title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Why do fans always always go off-high-medium-low and not off-low-medium-high?"
] | [
false
] | I always hate that I can't tell if a fan is off or not and always end up pulling the cord like 20 times over and over again trying to figure out if it's off or not. Wouldn't it make the most sense to have it go from the loudest and most obvious setting (high) to the off position? Is there something with the design of ... | [
"The issue is overcoming friction when you need to get the fan going. At the low setting might be too weak to overcome the initial friction, even though it will keep the fan moving once it's spinning. Going first to the high setting makes sure that when you turn the fan on, it's able to start spinning. The off-h... | [
"Here is a graphic of how a shaded pole motor is wired",
" including a four position switch. ",
"You can see that the design is very simple and is also cheap to manufacture. There are no start windings or capacitors. Using the high speed (3) setting for start uses the entire winding to deliver power. This is... | [
"Not really. The speed control isn't a gearbox-type thing, it just changes the amount of electrical power going to the motor."
] |
[
"Since potential energy adds to an objects mass, would an object almost infinitely far from a gravitational source have almost infinite mass?"
] | [
false
] | I’m going off of this video here. I have zero background in this kind of thing, just curious. Seems to me if one blocked stacked on top of another block has more mass because it’s higher up, that an object much further away would have even more mass due to its greater potential energy. | [
"The potential energy contributes to the total mass of the system.",
"So say you have the Earth, with mass M, and an object, with mass m.",
"The gravitational potential energy of their interaction is -GMm/r.",
"Assuming the object is at rest in the rest frame of the Earth and is being held at a fixed distance... | [
"The Earth-rock system has a tiny bit more mass than it did before. For a 1 kg rock raised by 1 meter, it's about 100 femtograms."
] | [
"The Higgs mechanism gives mass to elementary particles in the Standard Model, but bound states of QCD (like protons and neutrons) end up having ",
" more mass than the sum of the bare masses of the quarks involved. This extra mass comes from QCD.",
"When people say things like \"All ",
" particles in the SM ... |
[
"In our bodies, do fat cells do anything other than just store energy?"
] | [
false
] | [deleted] | [
"Adipose tissue (fat cells) actually do play an important role in regulating body homeostasis and metabolism through secreting (at least one) hormone(s). Originally, adipose tissue was thought to be only a storage cell for excess fat. However, more recent research has suggested a much larger role for adipose cells ... | [
"Leptin is fascinating and is involved in the regulation of food intake and energy expenditure. Congenital lack of leptin or its receptor causes subjects to experience insatiable hunger and to eat to the point of morbid obesity.",
"People who lose weight and body fat consequently lower the leptin in their bloodst... | [
"To add, the secretion of leptin acts to regulate actions in the brain, more specifically the hypothalamus "
] |
[
"Where does helium in natural gas come from?"
] | [
false
] | [deleted] | [
"Alpha particle decay of naturally occuring radioactive elements, such as Uranium. The alpha particle is a helium nucleus. "
] | [
"http://en.wikipedia.org/wiki/Helium",
"Most terrestrial helium present today is created by the natural radioactive decay of heavy radioactive elements (thorium and uranium), as the alpha particles emitted by such decays consist of helium-4 nuclei. This radiogenic helium is trapped with natural gas in concentrati... | [
"That makes sense, not sure how I overlooked that. I guess the helium probably coincides with various uranium and thorium deposits in sedimentary rock which is why the western United States has a lot of it."
] |
[
"Why is August typically the hottest month for the Northern Hemisphere?"
] | [
false
] | If sunlight is the main source of heat, why isn't June (when the days are longer) the hottest month? Trade winds? Jet stream? Elliptical orbit? | [
"As an initial matter, I believe statistically July is actually the warmest month in the northern hemisphere. ",
"What I'm gleaning from your question is \"why isn't it hottest when the sun is at it's highest northern position on the globe at the Tropic of Cancer on June 21st?\" (I.E., that's when the days are lo... | [
"August tends to have a lot more humidity (in the US and Europe), and that certainly contributes to the general unpleasantness of August. "
] | [
"Thanks! Makes sense. And you're right, according to the almanac, July is hotter by two degrees. August just feels worse, I guess. "
] |
[
"Is space truly continuous?"
] | [
false
] | At places like black holes, does space exist there in a tangible sense? And with concepts like a Planck length, can we still find meaningful things at say ( / planck_length 2 ) or even ( / planck_length x ) as x approaches positive infinity | [
"The Planck length is ",
" - necessarily - a minimum length. It's just the length scale where we expect to need brand new physics to describe how things work. Sure, there are some theories in which space ",
" discrete, broken up into chunks around the Planck length, but there are others in which it's truly cont... | [
"We are here for science, not speculation. Additionally, intergalactic space is thought to contain as few as 10 particles per cubic meter, making your black ice theory rather unlikely."
] | [
"We are here for science, not speculation. Additionally, intergalactic space is thought to contain as few as 10 particles per cubic meter, making your black ice theory rather unlikely."
] |
[
"Why do radio stations occasionally pick up other broadcasts?"
] | [
false
] | Sometimes I'll be driving along and the broadcast will be perfectly clear, but then in a certain area I'll start hearing some other music or talking from another broadcast in the background. Why is that? Also, why are there "dead spots" in areas where the broadcast is otherwise clear? | [
"Shadowing by terrain, or multipath propagation causing fading (direct and reflected signals nulling). Either will cause the desired signal to reduce in strength at the receive antenna. What you hear is when a station further away has a better path to your receiver."
] | [
"The higher the frequency, the greater the shadowing and fading effects. Regular radio is around 100MHz, satellite radio is around 2300MHz. "
] | [
"The higher the frequency, the greater the shadowing and fading effects. Regular radio is around 100MHz, satellite radio is around 2300MHz. "
] |
[
"\"Stir with a wooden spoon.\" Why? What unholy mischief would a metal spoon have wrought upon my pudding!?"
] | [
false
] | null | [
"For jams etc, the trick is that sugars get up to very high temperatures and a wooden spoon is an excellent insulator. I guess silicone stuff would be ok, but I've not used any so don't know how it deals with sustained high temperature. I've certainly seen normal plastic utensils get knackered in hot sugar cookery... | [
"Some metals contain anti-microbial properties which started the belief that a metal spoon or metal cookware would ruin yeast based bread. Silicone should be just fine."
] | [
"So for jams, it's so you don't burn your fingers on the handle. ",
"For yeasty things, a blanket ban on all metals isn't strictly necessary - some would be fine, if you were sure what it was? What are the nasty chemicals? What would they do to my yeast/cake/me? Why do they make cutlery out of the Bad Metals if ... |
[
"What sort of cancer prevention mechanisms are used by plants?"
] | [
false
] | Considering they need sun light to live, it would make sense to assume they are also exceptionally subject to UV light and subsequently to cancer. Skimming through some papers that were only marginally relevant to this, it appears that plants do indeed show reduced incidence of cancer compared to what would be normally... | [
"There are several factors that go into this. They produce sun screens for themselves to protect against the sun, they produce antioxidants to try to mitigate DNA damage, and they have powerful DNA repair mechanisms compared to animals.",
"All of this pales, however, in the face of their anatomical resilience. Pl... | [
"Plants have an exclusive cancer prevention in the rigidity of their bodys. The solid cellwalls and hydrostatic pressure prevent a lot of deseases from moving inside of them. Cancer too is inhibited by this, and is forced to grow localy. As you might guess, that isnt exactly possible for use in animals.",
"Plants... | [
"I believe so yes. There is nothing that will carry cells around. Pardon me if I say anything inaccurate about the spread of cancer. My degree is in plants, not animals and certainly not humans so everything I know about that is in relation to mechanisms that plants have. All the animal knowledge I have is sparse ... |
[
"When someone breaks their neck and becomes a quadriplegic, why doesn't their autonomic system also get affected?"
] | [
false
] | null | [
"Thank you for the info."
] | [
"It can. The condition is called autonomic dysreflexia."
] | [
"It depends on the break. In a cross section of the spinal cord, the sympathetic fibers are more to the middle, while fibers carrying voluntary motor signals are more to the outside. In ",
"this page, look for \"intermediolateral nucleus\"",
", and also figure 3.7. Then figure 3.11 shows where the fibers for th... |
[
"If the Heat Death of the Universe is when everything reaches the same temperature, and all energy is expended, does momentum stay?"
] | [
false
] | And if momentum does stay, then what happens when two objects collide? | [
"As I'm sure you'll notice, I have no actual authority in this subreddit, but I'll have a go.",
"The eventual heat death of the universe is even worse than you think. The universe will (asymptotically) approach absolute zero, meaning nothing will have any momentum, precluding collisions.",
"If the universe were... | [
"2.How would friction play into this?"
] | [
"I'm sorry, I tried to reply to you a few days ago and gave up. Please don't be too insulted, but basically, you know far less physics than I had thought/hoped. I encourage you to keep asking questions, but sometimes the answer is \"You don't know enough to understand the answer to that question.\" Some things are ... |
[
"Is the temporary increase in volume when a material is heated proportionate to that materials specific heat in any way?"
] | [
false
] | Let’s just say for example a 1x1 ft cube of a metal is heated to the point where it physically grows. Is there a relationship between its specific heat and the new volume? Any defined formulas? | [
"Among very specific, highly symmetric, mono-atomic arrangements. Yes.",
"Paper - PDF Warning",
"More broadly, specific heat capacity is defined by several intramolecular factors that confound thermal expansion too much to draw any correlation across different types of materials."
] | [
"The phrasing of your question (\"heated to the point where it physically grows\") makes it seem as though you think that the hypothetical cube of metal will suddenly increase in volume when it reaches a certain temperature. Just to be clear: this is not the case. The cube would gradually expand as its temperature ... | [
"You basically have just described a phase change in matter. They occur whenever there is a discontinuity in a thermodynamic variable (first order phase changes, ie solids, liquids, gasses) or a discontinuity in any ",
"th derivative of a thermodynamic variable (higher order phase changes, ie superfluids, superco... |
[
"How far back in time can a person travel before the atmosphere is considered toxic?"
] | [
false
] | null | [
"Actually, it would make more sense that modern organisms have more derived and novel cellular properties that makes them more resilient to ancestral pathogens. If anything, everything else should be worried about the crazy new bacteria from which they have no protection from."
] | [
"We do okay down to ~16% oxygen... based on ",
"this graph",
" in your link, we might have a bit of trouble breathing down around 250 million years ago, but other than that, almost 400 million looks safe. Of course, that's just looking at oxygen... there's a lot more that can kill us than low oxygen."
] | [
"We do okay down to ~16% oxygen... based on ",
"this graph",
" in your link, we might have a bit of trouble breathing down around 250 million years ago, but other than that, almost 400 million looks safe. Of course, that's just looking at oxygen... there's a lot more that can kill us than low oxygen."
] |
[
"Two people are standing 1130ft away from each other on the outside of a plane that is traveling at just over the speed of sound. Person A in the back of the plane shout a message to person B. How long does it take to arrive/ will it arrive at all?"
] | [
false
] | null | [
"if the plane is moving just above the speed of sound, then person A on the back of the plane (outside of course) shouting to person B on the front of the plane will be very disappointed, because that message won't arrive, assuming person B doesn't read lips. the reason for this is, as you may know, sound travels i... | [
"inside the plane, this is just like you said. it's as if they weren't even on a (really long btw) plane.",
"Note that the speed of propagation ",
" depend on height, however, as most airplanes have variable cabin pressure."
] | [
"You should be able to hear your own voice as the sound would travel through your body."
] |
[
"Quantum explanation of Redshift."
] | [
false
] | So, I am slightly confused by red and blue shift. Here is the issue I am having trouble with. Electromagnetic radiation can be thought of both as a wave and a particle. When talking about Doppler shift in terms of electromagnetic radiation, it is easy to think about it as a wave. The problem I am having is understandin... | [
"E = pc. The speed of light is constant to every observer, but the ",
" of a photon is not. ",
"The two situations are the same when you use Special Relativity's equation for kinetic energy: E",
" = p",
" c",
" + m",
" c"
] | [
"the photons which we receive would have more energy than the photons which were emitted by the original source, how is this possible? ",
"The same way a ball that's thrown from a moving vehicle will have more or less kinetic energy depending on whether it's measured relative the person in the vehicle or a person... | [
"The photon and the electron simply differ in their charges under the global symmetries - mass, spin, etc. But they are both particles in the same way."
] |
[
"Does the pressure at the bottom of the ocean affect its freezing temperature?"
] | [
false
] | First, let me clarify something. If I fill a relatively unbreakable container completely with water and place it in the freezer, it won't freeze. This is because water expands when it freezes. Assuming I'm right about that, lets say the water beneath the polar ice cap drops below 0 degrees Celcius. Salinity aside, w... | [
"Let's talk about freshwater, because that's going to make things a little simpler. The key thing is that it doesn't start expanding when it freezes; maximum density actually happens around 4°C. This means that convection will cause the water to 'turn over' so that for lakes and such, the entire body of water nee... | [
"It was my understanding that at 4C, the water molecule takes up the least space possible, while it occupies more space when decreasing or increasing from there. As a result, water at the bottom of the ocean should be about 4C."
] | [
"Water can not stay liquid at just about 0K, no matter the pressure. The ",
"phase diagram of water",
" you mentioned clearly shows this to be impossible. The lowest possible temperature for liquid water is 251K (-22°C) at around 2010bar. At any lower temperature water forms one of its many ice phases or become... |
[
"Why is it that red, blue, and yellow are traditionally the \"primary colors,\" but in optics (TV screens, computer monitors, and rods/cones), red, blue, and green are the \"primary colors\"?"
] | [
false
] | [deleted] | [
"Red, blue, and yellow are simple primary ",
". They are ",
" yellow, cyan, and magenta. Pigments are subtractive colors, not additive colors. Combining them produces a darker color.",
"Red, green, and blue are referred to as ",
" not pigments. Light is additive, not subtractive. Combining these makes the r... | [
"They aren't arbitrary, the colors are chosen to correspond to the sensitivities of ",
"human cone cells",
". This is so they can get the best simulation of the full color spectrum with minimum intensity and only 3 different wavelengths"
] | [
"Also bear in mind that paint mixes differently than ink does. That is, it's not purely subtractive. Which is why we usually end up with red, blue, and yellow as the \"primary\" colours."
] |
[
"Can the side effects of sitting with bad posture be cancelled out with exercise with correct posture?"
] | [
false
] | null | [
"Eric Cressey, a Boston strength coach, writes often about postural correction and so forth and has referenced an idea he calls the ",
"23/1 Rule.",
" The gist is that you may be training appropriate posture during your strength training sessions, but keep in mind that this is only 1 hour out of 23 during the d... | [
"Thanks for the read, did a pretty good job of answering my question and even answered some other stuff."
] | [
"No problem, happy to help. Let me know if you have any other questions about related stuff, I can try to help."
] |
[
"What is the difference between Absolute and relative fitness, when it comes to evolutionary biology?"
] | [
false
] | null | [
"As you say, Fitness (or the hability to both survive and reproduce) may be absolute or relative. Fitness is the average contribution to the next generation made by one single individual.\nAbsolute fitness, is the ratio between the number of individuals with that genotype after selection to those before selection. ... | [
"I just wanted to point out that young wolves are called pups. Wolverines are entirely different animals, which are in the same family as badgers and weasels."
] | [
"Oh, sorry. English is no my mother languaje. The x-men Wolverine, is called \"Lobezno\" here that is the word used to name the wolves' children. "
] |
[
"Do domestic pets (Cats, dogs, etc.) menstruate?"
] | [
false
] | null | [
"No, cats and dogs have an oestrus cycle as opposed to a menstrual one (which is the domain of humans and higher primates) and this involves pretty much exactly the same processes, phases and hormones, except that at the end of the cycle, the endometrial lining (womb lining that has been built up to recieve an impl... | [
"Ahhh, thanks. That explains why I don't clean up my dog's menstruation. Apes, however, menstruate similarly to humans?",
"Edit - Is the parent comment wrong? Why the downvotes?"
] | [
"Yes, menstruation is limited to great apes like chimps, bonobos etc. This wikipedia article actually taught me a few things about which animals do and don't have periods. Interestingly bats apparently do! ",
"http://en.wikipedia.org/wiki/Menstruation_(mammal)",
" "
] |
[
"How does an electromagnetic wave propagate through a vacuum?"
] | [
false
] | I'm in an emag class right now and we have been learning all about fields and waves. I just go along learning all this stuff fine but there is one question that I still don't understand. I've tried looking stuff up online but it's confusing to me. Does anybody know how a wave propagates through a vacuum? It blows m... | [
"Electromagnetic waves aren't like \"regular\" waves - they don't need a medium to propagate in. Rather, an electromagnetic wave in a vacuum consists of self-propagating electric and magnetic fields - a changing E field induces a B field, the changing B field induces an E field, so on and so forth. ",
"You can se... | [
"Thank for the response! just to clarify B is the magnetic flux and E is the electric field, right? I can understand how, once started, the wave propagates off its own energy but what energy is actually being moved? Im not sure if I am actually making sense here. A current down a wire is the electrons moving pa... | [
"E is the electric field and B is the magnetic field. The point is that, in a vacuum, ",
". That's one of the reasons electromagnetic waves are special - nothing is being \"moved\", the electric and magnetic fields themselves are what's oscillating."
] |
[
"When you take the contraceptive pill does it help you stay fertile for longer, seeing as you're not releasing eggs from your ovaries?"
] | [
false
] | null | [
"No. You don't go through menopause \"when your eggs run out.\"",
"Contrary to what our awesome educational system may have told you, at menopause, you still have thousands of primordial follicles that were never ovulated.",
"The cessation of ovulation that occurs at menopause is a result of complex hormonal c... | [
"Op's question is based off one of the overly-simplified lie-explanations they teach sometimes in highschool health classes \"A woman goes through menopause when her eggs run out\" "
] | [
"I don't have the full answer but let me point out that fertility is not only based on the number of eggs a woman has, it's based on a combination of hormones and signals and the general vitality of the woman. "
] |
[
"A thought experiment about light speed"
] | [
false
] | Alright let's say we are an observer, O. EA and EB are photon emitters, and RA and RB are photon receivers. All four of these points are co-linear (and can pass through each other, for ease of the math), and O is not on that line. O, EB, and RB are in the same inertial reference frame B - that is, EB and RB's velocit... | [
"Simultaneity is relative. You're ignoring that, so the answers you get don't make sense.",
"For instance, both of the recievers will measure 1 second until the photon emitted by EB hits them. It'll be redshifted for RA, but it will still hit 1 second later. The problem is, this is 1 second ",
". Because of tim... | [
"I do not like simultaneity problems. They are not my friend and I hate them and wish them to die."
] | [
"Because I'm actually subtly wrong and go look at redshift64's answer.",
"Have I mentioned that simultaneity questions are stupidly difficult"
] |
[
"Why do I compulsively itch things if doing so only makes the problem worse?"
] | [
false
] | null | [
"We can't speculate about this here."
] | [
"What does that mean?"
] | [
"This is not a question that we can answer on ",
"/r/AskScience",
". You can try ",
"/r/answers",
" or ",
"/r/NoStupidQuestions",
" instead."
] |
[
"What is the origin of terrestrial water, in its massive quantity?"
] | [
false
] | [deleted] | [
"Relevant Wikipedia article",
"tldr: We don't know for sure, but most likely a lot of the water existed on Earth when it was created. There is evidence there was liquid water on Earth very shortly after the Earth was formed (4.4 billion years ago). It is implausible that all the water came from comets or other ex... | [
"Good question with the ratio of Deuterium in the water it is believed to have been delivered by comets. H2O is easily formed in interstellar medium. That medium coalescence together to form stars and planets. But also comets."
] | [
"Water is a polar solvent that can function to a useful extent as an acid or base, with a high boiling point and relatively low reactivity. There are lots of other useful characteristics of water. AFAIK, there isn't really another molecule that could take its place. It's speculation, but I think that extra-terrestr... |
[
"Consider a finite square region of Euclidean space."
] | [
false
] | On this grid there lie two points, "travellers". Each traveller starts on a random coordinate. In one turn, a traveller can either remain on the same coordinate or teleport itself to a random one. The goal is for the two travellers to end up on the same point at the same time. What is the optimal strategy a traveller s... | [
"So this is actually a cool thought experiment. Let's start with a finite region with ",
" number of grid points (if it's a 6 by 6 grid, ",
"=36).",
"a) If they have complete knowledge of the other's strategy, they can do two things. Either 1) have one traveler stay still while the other traveler teleports, o... | [
"The probability of landing on a given point is actually 0. The probability of landing in any given region is equal to the area of that region (assuming the given square has area 1). Since a point has area 0, the probability is 0."
] | [
"a) say \"let's meet on point so and so next turn\" then go there",
"b) it is completely random chance",
"c) the chance that they randomly meet is approaching zero"
] |
[
"Is it possible to use small tubes (nano tubes) to achieve strong capillary action to send water vertical to long height's ?"
] | [
false
] | I was thinking then could we not design a dam which pulls back all the water it sends down thus theoretical making a devise that runs forever ( I have just learned capillary action sorry if I got something wrong ) thanx in advance | [
"This is sort of how giant redwoods get water to their tops. The removal of water at the leaves (transpiration) is a big part of the driving force, but the capillary action of the tiny xylem tubes (diameter of around 25 microns) is essential. You're probably not going to get any kind of perpetual motion device out ... | [
"Thanx a lot I was just confused because of scientific paper which said you could pull water to extreme highest theoretical using smaller capillaries "
] | [
"The capillaries ",
" essential to the process, since a vacuum pump by itself can raise a water column a max of about 10 meters. There have been some ",
"interesting experiments",
" with etching tiny grooves in silicon that cause water to run ",
" via capillary action."
] |
[
"On my bike: is it more efficient to pedal fast in a low gear or slower in a high gear?"
] | [
false
] | As there is sometimes confusion: Edit: missed an S | [
"In 'armchair engineering' units you are more efficient in high gear (low cadence), you do not have to 'lift' your leg that often and that lifting doesn't need such a fast acceleration. ",
"In 'real world cycling' units you have to produce energy, with a light load (high cadence) you can produce that from bur... | [
"There are 2 limiting factors, and you have to take them both into account to determine the efficiency.",
"First: there's a limit on how fast you can pedal. So the faster you move, faster you have to pedal, if gear is kept the same. You'll reach a point where you can't move your legs any faster than the pedal is ... | [
"No net work on the object being pushed. There are many tiny pieces of work down throughout your body to generate the force you put on the object."
] |
[
"Is having a conversation with passengers in a car any different than having one with someone on a handsfree device?"
] | [
false
] | There's a lot of hooplah about using cell phones while driving, and some states have banned handsfree devices as well. My question, therefore, is this: If you use a handsfree device that allows you to never take your hands off of the wheel or eyes off of the road, is it any different than conversing with a passenger? | [
"The scientific literature is mixed on the dangers of talking on a cell phone versus those of talking with a passenger. The common conception is that passengers are able to better regulate conversation based on the perceived level of danger, therefore the risk is negligible.",
"http://en.wikipedia.org/wiki/Mobile... | [
"The explanation I have heard is that the brain must use more focus to process a (any) conversation where the other party cannot be seen. Normally, we relate and communicate face-to-face not only verbally, but visually as well. We pick up on facial ticks and body language during a discussion that communicates for... | [
"This is true, but you also need to consider KToff's point that if passengers are present, they can also participate in the danger-scanning process and thereby lower the risk of an accident happening, even if the driver does watch the passenger during the conversation. Would love that citation, anotherjames."
] |
[
"Do mammals have embryonic gills?"
] | [
false
] | Specifically, is there any phase in embryonic development wherein mammals have gills or gill-like structures? As a side question, are lungs, evolutionarily speaking, an elaboration of swim bladders in bony fishes? If not, how are they postulated to have developed? edit: Thanks for the answers guys! | [
"From your lower comment:",
"I seem to recall that, evolutionarily speaking, gills developed into some other throat structure in mammals, like perhaps the jaw and or larynx.",
"Yes, you are talking about the pharyngeal arches. In fish, they further develop into the gill support structure, which gets covered in ... | [
"That doesn't answer either question really. I didn't ask if one developed gills that then turned into lungs, I asked if mammals had gill like structures at any phase during embryonic development. I seem to recall that, evolutionarily speaking, gills developed into some other throat structure in mammals, like per... | [
"That doesn't answer either question really. I didn't ask if one developed gills that then turned into lungs, I asked if mammals had gill like structures at any phase during embryonic development. I seem to recall that, evolutionarily speaking, gills developed into some other throat structure in mammals, like per... |
[
"How does heating in electrical wiring work? I know that in most conductors if temperature rises then the resistance risies and higher the resistance more heat is produced. Shouldn't it create a feedback loop?"
] | [
false
] | null | [
"Ohms law states that the voltage of a circuit is equal to the current times the resistance. ",
"V = I * R",
"Therefore a circuit that runs on 120 V with a resistance of 120 ohms will have a current of 1 A.",
"Now let's say the resistance of the wire is 1 ohm and that a current of 1 A causes an increase in te... | [
"There is no feed back loop as the increase in heat, increases resistance which then reduces heat which increases heat etc etc etc. So basically the cycle will stabilise at a fixed temperature based on the current.",
"There are some materials which reduce resistance with heat but these are used in for certain app... | [
"In metals, the resistance increases with temperature which serves to reduce the current. In an incandescent light bulb, when the filament is cold, the current is high, but as the filament heats, the resistance of the filament increases, limiting the current and reaching an equilibrium temperature which is designe... |
[
"If you were to jump off a cliff on the moon, would you die?"
] | [
false
] | null | [
"Depends on how high it was. Lunar gravity is about 1.6m/s",
" , and there's no air to make for a terminal velocity. Velocity due to constant acceleration by distance is",
"v = sqrt(2*g*d)",
"So if you wanted to find the distance for a certain velocity that would become",
"d = v",
" / (2*g)",
"If you as... | [
"Acceleration due to gravity on the moon is 1.642m/s",
" while on earth it's 9.8m/s",
"So, just like on earth, it largely depends on how far you're falling. On earth, due to the relatively dense atmosphere, humans have a terminal velocity of around 120mph (117-210mph I'm told). Since the moon has no atmosphere,... | [
"the \"terminal velocity\" is equivalent to the escape velocity",
"I see where you're coming from (in that if you fell from infinity your velocity would be the escape velocity for that position), but I don't think it's really correct to phrase it that way: it's not \"terminal\" in any way, and if you dug a hole t... |
[
"Question about near speed of light travel"
] | [
false
] | [deleted] | [
"Oh come on, sending a spaceship to another star is perfectly possible. If Voyager was heading in the right direction, then at some point it would reach a star. I know you're pulling out the \"it's an impossibility, so science shouldn't answer this question\" line, but that doesn't apply here. That attitude certain... | [
"From the viewpoint of Chicago, the only thing that matters is the distance and velocity of the train. If it's travelling 1000 miles at 100 miles an hour, it will take 10 hours to cross that distance (regardless of the clocks in the train, we'll get there in a second).",
"So if you want to send two ships from her... | [
"From the viewpoint of Chicago, the only thing that matters is the distance and velocity of the train. If it's travelling 1000 miles at 100 miles an hour, it will take 10 hours to cross that distance (regardless of the clocks in the train, we'll get there in a second).",
"So if you want to send two ships from her... |
[
"Is anyone studying gene therapy? Thoughts for someone considering the field? [Repost from r/biology]"
] | [
false
] | [deleted] | [
"What exactly are you asking for advice about? I think it's a cool field, but right now the problem appears to be more engineering related than pure bio related. How do you get the DNA into cells, which virus would you want to chose, etc. The current problems are how to do it in a way where you won't get a huge ... | [
"Gene therapy where you try to change genes in your body is an amazing idea: the last frontier, genetic diseases, can be tackled, potentially! ",
"But what happened? From what I remember what happened eons ago, these things were (a) not very effective (b) not very safe. I am sure you can find wealth of non-scient... | [
"will be a practical solution [...] like cystic fibrosis and sickle cell",
"Before I go on, don't forget about the gene therapy for Leber's congenital amaurosis (",
"PNAS article",
", ",
"NEJM artice",
")!",
"It's just another one of those \"the future is NOW\" sort of things in science -- treating blin... |
[
"Is it anchorman or anchorlady?"
] | [
false
] | null | [
"This isn't a question regarding science, we don't care about what people's titles are."
] | [
"and you're not a scientist.",
"Perhaps ",
"r/AskReddit",
" would give you what you want."
] | [
"I disagree. I think this is a very important question, and that ask science is the perfect place for it. "
] |
[
"Would an object hovering inside a sealed container contribute to its mass? For instance, would a scale register a wasp hovering inside a tupperware?"
] | [
false
] | [deleted] | [
"We should be talking weight, not mass.\nDepends on how it hovers. Something like a wasp is hovering from flapping wings, and that works because those wings are pushing down on the air. The air, in turn, pushes down on the tupperware and that will have the same effect on the measurement from the scale.",
"If you ... | [
"Relevant Mythbusters: Birds in a truck.",
"Result: Busted - truck does not get lighter when birds flying inside the cage."
] | [
"Yes, a bee has mass, and therefore the mass of the bee is included in the mass of the wasp+air+container system. ",
"I think a more accessible example is a magnet. Consider that the scale it magnetic with its + pole pointing up and a magnet was suspended above with its - pole pointing up. The weight force on the... |
[
"If there was a universe before big bang there may be another before that but how did the first universe formed out of nothing?"
] | [
false
] | null | [
"Your question assumes that the ",
" a universe before big bang, which is not known, and can probably never be known. This may have been the first interation, or the second, or the 400th, and we would probably never know."
] | [
"But how did this universe if this is the first one start from nothing?"
] | [
"Nobody knows. Nobody will ever know (probably). This is (likely) just one of thoes things we cannot have an answer for. There are hypothesis, but they are (almost certainly) untestable."
] |
[
"Does Earth move with constant velocity?"
] | [
false
] | Does Earth experience acceleration or deacceleration? | [
"To add to this, since I suspect OP was more interested in speed than direction, the Earth's orbital speed varies from 29.29 km/s at its farthest point from the Sun (known as aphelion) to 30.29 km/s at its closest point to the Sun (known as perihelion). While the Earth is getting closer to the Sun (from early July ... | [
"Because velocity and acceleration are vectors, they have direction and magnitude. Simply because they are changing direction as we orbit almost circularly, we are always accelerating."
] | [
"Orbital velocity depends only on orbit's radius. No orbit is exactly circular so the speed always varies. But Earth orbit's shape is very close to a circle, its eccentricity is 0.0167. So we can say that the speed is almost constant."
] |
[
"If you are 1/6th your weight in water (on earth), are you also 1/6th your weight in water on Mars (or any other planet that has different gravitation)?"
] | [
false
] | null | [
"The buoyancy force is equal to the displaced fluid weight. So therefore,",
"where m is your mass, g is the local gravitational acceleration, d is the fluid density, and V the volume of displaced fluid. The weight ratio for you on either the Moon or the Earth is then,",
"This ratio doesn't depend on the surface... | [
"Absolutely. The apparent weight of an object with mass M submerged in water is Wapp = g(M - rho * V) where g is the local gravitational constant, rho is the density of water, and V is the volume of the object. W (\"true\" weight) is, of course Mg. So Wapp/W = g(M - rho * V) / Mg = 1 - (rho * V/M).",
"Basically, ... | [
"No, mass and weight being different should not be confused. In any case you misread OP. He/she is asking about buoyancy."
] |
[
"Does an amputee's necessary daily caloric intake lower? What about a paraplegic?"
] | [
false
] | null | [
"you're hitting on the right idea, but in the wrong direction. Someone with a prosthetic actually has to work a significant amount more than a person with an intact body. They have to compensate in balance for every action. Additionally even though advances have been made with the weight of a prosthetic, it is stil... | [
"At rest, the majority of your calories goes to your brains and organs, not your limbs which are mostly muscle and use energy mostly during strenuous tasks. Walking doesn't really count - I mean you only burn a couple hundred calories by walking for an HOUR, so imagine the use at rest.",
"So to answer your quest... | [
"Interesting insight, but you'd have to account for exercise too when computing the total daily demand. If an amputee walks on one leg, does that cost him more energy (to say, climb the stairs, walk (jump) around) and does that eventually level out?",
"Right after the amputation, your basal metabolic rate (energy... |
[
"What is the efficiency of riding a bicycle versus running / walking?"
] | [
false
] | On average, how much energy is required to bike a mile? To run and walk a mile? Dividing the two should give a percentage of how much more efficient riding is than running, no? How do different gears play into the amount of energy required to ride a bicycle a specified distance? | [
"On firm, flat, ground, a 70 kg person requires about 30 watts to walk at 5 km/h. That same person on a bicycle, on the same ground, with the same power output, can average 15 km/h, so energy expenditure in terms of kcal/(kg·km) is roughly one-third as much. Generally used figures are",
"1.62 kJ/(km∙kg) or 0.28 k... | [
"The yellow means your body lacks water, likely from the perspiration during your exercise. If you didn't drink more water than usual to make up for it, your body will be a bit dehydrated. As for biking vs. running, my best guess would be a very inefficient running form. Form plays a big factor in how efficiently y... | [
"There are a lot of factors. As bobtentpeg said, the mechanical advantage is one.",
"One thing that cyclists like to boast is that the power transfer efficiency of a well tuned professional grade bicycle is about 98%. That is, 98% of the force you apply on the pedals gets transferred to a push against the road.",... |
[
"How did the Mars Curiosity Rover take this picture of itself with no visible arm?"
] | [
false
] | null | [
"The \"selfies\" taken by Curiosity are actually composite images stitched together from multiple shots. The photos are taken by the \"MAHLI\" camera that is attached to a flexible robotic arm. In the stitching process, the part of the arm that is in the shot is edited out, because each shot would contain the arm i... | [
"It's actually a combination of a several different pictures taken by Curiosity's arm. They create a pathway for the arm that will take each pictures with the second Curiosity rover that stayed on Earth. Once they got the pathway done, they send it to Curiosity on Mars so it can take each pictures. After that, they... | [
"Engineering"
] |
[
"What are the dangers of smoking, say, 1 or 2 cigarettes a day?"
] | [
false
] | null | [
"You are right that the \"occasional smoker\" and \"social smoker\" categories don't seem to feature as prevalently is studies. You are also correct in stating that the risk of developing lung cancer increases with the amount of cigarettes smoked. ",
"A large European study on 158,488 people who never smoked da... | [
"Much thanks! Perusing your analysis and the sources you provided has been a pleasure, and very informative."
] | [
"What if we step back to even more sporadic smoking? Let us suppose a cigarette or two per month. And how significantly different would a cigar per month be?"
] |
[
"What exactly is that chill I get down my spine sometimes when peeing?"
] | [
false
] | You know, you're standing there, enjoying a nice leak, then you get that tingly chill down your spine. What's up with that? | [
"The following link is not scientific, but due to the lack of available resources on this topic, it provides a nice summary on the current absence of an answer for this topic.",
"http://en.wikipedia.org/wiki/Post-micturition_convulsion_syndrome",
" "
] | [
"came in to find a serious answer... found best answer ever instead"
] | [
"Death."
] |
[
"Can I get strep from sex?"
] | [
false
] | null | [
"Human Body"
] | [
"Human Body"
] | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"medical or safety advice",
"/r/AskScience",
"guidelines",
"If you disagree with this decision, please send a ",
"message to the moderators."
] |
[
"What are the realistic expectations of shooting at a gasoline filled barrel?"
] | [
false
] | Me and a friend were arguing about the reality of gas filled barrel explosions in movies. Why would a barel explode, because of the spark from the bullet against the metal barel? What if you had a plastic barel, so there is no sparks from hot metal-on-metal action? | [
"Leaking gasoline, mostly. Lead bullets, barring unusual circumstances, won't spark even on a metal barrel and ignite the gas."
] | [
"On top of that, gasoline doesn't explode when it's a liquid, only when it's a vapor. Liquid gasoline results in (relatively) controlled burning, so you'd have a brazier and not a bomb even if you used incendiary or tracer rounds."
] | [
"True. We did try some phosphorus rounds once, and they got a tank to light. Just sat there and burned for a while."
] |
[
"Could scientist send one of an quantum entangled pair of particles into a black hole and measure the effects on the other one?"
] | [
false
] | null | [
"The ",
"no-communication theorem",
" rules out obtaining any information about a particle from only having its entangled partner."
] | [
"Well, it's true that entangled particles aren't necessarily identical, but that's not really what the no-communication theorem is about. It's more that there's nothing you can do to one particle of an entangled pair to cause anything that a person with access to only the other particle will detect. So if you have ... | [
"It depends. Some things will break or at least degrade the entanglement (making a measurement, letting your particles interact with a noisy environment, etc). You can do certain other things that will leave the entanglement intact, though. And you don't even have to do the same thing to both particles. An example ... |
[
"Do you think it would ever be possible to \"tow\" a uninhabitable earth like planet, into the Goldilocks zone of a star?"
] | [
false
] | Not to sure of the methods that could be used. But it was just a random thought. Taking a planet, somehow moving it into a habitable zone. Edit: I don't have enough knowledge to keep up a conversation with this, nonetheless it is interesting. Thanks for the responses! | [
"You mean to ",
" an object of Earth's mass from rest to 1 m/s. That's an important difference; moving the Earth at 1 m/s requires no energy (Newton's first law).",
"But that calculation doesn't really settle the issue at all, since the gravitational field of the Sun is so important. So for example to move the ... | [
"The Goldilocks zone which we currently occupy is gradually moving away from the sun as it gets hotter. It will therefore become essential for us to move the Earth along with it to avoid being baked. Fortunately it can be done using a large asteroid or comet to steal gravitational energy from Saturn and deliver i... | [
"Here's some light reading for you, a fair bit of which is quite relevant: ",
"http://qntm.org/destroy"
] |
[
"Do Black Holes last forever after they've been created?"
] | [
false
] | null | [
"No. Black holes emit Hawking radiation, which reduces the mass and energy of the black hole. Unless it is gaining mass at a higher rate than it is being emitted the black hole will eventually dissipate. "
] | [
"Hawking radiation becomes a factor only in the extremly distant future. One can calculate the wavelength, at which the maximum of hawking radiation lies. This is solely dependent on the mass of the black hole.",
"By applying wiens displacement law, the temperature of the black hole is calculated. Turns out, the ... | [
"In case anyone's wondering, current models predict that the supermassive black holes at the cores of galaxies will last for about 10",
" years before dissipating."
] |
[
"Can a gas be heavier then a fluid?"
] | [
false
] | I was wondering if there is a combination of a gas and a fluid where the gas is heavier then the fluid. So if they are put together the gas will go on the bottom and the fluid on the top. | [
"Gas is a fluid. Do you mean liquid? In that case there is no gas that is more dense than any known liquid. ",
"There is a state of matter called a supercritical fluid that has some gas like properties and some liquid like properties."
] | [
"Yes, I misread your comment as was playing fast and loose with my claim. There are no gases that will be heavier than a liquid under the same physical conditions. You can't float liquid helium on xenon just short of its critical point, they don't exist at the same temperature and pressure.",
"Upon looking furthe... | [
"The density bit isn't quite true. Supercritical fluids have densities intermediate between gases and liquids, but there is a sharp density change. There is no point (edit: ie, no pressure and temperature) where a known liquid has a density less than a known gas. They differ by around two orders of magnitude."
] |
[
"What are the differences between Nusselt number and Biot number?"
] | [
false
] | These two values are so confusing since they share the same mathmatical expression. To my understanding, a Nusselt number is defined as h_fluid L_characteristic/k_solid. However, what does the difference in K value leads to? | [
"Nusselt number tells you whether conductive or convective heat transfer dominates across the fluid-solid interface. Biot number tells you whether significant thermal gradients will develop inside a solid by telling you the ratio of heat transfer away from the surface of a solid to heat transfer within the solid.",... | [
"Thank you so much for the clarification!!!!"
] | [
"In my experience, Nusselt number I use for heat exchangers, because fluid convection dominates, the empirical relations developed over the decades then let us calculate the heat transfer coefficient of various flows such as in pipes, etc.",
"Biot number tells you if you can handle a body as a lumped-sum model wi... |
[
"Could science ever truly bring back an extinct species, such as the Tasmanian tiger or similar? If so, why hasn't it been done yet?"
] | [
false
] | null | [
"The first big problem here is getting enough high-quality DNA out of a tiny, ancient blood sample. To start with, DNA is a pretty fragile molecule. When exposed it will start to break down in a time-frame on the order of days, and you're talking about millions of years. The likelihood that any ancient mosquito sti... | [
"It has already been done on an extinct species of goat: ",
"http://www.sciencedirect.com/science/article/pii/S0093691X08007784",
"Granted, the last of this species only died in 2000 and cellular samples had been gathered and carefully preserved. ",
"If I am not mistaken, the biggest hurdle in such an endea... | [
"Is not possible to extract the genetic material from a mosquito entombed in plant sap that, perhaps millions of years ago, sucked the blood from the species you are trying to bring back?"
] |
[
"How do plants prevent UVB damage (sunburn) to their DNA?"
] | [
false
] | [deleted] | [
"Here is a relevant ",
"paper",
" on the subject (pdf warning!)",
"Basically,",
"(1) They don't completely prevent UVB damage, and damage to cellular components, including DNA, does happen in plant cells to varying degrees",
"(2) However there are mechanisms in place to partially prevent this, such as hai... | [
"Its also really handy that the stuff thats really in the sun tends to fall off every year. Or every 7-15 years if its evergreen. And bark is not live tissue."
] | [
"The phenylpropanoid pathway is involved in this. ",
"paper",
" it makes phenolic componds which can absorb UVB. This is really cool because the evolution of this pathway is thought to be tied to the evolution of plants moving out of water. Giving them better and better UV protection until they could survive o... |
[
"Does gravity have a wavelength?"
] | [
false
] | [deleted] | [
"Gravitational waves have a wavelength, yes. Static gravitational fields do not."
] | [
"A rotating sphere probably wouldn't produce anything. While technically mountains and valleys on earth would, they are negligible. In orbital mechanics, bodies can be simplified to a point mass. As such, points cannot produce angular momentum, Via ",
"shell theorem",
".",
"Now an orbiting body, definitel... | [
"That was for anomalous B-mode polarization in the CMB that would lead to evidence for inflation. There's a bunch of extra stuff in that theoretical setup beyond the bare concept of gravitational waves. Orbiting stars lose energy in precisely the way that they would if GR's predictions were correct, and I don't thi... |
[
"Why do white dwarfs take so long to cool?"
] | [
false
] | After a planetary nebula, the white dwarf behind is only a few thousand kilometres in radius and is no longer producing thermal energy from nuclear fusion, so how does it take billions of years for one to cool to a black dwarf? | [
"It's kind of like the same reason that big animals retain warmth better\nin cold climates than small animals: they have more bulk retaining heat\ncompared to surface needed to radiate heat.",
"A white dwarf just doesn't have much radiating surface compared to the\nbajillions [1] of tons of super-hot star stuff i... | [
"You're probably already fairly familiar with the three noteworthy methods of heat loss: contact, convection, and radiation.",
"In this case we're looking at dense material, and the matter there isn't really being ejected like in a main sequence star via solar wind and the like.",
"So there's no contact with an... | [
"The white dwarf has a lot of heat energy in it because it's so massive; think of it as roughly kT per atom, where k is Boltzmann's constant and T is its temperature. On the other hand, its luminosity ",
"L = SurfaceArea* sigma * T",
"where sigma is the Stefan Boltzmann constant, is not so big because, althou... |
[
"Why the long period of antibiotics?"
] | [
false
] | Why do we have a long period of antibiotics as opposed to having one big dose and getting it over with? | [
"I think the responses by the other posts are really not accurate.",
"The correct answer is that sometimes a single large dose is enough, as in the cases of uncomplicated urinary tract infections. In other times, a single large dose is inadequate.",
"The correct treatment of a bacterium relies on a few factors,... | [
"This is an excellent explanation. I would add another side of the story, however. ",
"In a lot of cases, a long duration of antibiotic treatment also has to do with minimizing the selection of antibiotic-resistant bacteria from whichever infection that you are treating. ",
"Antibiotic resistance, as you may kn... | [
"We don't necessarily have long periods for antibiotics in all cases. For example, we treat uncomplicated gonococcal infections with a single dose of ceftriaxone and azithromycin. We can also treat uncomplicated UTIs with a single dose of fosfomycin (though this is less common than the typical course of Bactrim or ... |
[
"Can a credible source please explain what is going on with the European (or global if relevant) bee population? If so, what are the predicted (non-sensationalized) consequences? And why aren't the entities responsible being shut down permanently?"
] | [
false
] | Here is just one of many articles that has come my way over many months. However none of the sources seem all that credible... so if an expert in the field could please shed some light on what is /really/ going on... I'm sure a lot of us would appreciate it. Thank you. Article: | [
"I believe most of the problem was thought to be from systemic insecticides, specifically those using neonicotinoids. An extremely popular one of those is Thiamethoxam, which is made by Sygenta. Bayer has a lot of work with those types of insecticides too. France, I believe, already banned a lot of systemic insecti... | [
"I don't have any expertise in this area but there is a fair amount of literature on the subject, from what I have read a lot of people are looking at a rise in invasive parasites (specifically Nosemi bombi and Crithidia bombi).",
"This is probably compounded with loss of habitats and floral abundance and some of... | [
"Wasn't the consensus that while Bayer may be involved in the CCD, it can not have caused all CCD?",
"Bayer is not a popular company, partly due to it's history with the nazi's. The thing also is that I doubt sited like the one you linked. They are clearly biased and has the author the qualifications to make thes... |
[
"Is there a scientific field that joins physics, mathematics, computer science and biology?"
] | [
false
] | I ask because that would be the thing I'd like to study in university. I would want to work with artificial intelligence but also with physics and biology research. I'm currently studying computer science in the second semester. | [
"Bioengineering",
"."
] | [
"Computational biology",
"Mathematical and theoretical biology"
] | [
"Neuroscience maybe?"
] |
[
"Inconsistency in burning calories?"
] | [
false
] | One stalk of celery contains 5 calories and chewing, digesting, and absorbing the nutrients takes 8-9. Hence the term, negative calorie food obviously. Why is it then that an m&m, with 10 calories, supposedly requires you to run the course of a football field? | [
"From what I understand in the link provided, running the length of a football field would burn the equivalent of one m&m in calories. It's not taking into account the digestion and excretion of the m&m it is merely using it as a way of making it easy for people to comprehend how much was burnt. "
] | [
"But you burn 70 calories from folding clothes for half an hour. Unless m&ms are actually colorful black holes that require x amounts of calories to neutralize them, i don't see how this adage can ever make sense. Is it simply a huge misconception? "
] | [
"This... was not helpful at all. Detrimental almost. "
] |
[
"Obscuring of tall structure disproves flat earth theory. Is this a valid argument against flat earth? [need peer review]"
] | [
false
] | null | [
"'Planetary Sci.', 'Astronomy', 'Earth Sciences', 'Physics'"
] | [
"'Planetary Sci.', 'Astronomy', 'Earth Sciences', 'Physics'"
] | [
"Such questions are better suited for our newish sistersub ",
"/r/asksciencediscussion",
". Please post there instead."
] |
[
"Why does hot milk soak the cereal faster than cold milk?"
] | [
false
] | I have seen that if I take cereal with hot milk, the cereal absorbs the milk much faster and becomes like wet cardboard in a matter of seconds, while If I use cold milk, cereal remains crispy much longer. By what mechanism, does the temperature affect the rate of absorption? | [
"This guy",
" wrote a book to answer your question, and several others. I recommend you read it if you really are interested.",
"In short, liquids have lower viscosity at higher temperature, so the rate of absorption is faster. ",
"Washburn's equation",
" describes it quite well."
] | [
"Perhaps because the molecules that make up milk have more energy, causing them to bounce around more. This causes them to interact with the molecules in the cereal more frequently than cold milk. Since the cereal becoming mushy is just the result of the milk molecules moving into the cereal, increasing the rate of... | [
"That's basically correct. Molecules move faster (on average) at higher temperatures, meaning higher diffusion rates. ",
"Everything that depends on molecular speeds, such as diffusion rates (Fick's laws), chemical reaction rates (the Arrhenius equation), and so on, have an inverse-exponential dependence of tempe... |
[
"How lethal is it to receive the wrong blood type?"
] | [
false
] | I understand that there is a strong antibody reaction attacking the introduced red blood cells when the wrong type of blood is transfused. How bad are these reactions, and are they typically lethal? | [
"They aren't universally lethal, but they do constitute a medical emergency. Widespread activation of immune responses can have pretty devastating effects on the body, including cardiovascular collapse. Generally the reaction would begin within minutes of administering the incorrect blood type so a minimal volume i... | [
"ABO incompatible red blood cell transfusions are one of the most feared types of adverse reactions to blood transfusions because they can be very serious and potentially lethal. If ABO incompatible blood is given, that means that the patient naturally has antibodies that will bind to the transfused red blood cells... | [
"Followup question: what's the purpose of the antibodies that causes the reaction? Would antibodies to defend against the red blood cells of other humans actually be selected for, or do those antibodies have another purpose that just so happens to cause hemolysis?"
] |
[
"What happens if you throw things at the Sun?"
] | [
false
] | null | [
"Because of the conservation of angular momentum, whatever you deployed from such an elevator would simply remain in orbit. If you launched something towards the sun, it would take a tremendous amount of energy to overcome the momentum it has relative to the sun. It woulds take less energy to propel away from the s... | [
"To the first point, what if you exited orbit first or accounted for that?",
"Not sure I follow the second point. If you’re saying that the Sun is always moving and it wouldn’t be able to catch up, why couldn’t you just lunch it 183 days later when Earth is on the opposite side of the Sun? Then the Sun would be ... | [
"Either way, if you could launch a MASSIVE amount of “junk” at the Sun, could it do any damage to the Sun or otherwise adversely impact the radiation it emits?"
] |
[
"How dire is the situation with bee decline right now? Is it as critical as everyone seems to be making it out to be?"
] | [
false
] | null | [
"I may have a primate tag but I have worked extensively with wild bees. First lets define what a bee is, since most people use this word to define several different kinds of bee. ",
"European Honeybees",
": The female workers have a barbed stinger and when they sting you they do die (the barbed stingers are onl... | [
"The problem goes far beyond the price of honey. Honey bees are used to pollinate food crops around the world. Without bees, there would be a lot less food to go around."
] | [
"Not to nitpick but our world is not short on food. We have a net surplus, or at the very least the ability to have a net surplus, (when you include all the food we turn into fuel, booze, meat, etc.) We just have a distribution problem. We have areas that produce way more than they need, and areas that have less th... |
[
"What metabolic pathways are used by hibernating bears (Ursidae) to obtain and utilise energy throughout prolonged periods of seasonal fasting?"
] | [
false
] | Would be great to have an insight to the biochemical processes that allow them to survive throughout winter without running out of energy, as well as removing toxins from the body such as urea. Thanks in advance guys! | [
"This might be a little more than what you wanted, but in vertebrates its generally considered impossible to generate glucose (through gluconeogenesis) from the beta oxidation of even chain fatty acids (predominant). Fatty acids are converted to acetyl CoA from which GTP, NADH, FADH2, and CO2 are produced; however,... | [
"Bears literally don't produce (net) urea during hibernation. Lean muscle mass is preserved, and without extensive protein catabolism, there isn't any nitrogen-based waste to excrete. Energy is provided solely from metabolism of fats, and we have no real reason to believe it is significantly different from ordinary... | [
"Apparently the findings in the paper I linked were later disputed and overall the presence of the glyoxylate cycle in vertebrates is hotly debated in science."
] |
[
"Is there any real advantage to using a base-10 number system, or is the only reason we use it because we have 10 fingers?"
] | [
false
] | I feel like a base-8 system would be much easier to deal with. Since we're pretty much stuck with base-10, is there anything about it that gives it an advantage over other bases? | [
"When choosing a number system there are two factors to consider:",
"Binary is obviously low considering point 1, but numbers grow in length pretty fast. Having a 100-nary system will make numbers twice as short as we have them in decimal, but you'll have to learn ten times as much digit symbols.",
"If we look ... | [
"I have to ask here. Why do we assume that both points are of equal value? It seems to me that 2 is much more important than 1. We can learn all letters of the alphabet in various languages without a problem. We do, however, have much trouble remembering long sequences of numbers. In that regard, proving that base ... | [
"We can learn all letters of the alphabet in various languages without a problem.",
"But, at least for doing math without computers, isn't the number of fundamental results of operations also important? ",
"In addition to the digits, we have to be able to memorize basic sums and products (aka \"the multiplicati... |
[
"Why is HIV only contractible when introduced to your blood, and not when you ingest it?"
] | [
false
] | [deleted] | [
"It's important to note that HIV can't infect any random cell in the body. HIV only infects immune cells and, as such, cannot propagate in areas where those specific cells aren't present (for instance, your stomach). The virus only propagates when it escapes into the bloodstream through a sore or a cut in the mouth... | [
"It is my understanding that studies have found very, very low concentrations of HIV present in saliva, which means that it is theoretically possible (but impossible in practical terms) for someone to swap spit with an HIV+ person and contract the virus, as long as they had some kind of open cut or sore in their mo... | [
"Put very simply, HIV infects only immune cells (T cells) which are generally only found in the blood. By sharing drinks you are only (usually) sharing saliva, but sharing needles will involve sharing blood, and therefore virus particles."
] |
[
"When I look in a flat mirror from 1 foot away, do I see myself as someone would see me from 1 foot away, or do I see myself as someone 2 feet away would see me?"
] | [
false
] | I'm having a hard time figuring out if - because the light travels from me to my reflection, then back - the perceived distance will be doubled. Any explanation much appreciated! | [
"You see double the distance, or two feet. ",
"https://c6.staticflickr.com/5/4094/4924679557_01de06cfe8_b.jpg",
"This is because the \"virtual image\" light rays seem to be coming from the same distance behind the mirror."
] | [
"2."
] | [
"You to the mirror... one foot.",
"The mirror to the virtual image... one foot.",
"So you are seeing yourself as two feet away. Does that help?"
] |
[
"Large Hadron Collider Data Files?"
] | [
false
] | I often see pictures like this one in popular news and non scientific articles about CERN and particle physics. I assume it is supposed to represent the view straight on looking into the tunnel as two particles collide. My questions are, is this really a representative data file? Meaning, would a physicist actually loo... | [
"The yellow towers around the outside represent hits in the muon detectors.",
"The yellow towers represent energy deposits in the calorimeter. The picture doesn't show any detector elements beyond the inner detector (just the visualization of the calorimeter energy deposits just outside the inner detector). "
] | [
"The yellow towers around the outside represent hits in the muon detectors.",
"The yellow towers represent energy deposits in the calorimeter. The picture doesn't show any detector elements beyond the inner detector (just the visualization of the calorimeter energy deposits just outside the inner detector). "
] | [
"Cool, thanks. So it sounds like the image I posted is constructed from a data set, but the image itself wouldn't be something a physicist would analyze. It's more for fun."
] |
[
"Why Carbon Dioxide is an inorganic substance?"
] | [
false
] | null | [
"I'm not a chemist, but I did my fair share of orgo in university so I'll take a crack at this. The exact definition of what an organic molecule is is kind of subjective and seems to be historically based in many cases (basically, there's a paradigm people subscribe to that may or may not be representative for ever... | [
"Semantics mostly.. really carbon is carbon amd lifes gonna get its hands on it, hence the photosynthesis/calvin benson cycle.",
"Technically Organic chemistry really implies theres a carbon and hydrogen involved. Hydrogens and carbon atoms have similar enough electronegativities where those bonds are pretty damn... | [
"for all intents and purposes, consider it organic if you want. carbon tetrachloride is regarded as an \"organic solvent\" even though by mass it's mostly not carbon, has no C-C or C-H bonds, no chains or rings, and (hopefully) isn't found in living things (as far as i know). it's a distinction without a difference... |
[
"Is dehydration additive?"
] | [
false
] | By this I mean, if some individual were to exclude a small fraction of their required daily hydration (be it animal, human -- excluding plants, for now) does that individual eventually reach critical stages of dehydration (analogous to a plant)? It seems like an easy answer if a cow were only to get 1/2 the proper dehy... | [
"Not really. Your body is a homeostatic machine, so it will reach a new homeostasis - as long as the water debt is not so severe that you perish.",
"Here's a paper",
" detailing some of the changes in the kidney due to persistent vasopressin elevation from chronic mild dehydration.",
"And ",
"here's a pape... | [
"No, not in the pure sense you describe. To a limited degree your body can adjust to a range of hydration levels, by conserving moisture. So there is no exact right amount. Nor, on the other hand, can you be 99.9% dehydrated and then not die because you avoided the last 0.1%; you will just die slightly slower."
] | [
"A somewhat related question, if I may: why is dehydration so decoupled from thirst? I'd guess it would be a pretty important survival mechanism to be ",
" thirsty when you are dehydrated, and yet it doesn't really seem to be the case..."
] |
[
"What bodily structures allow insects to physically move?"
] | [
false
] | I study wildlife and fisheries at university but I've never taken an entomology course. What structures in insects would be the equivalent to muscle, tendons, ligaments, etc that allow animals to move? Like for example, what structures/mechanisms allow the stinkbug crawling up my wall to move its legs? Is it similar to... | [
"Insects (and other arthropods) have muscles",
", just like humans, and they work in the same way - by being connected to two different parts of the skeleton, contraction of the muscle causes a joint to move. The difference is that since the skeleton is on the outside, the muscles connect on the inner surfaces of... | [
"This is a really awesome, in depth answer. I'd just like to add that when I took insect ecology (we didn't go deeply into systematics/morphology really) my prof. Compared it to hydraulics. Since all insects have an open circulatory system, they've evolved to use their hemolymph kind of like a hydraulic fluid to mo... | [
"Wow that's really interesting, thank you for explaining that and providing me those resources! "
] |
[
"Could computer circuits be considered an artificial equivalent to a neuron in a brain?"
] | [
false
] | Or if a computer had the same number of circuits as neurons in a human brain could it function like one? | [
"On the theoretical level the brain is clearly a finite computer and thus we should be able to model it with sufficiently complicated circuits. Furthermore, a lot of ongoing research is looking to find computational structure in the brain that we could replicate more simply than modeling every single interacting pa... | [
"Here's an article about it"
] | [
"When i said yes or no and on and off i was referring to computer logic.",
"Human beings have a \"maybe\" switch. They also prioritize possible choices as in deciding on what to do right now i could go to bed, have a beer, respond to you or watch TV.",
"In fact in a minute i will get a beer and continue to resp... |
[
"The best theory seems to be that our universe currently is expanding. I have read several articles about it, but I havent found one that explains what its expanding into. Or what is outside the universe?"
] | [
false
] | I have a feeling its a very dumb question and I have missed something basic, but I have tried to google the answer without much luck. I can find algorithms for how its expanding, how long, speed etc, and also theories on how far it will expand and what will happen eventually. Now if I think about it like a balloon (pro... | [
"It's not expanding into anything, it's just that the distances between any two given points is getting greater over time."
] | [
"Alex Filippenko explains a few theories in this nice lecture ",
"\"Universe, Multiverses or Parallel Universes\""
] | [
"I will check that out thank you. "
] |
[
"How does safety glass work?"
] | [
false
] | One little break and it separates into thousands of relatively dull little pieces? It's ingenious... But how??! | [
"This is incorrect, annealed glass is cooled slowly to reduce stress. Tempered glass (AKA Safety glass) is rapidly cooled on the surface so its dimension is locked into place then the interior cools slower and tries to shrink as it cools. Since the surface is already cool the interior pulls the surface into compres... | [
"The surface of the glass is under compression while the interior is under tension. If you break through the compressive layer into the tensile layer you release a huge amount of energy and the entire sheet basically explodes. Those little pieces are not dull but small cubes are safer than big heavy shards.",
"To... | [
"Most laminate glass is not tempered, as it would be inconvenient if your windshield got hit with a rock and the entire panel shattered at once. Your windshield is actually the only major piece of glass on your car that is not tempered."
] |
[
"How fast are we moving away from the recently observed galaxies 13+ billion light years away?"
] | [
false
] | Recently, in a paper , the observation of galaxies 13+ billion light years away were observed. The light from these galaxies was thought to have been released when the universe was only 600 million years old. My question is simple, how is that possible, and how fast must we be traveling apart for light to take that l... | [
"This topic is not as easy as it seems.",
"The expansion of space does not \"count\" as objects moving away from each other, there is no upper bound on the rate at which space may expand, which sounds somewhat weird, but it has the effect that very distant objects can and do seemingly move away from us ",
"fast... | [
"The thing you're missing is that the space between us and the galaxy is expanding. The light from that galaxy is speeding towards us at the speed of light. However, we're sort of a moving target, in that ",
".",
"When the galaxy's light was emitted, say the spot in space we currently occupy was 1 million lig... | [
"Well, the existence of gravitational waves or gravitons has not been directly proven as far as I'm aware, but if they do exist they would probably behave as light waves and photons do, the waves would \"stretch\" as the space around them expands, just like the redshift effect of lightwaves. I'm not sure what you m... |
[
"Can someone hydrate themselves exclusively on beer?"
] | [
false
] | Two separate but related questions: Can someone hydrate themselves indefinitely on beer alone? If you are dehydrated and water is not available, is beer in any way helpful? Assume for both questions the alcohol content is approximately 6%. | [
"When a person drinks beer, large amounts of water enter the body; that lowers the concentration of metabolic nutrients, and because of the effect of ADH impairment, an equal amount of water does not leave the body in the urine. ",
"http://www.montana.edu/wwwai/imsd/alcohol/Jace/Final%20Drafts/kidney.htm",
"Caf... | [
"As long as you were also consuming enough salt so that your cells retained water and balanced out the diuretic effect. "
] | [
"How much would that be?"
] |
[
"What is the evidence for and against the diet that is supposed to \"alkaline\" one's body?"
] | [
false
] | This is the movement claiming that certain foods will have either and "acid or alkaline" effect on the body. | [
"There is no evidence whatsoever that this is a real thing. The pH in your body, particularly your blood, is very tightly regulated through the action of an enzyme called carbonic anhydrase, which is capable of reversibly converting carbon dioxide into carbonic acid/carbonate/bicarbonate.",
"If pH levels in your... | [
"I would add to this that every food you eat is first exposed to the highly acidic environment of your stomach, before it is passed into your intestines where it is exposed to bile (alkaline pH) and other chemicals that neutralize the stomach acid. ",
"Whatever pH your food has going in your mouth is irrelevant. ... | [
"Just chiming in purely to add the weight of numbers to this: it's complete and total nonsense that directly contradicts everything we've learned about biochemistry. It's like asking \"what is the evidence for and against the idea that pandas can soar gracefully through the air on moonlit nights?\" It's such an i... |
[
"What is the most poisonous substance that our own body creates?"
] | [
false
] | null | [
"Formaldehyde is far more toxic than acetaldehyde (ethyl aldehyde). In fact formaldehyde will kill you. This is why drinking methanol is toxic is because it is metabolized to formaldehyde. A fun fact is that if someone has accidentally ingested Methanol, you can save their life by having them drink a significant am... | [
"Competitive inhibition!"
] | [
"My old neighbor, a guy in his 80s, was a doctor back in the 50s. He worked with dialysis and they would often have homeless alcoholics come in, claiming to have been poisoned with methanol in order to be treated with liquor. "
] |
[
"Are there storms with lightning over Antarctica? If yes what happens when a bolt of lightning strucks the ice?"
] | [
false
] | null | [
"Thunderstorms are unlikely over Antarctica because thunderstorms generally require instability and moisture, both of which are rare at the polar south. If you live where there's snow in the winter, you may have noticed how it rarely, if ever, thunders during the winter. This is the reason why. Even during the war... | [
"Water is a very bad conductor of electricity to the point that pure water is a good electrical insulator. Seawater is not pure though - it has large quantities of dissolved ionic species within it which conduct electricity quite well. Ice does not have these, salts are rejected from the crystalline structure of ic... | [
"Salts are not locked in water crystals, they are removed as it freezes. This is what creates such high salinity in the waters around ice forming regions and helps to drive the thermohaline circulation. ",
"It’s slightly more complicated than that: when ",
"frazil ice",
" crystals form, salt accumulates into ... |
[
"Do we know what the Earth was like prior to the asteroid collision that formed the Moon? Could complex life have lived here?"
] | [
false
] | I've read the Earth was still molten, but I don't know if that's the popular consensus or more of a guess. I was wondering how likely it would have been for complex life to have lived here pre-Moon before getting being wiped out by the asteroid. | [
"It merged with the Earth/turned into moon."
] | [
"It's highly unlikely that there was life. The collision happed several hundred million years after the solar system formed. The Earth, at that point, couldn't have supported life.",
"Also it wasn't an asteroid that hit the Earth, it was a planet the size of Mars."
] | [
"You are too generous with your time. The present best estimates for the formation of the Moon is 4.527 ± 0.010 billion years ago (about 40 million years after the origin of the Solar System). The surface of the Earth was quite likely covered by a magma ocean, perhaps with a thin crust of solid material. The only m... |
[
"What happens to aluminum after heating then cooling?"
] | [
false
] | What happens to the properties of aluminum after it is heated to right before its liquid state then cooled down? Do the properties strengthen or weaken? How controlled does this process need to be? | [
"Do you mean \"how do the room temperature properties change after heating and cooling?\"",
"If it's pure aluminum, it won't have much effect at all. If it's a precipitation hardened alloy like the 2000 or 6000 series alloys, heating near the melting point, then rapidly cooling it is a solution treatment. The pre... | [
"Yes, I was meaning the latter. Thank you. "
] | [
"What happens to the properties of aluminum after it is heated to right before its liquid state then cooled down?",
"It softens, turns pink. There is a very very narrow margin where it has a consistency similar to taffy.",
"Do the properties strengthen or weaken?",
"Either of these can happen depending on th... |
[
"How can we reduce the amount of sleep time needed?"
] | [
true
] | null | [
"This has been asked a few times. Every time someone of authority has checked in they said that polyphasic sleep cycles were not good for you long term."
] | [
"Meth"
] | [
"I have a really messed up sleep cycle. It has always been that way for as long as I can remember.",
"I have tried taking different medications, and some work better than others, and the best worked for a few months, then things became really weird.",
"After stressing about it for years, I decided that when I w... |
[
"Where in Einstein's field equations (or other equations if needed) does gravity propagate at the speed of light?"
] | [
false
] | Obviously c is in the equation but it's in the denominator of a term, and it's to the fourth power. How does this translate into gravity propagating at the speed of light/causation? (Relatedly, is it significant that that term has 4 radial rotations about the circle in the numerator and c in the denominator?) Is gravit... | [
"Let's first answer your question about the significance of c",
" in the equations. The Einstein equations can be written as",
"R",
"-(R/2)g",
"+Λg",
" = (8πG/c",
")T",
"The terms are R",
" = Ricci tensor, R = scalar curvature, g",
" = metric tensor, Λ = cosmological constant, T",
" = stress-ene... | [
"As ",
"/u/midtek",
" says, it comes from looking at the Einstein field equations in the case where spacetime is flat plus some tiny fluctuations. These are what gravitational waves are: they're small ripples on an otherwise flat background, i.e., one without any gravity. (This describes spacetime where we are ... | [
"An important thing to emphasize here is that you really do need to do the calculation and be careful about it too, as ",
"/u/Midtek",
" says.",
"For example if you just impose some gauge conditions on GR and look at the equations you will see modes which have superluminal, sometimes even instantaneous, propa... |
[
"Why can't we use magnetism as an \"action at a distance\" force?"
] | [
false
] | I don't have a very good science background, but I know that magnetic forces are based on a field. Why is it not possible to use electromagnets to create some kind of interference with the field in such a way that produces some kind of an action at a distance? | [
"I think you might be confusing instantaneous action at a distance with regular action at a distance. Everything interacts through fields, so action at a distance is how all physics works. Some forces are very short range (the strong force is pretty much confined to the nucleus) but they still operate over finite d... | [
"This is how magnets are used in many applications, for instance the removal of metal from garbage or in mining."
] | [
"This is the principle behind applications such as electric motors, mechanical relays, as well as actuators, and solenoids. These devices use magnetic fields produced by electricity traveling through wires to operate."
] |
[
"What is the most fuel-efficient way to drive a car?"
] | [
false
] | This must have been studied at some point. Let's consider a highway with 70 mph limit and 40 minimum. I often see highways with three lanes of asphalt and one of concrete, the fast lane. Will that affect work done by the car? Also, consider using the AC or heater versus having the window down. Then, automatic versus ma... | [
"Maintain a constant speed as much as possible. Accelerate slowly. Minimize braking, because braking means you'll have to accelerate again later. In other words, don't tailgate. ",
"Peak fuel economy for most cars is roughly 55 mph (90 kph) but varies depending on the vehicle. This is why the speed limit in the U... | [
"I'd like some links that show that current fuel economy peaks at 55 mph...Actually, I'd even like to see the old ones."
] | [
"When possible, use engine braking to slow down, because modern fuel injection systems will not use fuel during deceleration."
] |
[
"does the torque required to pop a wheelie change with wheelbase?"
] | [
false
] | I know the basics of a vehicle getting front tires off the ground. Changing the weight balance and guaranteeing a lot of traction. My question is as the title says, torque. | [
"Think about a unicycle. With a wheelbase of zero it requires nothing to tip backwards. ",
"The wheelbase is not the actual issue, center of gravity is. So a car with a long wheelbase but has a bunch of weight behind the rear wheels, it will still very easily wheelie. On the other hand, a shorter wheelbase wit... | [
"Actually it is quite simple and intuitive. The simplest form would be find a point near the front center of the car that you can jack the car up. Now if you placed a scale below the jack and raised the front of the car up you would get a weight in pounds. If you measure the distance from the jack to the ground ... | [
"So is there any way i could calculate what it would take to lift tires, like an equation?"
] |
[
"How much of an effect does gravity have on life development?"
] | [
false
] | What started from an innocent look into the idea of sex in space turned into a complete brain meltdown when I started thinking more about the life cycle in a zero gravity climate. Here's a couple things I was wondering about, that if you have any ideas, theories, interesting articles or anything at all to add, feel fre... | [
"Cellular growth and development in microgravity is very interesting. Given how much the human body changes and/or deteriorates without constant force being applied, one can hazard a guess at how differently a human being might develop if conception and their entire growth cycle occurred sans gravity. ",
"For exa... | [
"I don't think we have good evidence about whether gravity is needed for proper development in utero. Certainly no one has done the experiment with people. Mouse studies seem to give mixed results but I couldn't find a good paper--here's one dealing with a particular stage of early development ",
"http://www.pl... | [
"Say that a child grew up with greater gravity than on earth, would that mean that he/she would develop stronger muscles and bones than children who grow up on earth, or just that he/she would be unable to move and not develop any muscles at all?"
] |
[
"Could combining vaccines cause the body to react incorrectly if only one infection become present?"
] | [
false
] | For instance if you take an mmr and a chicken pox vaccine together. If later on your body is hit with a chicken pox infection would it react in the same way as if you also had measles? Over produce or send chemicals/antibodies to the wrong organs? | [
"The U.S. Advisory Committee on Immunization Practices (ACIP) recommends that MMR and varicella (chickenpox) be administered at the same time starting at 12 months of age. There are no risks to these vaccines being administered at the same time. These are live-virus vaccines (meaning they are composed of very weak ... | [
"Wow I'm sorry but this post is completely terrible, and borderline immoral. The evidence you provided does not at all support the conclusion that it's \"far safer\" to space vaccines out, and reading through what you've cited shows incredible dishonesty. ",
"You completely took the authors out of context here is... | [
"Misunderstood. I'm sorry but you quoted a study and intentionally misrepresented their results. You took a study that had an experiment fluke which they recognized and concluded against your argument and then used the fluke to validate your position. ",
"It's disgustingly to misrepresent the authors of the paper... |
[
"What were those little tubes in old computers and how did they work?"
] | [
false
] | [deleted] | [
"What little tubes? Can you explain it better?"
] | [
"He's probably talking about ",
"vacuum tubes",
" . Rose to popularity as signal amplifiers and stuck around as electric switches with no moving parts before transistors were invented. The only time you see them in use nowadays are specialty audio applications and circuit designers looking to make an visual sta... | [
"Do you mean the little cylinders all over the circuit board? Usually several different sizes?"
] |
[
"Is it possible (however uncommon) for an isotope of the heavier elements to contain zero neutrons?"
] | [
false
] | Also, as these elements would be much lighter (I assume), could you then synthesize materials with them that were much more buoyant than normal materials? (perhaps even in air?) Thanks :) | [
"No. Even two protons (called Helium-2 or Diproton) is too unstable to exist (for long enough to be detected, anyway). Adding more would just make it even less stable."
] | [
"Neutrons are necessary to keep atomic nuclei together. Without neutrons to keep it together via the strong nuclear force the protons would repel each other as they have positive charges and the nuclei wouldn't form. Hydrogen-1 has no neutrons in its nuclei as it only has a single proton and thus it doesn't repel i... | [
"As mentioned, if an atom has too many protons it will undergo beta plus decay. The atom will release a positron and in the process turn a proton into a neutron. This process would continue until the atom had a stable number of protons and neutrons again. ",
"The opposite process, where a nucleus has too many neu... |
[
"How do we know that Vaccines aren't bogus and/or funded by 'big money'?"
] | [
false
] | null | [
"Please see the ",
"vaccines megathread",
". ",
"I'm not working in a pharmaceutical field, and there are a lot of privately held information for science in general, but there is close to no chance that something studied by so many separate organisations can be independently held a secret. It's easy to ignore... | [
"I'm not working in a pharmaceutical field, and there are a lot of privately held information for science in general, but there is close to no chance that something studied by so many separate organisations can be independently held a secret. It's easy to ignore every source remotely related to \"big pharma\", but ... | [
"Look in the thread I linked to first. There are plenty of studies linked.",
"Of course, most of the studies can be linked back to the organisations you stated, but ultimately, that's the reality of things. No one is going to conduct studies with no funding, and those organisations are the most capable sources of... |
[
"What happened to herd immunity?"
] | [
false
] | In the beginning of the pandemic there was lots of talk about reaching herd immunity but as the delta variant ravages throughout the world, it seems that all talk about herd immunity has ceased. Why is that? Or am i just misconstruing the situation? | [
"The proportion of the population that is needed to reach herd immunity is proportional to how effective the virus is in spreading. With Delta the threshold is much higher. ",
"Keep in mind here immunity is not a fixed number. It really means that there are not enough opportunity for the virus to sustain itself... | [
"The herd immunity threshold is ",
"1 - 1/R_0",
"It should also be noted that herd immunity prevents an epidemic but doesn’t immediately stop one in progress.",
"https://academic.oup.com/cid/article/52/7/911/299077"
] | [
"Every disease has an infectivity rate. r0 (pronounced \"R-nought\") is a theoretical number that each sick person would spread the illness to, assuming 100% of the population is susceptible and zero measures are taken to slow the transmission. ",
"This Wikipedia page",
" is a great resource. ",
"The biggest ... |
[
"Novel influenza in 1918?"
] | [
false
] | Was the Influenza outbreak in 1918 a “novel” outbreak like COVID-19? | [
"It's hard to say, the best answer we can provide is \"probably\"",
"Influenza wasn't new, there were flu-like diseases going back centuries/millenia before what we now call swine influenza was identified in 1918. That just happens to be the start of our records, so we call it h1n1. We base all current descripti... | [
"As an aside, the 1918 flu (or descendants of it) is still around today. A researcher dug up bodies from the 1918 pandemic that have been frozen in the permafrost in Alaska and did genetic analyses comparing that flu strain to today's strains.",
"“You can still find the genetic traces of the 1918 virus in the sea... | [
"That’s white Covid is starting to seem like to me, a new yearly flu."
] |
[
"How does the Kepler spacecraft tell the difference between a single large planet making a transit in front of its star and multiple smaller planets doing the same?"
] | [
false
] | I hope this question is clear. I roughly understand how the transit method of detecting extrasolar planets works (observing changes in the apparent magnitude of the parent star). I do not, however, understand how we account for the possibility of two or more other bodies making a simultaneous transit. Wouldn't such a... | [
"Two planets can only have the same period if one is much bigger and one is in the other's Lagrange point. If they have different periods, then we'd see the intensity dropping with different frequency for each one. It would be pretty cool if there was a planet at a Lagrange point, I guess. A Trojan planet.",
"Jup... | [
"At a minimum they require that three transits be observed, which will discriminate between single and multiple planets as well as drastically reduce false positives."
] | [
"Thanks! But how long does Kepler actually look at these stars for? Does it wait for multiple completed orbits? I understand how it would work in that case. It would still possible for two planets to make a transit at the same time even if they don't revolve with the same frequency though, which would be problema... |
[
"How come mouth bacteria doesn't become immune to toothpaste?"
] | [
false
] | null | [
"Does it also deprive good bacteria from food?",
"Is it ok to brush the tongue then?"
] | [
"Does it also deprive good bacteria from food?",
"Is it ok to brush the tongue then?"
] | [
".......... follow the recommendations. Yes brush your tongue. No don’t worry about the good bacteria. You’re seriously considering keeping something rotting in your mouth?"
] |
[
"What is this apparatus?"
] | [
false
] | null | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"Please post ID questions to one of the many ID ",
"listed in our wiki!",
"If you disagree with this decision, please send a ",
"message to the moderators."
] | [
"The link does not work admin"
] | [
"Sorry about that I'll try to fix it later. In the meantime you can try ",
"/r/whatisthisthing",
" ."
] |
[
"Can people with anorexia identify their anonymised body?"
] | [
false
] | There's the common illustration of someone with anorexia looking at a mirror and seeing themselves as fatter than they actually are. Does their body dysmorphia only happen to themselves when they know it's their own body? Or if you anonymise their body and put it amongst other bodies, would they see their body as it ac... | [
"It's important to note that the findings of this study (that anorexics have an impairment in their ability to make accurate judgments about their own body) do not suggest that they have a diminished awareness of their own body, but rather that their awareness of it is skewed. They don't lack information about the... | [
"I don't know about their anonymised body in particular, but there is a study that suggests that ",
"they can gauge other people's bodies more accurately than their own.",
"It would stand to reason that if they couldn't tell it was their body, they might also be able to judge accurately."
] | [
"I found an interesting paper regarding computer-based distortion being used as a clinical tool in the evaluation, research, and treatment of eating disorders.",
"From the ",
"article",
"(warning: links to a pdf):",
"A group of 20 admitted patients suffering from AN participated in an experiment,\nin which ... |
[
"A question about \"junk DNA\"..."
] | [
false
] | As I'm learning in Cell Biology, heterochromatin was once called "junk DNA." It's not involved in transcription, and it remains condensed during interphase. What my professor says, however, is that this portion of the DNA is actually just as, if not more important, than the genes active in transcription. What would mak... | [
"Not sure I agree with the idea that heterochromatin was included under the term 'junk DNA'",
"Let's clarify some things: heterochromatin is a term describing how DNA is packaged. In heterochromatin the DNA is densely packaged around histones, and transcription machinery is not able to access it, regardless of wh... | [
"You have genes that code for telomeres, which are involved in cell replication. But you don't need them all the time, so you regulate them (through various processes, epigenetics etc) so that certain genes are only expressed when they are needed ",
"So you've seen pictures of your DNA in a double helix, but then... | [
"Thank you for the response, and that image of the DNA helices in their knot form is incredibly cool.",
"Can you explain a bit further about epigenetics and how it's related to gene expression? I'm interested in doing research on epigenetics and I'd like to know more about it."
] |
[
"Why are lemon seeds seemingly randomly distributed about the center of the lemon?"
] | [
false
] | Lemons (which I buy from the market) have a high degree of axial symmetry. Rotate them around their major axis, and they're usually pretty similar from all angles. Cut one in half along the minor axis, and the segments are each about the same angular size. The albedo is pretty circular and uniform, too. And then, th... | [
"The seeds that you see are the ( ova? baby seeds? idk) ones that were fertilized while it was a flower. ",
"it starts out in a neat pattern when they are small and inside the flower but the ones that get fertilized are random ( due to pollination ). So, once the it drops its flowers and starts building its fru... | [
"I should start this off by saying that I do not know the answer to your question, but I can speculate. ",
"Questions in seed formation tend to be a huge pain in the neck because we rely on mutants (random or generated) to answer most of our questions. When you generate a mutant you usually get one or two, and th... | [
"Crop geneticist here. Like Xilon-Diguus, I should start off by saying: I don't know for sure. But I can suggest a couple possibilities for how to interpret this observation.",
"---",
"The framework for understanding answers to the question \"why does lemon seed distribution lack azimuthal symmetry\" has to com... |
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