title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"How accurate is Monty Python's \"Galaxy Song\" in relation to the current understandings of the universe/galaxy?"
] | [
false
] | Link to the song: Lyrics: I only ask because the song was written around 1983 (if not earlier, that's when the movie it was included in was released) and I'm sure advancements in measuring and accuraccy happen all the time. But then again I'm sure the song makes fairly broad sweeps in relation to the galaxy itself... I... | [
"http://en.wikipedia.org/wiki/Galaxy_Song#Accuracy_of_figures_quoted_in_the_lyrics"
] | [
"The short answer is that we don't know. There is evidence of larger bodies outside the universe that we can't observe. These massive universe sized things appear to be generating a ",
"flow",
" of the entire observable universe. We can only observe the universe within ~14 billion light years of us... and who k... | [
"It's fairly consistent with modern understanding. The only possible problem is the 'millions of billions' estimate for the number of galaxies in the universe. The number of galaxies in the visible universe is around 100 billion, but the number of galaxies beyond the portion of the universe we can see is unknown (i... |
[
"Does the Sun's gravity have a significant impact on the plate tectonics of the planet Mercury?"
] | [
false
] | I saw that Mercury apparently has active plate movement, and was curious if the Sun's gravitational pull has a significant effect, being in such close proximity. | [
"The short answer is yes. The plate tectonic activity on Mercury is caused by its proximity to the Sun. ",
"A slightly longer version. The tectonic activity of Mercury is due to tidal forces. Yes the same kind of phenomena we see on Earth that causes ocean water to rise and fall also causes this tectonic activit... | [
"Venus is affected and even Earth. As the distance between the planet and sun gets larger the amount of this decreases by a lot, but the effect is still there. ",
"So on Earth the moon causes tides which raise and lower sea levels around the earth. Sometimes the gravitational effect and the moon and sun become in... | [
"While cooling may be the cause of the tectonic activity on Mercury, it is inaccurate to say that the same side of Mercury always faces the sun! Mercury is in a 3:2 spin orbit resonance. This means it rotates 3 times for every 2 orbits it makes. ",
"Mercury's sidereal day is about 58.7 earth days long. This is ... |
[
"Why hasn't the Kepler telescope found anything in alpha centauri a or b or even proxima centauri?"
] | [
false
] | Is it because there are no habitable planets there? :( | [
"Kepler looks at a part of the Northern celestial hemisphere, near the constellation Cygnus, while Alpha Centauri is in the Southern hemisphere.",
"There has been a controversial exoplanet detection at the limit of detector capability, around one of the Alpha Centauri stars."
] | [
"Two reasons:",
"Now Kepler is not the only telescope we have looking for planets, and there are several different methods by which we can detect them, but all of them have limitations. For the most part they can only detect the larger planets closer to their stars. If a nearby star had a solar system exactly lik... | [
"There has been a controversial exoplanet detection at the limit of detector capability, around one of the Alpha Centauri stars.",
"I think it took a few years for them to get the Alpha Centauri Bb detection, which shows just how weak our detection methods still are for low-mass planets. And if it exists, then i... |
[
"Can you obtain an individual's blood type through DNA tests?"
] | [
false
] | null | [
"Yes, but that would usually be overkill. If you have a sample of the blood, you can just test the blood cells for the receptors directly."
] | [
"Professional geneticist here.",
"Agreed."
] | [
"Then sure. That would work.",
"The assay run by the commercial group ",
"23andMe",
" would do, though there are probably cheaper assays out there. Just from my memory of how much an assay used to cost, it looks like 23andme charges a hefty premium.",
"But let's not just take my word for it! Bring on the ci... |
[
"Awesome K-12 Science Experiment Suggestions!"
] | [
false
] | Here's the deal: I work at an alternative/hippy school and we have a science fair coming up. I want to do something that is relatively simple but off the wall and will be more than the baking soda volcano. Let the suggestions commence! | [
"Recreate the phase space diagram of a double pendulum: ",
"http://en.wikipedia.org/wiki/File:All.png"
] | [
"Something that ROCKED my world when I was a youngster was crushing soda cans by heating them and then inverting and dipping in water. Here ",
"is a video",
" if you aren't familiar."
] | [
"All I can add is that the most interesting experiment I remember from younger ages was the ",
"distillation of wood",
", although when we did it we just lit the gas coming out of the tube rather than distilling it.",
"Either way, the simple demonstration that the heating of wood, and the ignition of the resu... |
[
"Can you make something smell like chlorine without actually using chlorine?"
] | [
false
] | I started thinking about lab-created odors and flavoring agents and about how some are created by using the same molecules that make that thing smell or taste like what we expect it to. But if you wanted something to smell like, say chlorine or bromine, you wouldn't be able to without actually using those elements, wou... | [
"Well, chlorine as you find it in pure form is a diatomic gas (Cl2), while Br2 is a liquid at room temperature. What really matters isn't the molecule itself, but how it triggers the olfactory receptors in your nose. That's a lot more complicated, because there are different ways they can interact, and we don't rea... | [
"Yes it's like a hash function of sorts, in that several values can map onto a single one. (I believe the mathematical term for that is a surjective map) Two things that trigger the same response in your neurons must smell the same, reasonably. But two things that smell the same haven't necessarily originated in th... | [
"So, here's what's I'm thinking based on your response:",
"In computer cryptography, collision occurs when two unrelated values share the same hash. For instance, your password could be compromised by a completely different password simply because the stored hash value is compared and another password could possi... |
[
"Is it possible for a fire to exist that is large enough to deplete a significant portion of the oxygen on earth?"
] | [
false
] | [deleted] | [
"I'm saying that no matter how large a fire gets it will never have any effect on the amount of oxygen atoms in the atmosphere, unless the temperature is high enough for nuclear reactions to occur. Oxygen will just bind to other things until you're out of 'breathable air', but you won't run out of oxygen. ",
"Bre... | [
"I'm saying that no matter how large a fire gets it will never have any effect on the amount of oxygen atoms in the atmosphere, unless the temperature is high enough for nuclear reactions to occur. Oxygen will just bind to other things until you're out of 'breathable air', but you won't run out of oxygen. ",
"Bre... | [
"According to ",
"this website",
", there is already more Carbon in the air than in vegetation, so burning every plant on earth would less than double the CO2 in the atmosphere. Each new CO2 molecule would correspond to the loss of a diatomic oxygen molecule. ",
"However, that is so little CO2 compared to the... |
[
"Do super massive black holes decay?"
] | [
false
] | I'm sorry if this has been asked before or if it seems ignorant but recently I've been thinking about black holes. My question is will the super massive black hole at the centre of the Milky Way eventually evaporate causing everything to drift apart? I know that the more massive a black hole is the longer it will take ... | [
"At this stage in the universe's lifetime, they do not (or are not expected to). The cosmic microwave background is currently much hotter than the Hawking temperature of a supermassive black hole (2.7 Kelvin vs less than a picokelvin), and the CMB won't be cold enough for trillions of years or more before supermass... | [
"It's still I'm effect, but the black hole's simply absorbing more energy than it's emitting via Hawking radiation."
] | [
"Yes, it will. But you're underestimating the time required. Ignoring the cosmic microwave background (which will cause the black hole to grow until the background becomes cooler than the black hole's \"temperature\"), it will take around 10",
" years for a supermassive black hole with mass 10",
" solar masses ... |
[
"If the intense pressure of the sun can strip electrons from atoms, how much pressure would be needed to break protons and neutrons into more elementary particles?"
] | [
false
] | [deleted] | [
"There is some suggestions that the interior of a neutron star may produce an environment where a quark/gluon plasma is created. Whether this is considered a breaking of protons, I could not say for certain, but would certainly be interested to find out: ",
"http://en.wikipedia.org/wiki/Neutron_star#Structure"
] | [
"The strong, or colour force is the interaction between quarks and gluons. It absolutely dwarves the gravitational interaction between those same particles (note, however, that particles in astronomical object are affected by the gravitational field of ",
" other particles, while the strong force has a very small... | [
"This is neat! Does Strong Nuclear force only hold neutrons and protons together in the nucleus or does it hold quarks and gluons together as well? If so, how much stronger is Strong Nuclear force than Gravity?"
] |
[
"What does oxygen production in a tree scale better with? The amount of leaves or the who biomass of the tree ?"
] | [
false
] | Would a small tree with the same amount of leaves produce less oxygen than a bigger tree(more tree, more energy required, more efficient use of leaf surface area)? EDIT: Whole* biomass in title, ffs... | [
"By the ",
"leaf area index",
". O2 is a byproduct of photosynthesis so you want a measure of the photosynthetic area, not the mass.",
"Leaves that are not being illuminated are not producing O2 but do give off some CO2 due to ",
"cellular respiration",
". This does not mean that the entire tree is not gr... | [
"Yep. It's important to note trees only produce net positive oxygen while growing (which granted they are usually always doing). They do not passively produce more oxygen for the environment just existing. Conservation of mass; the carbon from the CO2 needs to go somewhere.",
"It's actually a bit of an issue. Hum... | [
"The 'carbon sink' of forests is not in their growth, but in the incomplete decomposition of the each tree when it dies. Not all of the carbon that went into creating each tree goes back into the air as a lot of the matter will get locked up underground. The buried dead trees are the coal deposits of 100s of mill... |
[
"(Informatics) Why did they (who?) invented the bite? Couldn't we just go on with bit?"
] | [
false
] | null | [
"Hi zampyx 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 followin... | [
"If you misspelled the \"byte\", you can read ",
"its history",
" by R.W.Bemer, the author of the first paper (source #1 in the linked text) which mentions the term."
] | [
"The same reason we have 26 letters when 2 would suffice, it makes things more compact and easier to immediately comprehend. "
] |
[
"How do chemists approach substance analysis?"
] | [
false
] | Suppose a chemist were given an unlabelled bottle of substance, about which only the immediately apparent physical characteristics were known. How would he/she go about identifying it? | [
"To give a layman interpretation:",
"IR - Every molecule absorbs infrared (IR) light in a characteristic way. Shining IR light through a sample and detecting which frequencies absorb allows us to know what types of molecules are in the sample.",
"Mass Spec - Through a variety of ways, we can \"weigh\" a molecul... | [
"Nowadays, the combination of IR, mass spec, and NMR will be enough for structural determination."
] | [
"ICP-MS first then."
] |
[
"Are there any macroscopic organisms that developed more recently than humans?"
] | [
false
] | I know that is relatively new as far as species go, but are there any newer species? How about taxa that emerged more recently than the first hominids? I threw the macroscopic in there because I figure there's probably a ton of new bacteria species, but I don't know that for sure. | [
"All the breeds of dogs that humans have created. (although they are technically the same species... but come on, look at a Rottweiler and a Chihuahua)"
] | [
"There's at least one species of fruit fly that's popped up in the past hundred years or so. Plenty more that have happened in the intervenening time, I'm sure."
] | [
"Sure there have been. The human species came out three million years ago. Statistically speaking, there had to have been quite a few new macroorganisms that have come about since then, and ones that have died out. Also not that the mean age range of a species on Earth is three million years, so species could have ... |
[
"What's happening under the ocean while a hurricane is above it? Is it as crazy/destructive/turbulent/etc as it is above or is it not really noticeable underwater?"
] | [
false
] | Sorry, but I asked this same question in the megathread a day ago, but did not get a response. Thanks! | [
"A Virginia-class submarine has a ",
"published max depth of 240m",
", so I presume you could sail one under a hurricane and basically not even notice it was there?"
] | [
"It's very bad right near the surface, but gets a lot calmer as you go down. Waves in deep water decrease in strength exponentially as you go down to a depth equal to the spacing between waves. So if you're deeper than 200 m (700 feet) or so, you might not even notice a hurricane is happening!",
"For comparison... | [
"yes under normal conditions the wind mixes only the upper tens of meters under the surface. A strong storm, such as a hurricane, will have a larger impact. But underneath you won't notice it in terms of water movement. I could image that for example the amount of marine snow changes. But I don't know for sure. "
] |
[
"Why isn't lithium the third most abundant element in the universe?"
] | [
false
] | To my understanding, hydrogen is the most abundant element in the universe due to its low binding energy and relative ease of creation in stars. Helium is the next most abundant followed by oxygen. Why is oxygen the third most abundant element in the universe instead of lithium which is the third in atomic number? | [
"The nuclear equivalent to chemical stability is ",
"binding energy / nucleon",
", which is shown in ",
"this",
" plot. Basically, the higher the BE/N, the more stable the isotope in terms of nuclear decay.",
"The maximum is at iron, which is why you hear stuff about stars dying when they start to produce... | [
"We ",
" the remnants. Some of the gas dispersed throughout the galaxy, the rest became stars and planets like ours. It was long enough ago that the original gas cloud has long been dispersed to the point that we can't pick it out from the rest of the interstellar dust.",
"Analogy: you pour milk into coffee. At... | [
"They're related. There's no more fusion to generate the energy holding the star up against its own gravity, hence the collapse. There is probably a real astrophysicist around here who can explain it better and more thoroughly than I can."
] |
[
"Is there a good way to quantify how \"random\" a given method of shuffling cards is?"
] | [
false
] | I used to shuffle cards the normal way, split it in half and then recombine, but then I realized: the topmost cards in the deck still stay mostly on top, and the bottommost cards still stay mostly on the bottom, so you're not really getting a completely random distribution, no matter how many times you shuffle the deck... | [
"In cryptography, there are multiple tests used to try to \"quantify\" how random a set of numbers is (usually a set that's been created by a random number generator). I'm sure you could assign numbers to cards and use similar tests. Look in any good crypto text and you should find some randomness tests. ",
"B... | [
"On the specific topic of card shuffling, Persi Diaconis, a former professional magician and professional mathematician, has written several papers comparing the randomness of different shuffles. He also has material on the \"fairness\" of dice I believe. I have only a passing knowledge of his work (I actually know... | [
"This is outside of my expertise but I can provide some examples of what you might do. As ",
"u/afcagroo",
" has mentioned, you can't get a great idea of how well a shuffling method works by shuffling once and looking at the result. ",
"You can start to answer the question \"how accurately could you guess the... |
[
"How does the iron peak phenomenon relate to nuclear binding energy?"
] | [
false
] | [deleted] | [
"Binding energy in this case, is the energy required to disassemble the nucleus of an atom. As such it's a negative energy i.e. higher binding energy indicates a favored lower energy state of the nucleus. ",
"An analogy might be a wooden spherical puzzle where the pieces are cut to fit together tightly. When ... | [
"Fusion of nuclei with mass lower than Iron/Nickel will yield energy because the nucleus that results from this fusion reaction will have a lower energy state per nucleon than the reactants did. Higher binding energy = the favored lower energy state of the nucleus.",
"Elements with a mass/atomic number higher th... | [
"Fusion of nuclei with mass lower than Iron/Nickel will yield energy because the nucleus that results from this fusion reaction will have a lower energy state per nucleon than the reactants did. Higher binding energy = the favored lower energy state of the nucleus.",
"Elements with a mass/atomic number higher th... |
[
"Ways to Image/Detect Tau Proteins in Neural Cell Cultures"
] | [
false
] | Hi! For a section of a multi-component research project at my university, I want to test the effects of dopamine quinone on neural cells in culture. The oxidation effects of quinone are known to promote tau polymerization and thus lead to neurodegeneration. How would I image/detect this process or the tau proteins them... | [
"You can use immunohistochemistry/immunocytochemistry/flow cytometry like ",
"/u/baloo_the_bear",
" says, but tau is present all the time, but you're looking for a specific pathological aggregation state of tau. It's not my specific area, but I believe that you're looking for the hyperphosphorylated tau state. ... | [
"You could try using a florescent antibody specific to tau protein, and then image. This will give you a good qualitative look at the levels of tau proteins but if you want a quantitative analysis you'll need to do some image processing (imageJ is pretty good for that). I'm not sure how you would go about capturin... | [
"Do they form foci when they aggregate? I suppose you could label, confocal image, and count tau foci?"
] |
[
"Why do those stripes form besides an/this nuclear blast? (Camp Desert Rock nuclear test)"
] | [
false
] | null | [
"Those are the trails from sounding rockets fired from the ground near the blast, nothing to do with the nuclear blast itself. By launching those rockets shortly before the blast, the initially vertical smoke trails will be deformed by the shock front of the explosion which gives visual evidence of the fluid motion... | [
"Yes, it's just to see how the air deforms around the explosion.",
"It has no impact on yield."
] | [
"People are saying \"better angle\" but that's only part of it.",
"By detonating a bomb at the right height, you can make the shockwave reflect off the ground and interact with itself constructively, creating what is known as a Mach stem. This means you can extend the size of a given area of blast pressure consid... |
[
"In miles, how wide is the band of twilight over the equator assuming it's equinox? Also, would d there be a difference between the dusk width or dawn width?"
] | [
false
] | null | [
"It depends on what kind of twilight you are talking about. Let's use ",
"astronomical twilight",
", which is defined as when the sun's center is 18 degrees below the horizon. You picked the easy case of equinox at the equator. Sunset actually occurs when the sun's center is 16 minutes below the horizon (since ... | [
"You also need to take into account the roughly 1/2-degree correction for atmospheric refraction. When the Sun appears to have just fully set, its top edge is actually a half a degree below the horizon. This effectively widens the twilight band on the Earth, although to calculate exactly how much would be a bit dif... | [
"Thanks so much! "
] |
[
"How are COVID virus mutations named (letters and numbers) and what is the difference between a \"mutation\" and a \"variant\" (Greek letters)?"
] | [
false
] | There are 'mutations' of the COVID 'delta variant'. P681R increases the viral load. Mutation D614G is thought to make the SARS-CoV-2 virus' spike protein more dense, and could help the virus more easily invade cells and evade the body's defenses. Mutation L452R may perform a similar function by thwarting antibodies. ... | [
"Mutations are the alterations in the genetic material that change viruses. A mutation is a specific change in a specific piece of the RNA resulting in a change in how the virus works.",
"A variant is the name we give to a virus strain with certain mutations. Not every mutation has to have a different name; some ... | [
"This is the long answer: ",
"https://www.cogconsortium.uk/what-do-virologists-mean-by-mutation-variant-and-strain/",
"More readable: ",
"https://theconversation.com/whats-the-difference-between-mutations-variants-and-strains-a-guide-to-covid-terminology-154825",
"Even more: ",
"https://www.news-medical.n... | [
"Bit of a nitpick, but D614G refers specifically to an amino acid (ie, protein) change rather than RNA change. While a nucleic acid change is requried to produce a different amino acid, that RNA or DNA mutation can range from one to three nucleobases depending on the swapped codon."
] |
[
"Why does the Falcon 9 have a 1-hour launch window to go into geostationary orbit?"
] | [
false
] | I understand that geostationary orbit is achieved with an equatorial orbit with a period of one sidereal day. What I don't understand is why there would be a 1-hour launch window (for the Falcon 9 currently on the launch pad at Cape Canaveral) if both the intended geostationary location and the launch pad are relativel... | [
"There will be a Hohmann transfer from LEO. ",
"The rocket is intending to go into a geostationary transfer orbit (GTO) so it may get into the desired location for a geostationary orbit. ",
"I don't see why this has a launch window."
] | [
"There are several other reasons for launch windows. First, it's probable that SoaceX IS trying for a specific intermediate orbit from which it start their GEO transfer, so that can be one. Avoidance of other satellites and space debris can be another - they want their intermediate orbit to be \"open\" so they can ... | [
"To launch into any orbit the launch site must be directly under the orbital path (ground track). Even though the final orbit is geosynchronous, there will be an intermediate orbit that SpaceX need to hit to get the right path. "
] |
[
"How is the Moon's rotation exactly in sync with its orbit so we don't see the other side?"
] | [
false
] | I've heard that its rotation kind of gets "locked" as it is, but what causes this? | [
"The phenomenon is called tidal locking, and is a well-observed occurrence from two closely-orbiting astronomical bodies. The gist is as follows. Say you have two bodies, A and B. A is smaller in mass. A and B both cause tides to each other due to the force of gravity. When the bodies are new to each other, they bo... | [
"will this happen to the planets and the sun eventually? "
] | [
"(layman) slowly - very slowly in some cases - yes.",
"but it happens so slowly that, for example, it's quite possible for the Sun to turn into a white dwarf, first.",
"and planets don't necessarily survive in orbit that long, either."
] |
[
"Do muscles get bigger instantly after lifting weights?"
] | [
false
] | A photographer friend of mine was telling me about how many male models pump iron directly before a photoshoot. He claims that it makes them look bigger and shape and muscle definition also looks better in the pictures. Is he telling the thruth? Can lifting weights give an instantaneous effect? And if so, just how muc... | [
"When you work out, the muscles look bigger, yes. This minor effect lasts a short time after your workout. ",
"However, most male models are doing something much more drastic: dehydration. It's not uncommon for cover models of 'fitness' and lad-mags to have difficulty standing unaided for most of the shoot, becau... | [
"Just to clarify this effect is often referred to as 'pump' and is due to increased blood flow to the muscle, increasing the total volume of the area, but not the muscle amount."
] | [
"Why would they want to be dehydrated?"
] |
[
"How was the speed of light first calculated?"
] | [
false
] | null | [
"The apparent lengths have nothing to go with relativity. It's just an optical effect. Because the speed of light is finite you see different parts of the image in different times so the image appear distorted. These distortions are actualy much more dominant than relativistic effects."
] | [
"The first relatively successful measurement was done by Roemer and Huygens by comparing the apparent length of astronomical bodies during different times in the Earth's orbit. "
] | [
"You can read about Roemer's measurement ",
"here",
"."
] |
[
"Walking on the Sun"
] | [
false
] | In the graphic novel "Watchmen," Dr. Manhattan claims to have walked on the surface of the sun. Assuming that he's not subject to being burned up, crushed, irradiated or whatnot, does the sun have a "surface" that one could walk on, or would the whole experience be more like stepping into a cloud? | [
"While there's no solid surface, such as the earth, the centre of the sun is EXTREMELY dense, about 1.622×10",
" kg/m3, so assuming you could survive the temperature at the centre, roughly 1.57×10",
" K, there would be a point as you descended through the outer layers that you would... I guess, float? and go no... | [
"No, there is no solid surface on the Sun. It is comprised of gases and plasma. "
] | [
"Good point!"
] |
[
"What causes the power to go out (& back on) during a thunderstorm?"
] | [
false
] | null | [
"The electric utility has circuit breakers called \"reclosers\" which trip if lightning strikes the wires or if the wires get blown around and momentarily contact each other. Unlike residential breakers, reclosers will automatically reset themselves three times in rapid succession. If the fault is still present af... | [
"High voltage lines have automatic riarm sequences because very often, faults are only transitory.",
"First, an event such as a tree touching the cables, causes the line protection to open the circuit breaker, because a fault is detected.",
"Then, after a certain time which depends on the country, legislation, ... | [
"Switchgears in your local substation trips and cuts off supply to your area when lightning strikes a transmission line or the switchgear itself. It will try to reclose and if the electrical failure (high short circuit current) is still there, it will cut the current again and remain opened until somebody removes t... |
[
"Assuming teleportation of matter could be achieved, the momentum of the matter is preserved in the process?"
] | [
false
] | null | [
"The answer to this question depends on how \"teleportation\" is assumed to work - since teleportation is not actually possible.",
"Your question is analogous to asking what unicorns eat. They don't exist, so any answer is equally valid."
] | [
"This type of hypothetical question does not have scientific answers."
] | [
"I think there may be a big gap in your understanding of quantum entanglement - it's not a kind of teleportation.",
"Back to my original point though - if you propose a hypothetical scenario with that many variables (how is teleportation of matter achieved?), the answer has that many equal variables. Like, if I s... |
[
"Can a physicist help answer some science questions for a sci-fi story?"
] | [
false
] | I'm working on a science fiction novel with an engineer, and we both have a desire to keep things as accurate and close to the real science as possible. Unfortunately i was an english student and have to get my answers from those who know better. Are there any scientists here can talk about the following problems? I ha... | [
"What are the current models on wormholes…",
"There's a ",
" to be said on this subject, but in my opinion your best starting point is this contrasting pair of 2005 papers on the basic logic of wormholes. They do ",
" comprise a comprehensive introduction to the topic, but they're a very good starting point."... | [
"I saw RobotRollCall has already commented, so this is probably redundant, so consider this a tldr.",
"1) The theory has been worked out, ",
"here is the metric",
". The problem is that when you solve Einstein's equation with that metric, you'll see you need something with negative mass to build it out of. Go... | [
"The Sun has a flair for making rainbows, fueling all life on Earth, and blinding people during an eclipse. It also occasionally has a flare that shoots out mostly protons."
] |
[
"Is evolution limited to \"random mutations\" or can other paths also be deemed evolution?"
] | [
false
] | [deleted] | [
"Evolution is the term used to describe changes in a gene pool over time. This can occur by various mechanisms; random genetic mutation being one among many. Artificial selection, such as that seen in dog breeding or horticulture can also induce evolution. Artificial selection imposed by humans can occur at the ph... | [
"Generally, all evolution refers to is the change in allele frequency over time for a given population.",
"\"Random mutations\" are actually not the main way evolution works! Most evolution works on existing variation within the population, for example, if you look at the thorns of a rose, it suddenly seems ridi... | [
"Evolution is so much more than \"random mutations\"! That's one of the biggest misconceptions about evolution in the general public. Like other posters have said, evolution describes changes in the gene pool (through allele frequencies) over time. What is the mechanism for this change? Natural selection! Esse... |
[
"I just drank some hot chocolate, can anyone tell me why sometimes dry powders take a long time to mix into liquids?"
] | [
false
] | When I took my milk out of the microwave, I poured in the hot chocolate mix. Just some regular Nestle Cocoa Mix. But I had to stir it for like 3-4 minutes, which ultimately just let my milk get cold. So I wonder, why is it that sometimes it seems to take forever for my hot cocoa mix to mix into my hot milk. | [
"There are two effects that immediately come to mind. First, you used cocoa as an example. Cocoa is rich in fats that give it it's flavor and good mouth-feel. Fats aren't soluble in water, as can be seen if you tried to take straight cocoa powder and dissolve it in milk. It can be done, but requires heating and h... | [
"I suppose it depends on the situation, but for something like a protein, these are macromolecules that are hydrophilic have an attraction to each other, and to water. They usually would be more attracted to water than to each other, so they dissolve readily. However, if a thin layer of water molecules gets in betw... | [
"Thank you very much for your answer. I'm glad someone could relate to what I was saying. "
] |
[
"What happens to the empty space when an oil well or oil rig depletes the source?"
] | [
false
] | null | [
"The ground subsides as the immense pressure of the crust above forces the oil out of the ground",
"."
] | [
"Here's the previous discussion:\n",
"http://www.reddit.com/r/askscience/comments/td8g8/if_i_were_to_travel_down_into_an_empty_oil_well/"
] | [
"Here's the previous discussion:\n",
"http://www.reddit.com/r/askscience/comments/td8g8/if_i_were_to_travel_down_into_an_empty_oil_well/"
] |
[
"[Physics] If space is a vacuum, and there is no matter in a vacuum, would someone really freeze to death in space?"
] | [
false
] | My physics teacher told us that you would freeze in space, but now that I am thinking about it after the fact it seems impossible because there is nothing to transfer heat to. Is there something going over my head or was he wrong? | [
"You would loose heat energy in the form of infrared radiation. Check out \"black body radiation\". "
] | [
"The downvote brigade is out again. :( Your answer is correct. Incomplete, and with imperfect spelling, but correct.",
"The other mechanism is water evaporation on the skin. It's probably more important than radiation, at least until you're dead, but both mechanisms operate concurrently."
] | [
"...if you were in direct sunlight you would be gaining heat faster than you were losing it.",
"No, not really. Near Earth, the solar \"constant\" is 1300 W/m",
" Unless you're dressed all in black, your albedo is about 50% - so you absorb maybe 650 W/m",
" The ",
"Stefan-Boltzmann radiation law",
" is... |
[
"why do you get goosebumps when you hear a song, or part of song, that you really like?"
] | [
false
] | null | [
"I think the technical term for it is ",
"frisson",
" which should help your googling"
] | [
"There's a whole subreddit devoted to it: ",
"r/frisson"
] | [
"I just found that, going to post it here... then saw you posted a comment to it. funny how that works. "
] |
[
"Where do babies come from? No...seriously."
] | [
false
] | My wife is pregnant. I cannot get my head around what is happening, physiologically, for a new human to be constructed. Where does all the new physical matter actually come from? I presume the raw materials are being supplied by whatever my wife eats and drinks, but what I want to know is 1) after this stuff has been b... | [
"The mother eats food, which is broken down into essential nutrients (sugars, vitamins, minerals, amino acids, fatty acids...) in her digestive tract. Those nutrients (just like for every other human) are absorbed into the blood where they are carried to different organs depending on the nutrient.",
"Sugars (gluc... | [
"Nope. The blood in the umbilical cord is from the baby. Babies start making their own blood very early on in the pregnancy (the third week after egg and sperm met). Their developing heart pumps it around and to the placenta too. The mother's blood and the baby's blood never really meet-and-mix, in the placenta the... | [
"can you explain how the blood in the umbilical cord is different from that of the mother? I've heard people keeping the umbilical cord blood for later use but I always figured the mothers blood was also the babies blood until the cord was cut and the baby's body starts making its own."
] |
[
"Human \"Hibernation\" and Radiation Damage"
] | [
false
] | [deleted] | [
"If you can specifically target and shut down cellular processes that consume a lot of energy but is not required in the hibernating phenotype, such as protein synthesis, but keep active other processes that are required to maintain cellular integrity, like DNA repair mechanisms, then you've solved the problem. In ... | [
"That depends on endogenous fat stores and the hibernating metabolic rate, but a few months, maybe? If you hook up an IV, then indefinitely if you can work out the long-term disuse atrophy issues (and probably a long list of other issues)."
] | [
"That's quite interesting, thanks! Can you speculate on how long a hibernation state could be sustained in a human before he would have to wake up and eat something?"
] |
[
"How would an animal that protects itself by ingesting toxic plants come to have that trait?"
] | [
false
] | Wouldn't members of the species who ate the plants before the immunity was developed die off? Would the immunity be selected for and then the animal would start ingesting the plant? | [
"Plant toxicity rarely kills, it just makes the animal sick. Animals that possess a genetic mutation that allows immunity from the toxin automatically has an evolutionary edge over other members of it's species. Think about the gene that prevents lactose intolerance in humans. Lactose didn't kill anyone but it ... | [
"\"Toxic\" doesn't necessarily mean \"deadly\".... The toxin may have been quite unhealthful to the animal early on. But not as unhealthful as the predator! So the trait of eating the toxin is selected for. Then, if another trait of resistance to the effects of the toxin arises, this then leads to an obvious advant... | [
"Not quite, but go-pills? That may be a different story..."
] |
[
"How is the Earth's core a solid?"
] | [
false
] | Wouldn't it make more sense if it were a liquid or plasma (Because of the heat) in a kind of stasis because of the immense pressure. While I understand that gases and liquid molecules move around far more rapidly because of there being more space between them is it not possible for the material in the core to be a plas... | [
"The outer core is liquid due to the heat; the inner core is solid due to the extremely high pressure."
] | [
"Seismic waves provide all the data we need to document that the outer core is liquid and the inner core is solid. Presence of a liquid outer core is shown by the ",
"P- and S-wave shadow zones",
". ",
"Evidence for a solid inner core",
" comes from reflection work by Inge Lehmann in 1936.",
"The outer co... | [
"Phase of matter depends on temperature and pressure. Liquids cannot exist at great pressure (or, rather, the corresponding temperature is much, much higher required to produce them). Plasmas require that it forms free ions with electrons, which won't happen unless it's already in gas form."
] |
[
"What is the effect of oil in the Gulf on evaporation and the weather?"
] | [
false
] | I've seen the sheen of oil on the water in the Gulf indicating that along with the thick crude there is thin oil spreading across the surface, and I know that it takes less than a teaspoon of thin oil to create a barrier on top of a large swimming pool. That barrier prevents evaporation and raises the temperature of th... | [
"I looked at my brown grass today and pondered the question and realized I hadn't heard any mention of it on the TV the whole time this has been going on. ",
"Maybe we'll get an answer here..."
] | [
"I've wondered the exact same thing. Will there be enough data to measure a difference from \"normal\" conditions? Will there be more heating and evaporation? Or will there less evaporation due to an oil barrier? One idea would be to compile days and weeks worth of doppler videos to see if there are any obvious pat... | [
"I too would love for someone to answer this. I'm in St. Pete. and am concerned for the natural beauty of the entire Gulf Coast and Forgotten Coast region. I'm an avid kayaker and am wondering how the inland flora and fauna would be affected by rain quality."
] |
[
"Are there positions of a chess board that are impossible to achieve legally?"
] | [
false
] | If I were to pick up a bunch of chess pieces and put them arbitrarily onto the board, is it possible for me to arrange them in such a way that two players could not eventually create the same state from the start of a game? Assuming a legal number of each piece, obviously. | [
"A simple example would be the starting position, but with the white and black pawns switched. There is no way for them to cross, without taking each other."
] | [
"Certainly.",
"Pawns have very restrictive movements so eg the only way a white pawn can get to a3 is from a2 or b2 (via a capture). Hence any position with white pawns on a2, a3 and b2 is illegal.",
"It is also illegal for both kings to be in check simultaneously. So all those positions are illegal.",
"Simil... | [
"Very elegantly simple example. I was going to suggest the whole black and white starting positions mirrored, but the argument for your example is simpler."
] |
[
"[Engineering][Space] How did the early scientists determine the dynamics of space atmosphere *and* be able to create suits capable of keeping a person alive in space?"
] | [
false
] | null | [
"vacuum is surprisingly non-deadly, you know? as in, pressure-wise.",
"vacuum is only one atmosphere of pressure less than what you're living in right now.",
"that's a pressure difference between what you feel about 2 meters underwater vs on the surface.",
"much bigger problem is people in the suits overheati... | [
"Hey thanks for the response"
] | [
"For all practical purposes the atmosphere is negligible in places where space suits (for outdoors) are used. It does lead to some drag with effects on orbits over months but that is not relevant for an astronaut in a suit next to a spacecraft."
] |
[
"Is there a way to stabilize yourself if you find yourself in an uncontrolled spin in outer space?"
] | [
false
] | So im writing a short story, and sadly i know more about science fiction than actual science. I have character who finds themselves spinning in outer space (weightless in a vacuum), similar to Sandra Bullocks character in the film Gravity. Is there a way for them to stabilize themselves or dispel energy? | [
"Although you can change angular velocity (i.e. extending arms), you can't change angular momentum. If you have have a heavy object that you throw from an outstretched arm it would be your best bet (throw to produce torque opposite of the direction of spin).",
"At least I think that would work."
] | [
"If you want them to ultimately stop spinning, an external torque must be applied to change (stop) their angular momentum. If you spin in space, you can decrease your angular frequency (how fast you spin) by increasing your moment of inertia. You can do this by simply stretching your arms or legs and put extra weig... | [
"This will change your orientation, but it can't change your overall angular momentum. At the end of each cycle (when your arms are in) you will be spinning just as quickly as you were at the beginning.",
"As ",
"/u/Ingolfisntmyrealname",
" explained, you need an ",
" torque to actually change your angular ... |
[
"If I had to run through a burning building, would I suffer less severe burns if my clothes were wet?"
] | [
false
] | Or, would the heat conductivity of the water and the "clinging" effect of the clothes damage my skin more quickly and leave it more vulnerable to burns? | [
"My fireman friend told me that there were always TWO people on the hose as they entered a hot blaze. The rookie was always the guy in front, because he felt the most heat, whereas the guy right behind him ( experienced fire-fighter) got the cooling mist that sprayed back. That would seem to indicate that water in ... | [
"The answer varies on the physics of the situation and the level of heat being radiated by fires around you. One thing to note, however, is that the water would do nothing to prevent asphyxiation from smoke inhalation, which is usually a larger danger than the actual fire itself.",
"Water has a high heat capacity... | [
"SOmething else to consider...the clothes properties. If you grab a cast iron pot with an oven mit, you don't feel much heat. If you grab that same cast iron pot with the same oven mit that has been dampened, you will almost immediately feel a burning sensation upon grabbing the pot.",
"Water works in both dire... |
[
"how does my body get vitamin d just from being out in the sunlight? or is the vitamin d already present in my body and the sunlight \"activates\" it in some way?"
] | [
false
] | null | [
"During exposure to sunlight, the ultraviolet B photons are absorbed into the epidermis and dermis layers of the skin, and 7-dehydrocholesterol (already present in these cells) is photolyzed to pre-vitamin D3 which in turn is isomerized by the body's temperature to vitamin D3. This vitamin D3 is ejected out of the ... | [
"Vitamin D is produced by the reaction of UVB in sunlight with a chemical called 7-Dehydrocholesterol that is already present in the skin. "
] | [
"They have: tanning beds. Its cheaper to go outside. 15-20 minutes outside will typically give you enough Vit D for the day. Getting the lightest of sunburns (1 Minimal Erythema Dose: dose to get the slightest of sunburns) will give you 10-25 thousand IU of Vit D."
] |
[
"How do we know aliens (if out there) require the same resources we do to support life?"
] | [
false
] | I've seen time and time again in press releases and news articles (most recently with NASA's latest release of the discovery of over 700 new planets) about how "___ number of planets found could support life". My question is, though, what is determining what supports life, and how do we know that aliens would require t... | [
"What is usually left out of those reports is \"Habitable for life ",
"\". ",
"What we are looking for is for environments which are similar to that of earth. Since we only have one sample of life in the universe, ours, we can only realistically look for life which is similar to our. ",
"Is it possible that t... | [
"Certain chemicals are physically and logistically more likely to support life. For instance, water is effective as a solvent, but liquid methane has similar properties, which is why scientist speculate that life might exist on Saturn's moon Titan. Carbon is exceptionally convenient for life because it bonds in ver... | [
"Essentially we know the most common building blocks of life exist everywhere in the universe..Oxygen, Hydrogen, Carbon and Nitrogen.. It's sensible to assume alien life would develop in a similar manner to how ours did."
] |
[
"How can an electromagnet powered by AC have \"standing\" magnetic poles?"
] | [
false
] | [deleted] | [
"What do you mean by \"standing\" magnetic poles?"
] | [
"He means non-oscillating."
] | [
"You can convert the AC signal to DC using a rectifier or similar device, so any design that works as a DC electromagnet can be powered by AC if you just add an extra component."
] |
[
"At any given time, could a line go from the center of the earth to the edge of the observable universe and not get intersected by any matter."
] | [
false
] | null | [
"Sure. In fact there are many more such rays — a line that starts at some point and extends without limit is called a ray; there's your trivia for the day — than there are rays that end at some particle. Our view of the cosmic microwave background — the surface of the sphere that contains the observable universe — ... | [
"The mean free path of a photon is currently much larger than the diameter of the observable universe. What cosmologists call ",
" — the moment at which electromagnetic radiation decoupled from matter and the universe became transparent, what the Bible describes as \"Fiat lux\" — was the moment when the mean free... | [
"I think the question OP is asking could be rephrased as: What is the mean free path for photon in the universe? ",
"According to the Wikipedia, average density of universe is estimated to be around one hydrogen atom per cubic meter (most of space is voids between galaxy clusters). Even bigger particles, like hyd... |
[
"If, in Hydrogen fusion, two protons metamorphose into one neutron, how can one neutron weigh the same as one proton?"
] | [
false
] | null | [
"Two protons react to initially form Helium-2, but this is incredibly unstable and rapidly decays to give either the two protons back, or deuterium, a positron, and a neutrino. Not sure where your one-neutron idea came from - did you forget to link the article you refer to?",
"EDIT: now that you've linked to the ... | [
"I'm not sure what article you are talking about. Its safe to say though that mass doesn't need to be conserved if we consider the conservation of energy."
] | [
"I guess this makes sense. The article didn't explain a lot of the process very well, I had an oversimplified idea of what goes on. Thank you"
] |
[
"Is there a \"maximum brightness\" or a \"maximum darkness\"? Can humans perceive either?"
] | [
false
] | That is, is there a limit or a minimum to how much light an object can emit, and can humans see that limit or minimum? I've been in caves without any light before, and it seems like that's the darkest anything could be. Is that true? | [
"It turns out the \"maximum darkness\" does not occur just by blocking all outside light, but also depends on the temperature of the object that is blocking said light. There is a thing called ",
"black-body radiation",
" (which maybe some of you've heard of if you're on this forum...). Black body radiation i... | [
"What we perceive as \"light\" is the existence of electromagnetic waves with wavelengths of 390-700 nanometers. Visible light, UV, X-rays, microwaves, Radio waves, they are all all electromagnetic waves with different wavelengths. Of course, you're talking about visible light. There can be a \"maximum darkness\" y... | [
"i remember reading the minimum visible light was a handful (as in <100) photons, which is quite amazing. (lycopodium says 6)\nFor maximum light, photons are bosons, so there is no limit to the density of photon in a given area. (unlike fermions that don't like to share energy levels)\nThe limit would be in the ene... |
[
"Why do Humans need to brush their teeth to fight infection and bacteria , while other animals do not ?"
] | [
false
] | Mad props to whoever knows! | [
"Keep in mind that our modern diet makes us more prone to dental caries than most animal diets; ",
"sucrose",
" is the primary dietary component responsible for the formation of cavities. Evidence suggests that human populations (eg, ",
"Eskimos",
", had very few cavities per person prior to contact with ... | [
"Well to start, plaque is what is called biofilm, which is secreted matrix of bacteria that is ",
" tough, and why it requires abrasives (toothpaste) and a good amount of elbow grease to remove. Moreover, it also causes bacteria to almost act as a sudo-multicellular organism, which is pretty cool if kind of irrel... | [
"As minute_pirate mentioned we have a high sugar diet. ",
"In some cases the foodstuffs animals eat, help clean teeth with a similar mechanical action. Dogs are often given chews to help reduce tartar build up. ",
"Rodents teeth constantly grow, so they don't really need to clean their teeth. "
] |
[
"In which ways do brains of left-handed differ from right-handed people?"
] | [
false
] | I'm interested in the difference between left- and right-handed persons. I don't know much about it, I've heard the language center tend to be on both sides if you're left-handed, otherwise it's more on the left side of the brain. I also got told the two hemispheres work better together in a leftys brain. I'll be glad ... | [
"A good answer to this was written up a while back by ",
"/u/theloniusjaz",
" \"About 98% of right-handed people have language in the left hemisphere, while only about 70% of left-handed people have language in the left hemisphere, with 15% showing bilateral activation and 15% showing language predominantly in ... | [
"There are multiple faculties that are lateralised in the brain, for example motor control and sensory perception is commonly cross-represented (i.e. your left hemisphere moves your right arm). ",
"Language is a bit of weird case, because it can be heavily dependent on one hemisphere (typically the left) and ther... | [
"Thank you very much! Do you know more about it? Or is the difference just in the language center?"
] |
[
"Are there infinitely many chemical compounds?"
] | [
false
] | null | [
"Theoretically I could just add one more carbon onto the end of a hydrocarbon chain, so ",
" yes - a ",
" uncountably infinite number.",
"In reality, given a finite universe, no. There are limited supplies of each element."
] | [
"No, it's countable. Cantor's argument only works with infinitely long sequences. Every compound you can come up with is finite. "
] | [
"since there are a fininte number of atoms in the universe and the size of the universe is also considered to be finite.",
"We don't know or \"consider\" either of these to be true."
] |
[
"What is the difference between straight hair and curly hair?"
] | [
false
] | I was wondering about the physical difference, if any, between curly hair and straight hair. | [
"A strand of hair is made of a dense network of dead cells and cross-linked proteins. It is formed in the ",
"follicle",
", and the shape of the follicle will have a large effect on the shape of the strand. Straight hair has a ",
"round cross section",
" while curly hair has a more ",
"oval or flattened ... | [
"Actually there is a ",
"group from MIT",
" that wrote ",
"a paper",
" about just this question. Because of gravity, the hair experiences different amounts of weight from top to bottom. At the top, the weight is high enough to force the hair into a straight configuration. They were able to come up with a mo... | [
"Why could it be that my hair is straight at the beginning but when it grows longer it starts to curl quite a bit."
] |
[
"Do particles move faster in the sun? I mean... Is time going faster in the sun than on Earth because of its gravity?"
] | [
false
] | I´m probably not making sense with my question... perhaps if you misunderstand it you can understand. | [
"In gravitational time dilation, the clock closer to a gravitational source ticks ",
" than the clock further away."
] | [
"Faster on the surface of the Earth, if we consider gravitational time dilation only."
] | [
"I just crunched the numbers. At the sun's surface time passes at ",
" speed from its gravity, while (to someone at rest with respect to the Sun) time on Earth passes at ",
" from its orbital speed. ",
"So time dilation from the Sun's gravity is less than that of the Earth's orbital speed, when considering th... |
[
"What is the heaviest hypernucleus?"
] | [
false
] | A hyper nucleus is an atomic nucleus containing at least one strange quark. I've looked around the internet, but I can't find a complete list. How many hypernuclei are known and what is the heaviest one? | [
"Hey, I just saw ",
"this paper",
" pop on up the arXiv and remembered this question. ",
"Bi!"
] | [
"Cool, thanks. This looks like exactly the kind of stuff I wanted to see. Unfortunately, I don't understand all of it; all I can really take away from it is that the half-life of hypernuclei is expected to taper off to a constant value with increasing mass. Is there any other important information in the article th... | [
"I wish I could. I think it's a terribly written paper actually; I can hardly figure out what they did."
] |
[
"Alcohol Use and Life Expectancy"
] | [
false
] | I've spent a few minutes Googling the deleterious effects of alcohol use on life expectancy, but I haven't really found anything substantial. Most people it seems fall into the low-moderate to high-moderate range of a few drinks per week. As someone in my 20's, I'm probably a bit toward the upper end, although far be... | [
"A large study in aprils BMJ attributed about 10% of all cancers to alcohol consumption. The relationship seems to be linear and the researchers conclude there is no safe level of alcohol in terms of cancer risk ",
"source",
"Cardiologists have long known that a small amount of alcohol seems to be slightly prot... | [
"If you want more info on this you might want to search for ",
"J (or U) shaped curve",
", which describes the observed mortality relationship with alcohol consumption.",
"I suspect the safest pattern would be to drink less when young and in moderation at more advanced age. This is because cancer risk is high... | [
"Thanks for this awesome response!"
] |
[
"If Neanderthals and early Humans could interbreed, why do we consider them different species?"
] | [
false
] | null | [
"Neanderthals (homo sapiens neanderthalensis) and humans (Homo sapiens sapiens) are not different species they are different sub species. "
] | [
"It should also be noted, even if they were separate species, the definition of species that's in your biology textbook doesn't actually reflect nature or reality. It reflect's mankind's desire to put things into orderly categories. The decision of where to draw the line for species was fairly arbitrary, and was ... | [
"You get second generation hybrids with ligers and tigons (Ti-Ligers, and Li-Tigons, we need better names...). There is evidence for second generation grolar and pizzly bears too. One was shot a few years back and no-one was sure if the hunter should be fined or not as one species was protected the other not. There... |
[
"If we ever make the switch to electric cars, wouldn't it make more sense to have battery exchange stations instead of battery charge stations?"
] | [
false
] | The way I've heard it, these batteries take hours to charge up. Nobody wants to sit at a charging station for that long. Wouldn't it make more sense to have a bunch of fully charged batteries waiting for the next customer and have either a machine, or a few strapping young lads switch out the battery? Would there be an... | [
"There would have to be a standardisation of batteries regarding size, power, connections and probably capacity, maybe more stuff too. That's all doable, it just needs to be agreed on by the industry. ",
"The biggest problem would be how to ensure that the batteries you were getting out were still in a good enoug... | [
"I have to disagree with you--I think it's not very likely that batteries will be standardized to the extent that you suggest is possible. ",
"Until newer battery technologies allow for smaller and lighter batteries--if this is even possible--electric car batteries will be custom fitted and built into the structu... | [
"By surrendering/rotating electric batteries at \"filling\" stations is also a good idea because:",
"It releases our battery technology from needing to find a solution for quick charging chemical batteries. (although I think there was a recent advance on this) The retailer can keep a running stock to have a suf... |
[
"Does DNA determine the size and shape of an organism or only what proteins it can create?"
] | [
false
] | I was wondering if coded within DNA are measurements such as how long my arm is or how tall I am, or if DNA only holds information about what each cell is supposed to do. Put another way, if our technology was good enough, could you tell what a person would look like, how tall they were, etc by only looking at their DN... | [
"In a way, both. ",
"DNA holds information about each protein that a cell in the body would ever need to create. Some of these proteins change how the information is read from the DNA: they start and stop production of other proteins. And some of those proteins start and stop ",
" proteins... it's a gigantic, c... | [
"Epigenetics",
" affect how \"expressed\" a gene is (which for a trait like \"size\" in humans effects multiple factors like growth hormone at a body-level view AND protein regulation at a cellular-level view) and that can most definitely be affected by environmental factors.",
"If you're interested in how gen... | [
"DNA has no effect on the size of an organism. Humans have ~25,000 genes and 3.2 billion base pairs. Mice have ~25,000 genes and 2.6 billion base pairs. Clearly we are bigger than mice",
"Source: \n",
"http://www.ornl.gov/sci/techresources/Human_Genome/faq/compgen.shtml"
] |
[
"Why are some people unable to learn math despite having a brain that solves complex math equations all the time?"
] | [
false
] | Take a hypothetical pool player for example. His brain knows how to deal with trigonometry, calculations of the necessary force needed to lead the ball as wished etc. But he gets an F every time at math tests. | [
"Your brain ",
" solve math problems though. It works by learning and association and 'fuzzy' connections, not through the rigorous logic that math is based on. That's why we 'jump to conclusions' all the time, and see patterns where there aren't any and so on. Our brains are associative more than deductive.",
... | [
"I've actually invented a board game that touches on this. It's called \"Jump To Conclusions\". It comes with a mat that you set on the floor."
] | [
"Layman here.",
"If that were true, anyone who got an A++ on the test would be a pool genius, and clearly that's not the case.",
"Your pool player might look as though he is using trigonometry, physics, etc, but he's not. He's using his experience. He knows that holding the cue at about this angle and hitting t... |
[
"What are the odds of science making the paraplegic walk in my lifetime?"
] | [
false
] | null | [
"A quick survey of ongoing clinical trials revealed over 500 trials related to spinal injuries. I'm no expert in spinal injury, but several of the trials looked promising even if many of them weren't exactly \"swinging for the fences\" in terms of a complete cure.",
"Also, we're just now starting to realize some... | [
"I would say, in your life time, for a situation like his, I would say there is very little hope. I think that there good chances of something coming online that if applied as soon after injury, of making spinal injuries much less severe.",
"The problem is, that after the initial spinal injury so many things happ... | [
"He's a crock of shit and tricks people into not understanding life expectancy vs life span. Raising life expectancy will not result in people living forever. It just gets more people living closer to a human maximum life span. ",
"Edit: Please stop replying to me when so many, many of you are missing the point h... |
[
"Classical Mechanics and D'Alembert's Principle"
] | [
false
] | This is a somewhat advanced and technical question, but I ain't getting any love over in . states that, for a mechanical system where the forces of constraint do not perform virtual work (i.e. work performed by a force due to a virtual displacement), that the virtual work performed by the quantity F-dp/dt (summed over ... | [
"My question is, is this proviso automatically satisfied by holonomic constraints?",
"No that is not how I understand it. See page ",
"12 through 21 of this",
"The statement is",
"1) if constraints do no virtual work and",
"2) the constrains are holonomic",
"then the equations of motion can be expresse... | [
"Yep, I've been reading Goldstein, that's what prompted my question. I understand what he says, but there is no straightforward answer in his text which answers my question, as you seem to recognize:",
"he does not say that holonomic constraints guarantee that constraints do no virtual work.",
"That is my quest... | [
"I don't know. What would we have to do to prove it does or does not?",
"The last line of the proof would read ",
" • ",
" = 0; or, conversely we can presume this and arrive at a contradiction. I'll be thinking on it."
] |
[
"What would happen if when you get a shot or something injected to your body, there was an air bubble in it."
] | [
false
] | You know when the doctor prepares a shot, he puts it right side up and squirts it so there air comes out? What would happen if there was still air in it? | [
"It could cause an ",
"air embolism",
". ",
"However, it takes quite a bit of air (>100mL) to actually cause a problem, so it's mostly to err on the side of caution."
] | [
"Air is usually removed for IV injections for the reason stated above, but for IM injections (into the muscle) air is usually left in the syringe to give the medication a small \"air boost\" into the muscle)"
] | [
"Or to act as a stopper to prevent the injected medications from oozing out. This is commonly used in subcutaneous enoxaparin injections. Most of the syringes are manufactured with a small air bubble in it."
] |
[
"What kind of forces are taken into effect when designing spacesuits?"
] | [
false
] | I'm more referring to the pressure difference between human ATM and the vacuum of space. | [
"You will need a material for the spacesuit that can maintain standard atmospheric temperature in the vacuum of space - think submarine, but the opposite. Besides that you will need multiple layers of protective material from radiation since you will not have Earth's atmosphere blocking particles from the sun. ",
... | [
"If you were just looking at how much force there is to withstand from the pressure, average male body surface area is 1.9 square meters, so assuming the suit has around that much area, and assuming 101kPa sea level atmospheric pressure, the total force exerted by the pressure would be around 190kN. "
] | [
"Actually, human skin can hold everything in. Some folks at MIT designed a form-fitting spacesuit that uses that very property -- it does ",
" have an air cavity between your skin and the innermost layer of the spacesuit. The only pressurized air cavity is the helmet -- the spacesuit just takes care of radiatio... |
[
"My 6yo wants me to ask you \"Why would a soap bubble retain and, seemingly, amplify the heat of hot water.\""
] | [
false
] | [deleted] | [
"Hmm, not quite. The soap bubbles contain water but are actually made of ",
"soap film",
". The soap film consists of soap molecules which have a hydrophilic and hydrophobic end. The hydrophobic heads all align together with the hydrophobic tails in parallel. This produces a film with a thin layer of water in ... | [
"You're close; the soap bubbles ",
" (hot) water, and water transfers heat much better than air does, so the handle gets hotter."
] | [
"So, not exactly water, but soap film ",
" water. Got it, thanks.",
"This produces a film with a thin layer of water in the middle, and layers of ",
" either side.",
"Isn't that supposed to say just \"soap\" instead of \"soap film\"? "
] |
[
"So a post-apocalyptic question…"
] | [
false
] | Life above earth(ground) is no longer viable But I’ve found a cave to hide in. Unfortunately I’m 200 feet underground in an old mine Can I use mirrors to bring the sun in and grow a garden? | [
"Mythbusters did something similar",
", and the major problem they ran in to is that the sun actually moves across the sky very rapidly, meaning they constantly had to adjust their mirrors in order to maintain lighting.",
"Now, if you had a computer controlled mirror on an actuator that could track the sun, you... | [
"Assuming you somehow made a system for scrubbing the air, I can't see a reason you couldn't grow a garden. Some plants do need UV radiation to survive, but they're the minority."
] | [
"Looks like they used flat mirrors. Better would be a parabolic reflector or Fresnel lens collecting the light into a fiber optic cable, which you could run directly to your underground lair. Plus that would make it a lot easier to keep your cave sealed off from the outside environment."
] |
[
"What are the ramifications of running out of helium?"
] | [
false
] | [deleted] | [
"It's more to do with the technical uses for which we apply helium. It's used for all sorts of supercooling applications, from medical MRI machines to scientific equipment like mass spectrometers and even the Large Hadron Collider.",
"Also, we're not running out of it, the problem is that the US has had enormous ... | [
"You'd have to fill lighter-than-air vehicles with something else, like hydrogen. That should be fine, though. "
] | [
"If we were to run out of helium, or at least got to the point where it was not economically viable to continue to use/harvest helium, are there other elements that could take its place in the applications we currently use it for today?"
] |
[
"If a beam of light passed by in front of you, is there any way to detect it without intercepting it?"
] | [
false
] | Let's say for the sake of argument that you're in the vacuum of space, and you have whatever instruments available that you might need. Now a powerful laser passes in front of you, perpendicular to your field of view. Without actually collecting any of the photons, would there be any way to tell that they had just pass... | [
"It depends on what you mean by \"intercepting.\" If your only requirement is that you can't \"collect\" the photons, then yes. You can utilize processes that interact with the photons without absorbing them. For example, if you shine light tangential to the surface of a conductor and very very close, with sensitiv... | [
"because once the light hits the background, it reflects back so that our eyes can intercept them."
] | [
"What method do they use to observe the particles in the classic double-slit experiment? Im likely terribly wrong but doesn't that reply on non absorption in order to support Heisenbergs uncertainty principle?"
] |
[
"Will putting the end of the garden hose underwater slow down the rate at which the pool fills?"
] | [
false
] | Is there a difference between letting the water fall into the pool from above the water line? | [
"Assuming constant pressure at the source, if you lower the hose end below the surface of the water, you add hydrostatic pressure, but you also correspondingly lower the elevation (static) head. Therefore the flow is equal.",
"Pressure at hose end = pressure from source + static pressure. Static pressure = elevat... | [
"The discharge pressure will affect the flow rate, yes, assuming a constant-pressure source. Keeping the end of the hose in the air ensures that the discharge pressure is atmospheric; submerging the end adds the hydrostatic pressure of the pool, meaning that the flow rate will decrease. ",
"Now, you're not like... | [
"Nope, it might in an insignificant manner increase the flow rate. ",
"Lets take the source of the water and assume it is in a tower 15 ft in the air. This 15 feet causes the pressure due to gravity to push the water out the hose. Now, you are trying to fill a pool above ground that is 5 ft tall. If you hold the ... |
[
"When we die, do all our cells die aswell?"
] | [
false
] | null | [
"Yes, all of our cells eventually stop metabolic activity once they no longer have oxygen and glucose. Then, all the organic matter in our bodies will eventually become part of another organism through decomposition. Even the mineral components of our bones will eventually decompose unless they are fossilized under... | [
"No, but they still have requirements to stay alive. Transplantatiin windows vary depending on the tissue/cell type. ",
"Corneas",
" can be harvested 24 hours after death and transplanted two weeks later. There are ",
"cancer cells ",
" that are still alive decades after the patient died. "
] | [
"Not all of them can, but there is a famous line called ",
"HeLa Cells",
" after the patient that had them, Henrietta Lacks. "
] |
[
"Why is it that when I get sick my mucus changes color?"
] | [
false
] | [deleted] | [
"Yes, but swallowing it also isn't particularly bad either, your stomach acid will kill most things"
] | [
"Its full of [hopefully] dead bacteria and their various secretions along with White Blood cells."
] | [
"Green mucus is often a sign of bacterial infection of your sinuses. Be sure to consult a doctor if it doesn't clear up within ~7 days or so. Being a frequent sufferer of sinus infections, they suck ass."
] |
[
"Is there any validity to this bedtime calculator, which calculates when you should go to bed based on sleep cycles?"
] | [
false
] | I saw this earlier, but having somewhat limited knowledge in the area of sleeping and its effect on the body, thought I'd better check it out with . | [
"The precision is way too high. I've heard of sleep cycles like this, but there's no way everyone has sleep cycles of the exact same length."
] | [
"To elaborate:",
"In humans, each sleep cycle lasts from 90 to 110 minutes on average (wikipedia article on sleep)",
"If you sleep for seven hours with a relatively short cycle of 90 minutes, you'll have gone through 4.667 cycles. If you have a cycle that's just a tad slower - 95 minutes - you'll go through 4.4... | [
"Yes, it has some validity. Almost everyone has a consistent pattern of brain activity when they sleep, called the sleep cycle. ",
"Here is a graph of a typical sleep cycle.",
"I recommend the detailed ",
"wiki article",
" on sleep. We know a lot about what happens, and why it's important to sleep."
] |
[
"Is getting oxygen from water more space efficient then a compressed tank of oxygen?"
] | [
false
] | I was searching on Google about how the ISS gets their oxygen up there, and it looks like they get it from separating water. My questions is, does using water to make oxygen give you more oxygen then you would get by compressing oxygen in a tank of the same size? Why do they use the water method? | [
"If you had a 1 L tank of water you have about 55 moles of water and if you used electrolysis to split all of it you would end up with about 27 moles of oxygen. In comparison to have a 1 L tank that holds the same amount of oxygen gas it would need to be compressed to about 40 atmospheres (600 psi). You could cer... | [
"Its also a considerable fire hazard. If you pass pure oxygen over an ember thats been created by an electrical short or what have you, you'll get a fire. "
] | [
"Potentially, but also remember that electrolysis produces hydrogen and oxygen rather than breathable air. While venting off the H2 isn't that hard you need to get a lot of nitrogen from somewhere. If you are bringing down 80% of the gas you need as compressed nitrogen it doesn't make as much sense to bring a who... |
[
"How much non-essential amino acids does the body produce?"
] | [
false
] | [deleted] | [
"I think it's 11 might want to double check that "
] | [
"Depending how you count them, I have come to understand that there are 8 Essential, 8 Non-essential, and 4 semi-essential. The 4 semi-essential being Histadine, Tyrosine, Arginine, and Cysteine. ",
"This question might be asking about the actual amounts produced of the amino acids. "
] | [
"Oh shit, I could have worded this so much better. What I meant was how much of a single amino acid does the body produce."
] |
[
"How do some predators know the vulnerable spots of prey animals?"
] | [
false
] | I'm thinking here of big cats, such as lions and leopards, but I'm sure this occurs in non-feline predators, too. In most nature documentaries, you see lions taking down a zebra by going for the neck, and then sometimes holding the zebra's mouth and nose shut to stop its breathing. How do lions know to do that? Eons of... | [
"A little bit of both really. It's instinct for most creatures to protect their head and neck, it's not too big of a leap for a cat to connect that as a weak spot on all animals.",
"Legs kick, hard to get a good grip from most other angles.\nIt's just the most sensible point of attack, that would be simple to lea... | [
"Do researchers know much about how instincts work neurologically? I mean, some instinctual acts are pretty high level, more complex than reflexes. So are animals born with neurons in certain locations connected in certain ways to give way to instinctual actions? "
] | [
"Predators do have instinct for how to behave in a scenario but a large portion of their behavior is learned. For instance, mountain lions have to learn that they can't attack the top of a porcupine (a painful lesson for youngsters). There are also behaviors that are passed down via tradition which may seem like in... |
[
"Would it be possible to combat retrograde Amnesia by memorizing life details as facts beforehand?"
] | [
false
] | [deleted] | [
"I don't think so.",
"Your memory of an event isn't necessarily what actually happened anyways. Every time you access memories, those memories have a tendency to change. We can have a constant and accurate transmission of science, for example, because we record those memories in a non-altering form.",
"Basicall... | [
"From what we do know about memory, autobiographical/episodic works differently than knowledge-based memories.",
"Plus, you'd have to start trying to memorize as facts well in advance of RA. But I don't think anyone plans on being amnestic. "
] | [
"That's interesting. As far as I understand process memory is preserved in retrograde amnesia so I imagine you could still write your signature even if you didn't remember your name."
] |
[
"Does water come to a boil faster when the lid is on, or does it not matter?"
] | [
false
] | Also please explain why... with both the layman and non-layman language, if possible! Thanks so much! | [
"As the water is heating up, the most energetic water molecules are able to evaporate and travel away from the water. If there is no lid, these hottest molecules escape, and the energy used to heat them is lost. If the lid is on, then this heat can stay in the pot, and the water will boil faster. You can try thi... | [
"With the lid off, a lot of heat escapes through the open top. With the lid on, much less heat escapes. Leaving the lid on brings water to a boil much faster."
] | [
"The lid, if it's metal, also reflects thermal radiation back down into the water. But I suspect that this isn't a big gain when compared to preventing escaping hot air and vapor.",
"Also, note that until the lid heats up, it's ",
" the boiling by taking up heat while allowing very cool water to drip back down... |
[
"In a space suit, in a vacuum, in a donut-shaped space station ala 2001 A Space Odyssey, will I continue to float freely when the station spins up? Or will I enjoy an artificial gravity?"
] | [
false
] | If the station has air in it, it seems that would eventually send zero-G objects towards the outside of the donut as the station rotates. But without air, is there any force to act upon a zero-G object floating in the corridor if the station's axis relative to the object's position doesn't change? | [
"Perhaps it is more precise to say that you will continue to float freely so long as you do not contact the sides, ceiling, or floor of the space station. Every time you touch any part of the spinning station that contact will impart to you some motion tangential to the rotation of the space station. Eventually, wi... | [
"If you were floating inside the toroid, then... another way of looking at it, is, the toroid is whirling around you. Or, you are flying around the inside of the toroid (and the universe is whirling around it outside). ",
"But if you are attached to the inside wall, then that becomes your reference frame, and f... | [
"If the air is rotating at the same speed as the station walls (which it would be after a while), then wind resistance would act to bring you to the same speed as well. Eventually."
] |
[
"Over 7000 people survived being infected during the SARS epidemic of 2002-2004. Has there been any research into the long term effects of the virus among this population? Is “Long-SARS” a thing like Long COVID?"
] | [
false
] | null | [
"\"Postviral fatigue syndrome\" or \"chronic fatigue syndrome\" (CFS) are typically used as a more general name for this sort of condition, and it can be triggered by almost any viral infection (including the common cold and the flu). There's no reason to believe that SARS would be any different. It's debatable whe... | [
"Regarding ME/CFS being similar to SARS Long Covid - ",
"This is recently being called into question.",
"https://molmed.biomedcentral.com/articles/10.1186/s10020-022-00548-8",
"Long-COVID has been compared to Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), which is an overwhelming fatigue that is... | [
"I emailed the author of the 2011 paper in 2020, and found that no further followup was done on these patients - they did not get better - just that the money dried up and blew away.",
"I note that the 'depression' in the papers title, common with longcovid studies (and chronic fatigue syndrome) uses improper sca... |
[
"Are there any stars in retrograde orbit around the galactic center?"
] | [
false
] | null | [
"Since galactic rotation is not solid body rotation, but rather composed by the \"average\" motion over all it's stars, we expect some stars to be counter rotating just by pure statistics. The most direct evidence thereof is scant because measuring distances to stars and their full 3D velocities is very hard. Howev... | [
"Think about scale: if the center of our galaxy harbors a supermassive (e.g. 1e6 Msol) black hole, than its radius is around 1e6 km. Its sphere of influence, the region within which the gravitational \"tug of war\" is won by the BH and not the galaxy, is double that around 2e6. Thats the scale on which an accretion... | [
"Wouldn't the whole accretion disk end up rotating all in the same direction, due to the way it gets formed and how elements in the disk interact with each other? ",
"If not, why does it form a disk in the first place, couldn't it be a sphere? "
] |
[
"How long does it take genetic traits like eye shape or skin colour to disappear?"
] | [
false
] | Assuming that the trait is no longer needed, how long would it take to vanish from humanity? | [
"Traits do not disappear simply because they are not needed. There needs to be some sort of selection against them. Either the trait must be detrimental to the species, or a population within the species must develop a new trait that will out compete those of the population which lack the trait.",
"Early humans w... | [
"Thanks, very informative!",
"Does breeding between different races effect anything?"
] | [
"Yes. See ",
"this post",
" for some info on that"
] |
[
"How do ice crystals grow upwards from a frozen surface?"
] | [
false
] | I hiked out to a frozen lake this weekend and when I arrived there were 1 1/2” thick sheets of ice along the outside of the lake’s rim that had ice crystals which appeared to grow upwards. My best guess would be that at night when it’s cold enough and starts to rain, as water approaches the cold surface, it freezes (al... | [
"Well my hypothesis is that is where all the moisture in the air is going and it just happens to form like that due to hexagonal freezing pattern, this is supported by all the crystals being at 60 degree angles from the surface of the ice or about. ",
"This video isn't the right answer but it is also interesting ... | [
"Thank you for a thoughtful answer! "
] | [
"also, capillary forces and surface tension might help water creep upwards? not sure, can an expert chime in?"
] |
[
"Are there any animals that start out bigger and get smaller as they age?"
] | [
false
] | I couldn't really think of anything, and google didn't turn up any relevant results, just things about brain size. | [
"There are a few species of frog, such as the ",
"Eastern Dwarf Tree Frog",
", whose tadpoles are larger than adults."
] | [
"Many insects do.",
"Aquatic insects are frequently much heavier in their nymphal, pupatic or larval forms, lighter as emergent adults, and then lighter still towards the end of their short lives in their \"spinner\" form.",
"Craneflies",
" are a good example. Their larval form is about the size of a cigarett... | [
"Male angler fish atrophy after attaching themselves to the female. "
] |
[
"When during the evolution of life did asexual reproduction turn into sexual reproduction between two different sexes?"
] | [
false
] | Evolution states all life started as single celled organisms that asexually reproduced... Well, how did asexual reproduction turn into sexual reproduction between two different genders? please answer, I am very curious :) | [
"I work in this area.",
"Oddly enough, sex has evolved independently multiple times. As far as when, shortly after eukaryotes emerged as the dominant fauna on earth ~1.5 billion years ago. ",
"The why and how is much more complex and still being debated. Some organisms were sexual and then \"lost sex\" such as ... | [
"Well, on the cellular level bacteria can exchange genetic information through the use of pili (tubes connecting one bacterium's innards to another's). It is likely that these forms carried into early eukaryotes, then into protists. ",
"Plants (descendants of green algae [protists]) have different sex gametes, ... | [
"Interestingly, the ",
"wiki article on the evolution of sexual reproduction",
" has only a ",
"short section on the origin",
" that mentions four different theories:",
"TL;DR: no one really knows"
] |
[
"How does the touchscreen of a mobile work?"
] | [
false
] | [deleted] | [
"Thank you for the answer!"
] | [
"Thank you for the answer!"
] | [
"Capacitive touch screens are one type of touch screen.",
"The conductive layer is ",
" the glass, below another protective surface. This protective surface must allow electrical charge to be transferred from the conductive layer to your finger or an appropriately charged stylus, on touch.",
"How is the chang... |
[
"(Biology) What individual particle in my body has been continuously contained inside me the longest?"
] | [
false
] | From the moment I was conceived, what cell or structure formed first which would have remained alive and unchanged in me until now? | [
"I'd put my money on the strands of DNA in some of your neurons stayed in you from mid-way through your womb-time. If you want to go further, and if you're a girl, some of your eggs probably have the most pristine (least no. of divisions) DNA in your body that were closest to stuff that was part of your early embry... | [
"If you count contaminants, there are some metals that are pretty hard to get rid of. If you had two plutonium atoms in your body at birth, chances are they're both still inside you. I'm not a physiologist, though",
"http://en.wikipedia.org/wiki/Biological_half-life"
] | [
"Sorry, you're confusing two concepts: biological half life and nuclear half life.",
"The body naturally eliminates things over time, and for most things the rate at which they are eliminated. That's more or less the function of the kidneys. The rate at which most things are eliminated is proportional to their co... |
[
"How can our tongue still taste sweet, salty, spicy and sour when our noses are plugged, but not flavors of the food?"
] | [
false
] | I'm sure as a kid, you would sometimes plug up your nose in order to avoid the taste of that horrible broccoli. I know that the reason this works is because your nose is necessary in order to detect the chemical "flavor" of the food, hence why plugging your nose makes it easier to fight that gag reflex, But why doesn't... | [
"Taste buds (which are all over the mouth) can detect:\nSweet\nSalty\nSour\nBitter\nUmami\nAll other flavour comes from the smell of the food, which is detected in the nose, which is why plugging your nose works for these, but not the taste"
] | [
"the two senses run along different nerves (olfactory tract and facial nerve primarily) and are put together into a cohesive experience in an area of the brain specifically meant to integrate sensory input (hippocampus)"
] | [
"Taste buds contain nerve endings with receptors on them that act as chemical sensors, activating when they bind with sweet/umami/etc. chemicals. The \"spicy\" sensation is also detected by nerve endings, but via a different receptor type called Transient Receptor Potential Vanilloid 1 (TRPV1), which isn't generall... |
[
"How does hydrogen have 4 bright emission lines at the same time but only one electron?"
] | [
false
] | I understand about energy levels, transitions, etc. However, with one electron how is it doing all those transitions at once? | [
"One electron in one atom isn't undergoing all of these transitions at once. When you look at an atom's emission/absorption spectrum, you're looking at a time average over a lot of atoms. Check ",
"this",
" out, it quotes the lifetime of the excited state in the 2P-1S transition as 1.6 nanoseconds. If you could... | [
"Things always seem simple once someone explains them to you well. Thanks a bunch."
] | [
"I'm not sure I get the question, but it seems to me that perhaps you don't fully understand the workings of energy levels.",
"First, hydrogen doesn't have just four emission lines - it has infinitely many. However, only a few of them are in the visible part of the spectrum. Perhaps this is what you're referrin... |
[
"Why does solar output fluctuate?"
] | [
false
] | I have been reading about prehistoric climate change and it seems that changing solar forcing has often been a very important factor. What causes these various increases and decreases in solar radiation? | [
"Solar output is not the same as solar forcing.",
"Solar output, as received on Earth, is called ",
"solar irradiance",
". It changes very, very slightly in a cycle (0.05% roughly every 11 years). Any cycles beyond these have only weak or indirect evidence.",
"Solar or ",
"radiative forcing",
" is the d... | [
"From ",
"NASA",
", ",
"The average intensity of solar energy reaching the top of the atmosphere directly facing the Sun is about 1,360 watts per square meter, according to measurements made by the most recent NASA satellite missions. This amount of power is known as the total solar irradiance.",
"A 0.05% f... | [
"A 0.05% fluctuation is about 1 Watt per meter squared",
"Moreover, it's important to note that Earth's temperature does not scale linearly with the amount of incoming solar radiation. The amount of radiation an object emits scales as the temperature to the 4th power; the converse is that the temperature of an ob... |
[
"Ask Anything Wednesday - Engineering, Mathematics, Computer Science"
] | [
false
] | Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical post? No question is too big or small for AAW. In this thread you can ask any science-related question! ... | [
"I have often heard the debate - is Mathematics invented or discovered? If you believed in the latter, it would imply that Mathematics is intrinsic to Nature.",
"If you subscribe to this opinion, how would you explain a concept like Complex Numbers existing in nature? Are Complex Numbers just a theoretical constr... | [
"This really is philosophical in nature, but I generally subscribe to the belief that math, science, engineering, etc... are just our ways of modelling the phenomena in our existence. "
] | [
"The key lies right here:",
"how does a collision at constant velocity have a Force?",
"If you have a collision, you are not experiencing constant velocity anymore. The moment you hit something, you begin to slow down (Or speed up I guess, if something hits you from behind). It is the acceleration that happens ... |
[
"Is it possible for a planet to be made almost entirely of water/liquid?"
] | [
false
] | Let's say its roughly the size if Mars and the only non liquids are meteorites that haven't quite corroded yet. What might a planet like that look like?I'm especially curious towars the center. Would the center remain a constantly boiling core? | [
"We have 2 mostly water planets in the solar system. Uranus and Neptune. Obviously these aren't mars sized, but they do give us some ideas. ",
"For instance, their water core is spinning with enough force that it creates a hydrodynamic effect that results in a magnetic field, but one that is notably off center. S... | [
"The problem with getting a planet of pure water is that planet-forming nebula generally contain very little water, initially. The current model for water formation is that rocky protoplanets accrete hydrogen gas, which then reacts with oxygen on the surface to form water. The oxygen will generally be bound up in s... | [
"I want to very much know the answer to this question, too!",
"",
"At the very least, it would have to have a water vapor atmosphere (or else, a crust made of solid ice depending on how much sunlight/warmth it gets), since liquid water is not a stable phase in a vacuum.",
"",
"Also, if the ball of water w... |
[
"Why do different people have different colored blood plasma?"
] | [
false
] | I donate my blood plasma a few times a month for some pocket change. I've noticed that my plasma is generally a yellow-orangeish color while other people's vary greatly. I've seen pink, yellow, dark red, orange and many combinations. Does it have something to do with your blood type? Mine has been a consistent color th... | [
"I am no expert and cannot give you a complete answer, but I offer you my $0.02 as someone who works with human blood samples on a daily basis.",
"Usually the factors that determine the opacity and color of the blood include level of hydration, blood lipids, and hemolysis (if any). Hemolysis adds the red tint, an... | [
"Yellow is normal; a funny yellow-brown color means the plasma/serum is icteric and contains bilirubin from hemolysis."
] | [
"Blood typing is pretty complex but it's based on proteins attached to the red cells. ",
"http://en.wikipedia.org/wiki/Blood_type",
" I don't think this can affect colouring but I can't say for sure.",
"You probably already know that blood plasma is the liquid that the red cells and all your other blood com... |
[
"Is there a limit on the \"brightness\" a typical fiber optic cable can carry?"
] | [
false
] | I want to give an example of what I mean: Supposing you are living underground, but you can't just make a hole in the ceiling to get sunlight, can you use fiber optic cable to catch the sunlight on the surface and redirect it to your underground home ? And if yes, will you be able to tell the difference ? | [
"As far as fiber optic communication goes, there is a limit. If the power in the fiber is too high, ",
" becomes significant and causes cross-talk between the channels in your wavelength division multiplexing system (and other degredations). But that limit doesn't really apply to illumination applications.",
"B... | [
"You're right, it will stop if you stop supplying power."
] | [
"This is why they don't run at powers high enough to cause fiber fuses. Instead they have optical amplifiers spaced out along the cable to regenerate the signal."
] |
[
"Why don't humans have the telomerase enzyme?"
] | [
false
] | I know cancer cells have this and can divide for ever. Why don't we? | [
"The telomerase gene that lengthens the telomeres is present in humans, but generally is only active in select human cells, ones that need to be able to divide throughout a human's lifetime. ",
"People often conflate telomerase with cells becoming more \"youthful\", but that isn't really the case. Cell DNA accumu... | [
"Humans ",
" have telomerase. ",
"Most ",
" cells express telomerase at low levels in order to maintain telomeres at an equilibrium length. "
] | [
"Telomere length is one of the main weapons the body has to control cancer. A normal cell will get to and through the reproductive age without having to rebuild it's telomeres. A pre-cancer cell will multiply wildly and burn of it's length a lot quicker. If it cannot rebuild it's telomeres it either stops, or dies ... |
[
"What keeps our gut bacteria from eating our live tissues?"
] | [
false
] | According to this our gut bacteria begin the large part of decomposition a few days after our death. So what's actively keeping them from eating us while also allowing them to thrive in our gut? | [
"Our immune system stops them from invading deeper into the body by providing physical barriers, secreting antibodies (IgA) into the gut and sensing and fighting ones that get too invasive. For instance while it was previously thought that bacteria being in the blood was a rare and deadly event, it is actually quit... | [
"Studies have shown that bacteria can circulate briefly in the blood after a bowel movement (~10% of the time) or after brushing or flossing your teeth.",
"That's a little disturbing. I suppose it isn't a problem if it's that common, but I wonder how does it get into the blood? The brushing makes sense (nicked gu... | [
"Between the cells that line the gut, there are inter-cellular junctions (called gap junctions) that form a seal between the cells. These junctions also function as a direct route of inter-cellular cytoplasmic communication. These junctions are maintained by certain proteins, and like all proteins require maintena... |
[
"Solar Flares and CMEs. What can we do to protect ourselves?"
] | [
false
] | So, solar flares and CMEs. How prepared are we for them? Do we have an early warning system? If one massive one happened, would all electronics really blow up? Do our power grids have some safe-guards to protect it from frying? What would happen if I turned off the main switch in my electrical panel and unplugged all ... | [
"We are not very prepared.",
"We do have an early warning system.",
"Even now, the center's Bogdan said, the most damaging emissions from big storms travel slowly enough to be detected by sun-watching satellites well before the particles strike Earth. \"That gives us [about] 20 hours to determine what actions w... | [
"Have there been any electronics (even wristwatches) in the north and south poles destroyed during stronger solar flares in recent years? Do Arctic/Antarctic research teams put everything in Faraday cages? "
] | [
"Can I unplug the battery connectors from the car battery to protect car electronics?\nThis would do nothing.",
"How would this do nothing? Do CMEs damage electronic equipment if it is unplugged/uncharged?"
] |
[
"Can humans sing chords?"
] | [
false
] | Can we create multiple frequencies at once, in order to form a chord? Can other animals create multiple frequencies? | [
"I don't think it's technically a chord, but some people can sing a tone and an overtone simultaneously. It's called throat singing and is practiced in various places in the world.",
"One example: ",
"http://en.wikipedia.org/wiki/Inuit_throat_singing"
] | [
"To be technical, they are multiple different notes, since they are all being expressed at once and are all resonating at different frequencies. ",
"But in every day life, unless it's coming out of a computer, every note we play on an instrument has overtones and harmonics, so we have colloquially state that a \"... | [
"http://www.youtube.com/watch?v=0M3YFK3sJ54&feature=related",
"Throat Singing Example",
"-edit I forgot to mention that the throat singing starts at :35 so you don't think I gave you a BS video"
] |
[
"Is there anything that duplicates the effects of phosphorescence (the stuff that lights up in the sea)?"
] | [
false
] | Basically something that you can put in water that emits light when you stir it around. I know it's a weird question, but... anybody? | [
"The \"phosphorescence\" of the sea is a type of bioluminescence caused by marine invertebrates utilizing the pigment luciferin and the enzyme luciferase. There are many species that utilize bioluminescence via these molecules. One well-known example is the firefly. ",
"As for \"something that you can put in w... | [
"So is there any way to recreate that?"
] | [
"A glow stick utilizes chemiluminescence, which is different from phosphorescence. "
] |
[
"If I had a space jetpack, how much force would I need to single handedly move the ISS out of orbit and hurtling into the unknown just by pushing it?"
] | [
false
] | [deleted] | [
"You need to give the ISS approximately 2.7 x 10",
" joules of energy for it to escape the Earth's gravity. Assuming that you have 1000 km to push the ISS, you would need 2.7*10",
" newtons. Or roughly 6 million pounds of thrust."
] | [
"Pretty close to what I got too.",
"The ISS is currently orbiting the Earth in a Low-Earth-Orbit (LEO, as it is commonly called) at an altitude of ~353.5 km.\nThis makes its semi-major axis ~6731.5 km. To exit earth's orbit we have to do what's called a ΔV burn.",
"ΔV = Vesc - Vo is our equation, where Vesc = ... | [
"I may be wrong, but the Newtonian equation for the gravitational force between two objects is:",
"F = (g x m1 x m2)/r",
"where F is force, g is the gravitational constant (6.6726x10",
" Nm",
" /kg",
" ), m1 and m2 are the respective masses of the two objects and r is the radius between the two objects.",... |
[
"Why do certain things that shock/scare us give us the jitters/shock which basically makes us useless and other things give us super strength(hysterical strength)?"
] | [
false
] | In this a man who would normally have the strength to pick up the bike by himself has a crash, gets the jitters and suddenly becomes unable to. While in other instances of scare/shock we're able to in some to lift cars off of people trapped under them. What environmental factors go into our subconscious brain from choo... | [
"I was waiting for this to come up. Yeah I agree the video was a bad example, but he took some time to even rock it up into the position where the wheels are touching the ground instead of up in the air. ",
"Basically what matters is that an average man who say could squat 200 pounds normally couldn't after getti... | [
"This happened to me on my motorcycle during an near miss crash with another vehicle. I had the jitters and couldn't immediately lift my bike, it's like my mind was so all over the place I couldn't focus my mind enough to continuously drive my muscles to lift my bike. Strange feeling, the best comparison I can make... | [
"But the jitters make you useless in both fight and flight. My question is basically, why do we get gittery while other times we get super strength(true in both fight and flight)? And on top of that what type of stimulus triggers either reaction and why?"
] |
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