of your skull and replace it with a transparent, temperature-controlled dome.",
"Ain't no \"what if\" about it: it's called a ",
" and it's used for chronic recording. See, for example, ",
"Figure 1",
" (warning: pdf - the only direct links I could find were fi... |
[
"[PHYSICS]What is a particle?"
] | [
false
] | I have often heard that particles are possibly just highly condensed/organized space-time or vacuum or something, but I don't know how much traction that thought has in the realm of modern physics. Basically I need to know some hypotheses (I'm not asking for objective truth here, just the current thoughts on the subject) on the nature of matter. | [
"Things like protons and neutrons are composite particles - collections of more fundamental particles.",
"As far as we know, electrons, quarks and photons (among others) are fundamental, indivisible, particles.",
"In Quantum Mechanics these particles are a bit point-like (zero dimensional) particles and a bit w... | [
"Actually, that is an incredibly useful description for the paper I'm writing. I'm comparing Vedanta philosophy (specifically the concept of Brahman) with Minkowski-esque conceptions of space-time, and one of the problems I had was that matter isn't \"ineffable\" enough. From your description though, it sounds like... | [
"Pretty much all of Quantum Mechanics is a description of the mysterious nature of particles.",
"Most of particle physics is an effort to understand particles better. As such scholarly articles are heavy on the math and tend to avoid the word 'mysterious'.",
"Perhaps something along the lines of ",
"M-Brane",... |
[
"Does sun-burned skin absorb Vitamin D at the same rate as normal skin?"
] | [
false
] | [deleted] | [
"Umm... I'm pretty sure skin doesn't absorb vitamin d at all. "
] | [
"I think wackyvorlon meant that the skin doesn't ",
" Vitamin D directly from the sun. ",
"Instead, skin uses the energy absorbed from the sun to ",
" Vitamin D."
] | [
"I think wackyvorlon meant that the skin doesn't ",
" Vitamin D directly from the sun. ",
"Instead, skin uses the energy absorbed from the sun to ",
" Vitamin D."
] |
[
"If the 2028 asteroid collided with the moon... what would happen? How would it effect life on earth?"
] | [
false
] | If the asteroid is estimated to be between 1.3 km and 2.8 km in diameter, what kind of damage would it do if it impacted the moon? Would it cause any problems here on earth? Give me any info you got on this thing! Edit: Responses are disappointing :( | [
"A 3km asteroid slamming into a 1700km moon would knock it out of its orbit? I find that very unlikely."
] | [
"Armchair science does not belong in ",
"r/askscience",
"."
] | [
"(layman here) It'd make a nice big explosion on the Moon (barely visible, maybe), and a nice-sized new crater, and maybe kick up enough moon dust fast enough to make a faint little invisible temporary ring around Earth (that'd disappear pretty quickly). ",
"But otherwise, not much. The Moon's much bigger than th... |
[
"How do you convert energy into cold like in a fridge?"
] | [
false
] | I get how you convert energy into heat in an oven, but how do you convert energy into cold in a fridge? | [
"Without going into much details, the basic refrigerating cycle (in a closed loop) looks like this:",
"1) compress the refrigerating gas. The gas temperature and pressure rise as a result.",
"2) cool down the gas to (almost) room temperature. Heat exchangers do that, they are usually placed on the side and the ... | [
"In case this explanation did not make it obvious, a refrigerator does not \"convert energy into cold\". Cold is by definition, the absence of thermal energy. You get cold temperatures in a given volume by ",
" thermal energy from this volume, not by converting it or destroying. A refrigerator sucks the heat out ... | [
"That's the way it's actually done, because using change of state extracts much more heat. But in principle it works fine even without this."
] |
[
"What is happening in my skin after a mosquito bites me?"
] | [
false
] | Can anyone explain what is happening, why it itches, why a lump forms, why it takes so long to return to normal? Thank you! | [
"When a mosquito bites it will inject its food source with its saliva, which acts as an anti-coagulant. The presence of this foreign material triggers a localized inflammatory response, resulting in the characteristic redness and swelling; and the localized release of histamines which causes the itching.",
"This ... | [
"And what does ammonia in things such as Afterbite do that cause the inflammation to die down?"
] | [
"Honestly? I have no clue. I even asked an entomologist PhD friend of mine and she didn't know how ammonia works for mosquito bites either."
] |
[
"What stops a helicopter in forward flight from automatically rolling?"
] | [
false
] | In forward flight, the counter-clockwise spinning blades of a helicopter would encounter more drag and lift on the right hand side, and less on the left hand side, due the variation in relative wind-speeds passing over the blades. There would be then, I assume, more lift on the right hand side side of the helicopter than the left. This would cause a rotation of the helicopter about its longitudinal axis, a.k.a rolling. Do helicopters have a mechanism for dealing with this, or is the effect just negligible? | [
"The effect isn't negligible. In fact, this was a major engineering problem that had to be overcome in early helicopter designs. Early prototypes would flip over fairly easily. I read a very readable, in-depth article on this in (I think) Popular Mechanics about 20-25 years ago, but I can't seem to find anything co... | [
"I did look it up. It turns out some of them have a system similar to variable pitch propellers on aeroplanes, whereby the advancing blade has a lower angle of attack whereas the returning blade has a higher angle of attack, the AOA being the 'flapping' whereas feathering is from what I can gather is in 'copters wi... | [
"The tips on a helicopter wing are generally traveling close to mach 1 (~761mph), Helicopters typically don't go more than 150MPH, so the difference is generally negligible. However it is worth noting that many faster/larger helicopters have dual rotors which spin opposite each other. I'm not sure that this would... |
[
"Are there any mobile, multi-cellular organisms that utilize Chlorophyll?"
] | [
false
] | Mobile as in creatures that actively move around in a controlled manner, not those which travel and replicate through spore-like methods. | [
"There's the sacoglossan sea slug, which practices ",
"kleptoplasty",
", utilizing the chlorophyll it obtains from algae it eats."
] | [
"The spotted salamander gets some energy, it seems, from a symbiotic alga in its skin: ",
"http://www.nature.com/news/2010/100730/full/news.2010.384.html",
"I know this doesn't strictly fall within OP's definition, but I thought it was worth mentioning."
] | [
"This is pretty cool:",
"Although Elysia chlorotica are unable to synthesize their own chloroplasts, the ability to maintain the chloroplasts acquired from Vaucheria litorea in a functional state indicates that Elysia chlorotica must possess photosynthesis-supporting genes within its own nuclear genome; most like... |
[
"Why can we see Mercury and Venus in the sky if they are within our orbit?"
] | [
false
] | I don't understand why we can see Mercury and Venus if their orbits are inside of our own? Surely we are looking out of our solar system thus couldn't see them unless during the day but then the sun would make it to bright to observe. Assuming it has something to do with refraction/geometry. | [
"The answer does have to do with geometry.",
"Consider the following arrangement:",
" Sun Venus\n\n\n\n XXX\n XXXXX\n EARTH\n XXX\n",
"Imagine you live at the 'H' on the above diagram of the Earth. In this configuration, the Sun will not be visible from that spot, so it'll ... | [
"We can see them because their maximum (angular) separation from the sun is large enough that we can see them as separate objects in the sky from the sun, especially during sunrise/sunset when the sun is obscured. ",
"Maximum elongation for Mercury is ~20-30º, which comes out to being visible for 1-2 hours before... | [
"Thank you so much!"
] |
[
"How important is it that I refrigerate my eggs?"
] | [
false
] | null | [
"The low temperatures do indeed inhibit bacterial growth, but there are several other factors.",
"First of all, the egg, when it is laid, is covered in a transparent protein coating. This coating keeps out bacteria and most gas exchange, and serves to keep the egg hydrated for it's month-long sit under a chicken ... | [
"My favorite part was his source."
] | [
"It would be beneficial. Also, it is best to wrap any potent foods (such as fish) since eggs have slightly porous shells and so can absorb the smells of other foods in the fridge. We had a final exam in food economics which was completely on eggs - it wasn't very ",
"xhilarating..."
] |
[
"How did Quantum Mechanics change science?"
] | [
false
] | Did Quantum Mechanics really have an impact on science, or is it just over-blown? Did the new ideas that were introduced actually change the way we do science or think about stuff (especially with atoms), or is it really not used that much? | [
"I do not believe it is an overstatement to call Quantum Mechanics the biggest revolution in both Physics and Chemistry since the work of Newton and Lavoisier.",
"There is a reason why we talk about \"classical physics\" and \"modern physics\", usually referring to the developments in the first half of the 20th c... | [
"Good, long list! I came here about to answer \"all of chemistry\" but you beat me to it. I'm biased as a quantum chemist, but I really do think it's one of the most underappreciated triumphs of QM. Even your post understates it! ",
"It's not just that we could calculate things - as you say, that's only been some... | [
"I honestly don't know where to start. Quantum mechanics is our best understanding of fundamental reality. Basically everything we understand about the universe is quantum mechanical, except einstein's general relativity. Its broadly agreed the biggest problem with general relativity is that it's not quantum mecha... |
[
"Can someone explain to me the fine structure constant?"
] | [
false
] | For context, I know a decent amount of physics (at least more than the average joe). I have an equivalent bachelors in physics (my college didn't offer it as an accredited degree) and I love reading about it. However, this is the first time I have read about it and I can't seem to figure it out. I understand that it is a constant between EM Waves and charged particles. But, when you have a quark (I know they cannot be isolated in standard energies but just go along with it) you have a charge of 1/3 so shouldn't the constant 'change'? Or does this not apply to all elementary particles? Also what else does this constant apply to? I read we have seen it pop up in many different arenas. I don't need the super dumbed down version, but dumb enough for someone with only a bachelor's. | [
"The fine structure constant is related to the coupling between charged particles (",
" of them) and the electromagnetic field. Gluons don’t couple to the EM field, so the fine structure constant isn’t really relevant for them. The strong force has its own coupling constant, which is qualitatively and quantitativ... | [
"It just means interacting."
] | [
"Particles with more charge (in magnitude) have stronger coupling to the EM field. The fine structure constant α is the coupling constant for particles with |q| = e, the elementary unit charge. For particles with charge e/3, the coupling constant is a constant multiple of α. No matter what the charge is, the coupli... |
[
"Do astronauts - or any scientists - have a written protocol for dealing with extraterrestrials?"
] | [
false
] | null | [
"Yes"
] | [
"I once read something on this actually:",
"If we were to meet extra terrestrials, they probably wouldn't look like us, and most likely they would send machines in their place. Biological creatures don't travel well for millions of light years, we get old. Machines don't.",
"These aliens will be advanced, ",
... | [
"Check whether it's true. If it is, tell other people."
] |
[
"Why do crops need rotation and/or leaving the field fallow to prosper, while trees are able to grow and prosper in the same exact spot for years?"
] | [
false
] | null | [
"We don't usually care how fast or how well the trees are growing on a year to year basis. However we are ",
" interested in making sure that a crop yields the maximum amount of food every single time we spend money to plant it."
] | [
"Crop rotation",
" is performed to fix nitrogen in the soil. Trees can also benefit if low growing, nitrogen fixing plants are placed between them as in ",
"meadow orchards",
". But it's not feasible to uproot trees on an annual basis."
] | [
"Crops need certain nutriients to grow and produce good yields. One of the most important nutrients is Nıtrogen. Crops are rotated historıcally with a cycle of one grain crop, one root crop and one nıtrogen fixing crop or leaving the field fallow. Nitrogen fixing crops include legumes, clover, peanuts and Alfalfa. ... |
[
"Medicine: What actually kills someone with cancer?"
] | [
false
] | You often hear that someone "died of cancer", be it breast cancer, prostate cancer, melanoma or something else but what is it that actually kills them? Is it the immune system going havoc and killing all living cells it can find? Do you starve to death as the tumour grows and all nutrients you manage to ingest are seized by the cancerous cells? Infections, like pneumonia? | [
"The easiest way to think of cancer is to think of the effect of weeds in a garden.",
"Weeds grow quickly and wherever they like, and they will choke out the plants you've intentionally put in your garden and either impede their function or kill them entirely.",
"In some cases, the weeds suck all the nutrients ... | [
"As a medical student I once had this very same question, but basically here are several physiopathologic ways it can happen.",
"\n1. Tumoral lisis syndrome. Cancer cells sometimes die quickly in big numbers, releasing potassium into the bloodstream, among other (toxic) byproducts of cellular degradation, wich ca... | [
"It depends on the cancer. With leukemia patients will die from infection or disease due to a compromised immune system, other leukemia patients die from internal bleeding from low platelets, some die from the stress a low red blood count places on the heart. With a cancer like bone cancer the death is completely d... |
[
"At the peak of infection if all cold or flu viruses could be taken out of the body and put into a cup, how much volume would they consume?"
] | [
false
] | I don't know how many viruses are typically involved in an infection or how big they are, but I suspect the things that consume our body with sickness would not take up very much space at all. | [
"This is some fun sounding math, I'll take a crack at it. ",
"Peak viral load titers for RSV (Respiratory Syncytial Virus - a common source of winter colds) have been estimated as high as 10 million plaque forming units (i.e. viable viral particles) per milliliter of respiratory secretions (statistic taken from ... | [
"It's possible to make an estimate, using the same math, we just have to swap in different numbers. Viral load titers in those dying due to Ebola ",
"have been measured up to 10⁹ plaque forming units",
" per ml of serum. ",
"Serum volume in an average adult male would be roughly 2.5 - 2.75 liters. ",
"Vo... | [
"Would it be possible to replicate this with something like ebola, where the virus has completely taken over?"
] |
[
"When we say the universe is 13.8 billion years old, is that with respect to some particular reference frame?"
] | [
false
] | null | [
"Hi ",
"/u/moon_physics",
",",
"When we say the universe is 13.8 billion years old, is that with respect to some particular reference frame?",
"It is! In particular, when physicists say the universe is 13.8 billion years old, it is with respect to the ",
"cosmic microwave background rest frame",
". [To ... | [
"I always hear that there is no \"true\" or \"basic\" universal reference frame (not sure how to put it but I think you know what I mean). Can you explain to me why this wouldn't be it?"
] | [
"It would make sense if laws of physics were different in that frame, but they aren't, it just gives us a more convenient one to use for some things on the scale of the observable universe (just like the Sun is a better reference frame than Earth when looking at the solar system)",
"http://en.wikipedia.org/wiki/P... |
[
"What would prove the many-worlds interpretation? What would disprove the many-worlds interpretation?"
] | [
false
] | null | [
"We know of nothing to either of those answers. Physics and experiments can't touch the results of the many-worlds interpretation. It's entirely in the realm of philosophy and completely detached from any physical meaning."
] | [
"The various mainstream interpretations of quantum mechanics all make the same predictions. (",
"http://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics",
") That means that there's no scientific way to tell them apart or 'prove' them against each other."
] | [
"The various mainstream interpretations of quantum mechanics all make the same predictions. (",
"http://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics",
") That means that there's no scientific way to tell them apart or 'prove' them against each other."
] |
[
"What is the nutritional value of an average human being?"
] | [
false
] | Average would be around 5'10" and 190ish pounds. Nutritional value being vitamins, protein and all those too. | [
"http://onlinelibrary.wiley.com/doi/10.1525/aa.1970.72.1.02a00140/pdf",
"Garn, Stanley M., and Walter D. Block. \"The Limited Nutritional Value of Cannibalism.\"American Anthropologist 72:106",
"Notable quote:",
"A 50 kg man might yield 30 kg edible \nmuscle mass if well and skillfully butchered, \n... | [
"10% body fat is no where near average for a male or a female",
"."
] | [
"10% body fat is no where near average for a male or a female",
"."
] |
[
"Mitochondrial Eve"
] | [
false
] | What is the scientific relevance of the mitochondrial eve? I'm confused becuase the Wikipedia reference has this quote: Each ancestor (of people now living) in the line back to the matrilineal MRCA had female contemporaries such as sisters, female cousins, etc. and some of these female contemporaries may have descendants living now (with one or more males in their descendancy line). But none of the female contemporaries of the "Mitochondrial Eve" has descendants living now in an unbroken female line. So there were other females as this "Eve's" comtempories with descendants, so why is this one ancestor of any importance scientifically? | [
"What it's telling you is that we are all descended in an unbroken female line from the MRCA because everyone, male and female, gets their mitochondria from their mother. The MRCA's female contemporaries likely had children but if they only had male children, or at any point the contemporaries' descendents only had... | [
"The other way around. \"Eve's\" contemporaries have no living descendants in an unbroken female line. There is only one oldest common ancestor."
] | [
"No. It is/was a continuous on going process and as we no longer have those sequences we have no way of estimating a) how many alternative mtDNA types there once were and b) the rate that they were bred out of the population."
] |
[
"Linguists of Reddit, how likely or unlikely do you think it is people will still speak English 2000 years from now?"
] | [
false
] | null | [
"I think if we discuss patterns in english linguistical changes over the past 2000 years and understand why they occurred, we should be able to have an interesting conversation about this question in a hypothetical way. What do we think english will look like in 500 years? In 1000 years? In 2000?"
] | [
"This isn't exactly my area and is slightly speculative.",
"Historical rates of language change would suggest that the English of 2000 years from now would be unintelligible to us. Certainly, the English of 2000 years ago would not be intelligible to us now. However, language is very much tied up with cultural ch... | [
"It is possible to estimate the way language will change, based on the way it has in the past."
] |
[
"What is the difference between a zygote and a dikaryotic cell in fungi?"
] | [
false
] | [deleted] | [
"Here's a quick answer for you, but I'm sure a panelist will be around soon to give you a more detailed description.",
"Dikaryotic cells are formed when compatible nuclei from two different cells break down the wall between the cells to \"cohabit\" a compartment without sexual reproduction. ",
"From here.",
"... | [
"No problem, glad I could help."
] | [
"No problem, glad I could help."
] |
[
"Watering with carbonated water?"
] | [
false
] | So let me know if I'm talking madness, but here's the question: If you were to water a garden/lawn/flowers with carbonated water during the daylight photosynthesis phase, would this be better than watering with just plain water? If so, does the mechanism have to do with delivering more CO2 to the soil, which the plants are trying to uptake in this phase, or does CO2 uptake not take place in the roots, but at the leaves? If this is not a beneficial thing for plants, why not? | [
"This is probably not a good idea. Carbonated water is more acidic than regular water because it contains carbonic acid and this will decrease the pH level of the soil. Changing the pH like this could be harmful or deadly for the plant."
] | [
"This is correct, but to answer the rest of the question, roots do take up some CO₂. ",
"See my other comment ",
"here",
"."
] | [
"You mean like fertilizer? It's usually in the form of nitrates, urea, ammonium. \nPlants can't break the N2 bond by themselves"
] |
[
"Are there actual wild horses in the Americas or are they all feral domesticated horses?"
] | [
false
] | Has anyone ever brought actual wild horses to the Americas? And are there wild horses still in Asia? Or have they been bred out with domesticated horses to the point that all the horses in the world are basically domesticated? | [
"Until recently, Przewalski’s horse, which lives in Mongolia was considered the last truly wild horse. As of a few years ago, though, ",
"DNA evidence suggests",
" they are actually descendants of domesticated horses, so likely there are no truly wild horses left."
] | [
"To clarify, the DNA analysis showed they are related to horses associated to the Botai culture. Now whether the Botai had domesticated the horses whose remains are found around their settlements is an ongoing debate. It's quite possible they just hunted them.",
"EDIT: In any case, Przewalski horses are a separat... | [
"From Wikipedia: While genus Equus, of which the horse is a member, originally evolved in North America, the horse became extinct on the continent approximately 8,000–12,000 years ago. In 1493, on Christopher Columbus' second voyage to the Americas, Spanish horses, representing E. caballus, were brought back to Nor... |
[
"Glovebox - backflow into positive pressure?"
] | [
false
] | We use a positive-pressure, argon-filled glovebox on a regular basis. There's a catalyst system which nominally removes trace amounts of water from the box - however, the moisture meter is wildly uncalibrated and unreliable. A situation has come up regarding the glovebox main vent. My lab-mates insist that if the vent is open (pipe ~ .5" diameter), then the positive pressure inside the glovebox prevents moisture from entering the box. I remember hearing that some backflow does occur, but I can't prove it. I've been looking for a report, book, or journal article which mentions this, but haven't had any luck. Any thoughts? Thanks! edit: The way that the backflow was explained to me was that the flow would be outwards for most of the pipe, but that along the edges, it would be inwards. | [
"If someone pulls their hands out of the gloves really fast, it's possible that you could suck some of the outside atmosphere in, but it shouldn't be standard procedure to keep the purge valve open while you're working. Otherwise, with an opening that small, you shouldn't get any backflow as long as the inside pres... | [
"The easiest way to tell if you have a leak is to turn off the circulator for about 10 minutes to let the temperature equilibrate, crank up the pressure, and listen for the box to refill. If you don't hear anything for about 10 minutes, you probably don't have a leak.",
"How long has it been since you regenerate... | [
"Ah, I see. I think the best way to convince your labmates that they're wrong is to point out that a pressure differential only really saves you in a static system, but the air in the glove box is constantly circulating. If gas quickly rushes past a leak, it can create suction that ends up contaminating the box. ... |
[
"How closely related are the Y chromosomes in a male lineage?"
] | [
false
] | Since Y chromosomes must always be transferred from the male parent, how closely related should the Y chromosomes be when tracing the male lineage? I.e., comparing the Y chromosomes of the son to his father, grandfather, great grandfather, and so on? | [
"Because the Y chromosome is transferred directly from the father and it is not mixed with any other chromosomes it is almost identical to the father's chromosome (and his father before him...). Any changes would be due to mutation. Also note that it is possible for the Y chromosome to pick up VERY SMALL amounts of... | [
"There are identical, save for mutations.",
"This naturally allows you to track ancestry. If you are a male, by comparing the Y chromosomes of groups of individuals, you can determine who descended from a common male ancestor. Because there are so many different Y chromosomes, this tends to lead at best to intere... | [
"Can't mild crossing over occur from the X?"
] |
[
"Have any wind turbines been able to break the Betz limit?"
] | [
false
] | I've seen multiple claims of new wind turbines that due to some characteristic, usually design, can output more energy than traditional wind turbines. Are these all hoaxes? | [
"The Betz limit is the theoretical limit. Real wind turbines are not reaching it, ",
"this modern one",
" (pdf warning) achieves around 45% max efficiency (compared to the 60% of the Betz limit). But if you look at the efficiency vs wind speed graph you can see that this maximum efficiency happen for a pretty n... | [
"No, they can't break the Betz limit as it is a limit in the strictest sense. It is a calculation of the energy extraction efficiency from a flow, and depends on the area of the rotor, as well as the area before and after the rotor. We have an imaginary 'tube' through which the fluid enters at one end, is slowed do... | [
"The Betz limit is a pretty strict limit; but not in the strictest sense - it has something of a loophole",
"Consider if we built our wind turbine to cool down the medium and chose a medium with a very low specific heat capacity where even a small change in heat leads to a large change in density (alternatively w... |
[
"[Medicine - Dermotology] What is the latest research on acne? Are dermatologists getting any closer to finding a cure?"
] | [
false
] | null | [
"Everyone please remember that no one is allowed to give medical advice. Any comment advocating the use of medication or certain brand names will be deleted immediately. Please no more personal stories about what worked and what didn't. This is a science forum, and all answers should be scientific in nature. "
] | [
"I'm not aware of anything groundbreaking just yet, unfortunately. The retinoids like Acutane are obviously very effective, but their side effect profile is less than desirable. (I dont think Acutane is even sold anymore, but I believe the generic still is)",
"http://www.ncbi.nlm.nih.gov/pubmed/10809858",
"Phot... | [
"Dermatology Resident here.",
"The short answer to your question is that no, there is no new groundbreaking research on acne. Acne is one of the most common dermatologic complaints, and one that people are willing to spend a lot of money treating. There is a lot of money invested in research for new products.",... |
[
"If I started out naturally left-handed as a kid, then was \"trained\" to be right-handed, can I teach myself to go back to being a leftie?"
] | [
false
] | I started off always using my left hand. But in elementary school, I was told by my teachers/father that holding the pencil in my left hand was the "wrong way" and was harshly trained out of it. I'm not sure if this is a direct result of it, but my handwriting has always been EXTREMELY messy. Even when I try really hard and go slowly, it looks like a child hastily scrawled it. I still have many of the personality traits and attributes that lefties supposedly typically have: I'm fairly artistic, very high verbal and language-based IQ, but also diagnosed with a learning disorder (dyscalculia) and ADHD, etc... I can still use my left hand pretty well for everyday tasks if I need to. So I guess my question is: can a natural leftie who has been trained to be a rightie become a leftie again? Is it bad to have your natural handedness trained out of you? | [
"The previous answers are touching on whether your preference for using one hand can return, but in order to really get a hold of handedness, you need to consider actual ability, not just preference.",
"The answer is yes, you can train yourself to be proficient with your left hand again. You can, in fact, do this... | [
"So far, no studies have shown that you can truly \"shift\" your handedness.. Even if you get more used (through indoctrination or similar) to using the other hand, your brain will still be pre-defined to prefering the hand you were born to use. This is of course, if we accept the theory (most commonly accepted) th... | [
"I was trained to be right-handed too, it resulted in me being ambidextrous. Its helpful at times but I'll always have bad handwriting."
] |
[
"How much does the expansion of the universe effect the approach of Andromeda?"
] | [
false
] | I know that the rate at which the universe is expanding is increasing, and I know that Andromeda is approaching us at some 2.35 billion miles a year (lifted from wikipedia). How much time does the expansion of the universe buy the two galaxies before they collide (as opposed to if the universe were static) | [
"It doesn't. ",
"Metric expansion doesn't occur within clusters of galaxies",
"."
] | [
"So then in areas where spacetime is curved that curvature stops metric expansion, or slows it to imperceptible levels?"
] | [
"it doesn't happen at all in mass-dominated regions of the universe. it only occurs in the vast voids between galactic clusters."
] |
[
"Are there any normal healthy parasites of humans?"
] | [
false
] | Multicellular organisms like ticks and fleas but are common in humans and perfectly normal/healthy like the bacteria in our guts. | [
"A parasite has a non-mutual symbiotic relationship with the host; the parasite benefits at the expense of the host. What you are actually looking for is mutualism - where both organisms benefit from their relationship. At the macro level we have domesticated animals like dogs, cats, sheep, etc. that one could argu... | [
"As ",
"/u/stankyhankypanky",
" pointed out, a ",
" is not normal nor healthy. If you have one, then you've got a disease (depending on which parasite, e.g: ",
")",
"In a parasytic relation, the host (us) will ",
" get a downside. In the Taenia example, they'll eat what you eat, leaving nothing but left... | [
"So are there any worm/insect like beings living on/within us that has a mutual symbiotic relationship with humans?"
] |
[
"How do the changing frequencies of music travel within one FM/AM frequency?"
] | [
false
] | And how are they played back accurately on a receiver/sound system? | [
"The carrier frequency (103.6 FM, for example) actually has a bandwidth of about 50 kHz (for FM broadcasting in the US). So, the station broadcasting at 103.6 MHz actually has a license to occupy the frequency range from 103.575 to 103.625 MHz.",
"This allows the changing frequencies to modulate the carrier freq... | [
"The M stands for modulation.",
"To describe a periodic signal such as radio wave, we use its frequency (inverse to the period, or time it take for a signal to do its full \"travel\" from 0 to the top say 1, back to 0, then to -1 and finally to 0)\nand its amplitude, its \"height\". (we also use phase but please ... | [
"The thing to realize here is that the audio frequencies of music are completely unrelated to the electromagnetic frequencies of the radio transmission (much in the same way that the frequency of a wave on the surface of a lake has nothing to do with the frequency of the light that you use to see it with).",
"The... |
[
"can a woman be pregnant with two different men's babies at once?"
] | [
false
] | sorry if this is a dumb question. i bet a coworker lunch that this was not possible. dont fail me reddit. baked ziti is on the line.. | [
"Yes, it's possible, and it can happen naturally. It's called heteropaternal superfecundation. It's rare in humans but there have been documented cases. ",
"This article",
" has an overview. "
] | [
"All fraternal twins are made from different sperm cells, so it isn't hard to imagine a scenario where the sperm come from different men. ",
"Even weirder, babies can be conceived days or weeks apart. It is called ",
"Superfetation",
", but it is very rare. ",
"Get cooking. "
] | [
"thanks for the reply. bought 2 baked zitis and a pizza last week to honor the bet. i was wrong, but it was delicious. 🍛🍕🍜"
] |
[
"Why didn't this mixture of Conc. Sulphuric Acid and Cyclohexane react as expected?"
] | [
false
] | [deleted] | [
"Can you describe what reaction you're trying to make? Are you sure you don't mean cyclohexene?"
] | [
"cyclohexene is not very stable in the bottle once it's been opened - they tend to form peroxides, and also polymeric contaminants, which might explain the multiple behaviours and the string-i-ness. Was it an old bottle? (supposed to dispose 12 months after opening if I recall) "
] | [
"cyclohexene is not very stable in the bottle once it's been opened - they tend to form peroxides, and also polymeric contaminants, which might explain the multiple behaviours and the string-i-ness. Was it an old bottle? (supposed to dispose 12 months after opening if I recall) "
] |
[
"How does steel reduce the tension on concrete?"
] | [
false
] | I was recently watching a documentary where they said "concrete has an incredibly high strength when being compressed but it cracks with tension". Why is there a difference in the two and how does putting steel in the concrete inhibit the tension on concrete? | [
"Civil engineer here. Compression and tension are different in terms of the direction of applied forces, or loads. Compressive forces are loads acting inward on the element, while tensile forces are loads acting outward. Think of compressive forces as pushing and tensile forces as pulling. So saying concrete has hi... | [
"When tension -pulling - is applied to concrete, cracks form easily in the concrete lattice, and further pulling opens up the cracks breaking the concrete. To see how cracks affect the strength of material in tension, consider how easy it is to tear a plastic packet once a tiny notch is cut into it.",
"When the c... | [
"Pre-stressed concrete is made even stronger by pouring the concrete over a lattice of steel rebar in tension and allowing it to harden. After the concrete has set, the tension on the lattice is released, further compressing the concrete. "
] |
[
"Since tectonic plates colliding form mountains, why aren't there mountains everywhere plates border?"
] | [
false
] | [deleted] | [
"Because not all plate boundaries are convergent. There are three basic types of plate boundaries, convergent (two plates moving towards each other), divergent (two plates moving away from each other), and transform (two plates moving past each other). Of these, convergent boundaries are where major mountain ranges... | [
"The extension in the Basin and Range is internal to the North American plate and represents the early stages of rifting. If the process continued a new plate boundary would be created eventually with a new mid-ocean ridge along it. A more advanced state of rifting is in east Africa, which has split the African pla... | [
"Exactly. And, at least on land, mountain ranges can form where plates diverge, as in the Basin and Range in the American West. There’s nothing like ascending the gently sloped side of a ridge or peak only to be confronted with a mile or more cliff on the steep side."
] |
[
"Happy Pi Day everyone!"
] | [
false
] | Today is 3/14/19, a bit of a rounded-up Pi Day! Grab a slice of your favorite Pi Day dessert and come celebrate with us. Our experts are here to answer your questions all about pi. Check out some past pi day . Check out the comments below for more and to ask follow-up questions! From all of us at , have a very happy Pi Day! And don't forget to wish a happy birthday to Albert Einstein! | [
"When did the Pi Day start being a thing? I mean, was Einstein asked by journalists \"Wow you were born on Pi Day?\""
] | [
"I remember first hearing about it in middle school as it was probably a cute way for math teachers to have some fun with students. Late 90s?",
"Mind we also celebrated Avogadro’s Day in chemistry on October 23, but that doesn’t seem to have caught on the same way. "
] | [
"There's also an algorithm to calculate an arbitrary binary digit without calculating the ones before it"
] |
[
"Does muscle make you more resistant to piercing wounds (shot, stabbed)? Does fat?"
] | [
false
] | Hypothetically, if we lined up a muscular person, an obese person, and a typical person, and had them shot in the same place, let's say abdomen, who would suffer less damage/trauma? Would it be different if they were stabbed? | [
"Doesn't entirely answer the question, but the MythBusters kind of did it:",
"http://mythbustersresults.com/coffin-punch",
"busted",
"Determining that the largest layer of fat around a human (Walter Hudson) would measure 16 inches, Adam and Jamie placed that amount of human-temperature cow fat in front of the... | [
"This would depend strongly on the type of bullet used. A frangible bullet, for example, will definitely not make it through 14 inches of muscle and probably not fat either. It's definitely not black and white like they are showing. Hollow points penetrate less than full metal jacket bullets. Smaller/faster ca... | [
"It's also worth noting that this is because the bullets have different lethality. Frangible and hollow points penetrate less because they are designed to impart more of their energy on the target rather than passing through and continuing past the target with energy that wasn't spent doing damage. Small bullets wo... |
[
"If I took a deep-see creature, whose body is designed to withstand tons of pressure, and brought it to a spot with less pressure pushing down on it (such as the surface) and stood on it, would it support me, or would I squish it?"
] | [
false
] | I know that most of the time bringing any deep-sea creature up from the depths will kill it almost immediately, but I'm asking theoretically about the creature's body's ability to withstand pressure. It's a stupid question, I know, but I'm curious! | [
"I think the impression you have is that deep sea creatures are somehow super tough because the pressure in the deep sea is so high. (?)\nThat's not really the case since there are no particularly special body plans for pressure. Here is why. As was mentioned before, water is incompressible. Doesn't matter how m... | [
"This gets at the mechanisms underlying the ability to live in very deep water, so I find it to be a rather interesting question. I hope some marine biologists can chime in on this.",
"I recommend reading answers to a related question posted on the UCSB Scienceline page ",
"here",
".",
"My attempt at a shor... | [
"It would depend on what kind of sea creature you would be talking about jelly fish, crustaceans, sharks, take your pick. I believe it has to do with the animals open circulatory system allowing water to pass through it. A controlled rise to the surface would not kill the animal. We often have unidentified sea crea... |
[
"Why are some groups of animals, like rodents, not sexually dimorphic? (or at least as obvious as other mammals) How have social systems pressured changes in sexual dimorphism? How are species that aren't sexually dimorphic able to differentiate sexes before encounters?"
] | [
false
] | null | [
"How are you defining \"dimorphism\"? Are you approaching it with human bias towards visible differences?",
"Remember that there are other important sensory and behavioral clues to look for. Smell, in particular during estrus, is quite powerful, as are certain innate behaviors associated with mating, such as beco... | [
"Minor addition--it is sort of possible for sexes to evolve without each other, as in the case of termites. Most of their expressive genes have migrated to the sex chromosomes so males and females share little genetic material."
] | [
"Minor addition--it is sort of possible for sexes to evolve without each other, as in the case of termites. Most of their expressive genes have migrated to the sex chromosomes so males and females share little genetic material."
] |
[
"How long will we survive if the Sun suddenly disappears?"
] | [
false
] | null | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"For more information regarding this and similar issues, please see our ",
"guidelines.",
"If you disagree with this decision, please send a message to the moderators."
] | [
"I know the situation is hypothetical and highly unlikely to happen, but I was interested in the effects of suddenly losing the heat and gravitational pull from the Sun, and if we are able to sustain life somehow without solar energy. I do understand your reason for removing though, maybe the question should be ask... | [
"/r/AskScienceDiscussion",
" is your best bet!"
] |
[
"What is it about cockroaches that makes them famously able to survive radiation from a nuclear apocalypse?"
] | [
false
] | Are they really the only (land?) animals that would be able to make it? Is this specific resilience an evolutionary advantage or just some kind of quirk of their biology? Thanks | [
"DNA is most vulnerable, and most difficult to repair, when it is exposed in solution and being manipulated by enzymes. One reason is just that when it is being manipulated, the two rungs can be detached, reducing the number of chemical bonds available to support the molecule. Another is that there's more opportuni... | [
"Study recently confirmed, that it's just because their cells divide slower than in other species, so they can survive longer. but when their cells divide, they are susceptible to the same mutations as any other species."
] | [
"But there isn’t a phase in the cell cycle where radiation can’t enter a cell. It can always enter can’t it?"
] |
[
"Has a species of carnivores ever evolved from a species of herbivores?"
] | [
false
] | I'm curious about this because, if there were a case of this, that would mean that at some point, one of the members of the herbivore species, through some kind of situation or another, one day ate another animal. Might be a dumb question, I'm not sure. | [
"Lots of living herbivores will occasionally eat animals. Here's a deer eating a bird: ",
"https://www.youtube.com/watch?v=sQOQdBLHrLk",
"Whales (carnivorous/piscivorous) are most closely related to hippos (omnivorous, tending toward herbivory), and after that to ruminants (herbivorous), then swine and peccarie... | [
"Generally speaking, a lot of lineages start off omnivorous, and then become specialized into either carnivory or herbivory. ",
"It's relatively rare that strict herbivores (",
"I say strict only in a broad sense, because many herbivores will on occasion eat meat out of necessity",
") can become obligate carn... | [
"Off the top of my head there are two that come to mind Therizinosaurus and the Giant Panda. ",
"Usually theropods are considered omnivorous or exclusively carnivorous (think T-rex or velociraptors), but this and it's relatives are unique; they evolved from a common ancestor that favoured herbivore behavior, and... |
[
"What is the largest nuclear explosion possible with the fissile/thermonuclear material Humanity has available?"
] | [
false
] | null | [
"Theoretically, yes. Practically, I don't know why you would. Since it is speculated that the fusion reaction is caused by ablative pressure from x rays, the x rays would travel faster than the blast wave. Thus, multistage devices can be built. However, the damage caused by the bomb is not linear with power. S... | [
"Yes and no. It is not a matter of pumping it in. It is a matter of what is known as \"staging.\" What you are basically doing is using bombs to start more bombs to start more bombs. ",
"An atomic bomb (fission bomb) uses chemical explosives to start a nuclear fission chain reaction. This is put inside of a heavy... | [
"Who was contemplating a 10000 Megaton bomb? I have never heard this in my life."
] |
[
"Why is the heliosphere elliptical or comet-like in shape?"
] | [
false
] | Is this because the Sun is rotating in the milky way creating a helio-tail? | [
"Yep. The Sun is orbiting the Milky Way at a different speed to the local gas, so the gas gets bunched up on the \"front\" side and streams out along the back. This is also true for the magnetic fields, which also get compressed on the front and stretched out the back. "
] | [
"Actually results from the Cassini and Voyager 1 & 2 probes last year showed that the heliosphere only has few tail-like features and that the shape is mostly spherical and not very comet like. ",
"NASA release",
"Nature Paper"
] | [
"thanks for corroborating that."
] |
[
"Which rodents have the largest territory?"
] | [
false
] | I know that beavers are technically rodents and have territories that can span up to multiple kilometers, but what about other (smaller) rodents - which species do have the largest territory? I hope someone can help me with this question, Google wasn't very helpful in that regard. Thank you! :) | [
"Gophers of any variety can take up large swaths of territory, and are organized amongst themselves.",
"Rats/mice by default are the most populace and can be found pretty much everywhere, but they don't really organize amongst themselves."
] | [
"Rats absolutely do organize amongst themselves in groups called packs. Larger rats dominate the group and prevent other males from mating with the female rats."
] | [
"I should have been more specific.",
"Rats will organize themselv s.on this small of a scale yes, but there won't be thousands working in unison like gophers."
] |
[
"Can sound be predicted in a computer simulation?"
] | [
false
] | Suppose I wanted to make a computer simulation of a rubber ball hitting a wooden plank. There are many physics engines that could do this and would make an accurate reproduction of what it would look like. Would it be possible for a similar program to predict what sound would be made by this? As sound is just vibration, would it be possible to model how the ball and the plank vibrate, and use that to make a sound? | [
"Here is something from Cornell on the subject:\n",
"http://www.cs.cornell.edu/projects/sound/",
"You'd be interested in their list of related publications."
] | [
"It's been done to some degree of success, I read a long article about it a few months back, I'll try to find it for you when I get out of work."
] | [
"Yes it is possible, but it might be computationally more difficult. Finite Element Modelling might be required."
] |
[
"Why oil fries, while water boils?"
] | [
false
] | null | [
"To boil is to heat a liquid to point of vaporization. Like water to 100 °C. Oils boil much higher, like 300-400 °C.",
"Fry is a cooking term meant to heat something up, possibly with oil to cook it and maybe brown it. You could stir fry with water but I think that's more like sautéing."
] | [
"When you put food in oil it's at s much hight temperature than boiling in water. As a result moisture in the food is boiled out which dies the food. Its also hot enough that browning (maillard reactions) and crisping can occur.",
"The bubbling when you deep fry is the water coming out of the food and vaporising.... | [
"The other responses have answered your question, but I wanted to mention this: You can cook in oil without boiling it, and you can cook in hot water without boiling it as well (like when you're using a sous-vide).",
"In both cases the liquid is being used to impart heat to the food."
] |
[
"Will I faint instantly if my heart stop beating?"
] | [
false
] | Or will I stay conscious until all the oxygen in my blood is depleted? | [
"If your heart suddenly stops, your blood stops circulating in your body, you don't have to wait for your blood to run out of oxygen because it doesn't matter if you still have free available oxygen in your blood or inside your red blood cells packed within the hemoglobin, it is stagnant.\nHowever you won't faint i... | [
"There are things called pacemakers..."
] | [
"Implantable Defibrillators (ICDs) exist, and are increasingly common.",
"They are more complex than pacemakers and have at least 2 wires - one in the Right Atrium (RA) and one in the Right Ventricle (RV). The RA wire can act like a regular pacemaker - ensuring the HR doesn't go below a minimum value - it gives a... |
[
"Why does mold grow on tea but not on water, milk, or juice?"
] | [
false
] | Is it because the tea has more nutrients than the water and less sugar than the juice and milk? The mold seems to grow relatively quickly -- maybe after 3 days of leaving cold tea sitting. The tea that I drink in particular is Oolong tea boiled from the leaves (no teabag), if that makes a difference. | [
"Juice - too acid.",
"Milk - too much competition from bacteria.",
"Water - no food!"
] | [
"Could be that you've boiled the water and killed off all the bacteria in the tea, while in the milk and juice, you haven't. Thus the bacteria in milk and juice cause spoilage much sooner than mold.",
"Though there are a number of other variables."
] | [
"I've seen quite impressive mold growing on fruit juice.",
"Don't remember what specific type of juice."
] |
[
"How Can I *Safely* Watch the Transit of Venus?"
] | [
false
] | null | [
"Go to home-depot/lowes/Ace hardware and check out their welding section. They should sell welder's glass. It's a heavily tinted glass rectangle, about 2\" wide by 4\" long. A piece should cost no more than $5. It comes in different tints, which are designated by a number."
] | [
"http://www.eclipseshades.com/safety.html#anchor138141",
"Basically, welding glass, highest grade you can get. That stuff got standards. ",
"Under no circumstances what so ever should you use crossed polarizers or black negatives or random stuff that looks dark or paints or various random dark stuff irresponsib... | [
"No it's actually the ultraviolet that's the problem - infrared will cause heating but you'd have to stare for a very long time for thermal issues to arise. On the other hand, ultraviolet starts temporarily damaging the retina in a few seconds and permanently bleaching photoreceptors in the retina and damaging the... |
[
"How do scientists determine the \"habitable zone\" for a planet to support life, if the surface temperature of the planet is highly dependent on its greenhouse gas composition?"
] | [
false
] | i.e. doesn't a planets ability depend on much more than just its distance from a star (given the stars solar ouput)? | [
"I answered a similar question here: ",
"How is the Goldilocks zone of a star defined, considering how much surface temperature can change due to planetary characteristics?"
] | [
"Without a greenhouse effect Earth would be constantly ice bound and unlikely to have ever produced life (at least that moved beyond the deep ocean)."
] | [
"Firstly we need to define what makes a planet habitable. The Earth it would appear is an almost perfect example, the presence of water and light and our planets surface temperature means that our planet is optimum for life to evolve and live.",
"There are two definitions of habitable zones around a star: the cir... |
[
"Is there a name for the actual origin of the wind, like how a river has headwaters?"
] | [
false
] | null | [
"Rivers have a beginning and end that is clearly defined and generally permanent. Wind is ever flowing around the earth in ever changing systems of pressure driven by the sun and the earth's rotation. Thus, its hard to clearly define the starting point of wind. Wind is really more analogous to ocean currents, which... | [
"Ah, this makes a lot of sense. I figured that this was the case, but was wondering yesterday if there was some little-known term. Thank you!"
] | [
"Wind doesn’t really have a beginning point but the geotrophic wind is kinda the origin of all ground wind. It is the wind of the higher atmosphere and everything “flows” down from there. It’s not the air itself that flows down from there but the wind speed which is a gradient with the geotrophic wind being the hig... |
[
"If a gas always fill it's recipient, wouldn't it's density be always determined by it's recipient?"
] | [
false
] | null | [
"Partially, it sounds like you are describing a scenario where you are controlling the volume and pressure of the system which both impact density. The other factor to consider is molecular weight, which is only dependent on the gas itself. If you had two identical containers and filled one with nitrogen and the ... | [
"The oxygen would fill the entire room for sure, and you would calculate its density based on pressure, volume and composition. Whatever density the original 1 mole was at would be reduced when you let it spread out. ",
"Another way to say it would be if you suddenly make the room bigger without adding any more ... | [
"And what if we have let's say 1 mol of oxygen and you place it in a HUGE room with a normal pressure of 1atm. The oxygen would fill the whole room lowering its density so much or it has a \"fixed\" density for that pressure and would have a determined volume(lower than room's volume)?",
"I'm sorry if this is a p... |
[
"What is the opacity of air (average, of course)?"
] | [
false
] | How much visible light does, say, 1 metre of air block? How far is it physically possible for a human on a flat surface to see through an Earth-like atmosphere? | [
"I couldn't talk about air's transmittance over 1m, but ",
"here's",
" the solar spectrum measured in the upper atmosphere and at sea level.",
"Source"
] | [
"I'm going to try re-submitting this with a different title.",
"Edit: ",
"It's not going well."
] | [
"Please link me. I would love to know the answer."
] |
[
"From above water, why can't I hear someone yelling under water?"
] | [
false
] | I was playing around with my siblings at a pool and they were yelling messages under water to eachother. Why can't I, above water, hear them? | [
"The energy required to vibrate water molecules with sound is much greater. Sound is the vibration (within a range of frequencies) of molecules. I think the technical reason is the hydrogen bonds between water molecules that cause tension. Molecules in the air, for the most part, are not hindered by intermolecular ... | [
"That doesn't make sense since people who are also under water can hear just fine. "
] | [
"You can hear clearly under water? That's amazing. "
] |
[
"Are humans apes?"
] | [
false
] | So humans are primates. And we evolved from apes. But are we considered apes from a taxonomy viewpoint? Edit: Wow. Thanks for all the great answers. This got a lot more attention than I thought it would. | [
"This is an old essay from ",
"Talk.Origins",
":",
"A giraffe has never given birth\nto a horse, as far as we know it. An ape has never given birth to a man.\nI will give a million bucks to anyone who can observe an ape giving\nbirth to a human. Even your mother, if such were true.",
" ",
"As such, you a... | [
"Yes. Ape (Hominoidea) is a superfamily and is made up of the families Hylobatidae and Hominidae. Within Hominidae there are four genera: Pongo, Gorilla, Pan, and Homo. I think you can take it from there!",
"As with all taxonomy, there is likely going to be some shuffling around and suggestions for reorganization... | [
"Adding to this in simpler words: the common name for hominidae is \"great apes\". This family includes gorillas, chimpanzees, and humans. "
] |
[
"What exactly is the spleen used for?"
] | [
false
] | A co-worker had said he heared some where that the spleen on an evolutionary scale was once used to help us drink water that was unsanitary. Since I had no idea I knew the people of askscience wouild know. | [
"The spleen is part of the reticuloendothelial system (now called the mononuclear phagocyte system.)",
"http://en.wikipedia.org/wiki/Mononuclear_phagocyte_system",
"Also see: \n",
"http://en.wikipedia.org/wiki/Spleen#Function",
"for a great summary of splenic function. Clinically, removing your spleen woul... | [
"So pretty much maybe back a few thousand of years or more the spleen was larger and maybe helped us to drink dirt bad bacteria infested water? If we look at it our water supply it has gotten tremendously better over the years. What started this discussion was that back in the Ancient Greek times they would drink 3... | [
"I doubt the spleen was larger thousands of years ago. The size of the organ wouldn't have anything to do with how efficient it is at getting rid of bacteria that have been coated with antibodies (which is its major function.) If the theory about \"bad water\" was correct, people in countries where the water supp... |
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