title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"What is that phenomena called when I pee in the toilet with a steady stream and a random drop seems to pop out from the toilet bowl (and land on the rim)?"
] | [
false
] | I know there's a name for this but I cannot remember it (not bad aim). Google search with the above question yields nothing helpful. Please help! Thanks! | [
"splash back or back splash? These are also names for guards in fountains and such to catch this."
] | [
"Searching for 'rebounding water droplets' turns up a lot of related articles."
] | [
"I believe that this is the scientific term for this phenomenon. At least, that's what all us grad students call it."
] |
[
"X-ray go through us, UV and visible light is stopped by us, and radio waves go through us; where is the cut off for radiation going through people?"
] | [
false
] | null | [
"Radio waves don't actually go through us, or, for that matter, food in a microwave, contrary to a commonly heard urban myth.",
"Only very high powered photons pass through us -- x-rays and gamma rays. And subatomic particles go through us, but with some chance for a collision along the way.",
"Neutrinos go thr... | [
"NIR penetrates deeper into skin than VIS, e.g. you can monitor brain flow transcranially. THz and mm/submillimeter-wave goes deeper still."
] | [
"If the energy of the radiation matches a specific energy transition in the atoms it travels through, then it is strongly absorbed. For instance, the energy of visible light matches the transition energy between different electron levels in a low-atomic-number atom (",
"http://en.wikipedia.org/wiki/Bohr_model",
... |
[
"Is the chance of winning the lottery on a ticket with in-order numbers the same as random numbers?"
] | [
false
] | Sorry if the title is confusing, I couldn't find a better way to phrase it. If 6 balls are pulled out of the lottery, is the chance of winning the same for increasing numbers in order and randomized numbers? For example: You pick your numbers in order to be: 1,2,3,4,5,6 or: 11,12,13,14,15,16 Or you pick random numbers to be something like: 24,11,14,3,27,35 Would you have better chances with the random numbers? I couldn't imagine the numbers being picked in order. It seems like the chances are a lot lower for that. But don't all numbers have the same chance of getting pulled? | [
"Both 1,2,3,4,5,6 and 24,11,14,3,27,35 have precisely the same chance of winning. Your evaluation of your chance of winning with 1,2,3,4,5,6 (extremely unlikely, like almost never) is closer to the correct chance and is how likely you should feel of winning with any combination you pick.",
"That said, there is a ... | [
"Interestingly, while the numbers you pick don't alter your chances of winning, they do alter the amount you are likely to win. If the options are 1-60 for example, you have an equally high likelihood of winning if all of your numbers are over 30 as under 30. But people like to pick birthdays etc as lottery numbers... | [
"Any set of numbers has the same chance of being drawn, but having randomly chosen numbers could be advantageous if you have a winning ticket. Depending on which lottery you are playing, the total prize money may well be split between all winning tickets. A lot of people pick regular sequences of numbers, so if you... |
[
"Why is iron attracted to a magnet, but chromium isn't?"
] | [
false
] | (Below 38 degrees Celsius, at least.) The explanation I've always gotten is, roughly, 'well, in chromium each atom pairs with another atom, cancelling out the magnetic field' (i.e. antiferromagnetism) - but this leaves a lot to be desired. Why do such pairings form in chromium but not in iron? And why do such pairings form in such a way to cancel out the magnetic field? On a large scale, it's energetically favorable for magnets to orient themselves such that their fields add - why is it any different on an atomic scale? | [
"Hi, ",
"wikipedia",
" has a decent (and much better than I could do in a reddit comment) explanation of how ferromagnetism (permanent magnets) work. To properly understand why in some atoms parings are made and others are not requires a decent amount of ",
"quantum mechanics",
" at the 2nd/3rd year undergr... | [
"Why do pairings cancel out the magnetic field? All electrons have a magnetic moment (this is what gives rise to the magnetic field), it's orientation is dependent upon the particles' spin (either up or down). Due to the PEP, electrons in a filled shell will always pair up (one up and one down) and their magnetic m... | [
"The gist: electrons define magnetism as a side effect of quantum spin. The more electrons with the same spin (up) and no countering spin (down), the more magnetic the atom can be. Each orbital has two electrons in it - one of each spin. A valence shell has X number of orbitals in it, and each shell has more orbita... |
[
"Looking back in time at our children- Using telescopes? (Galaxies example)"
] | [
false
] | [deleted] | [
"A telescope can only pick up light that reaches it. It can't reach out and grab far-away light.",
"As you get into your spacecraft, the light reflected from you leaves Earth and starts traveling towards Kepler-22b. You take off at the same time, traveling at 99.9999999999999999999999999999% of the speed of lig... | [
"Not unless you traveled faster than light, which is impossible according to our current understanding of physics."
] | [
"(Faster the light, means we arrive there before light does, so we are arrive before time does), In that scenario, it would work, ok.",
"But say we were traveling 99.9% as close to the speed of light, without ever actually surpassing it. (Assuming we could) ",
"We reach the planet with my #nth grand child bei... |
[
"Why does all visible light travel at the same speed through a vacuum, but not through a medium?"
] | [
false
] | Additionally, does this apply for all other types of radiation in the electromagnetic spectrum? E.g. radio waves travel slower through a medium than UV waves? | [
"Alright thanks for clearing it up. Seems like I had some things mixed up there."
] | [
"That's a misleading explanation, especially as the poster above you has the proper explanation (it excites other charged particles and the interaction between the emitted photons from them slows the group velocity). ",
"See the following from Sixty Symbols: ",
"https://youtu.be/CiHN0ZWE5bk",
"Also: ",
"htt... | [
"That's a misleading explanation, especially as the poster above you has the proper explanation (it excites other charged particles and the interaction between the emitted photons from them slows the group velocity). ",
"See the following from Sixty Symbols: ",
"https://youtu.be/CiHN0ZWE5bk",
"Also: ",
"htt... |
[
"Why does the 5th (pinky) finger, have its own extensor but not its own flexor? Why do why need to extend it in isolation from the other digits?"
] | [
false
] | null | [
"It does have a flexor muscle, the flexor digiti minimi, which is part of the 3 intrinsic muscles of the pinky. The pinky needs to be able to extend and flex in isolation so it can cross and touch the thumb. If it wasn't for the opponens muscle, then we wouldn't be able to grasp items in the manner that we do now... | [
"The hand is pretty complex and there are lots of factors that go into this answer. I'll try to explain this the easiest way possible. Basically, all your fingers have two main flexors and one main extensor. The muscles for these tendons are located in the forearm. The flexors are the FDS and FDP (flexor digitorum ... | [
"Indeed--if it didn't have it's own flexor and extensors our musical instruments and keyboards would likely be arranged differently. ",
"The thing the OP is experiencing is reduced cortical representation of the fourth digit. Our brains dedicate fewer resources to the independent control of the third and fourth ... |
[
"Is there a way to pull carbon from the atmosphere in order to make useful products like carbon nanotubes and graphene, thus providing a useful item while also lowering greenhouse gasses?"
] | [
false
] | Bonus questions: Can you do this in a way without producing other harmful side effects, such as eating away the ozone? Is it possible for this to be monetarily profitable? | [
"So there are several parts to your question. First, it is possible to pull carbon out of the atmosphere, for instance with CO2 scrubbers. There are a number of different versions, some using passive adsorption and other reacting with CO2 to form other compounds.",
"Generally speaking, it would be... difficult an... | [
"There's already operational plants that pull it from the air, mix it with water and electricity and creates a hydrocarbon fuel that can be burned in cars. To pull JUST the carbon from the air, you gotta either separate it, and/or combine it with another compound, which you can remove it from. Creating a hydrocar... | [
"The key thing here is energy everything is possible with enough energy but to capture more CO2 than the amount of co2 the capturing emmits think about energy and material. Many of these co2 caturing devices use massive fans wich need a lot of power"
] |
[
"If you windmill your arms in outer space, do you rotate or do you stay stationary?"
] | [
false
] | null | [
"You rotate for as long as your arms are kept spinning such that your total angular momentum stays the same as before."
] | [
"what would prevent me from stopping my arms spinning and ending in a different orientation then I started? ",
"Nothing, you can totally do that. That's how cats turn to land on their feet when they're falling, and astronauts can also ... you know what, a video is worth a thousand words.",
"https://www.youtube... | [
"No. If the total rotation of your body is zero, and part of it (your arms) is spinning clockwise, the rest of it will be spinning counterclockwise."
] |
[
"Do/Can \"equator-line-crossing\" hurricanes exist? if so, do they change their \"turning\" direction when changing hemispheres?"
] | [
false
] | Question is self explanatory. | [
"Is it possible? Well, sure, in theory. But hurricanes don't often form near the equator (because there isn't a coriolis force there, so normally cyclones cannot form). They ",
"can",
" form near there, but it's usually due to unusual effects. As far as crossing the equator: I can't find any examples (other tha... | [
"It is a myth that water in different hemispheres spins differently down the plug, but the Coriolis effect does affect hurricanes. ",
"http://en.wikipedia.org/wiki/Coriolis_effect"
] | [
"It is a myth that water in different hemispheres spins differently down the plug, but the Coriolis effect does affect hurricanes. ",
"http://en.wikipedia.org/wiki/Coriolis_effect"
] |
[
"When does evolution favor polygenic and monogenic traits?"
] | [
false
] | I ask because organisms tend to have a mix of both, but it seems to me that polygenic traits ought to be favored because they would be more resistant to disorders caused by unfavorable mutations. One unfavorable gene in a large system of genes has a relatively small impact on the phenotype compared to an unfavorable gene in a small system, where the change can cause large deleterious changes in the phenotype. But on the other hand there are plenty of monogenic traits. Is this 'just because', or is there an advantage to traits that are determined by relatively few genes? | [
"Well, its not that it favors one or the other, its simply a nature of the genetics of it. If a trait is based solely on one protein, its simply going to be monogenic because a single protein will only be encoded by a single gene. For example, ABO blood type consists of a single gene with 3 alleles. If you have the... | [
"That's a good example of a trait that's just because.",
"I was thinking more about genes that regulate some metabolic pathway. Like a gene that codes for an enzyme, and there can be other genes that regulate the production of that enzyme, or maybe even alter the enzyme structure (if that's possible), or produce ... | [
"Well, there are other genes that affect everything. A single gene codes for a single protein (or some form of functional RNA.) There are proteins that do play important roles in the functioning of various other proteins and there are some proteins that require other proteins to work. Fatty acid synthase, for examp... |
[
"How far are we away from economical synthetic/In vitro meat?"
] | [
false
] | says, it could be competitive around 2050. It is stated that in vitro meat has a lesser environmental impact, requires less energy to produce and does not harm animals. Is In-vitro meat a realistic and sustainable alternative to common animal-meat? What main problems have to be overcome in the next decades? Can in vitro meat substitute todays animal meat, or will it only be a small niche? | [
"HI!",
"I'm going to have a rant here about ",
" meat.",
"First off, this shit comes up every few months on reddit, and the massive response is always really positive, and everyone looks forward to 2020, or 2050 or whatever magical date that is proposed to be the date when this shit is cost-effective. ",
"L... | [
"http://www.guardian.co.uk/science/2012/jun/22/fake-meat-scientific-breakthroughs-research?CMP=twt_gu",
"2 independent researchers are working on it with different methodologies and are pretty close to a breakthrough. The price is the real problem."
] | [
"How long would we be talking to get to, say, 120% of current beef prices with similar fat content? At that level, I'd probably switch over. I'm not a vegetarian, but I can understand the cruelty and environmental impact arguments, and would have a harder time justifying my current choices if this was an economical... |
[
"What is the evolutionary advantage of an animal eating its young?"
] | [
false
] | [deleted] | [
"Howdy! This is a bit outside of my subject area, but I have ",
" background here in animal behavior. There are several good theories on why animals might eat or kill their young. For many birds, for example, it is to guarantee greater success of offspring within multiple egg clutches. ",
"If you read some ... | [
"There is one way I can think of that an animal might benefit from eating its own young: if an animal has recently spent much of its energy producing offspring, it may be in dire need of sustenance. If there are no readily available food sources, there are basically two possible scenarios: \n1. The parent dies, and... | [
"So... post-birth abortion?"
] |
[
"Why do we still detect background radiation from the big bang?"
] | [
false
] | Regardless of how long these microwaves took to reach us, wouldn't it have blown past us already especially if the event that generated it occurred in a very small volume? Is it bouncing around matter in the universe or being bent back around by gravity to make another pass at us, perhaps? | [
"Its not an afterglow like you think of the bright flash of a bomb exploding. It instead has to do more with the temperature of space. Its the leftover \"heat\" that occupies the space and we are detecting that black body emission.",
"You can think of it as everything start off super hot and dense and as space ... | [
"Thanks. That makes a lot of sense. I was indeed thinking of it like a flash of light not a hot \"object\" cooling down by radiating heat."
] | [
"Just to clarify, the microwave background is black body radiation emitted from the stuff that fills black or \"empty\" space? "
] |
[
"I heard a snippet on NPR that we are pumping so much water out of the Ogallala Aquifer that it is effecting the earths gravitational field. Can someone please explain this too me? How is it changing, why is it changing, etc."
] | [
false
] | null | [
"I was not commenting on the abuse of aquifers, just the abuse of scientific sounding language. Every movement of mass causes a change in gravity. Sublimation of snow every winter causes a change in gravity but we don't hear the evening news commenting on that. ",
"This is the same manipulative nonsense as referr... | [
"Gravity is a function of mass. Any movement of mass affects earth's gravitational field. If you move a shoe from one room to another, you affect the gravitational field. This is just the sort of 'framing' people use to generate anxiety or fear about specific causes. "
] | [
"I agree. The real story is how amazingly sensitive the GRACE mission is for measuring gravity anomalies. The popular press (NPR included) often confuses the technical ability to make very fine measurements with the need to make those measurements relevant. The same thing happens with radiation and toxins. Just... |
[
"What do we need to ingest water for?"
] | [
false
] | [deleted] | [
"Its a solvent, you need it to transport chemicals that would otherwise be a solid into and out of your cells."
] | [
"It also aids in preventing macromolecular crowding from becoming a huge problem."
] | [
"The main reason is because our kidneys require a lot of water to remove waste products from our blood. ",
"A human being ordinarily produces approximately 2 liters of urine per day, which means that you have to drink at least 2 liters of water per day. ",
"http://en.wikipedia.org/wiki/Ureotelic",
" ",
"ht... |
[
"What caused the moon to tilt slightly in the night sky?"
] | [
false
] | null | [
"What do you mean by tilt?"
] | [
"I mean that when you look up to the moon, the line of shadow (phases) it creates isn’t always vertical or horizontal. Sometimes it tilts a bit."
] | [
"The earth moon and sun do not lie on a perfect plane. Also, the angle of orbit of the moon relative to the earth changes. That is why we don't get a solar eclipse every day"
] |
[
"How close are we to the use of RNA drugs in humans?"
] | [
false
] | I have read the abstracts from a few papers lately with some promising results using RNA as a drug to selectively inhibit expression of unwanted genes. For example in or . These sound promising, but I wondered if anyone knows what barriers exist towards human application. For example, what is the route of administration? How can we get the RNA into the right cells. Will this cause immune problems? | [
"Hi there. I do undergraduate research in protein therapeutics and drug delivery. I've read some papers on such drugs as well. I think drug delivery itself is a huge area of research, let alone developing the drugs themselves. There many delivery methods, such as particles (often on the nanoscale), viruses (vir... | [
"If you could use these drugs to \"inhibit expression of genes\" couldn't you also reverse the effect and gain expression of good genes?"
] | [
"Not in the application that the OP is talking about. His application refers to the selective destruction of transcribed RNAs to prevent or seriously downregulate expression of those genes."
] |
[
"Is there any reason for the increase in severe weather?"
] | [
false
] | Tornados, tsunamis, and hurricanes seem to be a lot more frequent and severe than it was say 10-20 years ago. Is there a reason for this or has it always been like this. | [
"The problem is that there is no obvious trend in the actual number of these events; patterns have shifted, clearly in part due to global warming, but it is far from obvious that the trend is unambiguously upward. ",
"Instead, the reporting of these tragedies had become more common, and the dollar damage has incr... | [
"All of these points are correct. There are still the effects of shear that may reduce hurricane formation, in addition to potential changes in the time pattern of formation that could lead to weaker storms. The modeling that uses is very sensitive to assumptions, results are inconclusive, and so there there is sti... | [
"Some factors that bias our perception.",
"Journalism reporting it more because it's an easy story.",
"Doppler radar and satellites and other tech advances as well as the internet allowing anyone (including the journalists) to see and track every storm.",
"More people living in cities/regions with high flood ... |
[
"Why do bug bites and healing wounds itch if we're not supposed to scratch them?"
] | [
false
] | null | [
"Actually, pretty close I believe. The reason why bug bites are itchy is because the body releases histamine at the site of the bite as an immune response. The increased blood flow from the vasodilation flares up nearby nerve endings creating the itchy feeling. This is why hives are also itchy. "
] | [
"Actually, pretty close I believe. The reason why bug bites are itchy is because the body releases histamine at the site of the bite as an immune response. The increased blood flow from the vasodilation flares up nearby nerve endings creating the itchy feeling. This is why hives are also itchy. "
] | [
"I have thought that the toxin induces histamine release by our cells too, but apparently some spider toxins are actualy composed of histamines, see",
"http://www.sciencedirect.com/science/article/pii/S004101019700072X",
"I am assuming that the spider's normal prey is (a) smaller than a human (seems safe) and (... |
[
"If it's possible to see galaxies and planets billions of light years away, how come it is not possible to see whats on the planets themselves?"
] | [
false
] | Shouldn't we already have the technology to determine what a planet's atmosphere is made of based on the light it emits? Using that information, we should be able to refract the light which blocks our view of the surfaces of the planets and truly search for life. | [
"We don't see planets billions of light-years away. The range of observed exoplanets is about 10 to 25000 lightyears.",
"We can use spectroscopy (absorption and emission) to determine atmospheric compounds in some exoplanets.",
"Form the most part, we do not directly image exoplanets, nor do we have the resolu... | [
"As I said in another thread, planets in other solar system are very small on a cosmic scale and are positioned right next to a very bright light. It is hard to distinguish light from Earth-sized planets from the light from their star."
] | [
"Essentially for the same reason that you can see an apple with your naked eye, but not the individual cells that make up the apple. Distant planets are just too small, in terms of the amount of sky they cover, to get an image of them with current telescopes. "
] |
[
"Is there a reason why the gay community was initially the first to be hit hard by HIV/AIDS?"
] | [
false
] | null | [
"Somehow I feel like this is the wrong lesson to draw from this."
] | [
"A small number of gay men were ",
" sexually active and had a large role in spreading the disease. ",
"This guy",
" is notorious for being originally thought to be patient zero for HIV in North America. He claimed over 2500 sexual partners. Worse yet, the guy was a flight attendant and spread the disease all... | [
"I would add to this three things:",
"1) The gay community was hit very hard very early in the U.S., but that does not necessarily apply to other countries.",
"2) The AIDS epidemic struck after the development of antibiotics. Many STDs (particularly syphilis) had already become significantly less dangerous, and... |
[
"Is there weather on the moon?"
] | [
false
] | I know there is space weather, but are there any "weather" effects that only occur on the moon? | [
"The Moon has no atmosphere, so I'm unclear in what medium lunar \"weather\" would occur, or what form it would take.",
"The surface temperature varies according to its solar exposure and local geology, ranging from 120 ± 5°C maximum at the equator dropping to about -150°C at dusk, and cooling to -180°C. just bef... | [
"Actually the \"lunar atmosphere\" does change slightly during the day, so I suppose you could call that \"weather\".",
"But we are talking about trace amounts of particles that are only slightly more dense than the interplanetary medium. So there would be no measurable effects that even slightly compare to the w... | [
"They carefully planned the missions during the best time of day (lunar dawn). Also their suits provide some protection. "
] |
[
"Can I intentionally stop shivering?"
] | [
false
] | [deleted] | [
"There are several questions here...",
"Shivers are muscle spasms - usually you can stop them temporarily by either calming yourself (a few deep breaths) or by freezing the muscles (flex your abdomen and core - when the muscles are already flexing, they cannot shiver) but both of these methods are temporary. A be... | [
"if you are truly freezing (ie hypothermic) DO NOT run hot water over your body, you will go into shock and die! rather, cover yourself in blankets, eat soup, drink some tea but do not expose yourself to such a rapid change in temperature"
] | [
"This is true for extreme situations, however I thought we were talking about the average \"I'm in a really cold lecture hall and want to warm up\" kind of problem...",
"PS it also works in summer, use cold water to cool off."
] |
[
"What is in the vacuum of outer space?"
] | [
false
] | To clarify, what exists between, for example, to planets? There's no air or other gases (in most scenarios), so what fills the empty vacuum of space? It is my understanding that a perfect vacuum, an area in which literally nothing exists, is impossible, so by extension something needs to inhabit that area. So what exists in the void of space? | [
"Your understanding is what is only somewhat correct. Space is made up of a small, very countable, number of hydrogen atoms per cubic meter and some larger number of mobile particles like neutrinos and photons, though due to their nature, they do not change the properties of the vacuum that is space."
] | [
"To be more specific, the space between stars have an average of 1 hydrogen atom per cubic cm. The space between galaxies has 1 hydrogen atom per cubic meter. For comparison the best vacuum on earth can achieve on the order of a ",
"thousand",
" particles per cubic cm. So space is called a 'vacuum' relative to... | [
"the atoms aren't dense enough to be able to absorb any significant number of photons, this is called an optically thin gas. it's the same concept of why we don't expect any head on collisions between stars when 2 galaxies merge, although the odds are different, the idea is the same. "
] |
[
"If you try to swallow repeatedly in quick succession, why does it become progressively more difficult to do so?"
] | [
false
] | This confused me as a child, and it seems strange that there is some sort of delay between 'gulps' when swallowing just air. | [
"Swallowing is a reflex, it has to be triggered. The four phases of swallowing are oral, oropharyngeal, pharyngeal, and esophageal. The sight of something or placement during the oral phase actually triggers the reflex through the muscles and production of saliva. Without this, it is very difficult to swallow and t... | [
"The question was about the increasing delay not the fact that there was a delay."
] | [
"Thanks, this is a really informative answer. The Masako exercise is probably what I happened to be doing when first making this observation."
] |
[
"Does the effectiveness of sunscreen stop increasing when the SPF is higher than 30?"
] | [
false
] | I've been hearing that sunscreen doesn't actually get more effective at SPFs higher than 30, meaning that a 50 SPF sunscreen won't actually work better than a 30 SPF. Is this true at all and if so why? | [
"This mainly true. 50 SPF is technically better protection than 30 SPF, but only marginally - they each protect you from 98% and 97% of the sun's rays, respectively. Anything higher than SPF 50 is borderline ridiculous - an SPF 100 sunscreen still only protects you from 99% of sun's rays, even though you probably p... | [
"Those numbers don't look as good as they actually are. A sunscreen that blocks 99% is twice as effective as one that blocks 98%."
] | [
"Really? I don't understand sun and SPFs as well as I thought then... care to enlighten me?"
] |
[
"I have a question about Quantum Mechanics observation..."
] | [
false
] | Ok, I think I understand that unobserved an electron can exhibit both a wave and particle function, but observation causes it to collapse into a particle function (please shore up this probably incorrect knowledge) What I am interested in is how the electrons "know" that are being observed. What is it, specifically, about the observation that causes this collapse into one or another? What constitutes observation and what doesn't (if even a camera filming the event can collapse the electron function)? I'm a molecular biology undergraduate, so I'll understand complex scientific terminology, but am only really into physics/quantum mechanics as a "Popular interest" sort of thing. | [
"Observation in this sense requires interaction - ",
" interaction. ",
"This explains it",
" better than I could."
] | [
"Ok, I think I understand that unobserved an electron can exhibit both a wave and particle function…",
"Not really. This trips up a ",
" of people new to the subject. If it makes you feel any better, it's harder to explain succinctly than it is to understand.",
"The metaphor I like to use is of an elephant. W... | [
"…I do enjoy learning about the theories (read: not the maths!)…",
"There aren't any theories about any of this stuff separate from the maths. We can't observe anything at that scale; we can only build mathematical models and compare them to the results of experiments.",
"That might be what's giving you such a ... |
[
"What causes louder sounds to travel further than softer sounds?"
] | [
false
] | I just wondered what the scientific explanation of it is. | [
"Higher volume sounds directly correlate to the amount of energy they contain. There are two main factors for sound diminishing over distance. The first is the simple quadratic diminishing that happens as the sound has to spread out over an area. The higher the energy at the beginning, the more energy it will have ... | [
"Is this a strict inverse-square law? Also, why does sound travel further over water than over some other relatively unobstructed surface, like a parking lot?",
"EDIT: spelling"
] | [
"Is this a strict inverse-square law? ",
"I'm not sure if you're referring to the decibel/energy relation, or the rate at which sound disperses over distance. ",
"If you mean the first, then ",
"this article",
" explains the relationship. ",
"If you mean the second, then it is an inverse-square relation... |
[
"How does the electron move to different energy levels without disturbing the charge of the atom?"
] | [
false
] | When an electron moves up/down an energy level, it jumps over a gap of empty space. In doing so, what actually happens to the electron? It obviously cannot be instantaneously transferred from one energy level to the other because that would break the universal speed limit, so for a very small fraction of a second, the electron must be removed from the atom, right? However, if this is true, would we not see materials break down very easily, such as aluminium, in photoelectric effect experiments? The electron moves to another energy level as it attempts to remove itself from the atom, and in doing so jumps a gap. Because this electron cannot be transferred instantaneously without breaking the speed of light, it must, for a fraction of a second, seize to exist, and so the charge of the atom would oscillate as electrons bump up energy levels. Am I completely wrong? Or is this something that should actually happen with our current atomic model? | [
"When an electron moves up/down an energy level, it jumps over a gap of empty space.",
"Electrons don't have well-defined locations in space. There are not \"gaps\" between the different bound state wavefunctions, they can overlap each other in space.",
"In doing so, what actually happens to the electron? It ob... | [
"Well-explained. Thanks! ",
"So the charge still exists whilst the electron changes energy level?"
] | [
"That's correct."
] |
[
"Is the magazine, \"Popular Science\" credible?"
] | [
false
] | I've gotten Popular Science for a few years now but it's always felt they were more of a... kind of unproper scientific magazine, just jumping at stories to grab attention. Maybe I'm wrong but that's just how it feels. Also, could you suggest any good scientific magazines? | [
"Of all the popular science mags Scientific American probably does the best job because alot of its articles are written by actual scientists, about their own work."
] | [
"Lets just say I don't think many scientist cite articles in Popular Science. ",
"SA is good. But I also really have to hand Arstechnica (owned by reddit's parent company) alot of credit. They do a great job in covering (atleat in physics) science articles, and always point you towards sources if you are further ... | [
"That's not practical, most of them are not meant for laymen."
] |
[
"[Hypothetical] Steven Wright said. If you were in a vehicle traveling at the speed of light and you turned your headlights on, would they do anything?"
] | [
false
] | null | [
"Please see the FAQ"
] | [
"Can you link me?"
] | [
"You can find a bunch of posts by searching for \"speed of light flashlight\" or \"speed of light headlight\""
] |
[
"Are certain behavioral tics passed on genetically?"
] | [
false
] | I was talking to my sister some time ago when she pointed at the callous on my left index knuckle and said, "Um... why do you have that?" So I explained to her that I have a weird habit of lightly chewing on my knuckle while I use my computer/read a book/whatever. She then showed me her left hand and lo and behold, she had a callous in the same place, caused by the same habit! We aren't incredibly close siblings by any means -- I see her maybe once every few months (we live in different states). Is it possible that this habit is a genetic thing? PS. I should mention that I have two other sisters who do not do this. They are the youngest and oldest kids, with me and my knuckle-chewing sister being the middle kids. Also I'm the only boy, if that changes anything. | [
"Do either of your parents display this behaviour? Most likely it's a learned behavior from when you were kids, and not genetic. I personally picked up habits from my father this way including the way I sit and a distinctive way of tapping my fingers on a hard surface when being patient."
] | [
"Just asked both of them and they said they do not. I looked at their hands as well. "
] | [
"I dont know about 'tics' but certain behaviour traits have been bred into mammals (dogs).",
"There is a BBC horizon documentary on the the history of dogs and the relationship with humans. They travelled to a research centre in russia where they picked 2 of the most docile wild wolves and bred them and carried o... |
[
"What present human behaviors are considered instinctual?"
] | [
false
] | Just curious about what behaviors we do that can be attributed to instincts. For example, the idea that men might prefer younger women because they are seemingly more fertile. | [
"Fear of snakes and spiders is probably inborn as well, as other primates seem to share it, even ones that have never seen a snake or spider.",
"Snakes yes. The instinctual fear of spiders and other insects is uniquely human. "
] | [
"Fear of snakes and spiders is probably inborn as well, as other primates seem to share it, even ones that have never seen a snake or spider.",
"Snakes yes. The instinctual fear of spiders and other insects is uniquely human. "
] | [
"\"Now all this together, combined with our conscious mind makes a complicated mess\"",
"The ",
"neuroscience of free will",
" suggests that even our conscious minds may be much less 'conscious' than previously thought"
] |
[
"Why does your brain need glucose to survive but when you eat a bunch of sugar, your body doesn't seem to like that and long term it causes all sorts of diseases?"
] | [
false
] | null | [
"Why you need glucose: Your brain (and all of your cells) rely on glucose to create ATP for energy. Because of the degree of specialization of neurons your brain is especially bad at creating energy (ATP) from things other than glucose, while your liver is great at it. It's true that you don't have to eat glucose... | [
"First thing first: the brain uses glucose ",
", not ",
". Your blood-brain barrier contains specific pathways to transport glucose into the brain for use as energy, but your brain can also utilize ketone bodies in the event that there is not enough glucose. [This is the reason why people on Atkins diets don'... | [
"You're confusing dietary ketosis with ketoacidosis.",
"Ketoacidosis is a dangerous metabolic state where the body produces a very large amount of ketones. Most commonly happens in diabetics.",
"Ketosis is a metabolic state where your body use ketone bodies for energy. ",
"Dietary ketosis is controlled and be... |
[
"If DNA reflects aging due to telomere length, why doesn't the DNA in sperm and egg reflect the parents' ages?"
] | [
false
] | [deleted] | [
"The enzyme \"telomerase\" exists for exactly this purpose. Telomerase is active in developing embryos, and extends telomeres back to their original state (",
"Developmental regulation of telomerase activity in human fetal tissues during gestation",
"). Telomerase shuts off in newborns (actually a little earl... | [
"Crossing over doesn't really effect telomeres. The answer to the OPs question is that telomerase becomes active in gametes, which can help to expand the length of the telomeres that were lost in the parental divisions. The other poster in this thread gave a good summary of this."
] | [
"Because they're a new reconstruction of their already existing DNA. And only 23 chromosomes at that. These are for reproduction obviously and are made to interlock with another humans 23 to make a child. Their telomeres are still shortening. But their newly generated half DNA isn't because it's a new combination e... |
[
"Why would it be bad for us to kill all the mosquitoes?"
] | [
false
] | Seriously, why can't we just have the mosquito holocaust and get on with our (much happier) lives? | [
"Other species depend on mosquitoes. Spiders, frogs, etc.",
"Good read ",
"here",
"."
] | [
"Excellent read, thanks for that. "
] | [
"Speaking for arctic ecosystems: the food chain is very short there and it would collapse without blackflies and mosquitos."
] |
[
"Does every star have an Oort cloud and Kuiper belt, or are they idiosyncratic to our sun?"
] | [
false
] | null | [
"The terms \"Kuiper belt\" and \"Oort cloud\" refer to the specific regions that surround our sun, so in that sense they are unique to us, but similar features probably exist around other stars. I don't know that they've been observed, but since they're populated by such small objects there's no reason to think tha... | [
"There is no reason to assume that our sun is unique in any way. It is probably a very common type of star/star system.",
"and by the way, we have never observed the Oort cloud, so it is not even proven that it exists at all. I mean we are very certain that it exists, we just haven't seen it yet. "
] | [
"Ah, I see. I wasn't sure if they were common to all stars, or if certain events in our sun's past had caused the to form just around us."
] |
[
"How large would a black hole with, say, the mass of our star be?"
] | [
false
] | [deleted] | [
"The Schwarzschild radius for a black hole with the mass of the Sun would be about ",
"3 km",
"."
] | [
"How those supermassive black holes at the centers of galaxies arise is an open question. Wikipedia has a decent summary of the topic; see ",
"here",
"."
] | [
"How those supermassive black holes at the centers of galaxies arise is an open question. Wikipedia has a decent summary of the topic; see ",
"here",
"."
] |
[
"How much does efficiency drop when the heat exchange fins on the condenser get pushed in (fouled)?"
] | [
false
] | Is the drop linear in nature? Is there already an existing model that describes the efficiencies lost? | [
"I'd say it's \"non-algebraic\", i.e. that there is no closed formula that can exactly describe the phenomenon. There are just too many variables involved in how air flows around a complex shape.",
"As long as air flow is more or less laminar, i.e. slow, I'd guess that there is practically no effect of a minor ki... | [
"The efficiency drop in your picture will be minimal, and no, it is most certainly not linear.",
"The heat exchange here works mostly by convection, see ",
"here",
". The bent fins will impact the airflow, which itself is highly nonlinear."
] | [
"So is it logarithmic? Exponential? Does anyone know?",
"I see a lot of these around that are fouled, as most people probably have - some minimally, and some pretty bad."
] |
[
"Why does everything in the universe tend to orbit in planes?"
] | [
false
] | Galaxies, black hole accretion disks, protoplanetary disks, planetary rings all have a disk formation. Is this because these systems are spinning? It seems strange to me that all the material "queues" up in a neat disk and doesn't skip the queue by "falling" off the sides of the disk towards the star/hole/planet. | [
"It doesn't queue in a flat shape. It averages out. ",
"Imagine you had a spherical system with a random distribution, eventually the average momentum would prevail, because each object acts on every other object through gravity. Many of the objects wouldn't be able to make the transition from their original vel... | [
"One thing I never understood is why the collapsing nebula's net angular momentum is non-zero. If the motions of the molecular could is random, should that yield zero or close to zero. "
] | [
"Close to zero, though, is not zero. Keep in mind that 99(.8?)% of the matter in our solar system is in our sun. That's .2% (actually less, I think it's .15% or so) that had enough angular momentum, after it was all said and done and averaged out, to stay afloat (so to speak) and out of the sun. "
] |
[
"When two billiard balls make contact, what is the surface area of the billiard ball that is actually touching the other billiard ball?"
] | [
false
] | I'm more curious about this scenario when the billiard balls are simply touching in a stationary position, as opposed to having one billiard ball collide with another billiard ball. How do you measure that single point that "connects" the two billiard balls? | [
"That depends on how fast they're moving when they make contact. There's no single point here; besides the fact that billiard balls aren't perfect mathematical spheres, they deform on contact. Even if they seem rigid, no material is perfectly rigid. Or if you like, everything behaves like rubber balls to an extent,... | [
"If both billiard balls start as perfect spheres, then this problem was solved by Hertz in the 19th century. ",
"Wikipedia",
" has the results, but not the derivations. The upshot is that the contact area is a circle of radius a, where a",
" = 3FR/(4E*). where F is the force holding the two balls together, R ... | [
"order-of-magnitude estimate of the area, ~10-7 m2 or so",
"For reference: That's roughly the ",
"cross sectional area of mechanical pencil lead",
"; between a pinhead (larger) and a human hair (smaller)."
] |
[
"Do planetary gravitational calculations assume an infinitely small point in space, or take into account the size and distribution of the mass of the planet?"
] | [
false
] | So I have little to no science background, beyond what I have picked up from wikipedia articles related to Episodes of stargate and too many hours reading and thinking about why I crash my ships in Kerbal Space Program. With that being said, how are the gravitational effects of a body, such as a planet or sun, calculated in relation to its size? I'm thinking that for a relatively small dense body, calculating its effect on another body at a relatively great distance would be a matter of calculating the effects of an infinitely small point with equal mass to the actal planet, with the same center of gravity. As if all of the mass of the planet were focused in a single mathematical coordinate in space, rather than distributed over several thousand miles of diameter. This seems like a simple equation, that the force between the 2 bodies would be calculated by their mass and distance, regardless of their respective size. How does this change for objects that are very close together? for example, calculating the pull of gravity of a person standing on its surface? From that distance, the distributiong of mass seems more significant, as it is not all focused in some far off single point, but distributed essentially on a plane that stretches out in every direction from the point where the person is standing, not just directly downward towards the center of the planet. Does that just get insanely complicated and a best estimate is used? Where this could get even more interesting would be calculating the influence of 2 very large, very dense bodies with no atmosphere passing extremely close to each other in space. Like 2 massive planets moving so quickly that they pass each other within a handful of miles without colliding. If the shape of each planet was irregular, it seems the gravitational interaction of various parts of the planet and the distribution of their mass would be crucial to understanding how their respective courses would change after passing. I imagine it would go far beyond the video game approximation of a planete, which would essentially be a massless solid sphere with an infinitely small center of gravity containing all of its mass, so the force of gravity just pulls directly to the core, no matter the distance to the surface. Another thought: how would this change the effect of gravity beneath the surface of the planet? If one were to theoretically dig a hole to the center of the earth, there would be no gravity felt except that of the sun and moon, correct? The planet's gravity would be pulling you equally in all directions from that point, essentially negating itself. Am I thinking of this right? edit: TLDR: In gravitational calculations, are planets big or small? | [
"In most simulations (using smooth particle hydrodynamics, I recommend the paper by Allison Sills et. al. 1998, or monahan 1992) masses are treated as point masses since reading the object as a distribution would be very computationally expensive. Also for a object which has enough gravity to form into a sphere the... | [
"For a perfect sphere with evenly distributed mass, the gravitational field ",
" the surface of the sphere is identical to what would be produced by a point mass at the center - whether you're 1 inch outside the sphere or a million light years. If the mass is distributed asymmetrically or if the object isn't a pe... | [
"There's an interesting result from Newton's law of gravity that the gravitational field at radius ",
" due to a spherically symmetric body is exactly the same as that of a point mass at the center whose mass is the mass of the portion of the body with inside the radius ",
". ",
"Shell theorem.",
" The ma... |
[
"How are electron spins read?"
] | [
false
] | I can't find an easy explanation that's part concept and part practice, and the wikipedia is more than I can absorb in 5 minutes. I'm looking for something like "an electron shoots down a tube, passes through a ________ which makes it do ________ and then it goes _________. Can it be "read" twice? How far can it travel before it is read? How about can it be kept running in a circle say, I wanted to read it, go home for the weekend, and read the same electron again later? I'm particularly interested in these secondary questions. best. Thanks for your time! | [
"http://en.wikipedia.org/wiki/Stern-Gerlach_experiment",
"Basically what you do is fire an electron through a magnetic field. Since the electron can be spin up or spin down, it is deflected either up or down, to produce two distinct patches on the detector. (",
"http://en.wikipedia.org/wiki/File:Stern-Gerlach_e... | [
"Charged things moving through a magnetic field are deflected via the right hand rule, i.e. perpendicular to the field lines, not towards the positive pole of the magnet. \nThe reason neutral atoms are used is so they can probe the magnetic effects, and not the electric effects of moving an ion through a magnetic f... | [
"it is not an electron that is shot through the magnetic field(its an atom with an unpaired electron), if this were to happen you would only get a single deflection point which would be towards the positive pole of the magnet. "
] |
[
"How is the Carbon-13 isotope formed?"
] | [
false
] | null | [
"There are many ways to form carbon-13. What is the context you’re interested in?"
] | [
"When it was first created, for example Carbon-14 was formed by cosmic rays, how did Carbon-13 come to be?"
] | [
"The same cosmic ray reactions that produce carbon-14 can produce carbon-13 as well. Spallation on a heavy ion can produce anything lighter than the parent nucleus."
] |
[
"I know water pressure is only dependent on depth not width, but is there a lower boundary where this breaks down?"
] | [
false
] | If the water is only a molecule thick, would the water pressure still be the same? | [
"Is this assuming a free standing column of water? Otherwise I would imagine capillary action would take over and dominate at some width (like a 1mm wide tube)."
] | [
"All those molecules are piled on top each others, like a bunch of mattresses, it's obviously very heavy at the bottom of that pile. What matters is not how wide those mattresses are, it's how many are piled on top of each other. Now the same applies for molecules!"
] | [
"The fundamental equations of fluid dynamics is often formulated in terms of a single particle. In a closed system where you have a stack of water molecules the pressure would still be only dependent on the depth (or length)."
] |
[
"At different temperatures, things are differently attracted or repelled magnetically?"
] | [
false
] | null | [
"Helium-3",
" changes magnetic properties at extremely low temperatures; not exactly what you're looking for possibly, but very interesting!",
"You may be talking about the ",
"Curie temperature",
" - the temperature at which materials can lose their permanent magnetism.",
"There are several different typ... | [
"God bless you. Thank you very much."
] | [
"Yes, definitely. For example the ferromagnetic properties vanish above a certain temperature, called Curie point. In general magnetic properties depends on how quantum states are populated. The population of quantum states is temperature dependent "
] |
[
"Why does Water evaporate at all when not boiling?"
] | [
false
] | null | [
"Consider what liquid water is. It's a collection of molecules bound together with hydrogen bonding. ",
"If a glass of water has air around it (which is normal), it has a gas above it which consists of a large number of gas molecules pounding it and hitting it at great velocity. Some of the gas molecules get defl... | [
"Short answer, no.",
"There's something known as the ",
"vapour pressure",
" of a liquid, which is the pressure at which the gas phase is in equilibrium with the liquid phase (as many particles are evaporating as are condensing at any one time.",
"At room temperature (25 °C), the vapor pressure of water is ... | [
"Thank you very much for the explanation :)"
] |
[
"In a combustion reaction, is it possible to stop the fire if you \"Add fuel to the fire\"?"
] | [
false
] | Combustion reactions usually produce CO2 and H2O as the products. So is it possible to have too much for a flame to handle and quench a flame? There it possible of having too much CO2 and H2O for a flame to continue combusting? | [
"The waste gasses won't really be the limiting factor. As a flame grows, the heat will cause enough convection currents to move the waste gasses away fast enough and replace them with oxygenated air. ",
"As an example of this taken to a large degree look up the Dresden firestorm. ",
"If there is a physical barr... | [
"Combustion reactions usually produce CO2 and H2O as the products. So is it possible to have too much for a flame to handle and quench a flame? There it possible of having too much CO2 and H2O for a flame to continue combusting?",
"This is a different question than your title asks. Too much waste products can ind... | [
"So there is no way of removing a non-premixed flame other than depleting the fuel(methane) source?"
] |
[
"Recent advances in Navier-Stokes equations?"
] | [
false
] | Hi all, I'm just wondering if anyone knew of any current research that's looking into exact solutions to the full Navier-Stokes equations? Also, has any progress been made on solving the full NS equations at all? I know about reducing them to something solvable by considering the Reynolds number, but apart from numerically, it's my understanding that we haven't solved them yet. | [
"For reference, the Millennium problem about the well-posedness of the Navier-Stokes equations can be found at:",
"http://www.claymath.org/millennium-problems/navier%E2%80%93stokes-equation",
"One of the more recent results is due to Terence Tao from 2014/2016",
"http://www.ams.org/journals/jams/2016-29-03/S... | [
"I feel like exact solutions for systems of equations are getting fewer and farther between. This is because it is becoming easier and easier to solve these equations numerically. A lot of people just ask \"why bother?\" \nI have a model of the atmosphere that solves the N-S equations, and it is really complicated.... | [
"Here",
"'s a good article on Navier-Stokes."
] |
[
"Would anyone be willing to help me learn some biophysics? I would like to know how much energy is expended from the firing of a neuron."
] | [
false
] | I have some training in physics from a military school. I'm kinda rusty but with some practice I can do stuff like find how much energy it takes to melt an ice cube, or something like that. I'm wanting to know how many joules of energy is required to get a neuron back to its ready state of firing. The resting po Some (hopefully) useful links I think the rough outline of what's going on is to get a potential energy difference of 65-70mV, we're going to need X amount of Joules to pump out X amount of ions to get that differential. I'm also curious to know how long it takes to convert sugar (I know there's different types so it may vary) into ATP. | [
"What you're looking for is the total wattage of the Na+/K+ pumps on a neuron. An action potential is primarily a passive activity since it uses Na+ and K+ concentration gradients. The Na+/K+ maintains this gradients by using 1 ATP to move 3 Na+ out of the cell and 2 K+ inside. The pump has to work even when the... | [
"The point I was trying to make is that an action potential is, in terms of energy, practically free. What a neuron spends most of it's energy is to maintain an imbalance of Na+ and K+ ions. During the spiking phase of an action potential, aka depolarization; Na+ channels open and Na+ rush into the cell. During ... | [
"According to ",
"this article",
", section 3.2, the PMCA pump has a rate of 30Hz (which I'm pretty sure means 30 ions per second). Although the article it references says the turnover rate is 150Hz? I'm not sure which figure is better, although there are always outside factors that can affect capacity. The... |
[
"Is there a universally accepted way to accurately measure or gauge an organism's level of consciousness?"
] | [
false
] | There are levels of consciousness from various organisms that varies from species to species, and even in a group of a particular species. For example, most animals are at the physiological level of Maslow's hierarchy of needs. Their main focus in life is to find the next meal, how to stay safe, and reproduce. Some aren't even self-aware and fail at recognizing itself in the mirror. My question is, have we accurately categorized species yet based on how conscious and aware they are of the reality around them? If so, how did we come up with a way of categorizing consciousness? E.g. Humans would be #1, followed most likely by primates, elephants, dolphins, whales, and some bird species like pigeons (not necessarily in that order.) Extending this question a step further, have we done this with just humans? Is our consciousness just based on our ability think and process information? Or is there some underlying mechanism like genetics that limits your IQ and ultimately how much information you are able to understand? Closest thing I can find related to different levels of human consciousness is this: | [
"Neuroscientist here, although nothing is accepted, one of the leading theories is that the unique information content in the brain can serve as a measurement, you can read about that ",
"here.",
"There are a number of other theories of similar flavour, such as the information complexity, or the fraction of con... | [
"I think the above is about as solid of an answer as can be given from the cog neuro field. ",
"Since I'm a neural correlate kind of neuroscientist, I think ",
"Palmiter's work with dopamine deficient mice",
" is interesting. Without dopamine, the mice lose several behavioral characteristics that arguably m... | [
"Short answer, no. ",
"We can ask whether animals have specific senses/sensations. For example, if an animal has ",
"nociceptors",
", perhaps this can be interpreted as the animal being capable of experiencing pain. ",
"We can ask what kinds of representations do animals have in general, like do they have a... |
[
"Is String Theory still a relevant Scientific theory?"
] | [
false
] | [deleted] | [
"It has yet to attain relevance.",
"However, a lot of very smart people think it will one day be relevant and that's why they're working on it.",
"If you want to read a polemic against string theory, check out ''The Trouble with Physics'' by Lee Smolin."
] | [
"String theory has evolved past the Theory of Everything that is still prevalent in pop science. People often discuss Brian Greene's An Elegant Universe, which is an archaic way of thinking about string theory. I would avoid it. Unfortunately, there are few resources for the public that talk about the new uses of s... | [
"it's just so elegant and wonderful a solution that it almost has to be right",
"I think this is one of the biggest cognitive flaws physicists and other researchers make - that the ultimately correct solution to a problem should be beautiful and elegant.",
"But we need to critically think about ",
" we would ... |
[
"Are rates of communicable diseases any different in countries where it is common to wear a face mask in public?"
] | [
false
] | There are some countries where it is extremely common for people to in public. And others where it is not common at all. Do those face masks really help anything? Do people get colds or flu less? | [
"To add to this, the disposable cloth masks are only rated for a couple hours max. So people that wear the same one for more than that are essentially getting the same protection as if you wore a linen cloth on your face. Which would only vaguely protect you from particles the size of dust.",
"A ",
"PM_2.5",
... | [
"Those face masks are NOT the type that would prevent ANY sort of bacteria/virus from getting in or out. They're mostly dust masks, for particles MUCH larger than germs. ",
"So, no, they don't help.",
"Not to mention that almost no one wears them correctly."
] | [
"That's incorrect. Surgical masks ",
" been shown to prevent the spreading of disease, ",
" you're sick. It is true that it doesn't stop you from ",
" sick, but that isn't the point. The reason people wear the masks is to wear them while sick, to prevent the spread of disease to those around them. ",
"That'... |
[
"Does Space-time have an elastic modulus?"
] | [
false
] | For background (and to ensure everyone that I'm not entirely full of it) I'm an Engineering student specializing in Structural Engineering. I was thinking about the implications of gravitational waves and the fact that they exist makes me think that space-time and matter are two entirely different things that interact with each other--that matter and energy merely influence deformations in space-time and past that have no true interaction with it. This is somewhat analogous, in my opinion, to structural mechanics. It seems to me as though the bending of space-time due to mass/energy is similar to a bar of concrete or steel yielding in response to physical or thermal stresses. So my question is--should my intuition satisfy reality to a certain extent--what exactly is the relationship between the bending of space and time and mass-energy? I know that Energy is related to mass via c2, and that there are likely some considerable complications from the puzzling nature of time, but does a general relationship between the two (or four I guess) exist? If so, what is it? | [
"The relationship between the bending of space-time and mass-energy, as you say, is that the Ricci tensor minus its trace times the metric (where the metric is a 4x4 matrix that describes the pythagorean theorem through spacetime and the Ricci tensor is a differential function of the metric) is equal to a constant ... | [
"It will take me a bit to figure out what you are saying (thank god I took that linear algebra class), but thank you so much for the answer!! Would this shear that is experienced from the change in the distribution of mass be the cause of tides?"
] | [
"No, tidal effects are caused by gradients in the gravitational field."
] |
[
"how did the water disappear on Mars?"
] | [
false
] | So, I know it didn't disappear per say, it likely in some aquifer.. but.. I would assume: 1) since we know water was formed by stars and came to earth through meteors or dust, I would assume the distribution of water across planets is roughly proportional to the planet's size. Since mars is smaller than earth, I would assume it would have less than earth, but in portion all the same. 2) water doesn't leave a planet. So it's not like it evaporates into space 🤪 3) and I guess I assume that Mars and earth formed at roughly the same time. I guess I would assume that Mars and earth have similar starting chemical compositions. Similar rock to some degree? Right? So how is it the water disappears from the surface of one planet and not the other? Is it really all about the proximity to the sun and the size of the planet? What do I have wrong here? Edit: second kind of question. My mental model (that is probably wrong) basically assumes venus should have captured about the same amount of H2O as earth being similar sizes. Could we assume the water is all there but has been obsorbed into Venus's crazy atmosphere. Like besides being full of whatever it's also humid? Or steam due to the temp? | [
"water doesn't leave a planet. So it's not like it evaporates into space",
"This is the part you're missing: it actually ",
" escape into space! ",
"There are actually ",
" of processes that cause atoms and molecules to escape a planet's atmosphere into space (",
"atmospheric escape",
"). There are ther... | [
"Earth's gravity (and temperature) don't allow it to hold onto hydrogen significantly longer than Mars. Molecular oxygen, on the other hand, is too heavy to be lost to this same Jeans escape process from either planet. Atomic oxygen and water vapor can be lost from Mars this way. Though, other modes of escape do al... | [
"Nailed it.",
"UV light splits water into hydrogen and oxygen. The hydrogen is light enough that it escapes into space. The heavier oxygen bonds with minerals on the planet's surface, such as the iron compounds, turning them to rust, which explains Mars's red colour.",
"There's actually pretty significant ice... |
[
"Why, when I drop water from the lid of my pot on-top of my hotplate, it beads up into a sphere, rolls around the hot surface, and eventually (~30 seconds) it evaporates?"
] | [
false
] | Why does it not immediately evaporate? Could it possibly be water impurities? | [
"It takes energy to change the water from a liquid into a gas. The evaporation is limited by how fast heat energy can be transferred from the hot plate to the water droplet. ",
"The drop balls up and rolls around because the water touching the plate is constantly turning to gas, expanding, and escaping out from... | [
"It takes time for the energy from the hot plate to the water to transport. Water doesn't just suddenly rise to its melting point, well not all of the water does at the same time. So the molecules move around until all parts of it has reached the melting point and it evaporates."
] | [
"Ok, thank you, that makes sense. I suppose my hot plate was not as \"hot\" as I expected."
] |
[
"Where did all the peanut allergies come from?"
] | [
false
] | [deleted] | [
"This Straight Dope article",
" may give you some insights into this. Anecdotally, there probably isn't an increase in actual incidence---with increasing awareness, so too increases the number of parents who claim their little Snowflake has an allergy because he/she didn't want a peanut butter sandwich. A pediatr... | [
"Wait, what? People actually do this? As someone who will most definitely die if a peanut touches my lips, that's pretty insulting. "
] | [
"Sadly, people actually do do this. The specific allergy I was discussing with my friend at that time was wheat gluten* allergy.",
"One family in particular had a child who was suffering from diarrhea. As we all know, the causes of childhood diarrhea are innumerable, as children are the main reservoir for most in... |
[
"What's the beef with Group Selection?"
] | [
false
] | I was reading last night about E.O. Wilson and his push for group selection. On it's face, his idea seems to be much more reasonable than kin selection. I read which was a little helpful, but the example seemed a little contrived, so was unconvincing. It seems like it over-values the impact of a lone selfish actor. I can understand the "realm of consequences" (for lack of a better term), where the benefits of altruism are limited geographically and limits the spread of the behavior to something less than "a population." But it seems more reasonable than kin selection, unless there is some mechanism I'm unaware of that organisms innately have for telling whether or not they're related to another organism. | [
"Well 8 upvotes, no downvotes. I know this is an issue for which many people feel passionate about (was anyone else surprised that no one mentioned kin selection in the \"what is the most controversial question in your field today?\" thread a few days ago?), and there is just too much information to cover. So I p... | [
"The old explanation for why people acted so altruistically was what is called a \"missfire\". As the story went, way long ago we lived in such small groups that everyone was so related, we did not even need mechanisms to distinguish kin from non-kin, because we were all such close kin!",
"This has now shown to b... | [
"I work in this field, so I feel a lot of the push back you seem to be tapping in to. Hopefully I can therefore answer your question as to where the beef is coming from.",
"There are a couple pushbacks, one I find more reasonable than the other.",
"The first is a reverse appeal to the naturalistic fallacy. Some... |
[
"Is there a distance at which the human eye could see the Andromeda galaxy the way it looks on long exposure pictures? (with its full arms, colours etc.)"
] | [
false
] | I know that on Earth it's impossible, but I haven't seen evidence that outside of our atmosphere humans can clearly see Andromeda in all its splendor still. Which makes me wonder, is it even possible for our eyes to see it the way our telescopes and cameras can reveal it (maybe it's just too large and too much of the light is lost by the time it reaches us), and if yes is there a theoretical distance at which the human eye could capture its majesty? | [
"We are able to see one of Milky Way's spiral arms (the one we're in, of course!), which are much dimmer than the galaxy's core. \nIs it not safe to assume the same would be true if we were inside the Andromeda Galaxy, instead?"
] | [
"It's not obvious by eye what you're looking at in the night sky is a specific spiral arm. Rather, you see a sum of the light from the disk, not of an individual spiral arm. If we were orbiting a star not in a spiral arm, or if there were many spiral arms between us and the center, the Milky Way would look very sim... | [
"I believe every object can be accurately resolved with any optical instrument (including our eyes) if you are at the right distance.",
"In astronomy, the minimum angular distance you can resolve with any optical instrument is given by the equation",
"x = 1.22 * lambda/D",
"where x is the minimum angular size... |
[
"Is it possible to build up an immunity to allergens?"
] | [
false
] | Not food allergies but things like pollen and dander. If you are around something you are allergic to for long enough will you stop being allergic to it? Thanks for the amazing responses from everybody. Since it seems that building and allergen tolerance can vary widly from person to person I'm going to look into getting a HEPA filter,great idea gfpumpkins, and also look into seeing if an allergist is covered by my insurance and getting back on a shot regiment. | [
"Yes, but it depends.",
"Some people will react worse and worse every time they are exposed to an allergen, that is called Sensitization. ",
"Some people react better and better every time they are exposed to an allergen, that is called Desensitization.",
"Sensitization or Desensitization can occur with any a... | [
"I believe I had some delicious beer available to wash it down."
] | [
"This idea can be used for allergy treatment",
"Desensitization or hyposensitization is a treatment in which the patient is gradually vaccinated with progressively larger doses of the allergen in question. This can either reduce the severity or eliminate hypersensitivity altogether. It relies on the progressive s... |
[
"I have heard it claimed that the current vaccination schedule for infants in the US hasn't been well tested for safety (heavy metals) & that each vaccine is generally tested in isolation. What is the best evidence for and against that claim?"
] | [
false
] | null | [
"Hi 60percentg 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 foll... | [
"Medicine"
] | [
"Medicine"
] |
[
"How did they create a strain of X. campestris that grew on lactose instead of glucose?"
] | [
false
] | I was reading about Xanthan Gum, and the Wikipedia article reads, "Whey is composed mostly of water and lactose, so researchers developed a strain of X. campestris that would grow on lactose rather than glucose." How did they accomplish this? Did they just slowly replace the medium's glucose with lactose, with the bacteria evolving on their own? | [
"Under normal conditions, XC preferentially uses glucose as an energy source when they are both available. When lactose is used it is cleaved to produce glucose and galactose, thus an additional step in the growth pathway. Normally, XC has a low level of beta-galactosidase, the enzyme that hydrolyzes lactose into g... | [
"But how did they do it? How does one \"develop\" a different strain of XC?"
] | [
"First source: \"In this study, a beta-galactosidase expression plasmid was constructed by ligating an X. campestris phage phi LO promoter with pKM005, a ColE1 replicon containing Escherichia coli lacZY genes and the lpp ribosome-binding site. It was then inserted into an IncP1 broad-host-range plasmid, pLT, and su... |
[
"When large areas are logged I assume a lot of nutrients are being taken away with the wood... How are these nutrients replenished? If an area is logged for thousands of years, over time will it lack enough nutrients to grow healthy forests?"
] | [
false
] | null | [
"What about minerals like magnesium?"
] | [
"C, O and H are in water and the air. S, N and P are sometimes limiting, but are present in soils and/or water or there are other ways they are incorporated (e.g. nitrogen fixing bacteria).",
"For other elements it depends, but many are relatively abundant in rocks and soil (Mg, Ca, Fe, Zn, Mo).",
"Scroll down ... | [
"You must remember that plants can 'add' new energy to the environment via photosynthesis. Most nutrients can be synthesized by decomposers. As long as there is a basic food chain in set, the environment will heal."
] |
[
"I'm building a still. An experienced moonshiner I know recommends using copper (it evidently produces the highest quality liquor). Is there a health risk involved with ingesting alcohol that is exposed to copper at high temperatures?"
] | [
false
] | I want to make good shine, but I also want to make safe shine. Is copper toxic? | [
"Hmm...",
"http://www.google.com/search?q=copper+cookware+safety",
"http://www.google.com/search?q=copper+toxicity"
] | [
"it's illegal, but you only get in trouble if you try to sell it"
] | [
"it's illegal, but you only get in trouble if you try to sell it"
] |
[
"Based on the Voyager probe trajectories, is it possible to calculate where they will end up thousands or millions of years in the future?"
] | [
false
] | null | [
"Their trajectories out a few tens of thousand years are known, since they will remain in the Sun's gravitational sphere of influence for most of that time. ",
"Within a few hundred thousand years, the Sun will be an inconspicuous speck of light in the Voyagers' skies. Their future trajectory will be influence... | [
"Does anyone know what their end of life sequence looks like? Do they just keep trying to transmit or go into a stasis, etc?"
] | [
"I believe they're scheduled to run out of power in 2025.",
"\nThey're only really using fuel for turning around and occasional transmitting now, though, so it won't stop them from continuing on through space"
] |
[
"/r/askscience, are those \"flesh eating\" bacteria on the news really flesh eating?"
] | [
false
] | [deleted] | [
"Necrotizing fasciitis is most certainly real. It leads to a break down in the skin, hence being called \"flesh eating\" ",
" infections can be one cause of this disease, which I find interesting. You can have essentially the same bacteria causing multiple different diseases (strep throat and flesh eating?!?).... | [
"Necrotizing fasciitis can also be caused by ",
"."
] | [
"It can be caused by a few bacteria. In relation to the news, it seems MRSA is being reported as \"flesh eating bacteria.\"",
"http://www.ncbi.nlm.nih.gov/pubmed/18005776"
] |
[
"This morning as I stirred my coffee it happened to be on a kitchen scale. I noticed that the weight of the spoon registered on the scale, even when I was holding it. Why?"
] | [
false
] | To confirm, I dipped and removed it several times while holding the spoon. Each time I dipped the spoon in (without touching the bottom) an extra 2g registered. Is it the weight of the spoon that registers or the weight of the displaced water? Why doesn't the spoon feel lighter when I do this? | [
"The coffee provides a buoyant force to the spoon, pushing it up, making it lighter in your hand. The counter to this force is added weight on the scale. "
] | [
"~ 2 cm",
" of spoon displaces 2 mL of coffee. Buoyant force is the weight of the liquid displaced. Coffee's probably about ~ 1g/mL. Buoyant force should add about 2g to the scale. Numbers check out."
] | [
"Why doesn't the spoon feel lighter when I do this?",
"A high school project estimated the average weight of a conventional teaspoon made of metal to be approximately 25 grams.",
"The material that the teaspoon is made of is dense enough that the lift produced is a small fraction compared to gravity, which is a... |
[
"Why does water expand when it freezes?"
] | [
false
] | null | [
"Silicon, silicon dioxide, germanium, and other solids that have a tetrahedral structure also expand upon freezing for related reasons."
] | [
"Silicon, silicon dioxide, germanium, and other solids that have a tetrahedral structure also expand upon freezing for related reasons."
] | [
"Yes, the most common example you'll know is salting roads in winter. ",
"The sodium chloride salt 'blocks' the formation of the perfect crystal structure easily, and makes the freezing point lower than pure water (therefore it stays liquid at lower temperatures). Eventually the temperature will be low enough tha... |
[
"How do physicists use lasers to \"cool a cloud of atoms?\" I would think shining a laser on something would heat it up."
] | [
false
] | I read that phrase in this article and I don't understand how this is possible: | [
"Atoms absorb light at specific frequencies, and if you shine a laser at a frequency slightly higher than one of those, atoms that are moving faster towards the source will absorb due to the Doppler effect causing the frequencies to match. This selectively changes the momentum of only the faster atoms, lowering the... | [
"Though laser cooling does seem a little counter-intuitive at first it works, and can be understood fairly easily. For a vapor of atoms, the overall temperature is related to the average velocity of the atoms by the Maxwell-Boltzmann distribution ",
"[1]",
", so to cool them, they just need to be slowed down. L... | [
"and if you shine a laser at a frequency slightly higher than one of those",
"I think you mean a laser of lower frequency. A higher frequency laser will be absorbed by atoms moving away from the source."
] |
[
"Do mosquitos hide in predictable locations?"
] | [
false
] | I've noticed that if there's a mosquito in the room, and I swat at it but fail to kill it, it usually seems to disappear for about 30 minutes before it tries to come after me again. I'm curious how programmed or predictable mosquito behaviors are. For example, does it actually have a behavior like "if swatted at, lay low for 30 minutes before trying again?" Or am I just imagining the correlation? Second, if they do have a "hide" behavior, do they choose predictable locations? Do they prefer corners of the room? Areas with less light (do they even use light in making their decisions)? Do they go low to the ground? High on the ceiling? Do they use air currents and calmness to choose a spot? It seems like I usually find mosquitos hiding out in a shadowy corner near the floor of the room, which is infuriating because if it would just hang out in the open against the white, well-lit wall, it would be a lot easier to hunt them down. This correlation could definitely just be my own confirmation bias at play, though, so I'm curious if much is known on this topic. EDIT: Thank you for the lovely replies so far! I just wanted to clarify that I'm not actually that interested in *where* mosquitos hide in a descriptive sense, I'm more interested in how and "why" they make their decisions... like which senses do they use most (vision, smell, touch), and do they actually have different phases like hunting vs. hiding, or are they just sort of always doing the same thing and flying around aimlessly until they detect prey, then go for an attack? EDIT 2: Well this post blew up! You may notice that it's a bit of a comment graveyard... sorry but askscience has strict commenting policies and the mods had to remove most of the replies. The vast majority of replies were either 1) personal tips for hunting mosquitoes, or 2) personal anecdotes on where mosquitoes hide. Precisely one comment linked to an actual scientific research article (thank you !) showing that at the very least mosquitoes can learn to associate being swatted at with certain chemical odors, and then avoid the source of those odors (people) in the future. I didn't feel satisfied so I spent a few hours trawling the literature... turns out there's simply no research on this topic! We know a great deal about mosquito hunting behavior and how it finds its target, but seemingly nothing on hiding behavior. It's not even clear whether there exists a "hiding" behavioral program, or if they're just sort of always on the hunt and are just updating their attraction/aversion biases in response to swats, etc. However, after reading up on it I do think it's safe to say that the majority of the hunting/hiding behaviors are instinctual and not learned. It turns out adult mosquitoes are only alive and hunting for ~2-4 days before they stop and spend several days digesting + laying eggs (they typically repeat this hunt/rest cycle ~3-4 times before they die). Furthermore, a mosquito can collect all the blood it needs in one meal if left undisturbed, so in reality it typically only feeds on 1-5 people before stopping. Therefore, even though to us it seems like mosquitoes are constantly present and attacking us, from a single mosquito's perspective it may only ever encounter a few humans (less than 10) in its life cycle, and over the course of only a few days. That isn't a lot of data for the mosquito to "learn" with. So, if the possible answers to my original question are 1) it's random, 2) they have instinct-driven preferences for hiding, with a lot of variation between regions/species, or 3) they learn where to hide from experience, we can probably rule out #3. | [
"There is a wealth of research on mosquito behaviour but mostly in relation to the ones that spread diseases. ",
"This paper: ",
"https://www.researchgate.net/blog/post/mosquitos-learn-to-avoid-people-whove-swatted-at-them",
" shows that they 'learn' to avoided being swatted. From the article 'the insects’ a... | [
"There is some vague themes with some mozzies. ",
" species, for example, need to rest after feeding, and will typically head for the nearest wall to nap and digest for a bit."
] | [
"The real wacky bit is watching the mosquito bite with an \"X-ray\" view. The \"needle\" on it's face is just a sheath, and the actual feeding apparatus is quite flexible. The sheath bends out of the way, the proboscis pierces the flesh and then... wiggles around till it finds a vessel. Up and down, left right, in ... |
[
"How deep is the magnetic North or South Pole?"
] | [
false
] | I assume the magnetic North and South Pole aren't positioned at the exact surface of the planet, just like how the poles in a bar magnet aren't exactly at the very ends of the bar, but a bit more towards the middle. If that's correct, do we know how deep they are underneath the surface? This question came to me as it was mentioned in Jules Verne's Journey to the center of the earth. | [
"From electromagnetism, magnetic fields actually have no source, field lines are entirely closed loops. If you followed a compass north you would reach the north pole, where the compass will fully point down into the ground. Continue to follow, and you’ll eventually reach the south pole. "
] | [
"Well the convection of the Earth's molten outer core, which is driven by heat escaping from the inner core, creates earth's magnetic poles/magnetic field (this is the geodynamo theory...probably one of the cooler named things in Earth Sciences - here's a pretty cool computer simulation that does a great job descri... | [
"Unfortunately not that I'm aware of. ",
"Here's the article without a paywall/login (sorry I tend to forget about journal paywalls due to university internet). ",
"https://websites.pmc.ucsc.edu/~glatz/pub/glatzmaier_roberts_nature_1995.pdf"
] |
[
"What exactly is 'shock', and how does one die of it?"
] | [
false
] | null | [
"\"Shock\" is medically known as Hypoperfusion, which is inadequate perfusion of oxygen to the body systems. ",
"There are a number of different ways that hypoperfusion can occur, such as a sudden, massive loss of blood (known as hypovolemic shock). Edit: removed some incorrect information here. See the clarifyin... | [
"Not at 1 atmosphere of pressure, on air, no, it's not really possible to have an over abundance of oxygen in the tissues. One atmosphere of pure oxygen ",
"can result in hypercapnia (low CO2) in the blood",
", which decreases the breathing reflex, among other problems, but it's not likely to be fatal. Note, th... | [
"A clarification/correction should be made:\nAnaphylaxis is a histaminergic reaction of the body in response to foreign proteins entering that the person has been sensitized to. The swelling of the airway and choking is due to angioedema (localized swelling due to increased extravasation of fluid) and causes asphyx... |
[
"Graphing Help??"
] | [
false
] | Not sure if this is the best place to ask this, but I was wondering what kind of programs people use to present their data. I currently use , but I find it difficult to use and not very good looking... I have an idea for a graph that plots x, y, and z with x and y on the normal axes, but z as the size of the plot point (i.e. larger circle for larger value of z). Does that make sense? Can anyone help me out? Thanks, Reddit! | [
"depends on your range of values for Z",
"you could use prism if it is 8ish"
] | [
"I don't use it personally, but I took an intro course on ",
"ggplot2",
" using R. Ever heard of it? It makes pretty graphs but takes a bit of syntax understanding to 'program' the graphs correctly."
] | [
"Interesting... I'll give it a try... thanks!"
] |
[
"Why are deserts formed and is it possible for a desert to be permanently \"de-desertified\"?"
] | [
false
] | [deleted] | [
"So deserts are primarily created due to geography which blocks rainfall and prevents large areas of lush green vegetation from developing. ",
"De-desertification would be difficult, this is because it would always have to be heavily managed. There is no way for a greening of the desert to be maintained naturally... | [
"Hadley cells are the reason for deserts. It is dry air riding at the equator and falling at 30°s, North and South. This dry air let's the land evaporate more moisture than it receives. ",
"Southern California farming techniques have transformed some desert areas, but needs constant upkeep. Using a dripper system... | [
"Thanks a ton! This makes sense."
] |
[
"If you eat raw fruits with a total of 5g of sugar. Then you eat a piece of candy with 5g of sugar. Will your body know the difference when it is breaking them down?"
] | [
false
] | Is sugar, sugar no matter its source? Or is refined processed sugar (candy, soda, etc) not as healthy as natural sugars found in fruits? | [
"If we assume that the sugar composition (i.e. ratio of fructose, glucose, sucrose) of the fruit in question is identical to the other \"unhealthy\" food (which is a false assumption), the fruit will still be considered healthier due to the fiber content of the fruit. This often slows digestion, and as a result pre... | [
"Searched",
"Relevant ",
"discussion",
"Original question by ",
"Snapdr",
"Does the sugar I consume by eating, say, a banana or an apple, affect my body in a different way than the sugar I would take in from drinking soda or eating candy? Are fruits considered healthier because they are generally lower in... | [
"Sugar is sugar, but the fruit is packed with fiber the candy bar doesn't have. Fiber negates a lot of the negative reactions in your body caused by sugar. Search YouTube for \"sugar the bitter truth\" for more info. "
] |
[
"Question about why we and nearly all creatures display senescence"
] | [
false
] | All my life I've only heard two explanations for senescence. That it is either because of the inevitable accumulative damage of biological processes or the mutation accumulation theory of aging or a combination of both. In other words we die of old age because of metabolic damage that is an intrinsic side effect of being alive. Or we die because our genes don't care how we're doing after we have kids. So genes and genetic errors that kill us when we're 50+ never get fixed. However thinking about this there seems to be another theory that makes a lot of sense which I've never heard discussed: If a species fitness for its environment didn't decrease after it has reproduced the adequate amount then there would be no room in the environment for its children or its grand children. Assuming that the mortality rate for a creature in its prime is lower than that of a child, adolescent or a parent burdened with the care of either then if it didn't age evolution and with it the species ability to adapt to change would slow to a halt. At this point the species if extremely vulnerable to extinction should the environment change quickly. In addition if our non-senescent creature were in competition with a senescent creature the senescent creature would probably take over because it would evolve so much quicker. Therefor could it be that evolution is not simply apathetic to senescence but that it actually encourages it? It wold be nice if an evolutionary biologist could either: give me the name for this theory or tell me why it's wrong or right or unknown. EDIT: Also if the mutation accumulation theory of aging were correct wouldn't evolution favor extending the reproductive stage of life indefinitely? What's the point of menopause if not to prepare for killing the creature so that there is room in the environment for it's children. I mean in many creatures successfully spawning is an incredible and rare achievement. Once you have one of these superstars of your species why wouldn't you do everything in your power to allow it to reproduce for as long as possible? Why kill it? | [
"Some very interesting things along these lines have come out of Richard Lenski's work with the long term evolution project. Basically, it says that genomic flexibility is more advantageous than adaptation to a niche. This would make it less preferable for great-great-great grandma to still be cranking out offsprin... | [
"I'm not sure if I understand the question, then. Yes, what you describe above is a known phenomenon in certain species. ",
"In most species it's not a factor, though, because the pressures you describe never come into play. Predation, infection, injury, etc take out most of the older generation anyway, so the po... | [
"Thank you,",
"A lot of great information there however I still don't feel satisfied. So my issue with the the mutation accumulation theory of aging was it seems that it only takes into account generational kin altruism (which suggest that longer life is preferable) and not generational kin competition (which su... |
[
"What are gluons, taus, neutrinos etc.?"
] | [
false
] | What is the deal with all of these subatomic particles and what meanings they have? I don't understand much beyond protons, electrons, and that quarks form protons and neutrons (just neutral mass). | [
"Gluons are the gauge bosons of the strong interaction. They're the field quanta of the field that holds baryons — particles made of quarks — together, and also to a lesser extent atomic nuclei.",
"The tau is the third-generation charged lepton. You can think of it as an electron, only more so.",
"Neutrinos are... | [
"I've been curating an ",
"r/sciencefaqs post",
" on fundamental particles. There may be some interesting reading in there for you. Perhaps if you start there and have some specific questions about certain particles and their properties?"
] | [
"Don't get fooled into thinking the universe \"needs\" anything. But for example, consider the decay of a neutron. A neutron has either +½ angular momentum or –½ angular momentum; you have to have two decay products to conserve charge (one positive and one negative), but fermions have half-integer spin, so you need... |
[
"Is there any possible sun-planet-moon configuration that would yield a full moon every night?"
] | [
false
] | As in is there a set parameters (i.e. orbital distances, mass ratios, etc.) that would cause the moon to be "stuck" in "full moon position"? | [
"I think the only way this would work is if the moon was trapped at the L2 Lagrange point, so that it orbited with the Earth but slightly farther out. This is an unstable orbit though."
] | [
"Not quite. It would just need to be within 42,164 km which is the distance of a geostationary orbit, i.e. Has a period equal to 1 day. As the moon is smaller than this distance it is possible, but the tides would be something fierce for both bodies. "
] | [
"Not quite. It would just need to be within 42,164 km which is the distance of a geostationary orbit, i.e. Has a period equal to 1 day. As the moon is smaller than this distance it is possible, but the tides would be something fierce for both bodies. "
] |
[
"If a chemical is a dermal sensitizer, does that mean that it will be incompatible as an implant material?"
] | [
false
] | [deleted] | [
"Yes. Implants that are not biological in origin (in which case they are tissue-matched or acellular and don't need any matching) must be what we call biocompatible, which means they are non-allergenic and nontoxic. Silicone and titanium are popular choices. Before a device is allowed to go to market it must underg... | [
"To address your example directly, I believe that in practice \"silver allergy\" is actually an allergy to nickel. Silver jewelry often contains enough nickel to trigger a reaction in sensitive individuals. A medical implant made of silver would be expensive and I do not know of any actual use of silver in implants... | [
"To address your example directly, I believe that in practice \"silver allergy\" is actually an allergy to nickel. Silver jewelry often contains enough nickel to trigger a reaction in sensitive individuals. A medical implant made of silver would be expensive and I do not know of any actual use of silver in implants... |
[
"I was taught that the brain's sulci and gyri exist to increase surface area because the skull limits brain growth. So what would a brain look like if it was grown outside of a skull? Balloon-like?"
] | [
false
] | [deleted] | [
"Even if a brain were just grown outside of a skull, it would still look like a brain that you recognize (or close to it.) It doesn't start folding in because it reaches the skull and bounces back, it starts folding in because that is how it's programmed to develop.",
"Some people are born with ",
"smooth brain... | [
"I'm not really sure how you would do this in an animal, considering everything kind of develops and grows in size in coordination so you couldn't really just remove the skull once it's grown and then expect the brain to keep growing or something. There are a few experiments which may give some insight though. Fo... | [
"There have been a couple of papers this year that show some gyrus formation in mice after forced expression of particular genes: ",
"Fgf2",
", ",
"Trnp1",
"It's all sort of a novelty at the moment, though -- there's still a lot to learn about the process of gyrification."
] |
[
"Scientists of reddit, have you ever made or contributed to a scientific discovery?"
] | [
false
] | [deleted] | [
"Most research contributes to its respective field in a new but small way. With that said, you'll find that a lot of things \"discovered\" on a daily basis are very technical, and would have little to no relevancy to people outside of that discipline. For example, my research involves using numerical fluid simulati... | [
"I discovered how to make normally 8 feet tall pole beans grow ",
"8 inches tall with the same yield",
". Here's what the ",
"internodes",
" look like.",
"I may have discovered that ",
"chlorophyll B",
" can fluoresce ",
". I'm still getting review on this one."
] | [
"This illustration gives a general idea of how discovery works in the field of science",
"Most of it is baby steps, not something that has immediate profound implications."
] |
[
"Are there any wild animals that are showing signs of adapting to cars? IE: Looking both ways before crossing the street"
] | [
false
] | null | [
"Yes, in fact birds such as crows have been known to use cars to their advantage. They are able to learn when traffic stops and goes at lights and will then drop a hard nut into the road to be crushed by cars and wait for traffic to stop to retrieve the insides. So, not only some species adapting, some are using ca... | [
"In Chicago, coyotes have adapted to traffic. ",
"https://www.google.com/amp/www.chicagotribune.com/news/ct-downtown-coyotes-met-0117-20150116-story,amp.html?client=safari",
"\"The footage revealed coyotes astutely waiting on passing cars so they could safely cross streets, using sidewalks and other walkways,... | [
"Hi FUCITADEL 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 follo... |
[
"The Large Hadron Collider can allegedly reach 4 trillion Kelvin, is this theoretical, are there repercussions of producing that heat?"
] | [
false
] | null | [
"It's not just theoretical, it actually happens. The \"repercussions\" are intended: to produce quark-gluon plasmas, hadronic jets, etc. using relativistic heavy ion collisions."
] | [
"If you're thinking of repercussions as something you have to deal with and vent away, note that only a very tiny amount of matter gets to that temperature, and is thus not very harmful. If you magically had an atom that was 10",
" Kelvin in your room, nothing interesting would probably happen.",
"I would imagi... | [
"yes, however",
"exponentially more",
"\"more\", not \"exponentially more\". \"exponentially more\" isn't a thing. the word \"exponential\" designates a certain type of growth. not a \"large difference in magnitude\". "
] |
[
"How does insecticide work? Particularly for ants."
] | [
false
] | I just woke up to a disaster in my kitchen and nuked them all in roughly ten seconds. They stumble around a bit before dying completely. Can anyone explain what exactly is happening to these critters? | [
"The majority of ant insecticides are ",
"Pyrethriods",
". These, in general, cause paralysis through shutting down Na+ channels (these channels are important for passing nerve signals around your body).",
"Interestingly, they tend not to affect humans because we have more enzymes to break it down."
] | [
"No. Borax is sodium tetraborate (as the hydrate). It is classed as a physical insecticide. I don't know the mechanism for sure, but it probably kills ants by dehydrating them or causing a fatal chemical burn."
] | [
"No. Borax is sodium tetraborate (as the hydrate). It is classed as a physical insecticide. I don't know the mechanism for sure, but it probably kills ants by dehydrating them or causing a fatal chemical burn."
] |
[
"Why does touching one tine of a tuning fork stop both tines from vibrating?"
] | [
false
] | I was playing around with a tuning fork that I found today, and discovered that this stopped both sides from vibrating and ended the tone. Why doesn't the other side keep vibrating? | [
"If I remember right, the length from one tine, down and around the curve, and up to the other is proportional to the frequency of the note. When it vibrates, the wave is travelling the whole distance and bouncing back at the end of the tine. ",
"When you touch one tine, you're dampening the vibrations so when th... | [
"This answer is pretty correct. One modification.",
"the length from one tine, down and around the curve, and up to the other is proportional to the frequency of the note.",
"The length of the tuning fork is exactly one wavelength long.",
"You can see what I mean in this video.",
"Note that both ends of th... | [
"I worked for a while with the tiny quartz tuning forks used in watches. We would remove it from the can, and clamp one side down, and use the other side as a ",
"tapping mode AFM",
". It vibrated just fine, but at a different frequency, and a lower quality factor than the untouched fork.",
"Long story shor... |
[
"Will a diesel semi truck explode?"
] | [
false
] | I'm watching the season 6 premiere of Burn Notice (yeah, I'm quite a bit behind), and about 10 minutes in, Michael stuffs a burning rag into what appears the be the gas tank, and the truck goes up in a fireball. Diesel is hard to burn...it's not gasoline after all. Would this actually work? Is it possible to cause a Truck's diesel tank to explode? | [
"Correct, however, what was described in the question generally will never happen. First, diesel has both a high flash point, and a high ignition temperature. When we burn diesel for training, we have to use a great deal of gasoline just to get it started.",
"Furthermore, there is very little oxygen in the fuel t... | [
"http://www.engineeringtoolbox.com/fuels-ignition-temperatures-d_171.html",
"For flash and ignition temps "
] | [
"A tank of any sort of hydrocarbon fuel ",
" explode under the right circumstances. TV explosions are always way over-dramatized, and the likelihood of it happening like that is fairly rare in real life. ",
"For a explosion to happen, it is the fuel vapor and air mixture in the tank that ignites violently. T... |
[
"Why aren't satellites infinite sources of energy?"
] | [
false
] | null | [
"If you take energy away from a moving object, then it has less energy. Eventually it will stop moving, and you can no longer get anymore energy from it."
] | [
"Well how do you propose to extract kinetic energy from the moon?",
"Some tiny fraction of the moon's energy is already being lost to ",
"tidal heating",
". But it would be an engineering feat to turn that directly into usable power."
] | [
"Well how do you propose to extract kinetic energy from the moon?",
"Some tiny fraction of the moon's energy is already being lost to ",
"tidal heating",
". But it would be an engineering feat to turn that directly into usable power."
] |
[
"How to insects grow hair/fuzz when they have a hard exoskeleton?"
] | [
false
] | null | [
"Hello and very fun question! Many arthropods have hairs or spines that have many functions. They are connected to the arthropod via pores or sockets for larger spines within the exoskeleton (cuticle). I love spiders as an example of arthropod hair, so we're going to move in that direction as I explain what the hai... | [
"Oh! I'm so sorry, I forgot to mention their use! They allow for a better grip, even on smoother surfaces. So spiders that do a lot of active hunting and climbing need them to get around."
] | [
"Great answer. It piqued my interest enough that I have to ask: what do the scopulae do?"
] |
[
"I heard about ~1.5% of our genome is exons. Were primitive organisms composed of so much \"junk DNA\"?"
] | [
false
] | [deleted] | [
"1) ",
"Noncoding DNA (aka Junk DNA)",
" has actually been shown to have a great deal of functionality. This isn't to say that we know everything that it does, but it certainly doesn't appear to be useless. Largely these regions appear to be involved in gene regulation, which is absolutely essential for makin... | [
"Another reason that evolution wouldn't have rooted out introns (reads: evolution does not select ",
" traits, merely doesn't select ",
" them) is that there is massive (relative) redundancy in the case of mutation of UV damage. The more DNA you have, the less likely a critical base pair will be damaged."
] | [
"there is massive (relative) redundancy in the case of mutation of UV damage. The more DNA you have, the less likely a critical base pair will be damaged.",
"I've heard this before and I'm not sure if it is actually true. The mutation rate from UV light is dependent on how often a high energy photon hits a stran... |
[
"How do we get Vitamin D from sunlight?"
] | [
false
] | I never really understood why, like do we have some special organelle in our cells that convert sunlight to vitamin D or is it something entirely different? | [
"It’s a photochemical reaction. ",
"There’s a chemical in your skin called 7-DHC that’s photochemically reactive to light between the wavelengths of 290 and 320 nm. These wavelengths are part of the sun’s spectrum and what is often referred to as UVB radiation. When 7-DHC reacts with UVB light, the product is dho... | [
"Vitamin D3 sythensis is regulated by hormones in the skin. Simply put, when there’s a lot a vitamin D3 in the system, the body will stop producing vitamin D precursors. ",
"There’s also regulation later in the process. Vitamin D synthesis is also down-regulated by the FGF23 protein acting on a transport protein ... | [
"So is this process continuous as long as you are in the sun?"
] |
[
"Why can completely paralyzed people often blink voluntarily?"
] | [
false
] | null | [
"Blinking is a motor function controlled by the facial nerve, the seventh cranial nerve. Cranial nerves come directly from the brainstem, bypassing the spinal cord. Cranial nerve reflexes are often used to assess levels of brain function (diencephalon, mesencephalon, and medulla). "
] | [
"It's like as if all the network switches are down, but your face has a direct line to the server. Very interesting. Thanks!"
] | [
"Or if your computer is the brain, you can't access the network but your speakers still work fine as they're plugged straight into the computer without passing the router. You don't have any Internet access, but can still communicate with your neighbors if you turn the volume up."
] |
[
"If a wave is cancelled out by another wave (destructive interference), where did the energy go?"
] | [
false
] | This question sprouted from trying to explain how noise-cancelling headphones work, but I also wonder about other waves. If two laser beams in a vacuum come out of a semi-transparent mirror, one half-wavelength apart, would only darkness emerge? But, energy cannot be destroyed. Where did it go? | [
"Whenever you have destructive interference in one place, you have constructive interference somewhere else, and that somewhere else is where the energy goes. In your example of the half-silvered mirror, if they're one half-wavelength apart on one side then they'll be in phase on the other side."
] | [
"The positive energy of one wave is canceling out the negative of the other.",
"Energy is always positive -- even for antimatter and for waves. There is no \"negative energy\" in this situation. Hence the question of where the ",
" goes when you have interference."
] | [
"The positive energy of one wave is canceling out the negative of the other.",
"Energy is always positive -- even for antimatter and for waves. There is no \"negative energy\" in this situation. Hence the question of where the ",
" goes when you have interference."
] |
[
"Why are Hydrogen(1) and Helium(2) highly abundant in the universe, while Lithium(3) and Beryllium(4) not that much?"
] | [
false
] | I came across the other day. I made a quick search but didn't find much. Can someone explain? Is it due to the state? Or due to their reactivity? | [
"Production of lithium from helium is highly ",
", meaning that it consumes massive amounts of energy instead of creating it. Secondly the fact that it's endothermic results in a significant ",
" that needs to be overcome, on top of the powerful electrical repulsion between nuclei.",
"The most likely way one ... | [
"Oh wow, thanks for your answer. Just some follow-up questions, what is this ",
" you talk about? Is it measured somehow? And what type of energy is it exactly?"
] | [
"The energy barrier is usually a general term for the amount of additional energy required for a reaction to occur. The form in which the energy comes isn't exactly important, but it generally involves heat energy. You can measure the energy barrier of a reaction by adding energy and noting when it occurs, or perfo... |
[
"Why does a vaccine have to be injected through a needle?"
] | [
false
] | If a virus, like Sars-Cov-2 can enter the body through orifices, why can't preventive medicine like vaccine? Wouldn't it be a whole lot nicer and easier to orchestrate if everyone could just get a nose spray "vaccine"? I'm sure if it were possible the brilliant minds of several scientists would've thought of it, so I know I'm not proposing something groundbreaking here, but I'm wondering why it is not possible. | [
"Lots of reasons:"
] | [
"Regarding the first point, our mucous membranes are filled with enzymes called ribonucleases specifically because we don’t want RNA from the outside world getting into our bodies (as it could be a virus!). ",
"Injection gets around (some of) our normal anti-viral safeguards. ",
"https://en.m.wikipedia.org/wiki... | [
"to add what others have said, people are working on ",
"microneedle patches",
" that can be used instead of a direct injection"
] |
[
"How do the instruments of probes sent to the far reaches of the solar system not freeze/malfunction due to extreme cold and other issues?"
] | [
false
] | null | [
"They are engineered to withstand the conditions for the duration of the mission (and sometimes beyond) from the very beginning, by making them temperature-tolerant and warming those systems that need higher temperatures to operate. Have a look at what for example the ",
"ESTEC Labs",
" have regarding testing e... | [
"Thermal management is a very important aspect of building spacecraft. Taken as a whole you have to deal with the energy received from the sun or other bodies via radiation, the energy lost to space via radiation, and the heat generated by the spacecraft itself and keep the instruments at a temperature where they c... | [
"One other thing to consider is that a lot of components of these probes will only work if they are very cold. WMAP, COBE, and Planck measure 2.7 K radiation. If they are warmer than that, their own thermal signatures will drown out the signal they are trying to measure. "
] |
[
"Why are many natural satellites in space found to be tidally locked or in a synchronous orbit?"
] | [
false
] | null | [
"Short answer, it's the most stable state, and they have been there a LONG time.",
"Natural satellites in less stable places have a habit of being knocked about by other objects. The effect can be subtle, but over long enough time periods can destabilise another body. This either sends it flying out of the system... | [
"Thankyou"
] | [
"Nature favors the stable. That is, we are more likely to see stable things than any particular unstable thing."
] |
[
"What am I really smelling, when I smell rain coming?"
] | [
false
] | null | [
"You are smelling ozone (O3), as well as something called 'petrichor'--the mixture of odiferous molecules that are are moved from surfaces into warm, damp air that tends to blow around before a rain storm. There is an SA article about this very phenomenon ",
"here",
"."
] | [
"As a microbiologist, I can't let that answer sit without elaborating that the 'mixture of molecules' you and the article are referring to are (at least in part) created by ",
"Actinobacteria",
". The name of the compound is even means 'Earth Smell' in Greek! How cool. "
] | [
"Additionally, your nose is more efficient at picking up smells when there is moisture present, hence why shower farts smell considerably more heinous than standard ones"
] |
[
"How does the anisotropy/transmission axis of polarizers work?"
] | [
false
] | So polarizers have optical axis that block or let through the corresponding polarizations of light, but it also depends on how much the polarizer is rotated, like shown in Malus's Law. Somehow, the polarizer isn't the same when viewed from all direction or otherwise the light transmitted would all be the same regardless of polarizer orientation, so what is it about the polarizer that makes it have a directional dependence on light transmission? | [
"Electromagnetic radiation is a vector, so its transverse profile has an amplitude AND a direction. (e.g. vertical or horizontal polarized light). For the same reason, a polarizer, as you mentioned, also has a direction. (often called s and p). You now need to 'match' these directions for the proper result you want... | [
"A trained eye in optimal conditions can actually detect polarized light. ",
"https://en.wikipedia.org/wiki/Haidinger%27s_brush",
" One of the easiest ways to do this is with a white LCD screen. The effect is extremely subtle, though."
] | [
"A polarizing film consists of long molecules in a parallel orientation (like a picket fence). Electro-magnetic waves with polarization parallel to the long axis of the polarizing molecules are transmitted preferentially compared to EM waves polarized orthogonal to the main axis of the molecules. The latter orient... |
[
"Why does a star need to go supernova before it turns into a black hole?"
] | [
false
] | What does it get rid of or gain that it doesn't already have? | [
"Mackinstyle is more or less correct. A ball of gas that is big enough to ignite fusion (a star) will be in a state of hydrostatic equilibrium, where the push of the fusion resists the pull of gravity. When the fuel for fusion runs out, gravity dominates and it begins to collapse. But then the pressure becomes grea... | [
"and then the black hole starts slowly losing mass in the form of Hawking radiation (unless it picks up more mass from rocks)"
] | [
"This isn't my specialty, but my understanding is that the fusion reaction occurring in a star resists the inward pull of gravity. When a star has run out of matter to fuse, collapse can occur. Depending on the mass of the star at this point, a number of things can happen (black hole, neutron star, white dwarf).",... |
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