title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"How much speed does the jet engine of an F-18 Super Hornet add to the USS Kitty Hawk [image relevant]"
] | [
false
] | [deleted] | [
"Using values found online for thrust (63.3kN) and mass of the carrier (~80000t), I calculate that the carrier will gain an additional acceleration of ~0.0008m/s",
" without accounting for drag."
] | [
"Basic F = ma equation, rearranged to F/m = a and plugged in the numbers to get acceleration."
] | [
"Basic F = ma equation, rearranged to F/m = a and plugged in the numbers to get acceleration."
] |
[
"Do our bodies send a signal to our brain to wake up when we are cutting off circulation to an arm or leg while sleeping?"
] | [
false
] | I've woken up more than once with completely 'dead' limbs. Does the body know what is happening? | [
"Yes, and no. Let's consider your hand \"falling asleep\". When a body part falls asleep, what is happening is that there is pressure on the nerve innervating that body part. You sleep on your elbow, and can compress the ulnar nerve at the elbow, and the medial part of your hand falls asleep. ",
"Now, the int... | [
"Is there any detriment or chance of permanent damage to sleeping on your arm like that?"
] | [
"If the numbness goes away in a few minutes after the pressure is relieved, not really. If it lingers, you need a decompression procedure. But remember, this is not medical advice, this is reddit ;)"
] |
[
"Why aren't archaea human pathogens?"
] | [
false
] | I'm an undergraduate microbiology student, but I am still pretty mystified by archaea. I realize archaea weren't discovered until relatively recently, but why aren't they more important from a human perspective? Do you think they will eventually be seen as important as bacteria? What's the freakin' deal with archaea?! | [
"That is an EXCELLENT question, and unfortunately there is not a very good answer yet. It's not fully known, but there are some ideas.",
"It has been proposed that because Archaea use different cofactors in their metabolism, eukaryotes don't provide a good \"food source.\" But this isn't completely satisfactory, ... | [
"Although many extremophiles are archaea, not all archaea are extremophiles. This isn't a good reason for the lack of archaeal pathogens."
] | [
"Wow, thanks for the awesome answer! I didn't even know Archaean phages existed. Time to do some reading!"
] |
[
"If a patrticle is executing uniform circular motion under gravitational fprce, then why does it not fall to the center?"
] | [
false
] | So if a particle is executing uniform circular motion, then it will accelerate and acceleration means that it will radiate energy and then come closer to the center and finally fall into it or become a part of it. Why does this not happen? | [
"It does radiate energy. It just radiates so little energy that it's almost impossible to detect, and so little that it would take many lifetimes of the universe before the Earth would fall into the Sun (in fact, the Sun will likely engulf the Earth in its red giant phase before you'd ever notice the orbital decay)... | [
"Quick caveat, it's gravitational waves -- gravity waves are a type of wave in fluids, and are important in atmospheres. It's quite annoying when you work on gravity waves and people mostly think you mean gravitational waves XD"
] | [
"Gravitational Radiation is also called Gravity Waves",
" waves. ",
"Gravity waves",
" are things like water waves.",
"We had many successful detections of black hole mergers and a few neutron star mergers. ",
"Wikipedia has a list",
"."
] |
[
"Why are there drug effects in nature?"
] | [
false
] | Why can some plants be refined to give hallucinigenic, depressant or stimulant effects? How is this a defensive attribute for any plant? I know that we must refine, combine or cause a reaction in plant chemicals to obtain the effects, but why do the chemicals exist in the first place? | [
"Some of the chemicals are toxins used by the plant to defend themselves. Those can have hallucigenic effects for a human, but might not for an animal that happens to eat the plant."
] | [
"Evolutionarily speaking, things like poisons and whatnot work from the ground up. If a plant usually gets eaten by a certain bug and over time develops some sort of a poison mechanism, it only has to be poisonous to that bug, the effects it has on other organisms doesn't matter.",
"In a sense, nature likes to cu... | [
"In addition to toxic effects (like caffeine's natural insecticide effect), many plants may naturally produce chemicals for their own needs, which just so happen to have psychotropic or similar effects in people. ",
"As plants and humans have vastly different body structures, we are affected differently by chemic... |
[
"If the circuit is broken, does the capacitor still hold charge/pd?"
] | [
false
] | if the circuit is set up like this, where the open end is a fly lead which could connect to the other side of the battery, before it does, is there a charge on the plates? is it half the maximum charge (i'm just guessing that the p.d halves and so the charge does too, idk) thanks Battery------Capacitor-------open end | [
"Theoretically, with an ideal capacitor, yes.",
"Practically, no. Capacitors undergo a phenomena called the leakage effect, or bucket effect.",
"Imagine you have a bucket with a tiny hole in the bottom. You start filling the bucket with water, and the hole really doesn't matter because water is constantly comin... | [
"Yes. If its discharged and in an open circuit, it will not charge back up"
] | [
"thank you very much! i have an a level physics practical in a couple days and its about capacitors and this really helps!! So if i want to discharge a capacitor and leave it discharged, i can discharge by putting a wire across it and then leave it with one side attached to the source?"
] |
[
"Is it possible to have animals that are taught skills, teach those skills to their offspring?"
] | [
false
] | Not really sure what to flair this as, but I guess psychology? Like say you teach a bird to use a tool or item to do something useful, will they teach other birds they like and/or their offspring? Or do those learned skills disappear once they're gone. | [
"Orca whales have ",
"learned to hunt seals on icebergs",
" by capsizing the icebergs. They then pass that on to their offspring. ",
"Capuchin monkeys in Brazil are something like ",
"3000 years",
" into their own stone age, again suggesting that these learned skills are passed on.",
"I'm not sure what ... | [
"Some animals will copy each other, some won't. So maybe but not for all species. Crows for example learn to break nuts by droppibg them on the road for cars to drive over them.",
"It's a big difference between dogs and wolves too. If you take 2 wolves and make them solve it but first you show them so solution, f... | [
"Not sure if we're making a distinction between ",
"- the offspring just learn the skills",
"or ",
"- the parents ",
" the skills.",
".",
"Milk used to be delivered to people's homes every morning. It came in glass bottles with foil or cardboard caps, and was left outside the front door. ",
"Bir... |
[
"Why does scalding hot water feel so orgasmically good on poison ivy or hives?"
] | [
false
] | null | [
"It's the same feeling you get when run hot water on mosquito bites. Basically you are stimulating the nerves and overloading them with the hot water. ",
"Source: ",
"http://www.peoplespharmacy.com/2009/08/01/hot-water-for-itchy-bug-bites/",
"Usually you stimulate the nerves through scratching, although that ... | [
"I can confirm the same for eczema (atopic dermatitis). Awesomeness aside, my dermatologist pointed out the heat is damaging to the skin and can do more damage to the skin (depending on temperature and duration of course)."
] | [
"The way you guys are describing this almost makes me want to do it on purpose... :/"
] |
[
"Is it possible to use a commercial motion sensor aimed at mirrors to activate? Given any type of commercial sensor"
] | [
false
] | I've always wondered if the light reflected off a mirror can trigger some of these sensors. You could extend the range or improve on the detection angle quite easily. | [
"Motion detectors might be using ultrasound, where a mirror is of course useless. A detector using Infrared will detect motion in the reflected view, but with the following caveats:",
"transmission of IR light through the coating and glass layer. If the glass absorbs too much IR, range of detection in the reflect... | [
"Actually, ultrasound-based detectors will probably reflect off a glass surface in much the same way. "
] | [
"It will reflect off the surface diffusely, just as from most other hard surfaces, so unless you want to use the mirror to look into an opening with a huge open space all around, your acoustic signal would bounce off other walls just as well and you don't need a special surface for reflection."
] |
[
"I've never been very good with electronic hardware. Is there any chance that I could get an explanation of these circuits?"
] | [
false
] | I'd really like to simple know what's going on in layman's terms. Thanks, in advance. | [
"A) Differential amplifier, gain is determined by the left hand R",
"B) Inverting amplifier, gain=-1",
"C) ",
"http://www.analog.com/library/analogDialogue/archives/39-05/op_amp_applications_handbook.html"
] | [
"B) Inverting amplifier, gain=-1",
"Iff ",
"R2 == R1",
". More generally the gain will be ",
"-(R2/R1)",
" ."
] | [
"i'd look for circuit design software, that would allow you to figure out the working of any design. There's some links on this page for example: ",
"http://www.electronics-lab.com/downloads/schematic/index.html"
] |
[
"How do we know the half-life of things that have the half life of thousands of years?"
] | [
false
] | Im trying to wrap my head around half life, and i trying to understand how do we know that radium has the half life of 1600 years? I understand smaller times (countable times) like time/days (average blahblah) but how is it tested for thousands of years?? | [
"How do you check the speed of a car in km/hr if you don't measure it for a full hour? You measure it for a much shorter period of time and extrapolate, assuming the speed is constant.",
"Likewise, you can measure how much material has decayed over a much shorter period of time, and extrapolating it on an ",
"e... | [
"This answer is incomplete. The measurement is far more difficult than that. Things with short half lives (less than a few years) are easy to measure. Once you get into the longer half lives, things are more difficult. Your sample will not have a large change in activity over time. Thus, the normal way of meas... | [
"Radioactive decay follows something known as ",
"first order",
" kinetics, which takes essentially the same form as compound interest. The net result of that is that the rate of decay is really only dependent on one variable, which is the so-called decay constant (which you can convert into a half-life). The... |
[
"Where does food go when it “goes down the wrong pipe”?"
] | [
false
] | null | [
"Very interesting! So is it possible for a small piece of food to actually make it down the trachea into the lungs?"
] | [
"A little anatomy lesson here, bear with me. In your throat there is a little flap called the epiglottis. The epiglottis closes off your windpipe (trachea) whenever you swallow or eat. (Hence not being able to swallow and breathe). This prevents food and other objects from entering your lungs. (Only want air going ... | [
"Yep! When anything enters the lungs that's not supposed to, it's called aspiration. The consequence is often pneumonia.",
"Check out more ",
"here",
"."
] |
[
"Where do photons go after they enter your eyes?"
] | [
false
] | What happens to them after they enter your eyes? I assume they hit the retina (or whatever part of the eye absorbs light), but then what? | [
"A photon enters your eye and strikes a protein called ",
"rhodopsin",
". The energy of the photon is absorbed and used to cause a chemical change in the structure of the protein. This chemical change kicks off a biological pathway that ultimately results in vision. Ultimately, energy in photochemical systems l... | [
"More details at ",
"http://www.reddit.com/r/askscience/comments/ofv7o/what_happens_to_photons_after_they_reach_my_eye/"
] | [
"No prob!"
] |
[
"How does oxygen affect the environment? Is there any way is does other than keeps things alive through breathing ?"
] | [
false
] | [deleted] | [
"Many ways. It reacts with iron to produce rust aka iron oxide, it gets split by sunlight and reacts to form ozone in the atmosphere. The ozone layer is important for shielding the planet from uv radiation. When somethings burns aka combustion it is reacting with oxygen to form co2 and water."
] | [
"It has shaped the course of history. Because Iron reacts to form Iron oxide, it is not found as pure usable metal but rather as iron ore. If Iron could exist as pure metal than the iron age probably would have occurred much earlier because there would be no need for people to have developed the necessary process a... | [
"It has shaped the course of history. Because Iron reacts to form Iron oxide, it is not found as pure usable metal but rather as iron ore. If Iron could exist as pure metal than the iron age probably would have occurred much earlier because there would be no need for people to have developed the necessary process a... |
[
"Why do British singers seem to lose their accent?"
] | [
false
] | I've heard that this has something to do with old English sounding more like American English today - is that true? | [
"Singing is not the same as speaking. If you take classes on how to sing they teach you to open your mouth certain ways and to breath certain ways. There are more efficient ways to make sound when singing and these are pretty much universal.",
"It's not so much that British singers sound more American, it's that ... | [
"Too true.",
"For those who have not had training though you often see the same effect. Many pop/rock singers historically have not had a ton (or any) vocal training but have learned by example.",
"For example, the excuse put for by the Beatles was that they learned rock & roll by listening to Elvis and other ... | [
"Or even better, listen to some non-English pop songs. The sounds of the words themselves will sound very familiar to you (though of course the lyrical content will be unintelligible). Whether you're listening to Korean-pop, Ukrainian disco, or Billy Idol, each singer uses basically the same uniform ideal vowel and... |
[
"A few questions about entropy on a cosmological scale"
] | [
false
] | [deleted] | [
"Heat death doesn't mean the temperature is approaching zero, it means that the temperature of the universe would become totally \"uniform\". More precisely, there is no energy available to do work (aka free energy).",
"If we consider (global) entropy increase as a fundamental law, yes, the entropy of the univers... | [
"Cool! Thank you, so then, does the question \"what is the temperature of the Heat Death\" have no real meaning?"
] | [
"Heat death doesn't necessarily imply that the temperature of the universe is ",
" uniform, just that there is no ",
". So no, the question is a bit ill-defined. Generally heat death is just considered the maximum entropy state (by definition)."
] |
[
"How did the early astronomers know which planets were closer and further from the sun and in what order?"
] | [
false
] | [deleted] | [
"Annual parallax doesn't actually work with the planets, because they move drastically over a year. You can do parallax with multiple observers or using the rotation of the Earth, but I don't know if that's the way it was done."
] | [
"Well, Mercury and Venus never stray very far from the sun in the sky and are thus typically visible during twilight hours (in daytime it being too bright to see them). Whereas Mars, Jupiter, and Saturn seem to move around the whole sky over the course of several months – half the time they’re on the ”near side” o... | [
"Once you develop heliocentric theory:",
"Planets closer to the sun from Earth can never be seen at \"opposition\" to the Sun, because Earth will never be between them and the Sun. You can never see Mercury or Venus at midnight, only in the early morning before sunrise or in the early evening after sunset.",
"P... |
[
"I've always wondered, if the External Tank on the Space Shuttle was jettisoned after the Shuttle had already achieved a stable preliminary orbit, how did it re-enter the atmosphere to burn up?"
] | [
false
] | null | [
"The final orbit wasn't achieved using the main engines but the ",
"Orbital Maneuvering System",
" instead (they are also used for deorbiting). They are the two smaller cones above the three big main engine cones at the rear of the shuttle. At the point where the external tank is jettisoned, the space shuttle i... | [
"I had absolutely no idea. Thank you.",
"Wikipedia says those boosters had only 300 m/s of potential delta/v in them. If I've learned anything from Kerbal Space Program, that isn't very much at all. Is the orbit just so low that only a little burn takes them into the atmosphere, which does the rest of the work fo... | [
"300 m/s is a fair amount of delta-v for on orbit maneuvering. Dropping from a 400 km orbit (ISS altitude) to something low enough to reenter the atmosphere needs less than 100 m/s delta-v.",
"Yes, the atmosphere does nearly all the work getting you down from LEO velocities to standing still on the ground. This i... |
[
"Why are fevers cyclical?"
] | [
false
] | Sometimes when fighting off a virus, bacteria, injury, etc., the body fluctuates between elevated temperature (fever) and normal temperature. This causes a cycle of chills, sweats, chills, sweats,… Why does the body not maintain an elevated temperature until the “problem” is resolved. | [
"as your body fights off the virus the viral load drops, the fever reduces, the body becomes more hospitable for the virus again, the virus is reproducing in cells teh whole time, the cells burst, the viral load shoots up again, the body responds with more fever. I'm sure someone will explain it in more detail but ... | [
"To add to this, from the perspective of someone with biology training but not medical…",
"It is entirely possible that this is an evolutionary response. Fevers kill the disease and, if they go on long enough, the host. ",
"It makes complete sense that a cycling fever provides the most likely survival of the ho... | [
"It's also worth mentioning that the human immune system is an insane rube goldberg machine where almost every pathway has multiple mechanisms of negative feedback regulation. It's almost universal that when your cells sense a cytokine produced by a viral infection, like interferon gamma, they respond to it (infla... |
[
"Does the velocity of a photon change?"
] | [
false
] | When a photon travels through a medium does it’s velocity slow, increasing the time, or does it take a longer path through the medium, also increasing the time. | [
"I'm of the mind that the term \"the speed of light in a medium\" should be forever abolished. Light does not travel at all through a medium. Rather, an EM wave incident on the boundary between the vacuum and a material INDUCES A POLARIZATION WAVE in the material. It is this polarization wave that is making the ... | [
"This is just one way of modeling the system. There are various other ways to model it, such as the polariton model where a photon plus some atoms together make up a particle (well, quasiparticle) called a polariton. That particle has mass and thus travels slower than c. Here is a nice youtube video with explanatio... | [
"I mention a polariton description in one of the comments but honestly one should really only talk about such a description in certain circumstance. A classical EM wave is not at all a quantum mechanical object, in the language of quantum electrodynamics it's what is called a \"coherent state\", which is a state t... |
[
"How far does a million dollars go in your field of science?"
] | [
false
] | null | [
"A lot of post-docs. There's not really much equipment to buy in math."
] | [
"\"Adding to that, we'll fund your dig for another 5 years..\" - Hammond"
] | [
"That's probably about how much it cost to set up our lab."
] |
[
"Why does milk go bad after only a few weeks, but butter can stay edible for months or even a year refrigerated?"
] | [
false
] | Butter is just churned cream, so I wouldn't think there would be any preservatives acting to keep it fresh that milk does not have (other than possibly salt?). | [
"Water content and salt. Butter doesn’t enough water in it for microbes to comfortably live in there. Salting butter also helps to preserve it by increasing the osmotic pressure on any microorganisms that try to get a foothold. ",
"The bigger issue with butter (and other fats) is oxidation. The unsaturated fatty ... | [
"Butter doesn’t enough water in it for microbes to comfortably live in there.",
"Butter is approximately 10-20% water, so plenty left. However, the water is emulsified - spread evenly throughout the fat as tiny globules - so not readily available for microbiota. Furthermore, it has a low carbohydrate and protein ... | [
"Interesting, I hadn't thought about the oxidation aspect. Thanks for the explanation!"
] |
[
"Since color and sound are both observed as waves, would it be possible to create intervals of color \"harmonies\" (combinations of colors that look good together) in the same way one manipulates tones?"
] | [
false
] | [deleted] | [
"No, not in the same sense as harmonies in sound exists. While there are colors that go well together in the sense that they are aestethically pleasing, this has nothing to do with \"harmonies\".",
"Harmonies in sound stem from harmonics (",
"http://en.wikipedia.org/wiki/Harmonic",
"), i.e. multiples of a fre... | [
"We do have that. Take out a color wheel and pick a color along it. The color on the opposite side is called that colors complement. This premise is used all the time in design(take a look at movie posters. Many will use orange and blue because those are complementary colors)."
] | [
"The color wheel has little to do with frequencies. Blue is near to red, where frequencywise they should be at opposing ends.",
"In that sense, this is not at all like harmonies in sound."
] |
[
"Could all three stars in systems that Gliese 667 C or HR 8832 are a part of be visible from their planets at the same time?"
] | [
false
] | I'm a writer, and I like to have some realism and credibility when developing space-faring systems. I'm asking because dual star systems are visible from the planets. I was wondering, if that was the case, then would all three of a tri-star system would be in the sky at the same time or would it depend on where the pla... | [
"This",
" is probably a pretty accurate representation of what the view would be from Gliese 667Cc. The red dward this planet orbits would appear a little larger than our sun appears on Earth, and the other two stars would be bright enough to be seen in the day, but very small in the sky."
] | [
"Thank you! That was exactly what I was looking for. "
] | [
"Okay, thank you. That also really helps! Sometimes I find really good info online but it's aimed at professionals not at laymen, so clarification on where they'd be during what time of the year is super great info because it helps me plan storylines. "
] |
[
"How can birds sit on the uninsulated cables on power lines without dying?"
] | [
false
] | in our neighborhood there are two uninsulated live wires and then some other insulated cables below them on the power poles. How are birds and squirrels able to touch the uninsulated ones without being shocked? | [
"Because they are not grounded. For electricity to flow, it has to have a pathway to ground or be in the path of a full circuit. When a bird sits on a wire, it's at the same voltage potential as the wire, so no electricity flows. ",
"Check out this video of a lineman who was dropped off on some high voltage wires... | [
"There is no potential difference (voltage difference).",
"For electricity to flow, there has to be a potential difference. In the case of your electric plug at home (if you are in the US), one side is at 120 Volts AC and the other is neutral (0 Volts). The ground is also 0 volts, by definition. ",
"If hypothet... | [
"In basic terms, yes, although it can be a little more complicated with things like arcing through air because of high voltages. I found this link that says more about the subject: ",
"https://en.wikipedia.org/wiki/Live-line_working"
] |
[
"What happened to Acid Rain? Is it still a problem in the developed world? Third World?"
] | [
false
] | Just wondering if Acid Rain is still a problem or have we put measures in place to solve the problem? | [
"Environmental engineer here working in air quality and pollution control. I can cover at least the history of the issue in America. ",
"Acid rain is caused by the release of specific gases (SO2 and NOx) during combustion, mainly the burning of coal. Before the Clean Air Act and the EPA, regulation of these pol... | [
"Worth mentioning the reduction of sulfur in gasoline/diesel/fuel oils. Here in Sweden there aren't any coal plants (other stuff is burned though, including household waste), but smokestack scrubbers and lower-sulfur fuel has reduced the total SO2 emissions by over 95% since 1980. Despite the relatively low emissio... | [
"Sure, and this still happens today. But who pays the imposed fine? The state? The industries of the state? Which state upstream and which polluter in that state is most responsible for the acid rain that fell hundreds of miles down stream? A case like this will be difficult to prove and easy to defend. So, by ... |
[
"Why do organisms who naturally eat rotting food not get sick?"
] | [
false
] | Obviously the bacteria aren't eating one another, but why don't, for example, ants get sick from eating bacteria that would kill us? For that matter why don't mammalian scavengers or vultures? | [
"I know Vultures have highly corrosive stomach acid that neutralizes bacteria like botulism.",
"They also pee down their legs to kill off the bacteria accumulated from standing on rotting bodies.",
"I'm also going to guess that organisms like Maggots, Vultures etc.. have highly evolved immune systems that take ... | [
"Many things that are harmful to one organism are not harmful to another. Simply because rotting flesh is harmful to us, does not make it so for other animals."
] | [
"They also pee down their legs",
"Well that's my favorite new thing I've learned today."
] |
[
"AskScience AMA Series: We have made the first successful test of Einstein's General Relativity near a supermassive black hole. AUA!"
] | [
false
] | We are an international team led by the Max Planck Institute for extraterrestrial physics (MPE) in Garching, Germany, in conjunction with collaborators around the world, at the Paris Observatory-PSL, the Universite Grenoble Alpes, CNRS, the Max Planck Institute for Astronomy, the University of Cologne, the Portuguese C... | [
"Thank you so much for being here to answer our questions. It's very much appreciated.",
"What are the most surprising findings after all these years of hard work? ",
"What effects are the black hole having on the Milky Way?"
] | [
"In some sense it is always surprising how well the theory and the preditions of Einstein's General Relativity work.",
"\nEven close to one of the most extreme objects we can imagine, a supermassive black hole, the laws of physics work and govern the motion of the stars. Despite beeing 100 years old, Einstein's t... | [
"Did the results rule out any alternative gravity theories or parameter spaces?"
] |
[
"Do neurons respond to certain states, or to changes in states?"
] | [
false
] | I heard somewhere that neurons do not respond to states, but instead to the transitions between states. I googled the question, but I am not really sure what I am looking for. If this factoid is true I would love some more info/sources. I am partucularly curious what the implications of this would be vs. a state based ... | [
"Both. Some neurons are excited by a static stimulus (like an image of a face), while some neurons respond to \"changes in state\", like the neurons that detect motion. "
] | [
"There are neurons specialized for both. Search for onset and sustained response neurons. There are many examples in the auditory and visual systems."
] | [
"Thanks! That seems like what I was looking for."
] |
[
"Why is the standard (or most common, at least) tuning fork tuned to A, and is it just a coincidence that the frequency (440hz) is such an even number?"
] | [
false
] | [deleted] | [
"The relevant Wikipedia article is ",
"this one",
"."
] | [
"Our perception of what sounds sharp/flat is heavily influenced by our cultural upbringing. Western music is primarily based on the 12 tone scale (C, C#/Db, E, etc.) while eastern music cultures such as Bulgarian, Indian, and Chinese often use scales with more notes or smaller spacings. These scales sound flat or s... | [
"We needed a standard, so it got set to something nice and even. It's an arbitrary number."
] |
[
"If a container of saltwater is placed in an electric field, will the positive and negative ions all move the the edges?"
] | [
false
] | null | [
"Yeah, you can read about it here: ",
"http://en.wikipedia.org/wiki/Double_layer_(interfacial)"
] | [
"The simplest way to think of it is that positive moves one way and negative moves another, but you're correct. In systems of charged colloids (like charged beads in salt water), the layer of ions around the charge negates it."
] | [
"Oh in that case a paper detailing stationary electric fields in ionic gels says that there will be a gradient that forms as a result of the field, as expected this gradient is exponential and crosses through a neutral area in the middle",
"But I think that was already said ",
"http://journals.jps.jp/doi/abs/10... |
[
"Why is beet juice a good addition to de-icers from a chemical stand point?"
] | [
false
] | I want to ask why the addition of beet juice to de-icers is beneficial from a chemical point of view, for example adding it the calcium chloride and salt brine then spreading it on roads to keep them clear of ice. | [
"It's not quite what you'd get out of a juicer that is being mixed with salt. It's more like molasses that's obtained by boiling down sugar beet extract. Sugar, just like salt is capable of lowering the freezing point of water. It is sticky, so it has the advantage of not running off roads quite as much as salt ... | [
"That's right. Freezing point depression is one of the colligative properties. Basically you could add anything to water and it will lower its freezing point. Salt is used most often because it's very cheap and will actually lower the freezing point a little bit more. Hope this helps!"
] | [
"Thanks for you're insight on the matter, so would the extra sugars cause water to freeze at a lower temp because of the addition of extra molecules?"
] |
[
"If the Earth's core is as hot as the sun, why does Earth melt?"
] | [
false
] | Last night I was explaining to my girlfriend the article in the science subreddit yesterday about the Earth's core being out of sync. One of the comments in the thread said the Earth's core is as hot as the sun which I told my girlfriend. She then asked why doesn't Earth melt if it's that hot. I couldn't explain it. | [
"The earths outer core ",
" molten. That's why the inner core is able to rotate at a different rate to the rest of the planet - the liquid outer core provides the decoupling. The inner core is solid because of tremendous pressure, the mantle and crust are solid due to decreasing temperature and a change in chemis... | [
"The inner core is as hot as the surface of the sun (the center of the sun is much ",
" hotter).",
"As a matter of fact, the earth is melted inside (",
"https://en.wikipedia.org/wiki/Structure_of_the_Earth",
"), at least partly. The inner core is under so much pressure, that it is solid despite the temperat... | [
"There is melting, but the mantle is largely silicate, and generally an excellent thermal insulator.",
"The way to look at it is more like the Earth started off completely molten, and the heat inputs have reduced over time, so it is becoming increasingly cooler and therefore solid."
] |
[
"Electricity in a Maze?"
] | [
false
] | Simple question, probably not too hard to set up experimentally, but I thought I'd ask: If one did the following: Question: Would the electricity "choose" the shortest route through the maze? Let's say we introduce iron filings to the conductive gel. Would we see electromagnetic changes in only those filings which were... | [
"The electricity would flow along ",
" paths between the entrance and exit, with more current traveling through shorter paths of less resistance."
] | [
"This may be of interest to you: ",
"http://www.youtube.com/watch?v=ap7j2cwApmc"
] | [
"In a real maze (paths with non-zero thickness) there will be a small amount of current flowing out to the end and back in the dead end paths. The net current flow through any surface across a dead-end path will be zero, but that doesn't mean there will be no current flow at all in dead-end paths."
] |
[
"How far has gene therapy come? Has it successfully treated or cured anything? What?"
] | [
false
] | null | [
"What do you mean by how? Are you asking how gene therapy works?"
] | [
"Well, there are various methods now, but classical gene therapy is done using viruses.",
"Viruses work by infecting cells and introducing their own genetic material for the cells to make proteins from. Normally the genes viruses carry only code for genes to make more viruses- however we can now engineer these vi... | [
"Bacteriophages infect bacteria, and not mammalian cells, so no, although they do serve a similar purpose in transferring genes.",
"The cancer-causing problems of gene therapy arise with the viral DNA integration step. When the viral DNA inserts its DNA into that of the host cell, the insertion location is random... |
[
"[Meme] AskScience Memes! The next generation in Science Education."
] | [
false
] | Here at we're always on the forefront of teaching, education, and science outreach. We are known as being one of the more heavily moderated subs out there. This effort keeps the discussion here on point and scientific. However, as I have taken over this subreddit I've realized that we're losing out with younger kids be... | [
"Are the mods going to remove memes that aren't dank enough? I think it's important that we continue to maintain the quality of comments in ",
"/r/askscience",
"."
] | [
"That brings up an interesting point"
] | [
"In order to preserve the quality of posts and prevent reposts of memes, I think we should institute a peer-review process for memes to determine if they are indeed dank enough. "
] |
[
"Why can’t mules reproduce?"
] | [
false
] | [deleted] | [
"A mule has 32 horse chromosomes and 31 donkey chromosomes. A total of 63 chromosomes. Normally, an organism would have two copies of one chromosome, one from the mother and the other from the father. However, for mules, they will get two different sets of chromosomes since the mother is a horse, and the father is ... | [
"It should be noted that there are organisms where populations differ in their karyotype while still being compatible. This is quite common among rodents, where population of the same species can be easily identified with their karyotype, but still produce viable and fertile offspring.",
"So I don't know enough a... | [
"Mules ",
" reproduce - it's just ",
" uncommon (only 60 cases recorded in the last 500 years). But, that being said, the other responses re: the genetic component fill you in on why that's the case. ",
"https://www.npr.org/2007/07/26/12260255/befuddling-birth-the-case-of-the-mules-foal"
] |
[
"Why does it become increasingly more difficult to fold a single piece of paper in half?"
] | [
false
] | It is often said that you can't fold a piece of A4 paper in half more than 7 times. Why is this ? Would it be easier with a piece of paper the size of a football field ? | [
"Because every time you fold it, the thickness increases by a factor of two. Thus, after the first fold it's twice as thick as a single piece of paper. Then it's four times as thick, then eight, then sixteen, then thirty-two, then sixty-four, then after the seventh fold it's one-hundred twenty-eight times the thick... | [
"Here's",
" a cool link about the mathematics involved in folding a piece of paper in half."
] | [
"Great reply ! The Einstein quote \"If you can't explain it simply, you don't understand it well enough\" comes to mind! Thanks."
] |
[
"Can 10 individual 5-watt speakers create as many decibels of sound as one 50-watt speaker?"
] | [
false
] | null | [
"In simplistic terms, yes. Speaker coupling can yield a decibel gain but individual driver efficiencies and the enclosure design will also come in to play. The principle is that you can get an overall db gain by aligning the drivers in a plane. This is why sound reinforcement systems use arrays of aligned drivers. ... | [
"This question is incomplete, you can make a single speaker with 5 watts going through it be as loud as a speaker with 50 watts going through it. What matters there is sensitivity of the speaker. That is the measurement that specifies dB/W @ 1m. A speaker rated at 93db/W @ 5 W will be just as loud as a speaker rate... | [
"Not quite.",
"Every 10 decibels is perceived as being twice as loud, but is actually ten times as much energy.",
"Want to make it sound twice as loud? You need 10 times as much power!"
] |
[
"Hive insects - How do they evolve?"
] | [
false
] | If most of the worker ants and bees don't pass on their genes through the queen, then how do they evolve to their specialized tasks? How did these hive species begin in the first place? I know the entire hive acts like an organism and the success or failure of a hive depends on the abilities of the workers, but is ther... | [
"I'm sorry to be the \"link to wikipedia\" guy, but I'm not in the mood to compose a thorough enough explanation, and I can't let you go with just a 2 or 3 sentence answer.",
"The prevailing theory for years has been ",
"kin selection",
", but Martin Nowak and EO Wilson (a very famous sociobiologist) have rec... | [
"I can't speak to how insect colonies evolved highly specific job roles, but I do know a little bit about insect genetics, which might help answer a portion of your question.",
"Many insect species are categorized as having a ",
"Haplodiploid sex-determination system",
". Female workers are derived from a fe... | [
"damnit, for months i wait for this question to be asked so i can whip out my haplodiploidy knowledge. foiled again... However, i have heard that when you actually look at the genetics, haplodiploidy is not enough to explain the eusocial behavior (not sure on the specifics, just something i heard in a lecture awhil... |
[
"What parameters about the gas decide it’s compressibility?"
] | [
false
] | null | [
"The compressibility is defined by κ = -(1/V)(dV/dP), but you have to be careful about what quantities are being held constant when you take the partial derivative dV/dP.",
"The simplest kind of gas is the ideal gas, obeying PV = NkT. We can find the isothermal compressibility by letting T be a constant and diffe... | [
"Thanks a lot for your answer! This was really interesting."
] | [
"If you're asking from an applied aerodynamics sense, that would depend primarily on the Mach number, which in aerospace contexts is generally taken as anything above ~ Mach 0.3 as a rule of thumb.",
"This is actually quite closely related to the previous comment, as the speed of sound is directly related to the ... |
[
"Does logarithm of negative numbers have any meaning?"
] | [
false
] | I know that there is no real solution to logarithm of negative numbers, but I understand one could define log of natural number using the Euler's identity, as exemplified by ln (-1) = (pi)*i. Does this kind of definition have any physical/mathematical meaning at all, or is it useful to solve certain problems? Thanks a ... | [
"Physicist here, we use complex exponentials when representing the amplitude and phase of a wave of light. It is based off Euler's formula and can help make solving problems involving light much easier to calculate.",
"When finding the phase of the light we have to take the logarithm of a complex number. In the s... | [
"Physicist here. I would add that phases also play a big part in calculating on anything quantum, not just in the (classical) theory of light.",
"The thing about phases (say we have a phase p) is that we never observe them directly, we only ever observe their effect through the exponential e",
". As freakyemo c... | [
"As others have mentioned, you can interpret the logarithms of non-positive numbers in terms of Euler's identity, up to an ambiguity in the complex part. That is, e",
" is unchanged when you replace t with t + 2 pi.",
"Now the logarithm is the inverse of the exponential, but when dealing with functions we need ... |
[
"Can I kill termites in wood by baking it in the oven? If so, how hot should it be?"
] | [
false
] | A couple years ago me and my niece cut down a cedar tree to use as a Christmas tree. I kept it inside the workshop and have been using it to make various projects, but I've used almost all of it. So I went out and cut off the 3 or 4 foot stump that was still in the ground and found that it has termites in it (not bad... | [
"A quick search turned up this article: ",
"http://www.beyondpesticides.org/alternatives/factsheets/Termite%20Control.pdf",
"It lists the temperature used in commercial microwave devices for killing termites to be 190 Fahrenheit. Termites on their own would definitely cook in an oven at 350, but the wood (and a... | [
"**",
"**",
"Wood will begin to char as low as 250º F and certainly the loss of water from extended time in the oven will ruin the wood.",
"Please don't risk burning your house down to save a few dollars.",
"http://www.tcforensic.com.au/docs/article10.html"
] | [
"I only regret that I have but one upvote to give for this answer. Thanks a lot. I tried googling it with no luck but didn't spend a whole lot of time searching since it didn't seem like a very conventional thing to do. That's exactly what I needed to know. And of course, you're right about Bradbury's book \"F... |
[
"If fish all poop in the ocean, why is the ocean not a huge bacterial cesspool, unsafe to swim in?"
] | [
false
] | null | [
"The ocean IS a huge bacterial pool. That said remember that your body has more bacterial cells than it does \"human\" cells. Not all bacteria are dangerous to human/animal life. "
] | [
"This is true, but it's only by number, certainly not mass."
] | [
"Have you ever pooped outside? I have. Flies swarm within seconds."
] |
[
"Where do four dimensional objects exist?"
] | [
false
] | We obviously live in a three dimensional world and can only perceive objects in three dimensions (or lower). But there is a fourth dimension, in regards to space and not time. Where are these four dimensional objects? | [
"The simple answer would be that 4 dimensional objects are in the fourth dimension. I know this doesn't really answer the question that you are asking and I imagine you are wondering why we cannot not perceive these objects. The answer to this question is that from a lower dimension you simply cannot perceive a hig... | [
"Not sure I agree. If there is a 4th spatial dimension, and it is not a \"curled up\" dimension but rather has near infinite extent like our 3 spatial dimensions, then objects can exist in the 4th dimension, pass through ours, and we would see them while they intersected our 3D dimension. If a 4D sphere went whizz... | [
"Can a reference be given regarding the claim that \"there is a fourth dimension?\" As I understand, dimensions in physics have been developed as mathematical tools, but I do not know of any physical experiments which would give rise to the existence of 4d objects in our universe. For example, 10 dimensions in stri... |
[
"Are universal constants really \"just the way they are\"?"
] | [
false
] | I ran across this article: Basically, the idea I get is that there's no point in considering changing or overcoming or using anything that is a "constant" when it comes to considering science. Is this correct, or am I misunderstanding? Is there no point to considering how to exceed the speed of light, or manipulate gr... | [
"It is possible that fundamental 'constants' do, in fact, vary from place to place (i.e. throughout the universe: we only measure most of these on Earth) but we have no reason to believe that's true. If the fundamental constants are, in fact, constants then there is no reason to try and 'break' them: but that is a... | [
"But you have to keep in mind e is the fundamental unit of charge purely for historical reasons. They didn't know about quarks and their silly charges when they decided the electron charge was the fundamental unit."
] | [
"Yes, my point exactly. If they didn't bother to look because they reasoned that quarks had fractional charge and therefore are impossible: then we'd never have discovered them."
] |
[
"Why is the triangular inequality at the heart of the definition of a distance function?"
] | [
false
] | There was a post earlier today about distance functions. I could not understand why the triangular inequality is absolutely necessary to define a distance function... can somebody explain this in not-too-advanced terms? I'm eager to learn, but I'm no math major. | [
"\"distance from X to Y\" should be thought of as \"the length of the shortest path from X to Y,\" where things like \"length\" and \"path\" need to be defined. All three properties of a metric fall from this heuristic starting point.",
"There is no such thing as a path of negative length, and a path can only ha... | [
"A distance function should measure the best way to move from point a to point b. If there is another point c such that d(a,b)>d(a,c)+d(b,c) then there is a path from a to b through c that is shorter that the distance d(a,b), so what useful information did d(a,b) really give you about the distance from a to b?"
] | [
"Think about what would happen if the triangle inequality didn't hold. You would have an example of where the distance from A to C, d(A,C), is greater than the distance from A to B plus the distance from B to C, d(A,B) + d(B,C). It doesn't make sense that you can find a shorter route by including an extra point.",
... |
[
"What is the solid residue that forms on my tongue whenever I drink certain sweet drinks like lemonade and cranberry?"
] | [
false
] | I noticed this happens with only a few drinks, not the majority. Does anyone know what I'm talking about/ is this caused by a specific additive? Thanks | [
"So that's why I always feel like I'm coated with a layer of grease whenever I drink Coca Cola. (And incidentally, it's why I never buy sugary drinks anymore.)"
] | [
"biofilm and broken down carbs",
"lemonade and cranberry have among the highest sugar contents"
] | [
"I know what you're talking about, but I've been told by my doctor that it was just sugars that mix with my saliva/other fluids inside my mouth to make it more viscous. Also that the small food particles in my mouth and tongue catch the sugar, making me feel it more. "
] |
[
"Does solar activity leave terrestrial records?"
] | [
false
] | For example, would a massive solar flare leave any record of itself? Radiation in rocks, or that sort of thing? Is there any way to know about the history of solar flares or increased solar activity other than written human records? | [
"Oh, so much to tell.",
"The short answer is yes, via so-called cosmogenic isotopes produced by cosmic rays in the atmosphere and recorded in natural archives.",
"One example, radiocabon (C-14) gets involved into the carbon cycle after production. You can probe tree trunks and find radiocarbon atoms there. Thei... | [
"It should be clarified for readers outside the discipline that ",
" cosmogenic isotopes are produced by interactions with extrasolar cosmic rays, not those from our sun."
] | [
"How does it feel when someone posts a question in your key expertise?"
] |
[
"Can batteries absorb power from vinegar?"
] | [
false
] | [deleted] | [
"Just your imagination. Electric toothbrushes charge via ",
"induction",
" because there are no wires / contacts for the sake of remaining water resistant. There's no way for the vinegar to do anything to the battery."
] | [
"no, not at all. The bottom of the toothbrush is entirely inert, the only way to interact with the battery is via an electric or magnetic field. Look at the bottom of your toothbrush - it should be all plastic. There are no physical contacts for the battery to have any interaction there"
] | [
"no, not at all. The bottom of the toothbrush is entirely inert, the only way to interact with the battery is via an electric or magnetic field. Look at the bottom of your toothbrush - it should be all plastic. There are no physical contacts for the battery to have any interaction there"
] |
[
"Do drinks with caffeine dehydrate you?"
] | [
false
] | null | [
"This came up in a thread recently. Here's what I posted then:",
"I really disagree. Caffeine is a diuretic, but I have never seen any evidence that it's diuretic effect continues with long-term use and that your own physiologic stimulation of ADH in a dehydrated state will not overpower caffeine's effect. I thin... | [
"Caffeine is a diuretic"
] | [
"It depends on the caffeine content. I drink strong coffee and it definietely dehydrates me.",
"I can drink coffee all day and be gagging for water by the 3rd or 4th cup"
] |
[
"Are all physical objects moving through spacetime at the same speed?"
] | [
false
] | What is this speed and what is its unit? I know that a point in spacetime can be described by a 4-vector. We measured the maximum speed through space to be c. How do we know what the maximum "speed" through time is? Lots of questions, hope you can help :) | [
"All objects have the same magnitude of 4-velocity: u",
"u",
" is the derivative of 4-position x",
" with respect to proper time τ (time elapsed in the rest frame of the object).",
"i.e. u",
" = ∂x",
"/∂τ",
"The magnitude of 4-velocty (4-speed?) is an invariant quantity.",
"|u",
"|",
" = u",
"... | [
"Someone will chime in and say it's due to scattering or absorption and re-emission, which is a complete and utter myth.",
"I can't really explain it any better than ",
"this video",
".",
"Essentially, light as photons is only valid in a vacuum. In a material made of atoms (which have their own electromagne... | [
"By convention, 0 is time and 1, 2 and 3 are space.",
"Also x",
" = ct, so the units are of regular velocity"
] |
[
"What Are These Things in the Arctic?"
] | [
false
] | I noticed them on Google Maps a while ago but was never really sure what they are. They're like tons of little lakes/ponds. Here's a picture for reference or you can just look at the Northern coast of Alaska and Russia. | [
"All the following information can be found in either ",
"Permafrost: A Guide to Frozen Ground in Transition",
" by Neil Davis or in ",
"Land of Extremes: A Natural History of the Arctic North Slope of Alaska",
" by Alex Huryn and John Hobbie.",
"These are ",
"thermokarst",
" lakes and are an ubiquito... | [
"This answer is more likely than the lakes being distorted kettles. Kettles are bigger and more differentiated. "
] | [
"They may be streched kettles. Ice blocks were dragged onto the shore somehow and broken into a lattice. Those were buried. They melted. At some point there was another ice overlay that dragged the surface around.",
"There seem to be a few processes here. There were round lakes that formed in melted ice blocks th... |
[
"Can seismologists differ an underground nuclear test from blowing up the equivalent amount of TNT?"
] | [
false
] | With North Korea's nuclear testing activity despite the astonishing backwardness of the country I started wondering -- is it possible for them to just blast kilotonnes of TNT underground to fake a nuclear test? | [
"They can't fake the seismograph. Nuclear weapons have a distinct signature."
] | [
"They can't fake the seismograph. Nuclear weapons have a distinct signature.",
"Could you expand on that? Is it simply that they determine that there was no earthquake where they got a hit, or that the frequency and/or amplitude is actually quite different from what a natural earthquake generates? In ",
"this... | [
"Well first off, the signal on the seismograph looks different than an earthquake. I don't know where to find a picture of it, but it is based on both the s and p waves. Also, multiple stations can triangulate the location, and if it is in an area not known for earthquakes, it does help. Especially if it is in a... |
[
"For the cells that have been in my body since birth, do they contain the exact same atoms as at the time of my birth?"
] | [
false
] | I know that over time, our body replaces tissues, but some things aren't replaced, liked cerebral cortex neurons. Does this mean they contain the same atoms as I had at birth? Additionally, while the majority of my bone mass has formed as a result of food I've eaten while growing up, I did have bones as a baby. Are som... | [
"Yes, your body is made up of some of the atoms you were born with. I think the concentration of these \"original\" atoms would be moderately low since the body not only replaces cells, but also repairs cells continuously. This means that a cell could persist, but its constituents may have been replaced slowly ov... | [
"The universe doesn't keep track of particles well enough for your question to be answerable. It only keeps track of the state and configuration of all the particles, and not the particles themselves (we know this because of quantum mechanics' empirical results - if two particles in the same state were somehow diff... | [
"Except in practice that doesn't matter, since you can just look at it statistically. You're right that you might not be able to know whether any ",
" carbon atom is new or old, by quantum indistinguishability, but you could still look at, I dunno, the ratio of carbon-14 to carbon-12 atoms (or something) in a ch... |
[
"Is there a speed of a field?"
] | [
false
] | If an infinite negative charge appeared in the universe, would all electrons/matter instantly be repelled, or would there be delay in the charge appearing and other charges being affected? Does the same apply to gravitational and magnetic fields? | [
" Yes, there is a delay for information to propagate in quantum fields. The maximum speed information can propagate is the speed of light, so you're always feeling and seeing the universe with something of a delay. ",
" You're seeing the light from the sun with an 8 minute delay. You're feeling the gravity of And... | [
"You're seeing the light from the sun with an 8 minute delay. You're feeling the gravity of Andromeda based on its position and shape 2.5 million years ago. You're feeling the gravity of Andromeda based on its position and shape 2.5 million years ago",
"Just a small follow-up, because I think this is an important... | [
" Many things travel at that speed, and photons are a tiny part. Light is just the first one we thought about.",
"It should really be called \"the speed of causality\". All those fields and particles that are unconstrained by having inertia, happen to be limited to the speed of causality.",
"If we changed the n... |
[
"How does the drop height of a marble affect the wave length of the waves in a water tray?"
] | [
false
] | [deleted] | [
"How can a wave simultaneously have both a larger wavelength and frequency? (Assuming larger means ",
" wavelength and ",
" frequency.) Shouldn't these have an inverse relationship. That is, unless the speed of the wave propagation through the water is also affected."
] | [
"This relationship is called the ",
"Dispersion Relation",
" and for deep water it is approximately:",
"(Phase) Speed = 2*(gravitational acceleration) / (",
"angular frequency",
")",
"Though the group speed is the actual speed at which peaks and troughs will propogate, and it is half the phase speed."
] | [
"Thanks for explaining :)"
] |
[
"How does fat travel through your body and get deposited everywhere?"
] | [
false
] | I understand the basic digestive system with how food travels through your body, gets absorbed in the intestines, and then gets pooped out. But when you have excess food (ie gain weight/get fat), how is food transformed into fat and how does it travel through your body to get deposited everywhere? | [
"(1) How is food transformed into fat? Well, food already contains fat. It's in the form of ",
"triglycerides",
" (TGs). Body fat also consists of triglycerides deposited inside fat cells (adipocytes).",
"TGs can't cross a cellular membrane, so they are broken down into their constituent ",
"fatty acids",
... | [
"Fat is absorbed through the intestines and collected into chylomicrons and are taken to the liver through specialized lymphatic tissue called lacteals. "
] | [
"There are plenty of particles floating around in the bloodstream. See ",
"here",
".",
"what is the step before fats are sent via the bloodstream throughout your body?",
"My answer was admittedly a little dense so let's try this again.",
"In the intestine, dietary fats (triglycerides) are first broken dow... |
[
"Why does rubbing alcohol burn and why doesn't hydrogen peroxide?"
] | [
false
] | I was cleaning my cartilage piercing when I began to wonder. Is rubbing alcohol a better cleaner? Or was I wrong in assuming that because it hurt, it was cleaning better? Would hydrogen peroxide clean just as well? | [
"Household dilutions of hydrogen peroxide are not recognized as an effective disinfectant; rubbing alcohol and salt water are more lethal to bacteria. All peroxide does is clean; it's effective at removing dead skin cells.",
"Also, FIY, ",
"using hydrogen peroxide on wounds can disrupt normal healing.",
" Th... | [
"\"",
"\"",
"How does that not support \"hydrogen peroxide on wounds can disrupt normal healing\"? I'd define \"normal\" as \"scarless\".",
"Article on wound healing from a hospital.",
" \""
] | [
"OIC what you're saying, k. ",
"It still remains that hydrogen peroxide is not recommended for using on wounds, which is what the OP was asking."
] |
[
"How can doctors/labs tell what type of cancer a person has? And how can they tell what stage the cancer is at?"
] | [
false
] | For example, when a biopsy is done, what is being looked for? Is it a certain type of cell or cell growth? If they cant do a biopsy, can they tell just by looking at size and location of a tumor? It seems like there are so many types of cancers out there, how can they tell which one a person has? | [
"To add to this, it's a very complex question that can't really be answered without multiple textbooks-worth of text. Because it's different for each cancer.",
"When we biopsy, we're looking for malignant features. The pathologist is looking for telltale signs that the cells under the microscope are malignant. Yo... | [
"It seems like no one has answered several hours after you asked this so I'll give the broad answer, because I don't know any significant specifics.",
"Stage is usually a medical term describing the extent/size of the tumor and whether it has metastasized.",
"The type of cancer will be determined by pathologis... | [
"It's different for different types of cancer. For a lot of blood cancers, you can do flow cytometry to look for specific markers. For others you can tell from imaging (at least to a reasonable extent) and then you biopsy and look at the pathology."
] |
[
"How quickly is stellar fusion depleting the hydrogen in the universe? When will there be more heavy elements than hydrogen?"
] | [
false
] | Question in title | [
"Not very fast at all. Less than 10% of the mass of a star undergoes fusion during its entire lifetime. A lot of people have that misconception about stars and the sun. It is not a giant ball that is constantly undergoing fusion. Only a very small part of the core is, and the high energy output is only due to the s... | [
"The problem there is we don't have the advantage of the insane pressure and temperature from all the mass of a star. For fusion to actually create more energy that we use to create conducive conditions, the rate we have to make here on Earth has to be much higher."
] | [
"The problem there is we don't have the advantage of the insane pressure and temperature from all the mass of a star. For fusion to actually create more energy that we use to create conducive conditions, the rate we have to make here on Earth has to be much higher."
] |
[
"Why do we consider that a e- n=3 in hydrogen atom has more energy than in n=1, when in reality the energy needed ionize the eletron is more in n=1 than in n=3? Why do eletrons have tendecy to go to lower states of energy? What do you consider a lower state of energy?"
] | [
false
] | So.. what its bugging my mind is this.. N=3 has is suppose to be a higher energy leve than n=1 right?However in this level the ionization energy is lower than it is for n=1.As such shouldn´t it be that n=3 is a lower energy level than n=1? And how come eletrons have tendecy to go to a lower energy level?And what do you... | [
"Why do we consider that a e- n=3 in hydrogen atom has more energy than in n=1, when in reality the energy needed ionize the eletron is more in n=1 than in n=3?",
"The premise of this question is incorrect. It takes more energy to free a bound n = 1 electron than it does to free a bound n = 3 electron.",
"Why d... | [
"E",
" is the total energy (kinetic and potential) of the electron. Using the virial theorem for a 1/r potential, we know that <T> = -<V>/2, where T is the kinetic energy and V is the potential energy.",
"Since <T> + <V> = E, it follows that",
"E = <V>/2, and E = -<T>.",
"Note that the potential and total e... | [
"And how come eletrons have tendecy to go to a lower energy level?",
"Let's for the moment make the assumption you have one atom (and let's just consider ground state and one excited state) with no surrounding environment. There is only one possible configuration where the electron is excited in that one particul... |
[
"Would a circular 2d object in space that has two equally strong opposing thrusters oriented tangentially on its side start and stop rotating if the thrusters are pulsed sequentially, or would it begin to move as a whole?"
] | [
false
] | [deleted] | [
"One thruster would obviously induce a rotation. However, it would not just induce a rotation around the circles center.",
"Assume you give a very short pulse to one thruster you would send the object spinning and going forward.",
"If you pulsed the thrusters alternatingly, on average the disk would not rotate.... | [
"Not at all! The translational displacement can be quite comparable or much larger than the angular displacement depending on the frequency of your pulses. Let's look at Newton's 2nd Law for a system of particles (and continuous objects, such as the disk in this problem).",
"Σ",
" / m = ",
"Note that for a sy... | [
"Not at all! The translational displacement can be quite comparable or much larger than the angular displacement depending on the frequency of your pulses. Let's look at Newton's 2nd Law for a system of particles (and continuous objects, such as the disk in this problem).",
"Σ",
" / m = ",
"Note that for a sy... |
[
"Why is it that the majority of humans are right handed?"
] | [
false
] | null | [
"To be completely honest, I think scientists still could not explain why majority of us are right-handed. Concordance rates for handedness in monozygotic and dizygotic twins are low, suggesting there are more important players than genetics. From evolutionary perspective, there are some evidence pointing that the N... | [
"I'm surprised that no one in here has said coincidence. Some evolutionary traits aren't because they were necessarily adaptive, but rather because they weren't maladaptive. For example, the ",
"laryngeal nerve in giraffes",
" is likely not optimal, but it wasn't sufficiently maladaptive (and/or the correct m... | [
"What do you mean by «right hand is better for cooperation»? Do you mean it's better for our specie's cooperation to have a big majority using one hand over the other instead of a 50-50 divide or is there some objective difference between a right hand and a left hand?"
] |
[
"Is any of the following homeopathy trials rigorous?"
] | [
false
] | I have a friend trying to convince me to try homeopathic remedies for my illness and I, in turn, have being trying to convince her to stop taking them for hers. At the beginning, all she provided was anecdotal evidence, but this link goes further than that. I'm still of the opinion that homeopathic remedies don't work,... | [
"On the contrary, the more independent trials you look at, the higher the probability that there will be a few that came up \"significant\" just by chance. Even in a well-designed trial, there is always a small probability that you will get a Type I error just by chance (Type I errors are when the data seem to indi... | [
"The question you (and everyone else) should be asking is not 'does homeopathy work'; it is 'does homeopathy work better than similarly administered placebo'. From what I see in the writings you linked, none of them attempt to demonstrate that homeopathy works better than placebo."
] | [
"I only read a few paragraphs down, and scanned the rest, due to typos making it hard to understand (red flag #1)",
"My $0.02: It seems the author has prepared a literature review of some 307 scientific papers that (according to the author) support the idea that homeopathy \"works\". Most of these papers are fr... |
[
"Why do these gifs give a vivid impression of 3D, while video doesn't?"
] | [
false
] | link was just posted over in /offbeat. It has gifs of stereoscopic photographs with the image quickly alternating between the two perspectives. This gives me a very vivid impression of being 3D, while a shot from a film with a camera moving around the scene doesn't, though I'd have thought the cues that my brain is pic... | [
"What you're seeing is called ",
"structure from motion",
". Your brain uses the motion in 2D (along your retina) and the assumption that the world is fairly rigid and static (the complex motion doesn't come from weird warps in space) to infer vection (movement of the viewer) or object motion in 3D. This 3D mot... | [
"It's a ",
"stereoscope"
] | [
"It's because video doesn't shake back and forth like that. It would look 3D if it did. ",
"The feeling of 3D appears when each eye sees a slightly different picture, that's how you can feel distance. With picture moving like that you can see the angle of the photo and the distance between objects in it, as objec... |
[
"Why do I feel so tired when I'm doing something boring?"
] | [
false
] | Let's say I'm at work or in some classes I feel tired like I'm literaly falling asleep, but when class or work is over I feel like I can run a marathon. | [
"This article",
" gives a pretty succinct explanation:",
"People have an embedded sleep–wake cycle regulator controlled by a combination\nof two internal influences: circadian pacemakers and homeostasis [4], [6]. Environmental factors such as stress, noise,\nlight, excitement, anger, pain, and sleep fragment are... | [
"TIL, thanks."
] | [
"No problem. I know slightly more than the average Joe about sleep and wakefulness due to having narcolepsy with cataplexy and researching my own condition, but am not a bona fide ",
" as such."
] |
[
"Can mountain and lowland gorillas interbreed?"
] | [
false
] | If so, has this ever happened? What would the result be like? | [
"They are considered subspecies, not different species, so they can interbreed. I don't know if it's ever happened, hoping someone else can answer that. But the result would be a healthy intermediate gorilla. They live in troops, so I think the end result would depend on a lot of different factors. Does the troop a... | [
"Humans are actually very closely related! One of the main reasons is a bottleneck in the gene pool about 70,000 years ago. It only takes a few genes to be expressed differently to have drastic changes in looks.",
"The issue is that classification is always difficult. Deciding on species, subspecies, variant etc.... | [
"Serious question.",
"If this is the case for gorillas and many other animal species, then why arnt humans, with sometimes more extreme morphological differences, considered as sub-species?",
"A number of vets and zoologists I have asked this before were adamant human population groups can be clearly defined as... |
[
"[Astronomy] Say I had the land and resources to launch a teeny, tiny probe into space (Earth's orbit), all by myself, for purely scientific/personal achievement reasons. What's the legality of this? Presumably NASA would need to know, in case it interferes with other satellites. Am I even allowed?"
] | [
false
] | null | [
"Such questions are better suited for our new-ish sister sub ",
"/r/asksciencediscussion",
". Please consider reposting there instead."
] | [
"Please delete!"
] | [
"Duly noted. Would you like me to delete this post? Or just repost there? :)"
] |
[
"Is there an upper or lower limit on the wavelength of light?"
] | [
false
] | Is there anything beyond gamma or radio waves? What would generate them? | [
"On the low-frequency end of the electromagnetic spectrum, nothing interesting happens. You just get closer and closer to static fields, which can be thought of as an EM wave with a frequency of zero. There is not really a fundamental lower limit, since static EM fields are perfectly valid and perfectly normal. ",
... | [
"All photons have all energies, frequencies, and wavelengths; it just depends on what reference frame they're being examined in. There might be an upper limit though depending on how quantum gravity works."
] | [
"I'm pretty sure that a 'single photon' cannot collapse into a black hole, regardless of its energy. After all, the energy of the photon will be dependent on the frame of reference of the observer; I don't think it would be possible for it to be a black hole in one frame while not in another."
] |
[
"What's the deal with beer bellies?"
] | [
false
] | There's definitely a distinctly round belly that is often associated with drinking lots of beer, but why? I know you can't work out certain parts of your body to target your weight loss, I assume you can't target your weight gain either. Maybe I'm just not very observant, but I don't know if I've ever seen a woman ... | [
"I don't believe it has anything to do with energy from beer being stored differently than other forms of food (that's the part I'm not sure about). Men have a greater biological pressure for fat to be stored in their belly than women, who have fatty tissue stores in varying composition vs. men.",
"Just to give ... | [
"Chronic alcohol abuse causes one’s body to overproduce corticosteroids. This comes as an adaptation to dehydration and hypoglycemia, as well a consequence of alcohol interfering with the brain’s control of the endocrine system. Alcohol detoxification in the liver also slows the metabolism of cortisol, which allows... | [
"There are primary and secondary areas of fat storage. The belly is primary. Secondary storage areas like the arms and face are the first to burn off. Girls can have beer bellies, but they also hold more fat in other areas than men, like thighs, hips, breasts etc.."
] |
[
"What's the newest on bipolar type 2?"
] | [
false
] | null | [
"Hello,",
"This would be more appropriate for ",
"/r/AskScienceDiscussion",
".",
"Best."
] | [
"Ok\nBut why?"
] | [
"The question is open-ended."
] |
[
"How is it that I can type without looking, but if asked to recall the position of the keys on a keyboard I would not be able to do so?"
] | [
false
] | This is something I'm not sure is unique to me. Though with that said I do have some problems with my memory and I suspect it could be linked to that (and I mention that incase there's some interesting related nugget of information that we can discuss/ I can stop worrying about this as a symptom of my wierd memory!). M... | [
"Why couldnt you just simulate where your fingers are going and recite from that? (This is actually what I do, I'm a programmer and can type very quickly but like you can't recite the keys without moving my fingers)",
"The obvious answer is it's a reflex from repetitively doing it and your brain modeling the phys... | [
"This is because your memory for skill originates in a different part of your brain (the basal ganglia) than your memory for knowledge (the cortex).",
"You've probably heard of people with devastating memory loss. These people usually have trouble with their hippocampi. If you consider your memories as details, y... | [
"I honestly have no idea. I can type just fine and find certain words, but I'd have to do it a word at a time and try to cover the whole keyboard that way!",
"Thanks for explaining this though and that's really a great analogy with the throwing. ",
"What's funny is that this whole 'feel' for the keyboard has be... |
[
"Why is December 21 the shortest day of the year but the coldest in February?"
] | [
false
] | Assuming you're in the northern hemisphere... What causes the big delay? | [
"It's called ",
"seasonal lag",
"."
] | [
"Basically, it takes time for the heat absorbed by the land and sea to dissipate. The Winter Solstice marks the decline of the Northern Hemisphere receiving large amounts of direct sunlight, but it takes some time for all the heat absorbed by the planet to finally go away. This is the same reason that the coldest p... | [
"Its similar to the way that a driven RC circuit works (if you're familiar with electronics). The sun is like a driving voltage, each day it deposits some amount of energy that we can reasonably estimate as dE. This is similar to a voltage powering a resistor and capacitor in series. The capacitor is the \"stuff\" ... |
[
"Why is it that our teeth will rot fairly quickly if we don't brush them, yet other animals eat nasty stuff all the time with no problem?"
] | [
false
] | null | [
"The \"nasty stuff\" that animals eat isn't full of sugar."
] | [
"This ",
"has been asked",
" a few ways before ",
"But a couple short answers are:",
"We eat way more sugar and complex carbs(that break down to sugar) than our ancestors. Sugar is what turns to acid and plaque to cause cavities. The high level of sugars we normally consume do not happen in natural foods.",... | [
"So basically, the bacteria that causes cavities needs refined sugars to create plaque. There are three requirements for cavities",
"Sugar",
"Acid",
"Time",
"If you don't get enough of any one of these things, you don't get a cavity. Also, unlike carnivores, our teeth are close together and have the abilit... |
[
"Why does it feel warmer when it's snowing?"
] | [
false
] | Is it actually warmer? Or am I just imagining the difference in temperature? | [
"It can only snow within a certain temperature range, if it's too cold there won't be any moisture in the air. A warm front bringing moisture in will warm the air up some and lend enough moisture for snow to form. "
] | [
"Around here (Boston), it ",
" warmer when it snows. Recall that the air can't hold much water below 20F, so when it snows it warms up from 15F to 25F or more, then snows. "
] | [
"It can only snow within a certain temperature range, if it's too cold there won't be any moisture in the air. ",
"This is misleading; It can ",
" be too cold to snow, but it can can be too dry to snow. So yeah, a cold front has to meet up with a moist air front and therefore it's warm but insinuating \"It can ... |
[
"Are defibrillators portrayed accurately in movies and TV?"
] | [
false
] | I have a couple questions about defibrillators. First, it always seems like it's just up to the doctor how many times to try using them before deciding to give up. In real life, is there a guideline about when to stop and declare the person dead? Can a doctor get in trouble for trying too many times, or not trying enou... | [
"American Heart Association's latest guidelines for defibrillation",
"Overview with flowchart"
] | [
"There are ",
"guidelines",
", but the number of shocks actually given will depend on the situation. Most newer AED's actually have a telemetry monitor built in and will check to see if the heart has returned to normal sinus rhythm, then recommend the next step (another shock or CPR). There is a delay, but not ... | [
"Defibrillators are probably the most misused items in tv and movies second only to handguns. A doctor cannot overuse the defibrillator because the machine will not deliver a shock in the current machines unless a shock is warranted. The heart has to be in fibrillation before the machine will administer a shock. If... |
[
"Does the moon have any appreciable color?"
] | [
false
] | From here on Earth it appears white/gray. The moon landings were, from what I can tell, mostly in black and white or very desaturated. If I was to be standing on the moon, would I see any colors in the rocks, soil, etc.? | [
"Assuming it is grey, and rephrasing the question, why is space dust/are space rocks gray? Why not brown, white, green, red, etc. from what we have here?"
] | [
"The moon is actually rather colorful if slight hued grey is colorful.. ",
"http://www.rc-astro.com/photo/id1018.html"
] | [
"It's quite dark, but apparently the complete picture is complicated. ",
"The Moon has an exceptionally low albedo, giving it a similar reflectance to coal.",
"- ",
"http://en.wikipedia.org/wiki/Moon",
" - ",
"- ",
"http://web.archive.org/web/20080523151225/http://jeff.medkeff.com/astro/lunar/obs_tech... |
[
"After an animal dies, do chemical reactions and processes continue in their body?"
] | [
false
] | I'd always imagined that when a person or animal dies that all processes in their body would stop immediately, but this seems unlikely. I'm 17 but I've studied a fair amount of biology, so I'm guessing that respiration would become anaerobic fairly quickly. Does food continue to be digested, do processes like osmosis a... | [
"Things change rapidly, like you mentioned with respiration. However, interesting proceses still occur, such as that which produces ",
"rigor mortis",
".",
"I think of metabolism, and life processes in general, as those which combat thermodynamic equilibrium. When those processes stop, what is left is the p... | [
"Osmosis isn't a chemical reaction, fyi.",
"However, ",
" processes still occur. The body has only a small amount of available energy though, so things start slowing down, and stopping almost immediately."
] | [
"I only said it was a process, but sorry if I implied otherwise. I assumed that would be the case, but it just seems counter-intuitive to the idea I have of death. Life isn't that abstract though, I realise."
] |
[
"How does flyspray (i.e. Raid) work and do insects experience pain when they are killed by it?"
] | [
false
] | null | [
"I'm no insect physiologist, so I can't answer your second question, but I'll be glad to tackle the first.",
"Depending on what you're trying to kill, the spray will contain varying types of insecticides. However, in household products, you will generally see a group of chemicals known as ",
", which includes p... | [
"Just adding a little to Funkentelechys answer, the way it was explained to me that insects control their movements with a vast array of on/off switches, and the control comes from switching on and off the right things at the right time.\nSo when the Sodium channels can't close, you are effectively telling the flie... | [
"Flies certainly have a central nervous system. They are also ",
"capable of feeling pain,",
" though it's probably a more primal response (in other words, they don't have a high enough consciousness to feel pain as we do, but have nociceptors that will tell them to avoid something)."
] |
[
"How do parasites that reside in the intestines avoid being unceremoniously pooped out?"
] | [
false
] | It seems like there are several kinds of parasites that inhabit the lower digestive tract of many animals, and it's certainly in their best interest to remain there and feed. So how do they keep their real estate and avoid being discharged with the feces? | [
"Hooks and suckers."
] | [
"and pseudomembranes and some burrowing."
] | [
"Pretty much the same way our normal flora stays in there. We have over 400 different identified species of bacteria that live in our colon at any given time, and bacterial cells outnumber human cells in our body approximately 10:1. That normal flora helps prevent pathogenic organisms from finding a site to attach,... |
[
"Is it a myth or a fact that dogs can \"sniff\" cancer?"
] | [
false
] | Ive heard of it a long time ago, that dogs are able to detect/sniff/smell cancer but never knew whether that is true or if so where it originated from. Does anybody know? Im personally no expert with animals and biology but I doubt that dogs have the ability to do that. | [
"They're not perfect, but neither is traditional screening for early detection. Use of sniffer dogs is promising enough that we've worked on it since 1989. There are a lot of studies on it (use key words \"sniffer dogs cancer\" on Google Scholar), but the quality of those studies varies immensely. As ",
"/u/ondul... | [
"It seems like total BS upon hearing it.",
"But it turns out its true, dogs can smell certain kind of odor signatures that cancer makes. ",
"https://www.medicalnewstoday.com/articles/323620",
"I wasnt sure about the source but i checked them aparently they're good.",
"https://www.google.com/amp/s/mediabiasf... | [
"I think it is likely that dogs can be trained to detect some smells specific to cancers. But there also seem to be weaknesses in the studies cited. In ",
"one cited article",
" it seems like the dog was trained on samples from the same patients that were used for testing. If that is correct, the dog may “just”... |
[
"Why do immunities from vaccinations not pass from mother to child in vitro?"
] | [
false
] | [deleted] | [
"To have immunity you need to have your own cells that are making new antibodies as needed. Antibodies only last for a short time. Their half-lives range from 1-3 weeks, so they should be completely out of your body in the matter of a few months. You only get the cells producing the antibodies by an exposure to the... | [
"If nothing else, I have learned a lesson in Latin today."
] | [
"Our genes do not change every time we encounter a new antigen(foreign microbes) but the cells that are made from our genes do change as they replicate to adapt to new antigens we encounter. We have the genes to make a basic types of immune cells and it is what happens to the cell after it has been made that deter... |
[
"What is the audible click I hear when I electrically discharge and get \"shocked\"?"
] | [
false
] | What is producing this sound I hear when I, or anything, electrically discharge to a piece of metal? | [
"Thunder caused by lightning is produced by the rapid expansion through heating of the air through which the electricity arcs, causing a shock wave to propagate from the area of discharge. Static discharges are the same thing on a much smaller scale."
] | [
"A good way to think of it is to remember what sound is. It is a pressure wave that travels through air (although technically it could travel through any medium, but air is the most common medium in through which our ears detect the sound wave). The spark produced in a \"shock\" rapidly heats the air around it, cre... | [
"An interesting result of this is that it is possible to use this effect to create a \"plasma speaker\". Below is an explanation based on my understanding of how it works. If anyone else knows better, please chime in!: ",
"To do this, two conductors are placed near each other with an air-gap. A high voltage is cr... |
[
"Do Prime numbers change with base?"
] | [
false
] | E.G., we use Base-10, but would there be different prime numbres in base 12? 20? 99? | [
"A prime is a prime no matter which base you use to represent it. The fact of being prime or composite is just a property of the number itself, regardless of the way you write it or the symbol you use for it. 15 and F and Roman numeral XV all mean the same number, which is 3×5, so it is composite.",
"Let's take ... | [
"Being prime is a property of the quantity, so it does not depend on the langage I speak. ",
"Example : The number of symbols x in the expression \"xxxxxxxxxxxxxxxxx\" is a certain quantity. To say that this quantity is prime is to say that you cannot decompose this quantity of \"x\" into G groups of equal size S... | [
"You have 13 cookies. There is no way to fairly divide them up other than giving one to thirteen people. Or be a glutton and eat them all yourself. Regardless if you use base 10 or base 2, you are in the same predicament. The base is just how you describe it, 13 in base 10 and 1101 in base 2."
] |
[
"Science, approximately what percentage of humans that have ever lived are alive today?"
] | [
false
] | null | [
"6.38%",
" in 2009, probably more today."
] | [
"It should decrease into the 22nd century through declining birth rates from increased education."
] | [
"Will we ever get to the point where we see that percentage decrease?"
] |
[
"How did scientists of the late 1700s and early 1800s prove that meteors were rocks that fell out of the sky?"
] | [
false
] | Of course, there are plenty of religious and other objects that are claimed to have fallen out of the sky, and which are venerated, etc. but proving that they came out of the sky, to the satisfaction of all skeptics, is not the easiest thing. Especially given the state of the scientific arts at the time. | [
"Speculating here, will confirm on Wikipedia after.",
"With the discovery of Ceres and other asteroids, astronomers became aware of objects orbiting in paths between the orbits of Earth, Mars, and Jupiter. They could then presume that there were smaller objects that they could not yet detect, which might come clo... | [
"For the longest time, they denied it. Any witnesses to meteors falling were from the lower classes, so their testimony was automatically suspect and thus discarded.",
"I wasn't until one was witnessed by an educated member of the upper classes that they were taken seriously.",
"See: ",
"http://en.wikipedia.... | [
"So occam's razor meant that rocks did not fall out of the sky unless witnessed by the appropriate authorities.",
"interesting"
] |
[
"Can cross pollination occur between different plant species?"
] | [
false
] | In my Agricultural Science class today we were discussing how “superweeds”, weeds that are resistant to total pesticides, can be formed when a GMO crop (pesticide resistant) cross pollinates with a weed. I was wondering whether or not it is actually possible for this to occur? Isn’t it like trying to cross a dog and a ... | [
"If the evolutionary ancestor or closely related species(same genus) of the domesticated plant is a) present in the area and b) considered a weed, then yes it’s possible.",
"You also have to consider it the resistance mechanism is actually beneficial in a context outside of the farm. There’s no ecological issue i... | [
"Cross pollination can occur between species, this is hybridization and occurs reasonably frequently between plants. Domestic wheat itself is a result of several hybridization events, for example. ",
"You can hypothetically get superweeds if a weed species is similar enough to a crop species...don't think \"do... | [
"In evolutionary biology, there is a core concept called \"selection pressure\". \n",
"https://en.wikipedia.org/wiki/Evolutionary_pressure",
"In short - its the process where some \"pressure\" on a population, making individuals with certain genes more likely to reproduce. ",
"For pesticides, you have a chemi... |
[
"Everyone knows lead is toxic, but are there any technically positive effects on the body?"
] | [
false
] | Obviously any benefits are going to outweigh the toxicity of lead but after searching I didn't find any studies mentioning it. I did read that lead is absorbed into bones when other minerals are low so I wondered if it's actually giving some structure when that happens. We know some things that are generally bad for u... | [
"Lead, and many other toxic metals like mercury, cadmium, thallium, and uranium, have no known role in the human body. Our biochemistry is not equipped to deal with them at all so any amount will cause harm. The only safe level of exposure to these metals is zero."
] | [
"Yes. This is the secret of life. It's unsafe and in continuos danger but it doesn't care and continues its run!"
] | [
"People tried all sorts of crazy things with heavy metals in the 1800s - there are no positive effects.",
"It's possible you could maybe build some kind of drug that contains lead and is useful under ",
" conditions, like a chemotherapy agent. People have done similar things with metals like platinum. ",
"Bu... |
[
"How can we measure the absolute speed of something?"
] | [
false
] | [deleted] | [
"There is no absolute speed, only relative speed."
] | [
"I'm seeing some quick/not fully explained answers here, so here is a link to a series of askscience questions related to special relativity. ",
"A good summary of the simple questions about special relativity"
] | [
"No, velocities aren't additive. The formula is (v+u)/(1+v*",
"u/c",
" ). This is ~ v+u at low speeds, but the difference becomes significant at higher speeds. If you do the math you can see that as v and u approach c, the result also approaches c."
] |
[
"Can the principles for binding energy be applied to quarks?"
] | [
false
] | So in nuclear fission, large atoms are split and part of their binding energy gets turned into kinetic energy. Quarks are held together to form hadrons using the strong nuclear force the same way atomic nuclei are held together, with (from what I’ve researched) hundreds of times the amount of energy. I know from what w... | [
"The potential that binds nucleons to each other is localized, meaning that the potential asymptotically approaches some value as the distance goes to infinity. So a particle with an energy larger than that asymptotic value of the potential energy has enough energy to escape to infinity.",
"But the static quark p... | [
"That makes a lot of sense, thank you for answering all my questions!"
] | [
"The comment above is about today's universe where everything is \"cold\" and bound in hadrons. In a quark gluon plasma both quarks and gluons are free. Again the concept of a binding energy is problematic, but this time because things are not bound. You could ask about the energy to remove them from the plasma, bu... |
[
"Why isn't Asexual reproduction more common in the animal world?"
] | [
false
] | null | [
"Asexual reproduction does not allow for genetic diversity, so an organism that reproduces asexually is essentially making clones of itself. This has two major implications, one being susceptibility to disease. Entire populations of animals with the same genotype can be wiped out by a single virus. Also, since ther... | [
"asexual reproduction ultimately reduces variation in populations. This is due to asexual reproduction creates genetically identical offspring(apart from any mutations that arise). This means that over time populations that use asexual reproduction will be less adaptive to environmental change, as there is less va... | [
"Also, it's not fun."
] |
[
"How is heat dissipated from Earth and its atmosphere into space?"
] | [
false
] | For whatever reason, I was contemplating global warming from a heat transfer perspective on my commute home today. We have an enormous number of BTUs entering the Earth's atmosphere everyday; and, we have the vacuum of space surrounding us, and therefore no matter for the heat to dissipate to, the perfect thermal insul... | [
"It's all radiation, incoming and outgoing. If you want to be a pedant, you can look at miniscule amounts of particles from the solar wind entering the atmosphere at high speed and heating it up a bit and likewise gas molecules leaving the atmosphere cooling it down ever so slightly."
] | [
"The atmosphere is quite opaque for thermal radiation from the earth's surface, so it is the upper atmosphere that radiates into space (but also down towards the surface - this is the greenhouse effect). It has a temperature of about 255 kelvin. "
] | [
"Also to clarify radiation in this context doesn't mean ionizing radiation. Electromagnetic radiation with a roughly black-body spectrum is emitted from earths surface, most of this heads away into space which is at a temperature of 3K. "
] |
[
"Does air sink in water at the bottom of challenger deep?"
] | [
false
] | Weird question, but I was reading that the water pressure that deep down is over 1000 times that at the surface level. So a bubble of air would be compressed to 100x the density, correct? Air is 1.29g/L, while seawater is 1.04 /L. At that depth the density should make the air heavier than the water, and sink, correct? | [
"100*1.29 [g/L]=129 [g/L]=0.129[kg/L]. Air would still be less dense than water there. The required pressure to make air the same density of water is 827 atm. However, air will probably dissolve into the water before reaching that pressure."
] | [
"Pressure and density are only proportional for ideal gases. At sea level pressure that's a good approximation, at 1000 times that pressure it is not. It's in a supercritical state, which is a state between a gas and a liquid. ",
"This page",
" says nitrogen has a density of 0.3 g/cm",
" at the critical point... | [
"Air is much more compressible",
" than ",
"water is",
".",
"2000bar is 200Mpa, the units are different on those charts, but by 10,000 bar air will be more dense than water at around 20C.",
"E: I extrapolated poorly, read the response to ",
"/u/Origin_of_Mind",
" ",
"looks like these are the wrong c... |
[
"Why can I not draw exactly what I visualize in my mind?"
] | [
false
] | Say I want to draw a dog. In my head I can see the dog and descriptions of the dog simultaeniously, but when I tell my arm and hand to start drawing the resulting image is barely a shadow of what I saw. So what's stopping me from becoming art famous? oh yea, my hand has no idea what's on. | [
"While muscle memory is important, the difference between a good artist and a bad one is, in fact, what he knows. There's a picture dictionary in your head that your brain uses to quickly figure out what an object is. Each picture is called a \"schema\". How do you know what a house is if no two houses are the same... | [
"Former art student here.",
"The important thing to understand when drawing is that what you SEE is not what you PERCEIVE, and you have to draw what you SEE.",
"The example we were given in class was a simple children's wooden block. When we look at it, from a given angle, we see both broad and flat angles, an... | [
"The same reason you can imagine exactly what you need to do to hit a home-run, yet strike out. You need to be physically coordinated and skilled enough to draw it which is more about \"muscle memory\" and acquired dexterity through training than simple imagination. The brain is very good at dreaming images up- but... |
[
"Are there any workable theories for 'quick' and low energy deceleration of space craft?"
] | [
false
] | I realize that modern designs for space craft's speed means the 'top speed' can only be reached for a certain time, with the rest of the trip spent slowing the craft down again. Are there any theories on ways to speed up the slowing down processes and/or use considerably less energy to do so? | [
"That sounds horrifically iffy to me. ",
"That's like the stereotypical \"catching a bullet in your teeth\". ",
"the types of speeds needed to make interstellar travel feasible",
"Voyager 1 is currently leaving our solar system. It's both the fastest thing that we've ever built, and traveling at extremely sl... | [
"I'm not sure what the virtue is of spending time thinking about how to ",
" from that kind of speed when it isn't possible to accelerate something to that kind of speed in the first place."
] | [
"Except that wouldn't actually work. The premise is based on the idea of a completely mythical material that can turn gamma rays into mechanical work without ablating."
] |
[
"Do plants need to 'sleep'?"
] | [
false
] | Could you keep plants permanently under sunlight/similar light? Or do they need a period of non-photosynthesis, like animals seem to? | [
"To properly develop, they usually require 8 (?) hours of near or total darkness per 24 hour period.",
"EDIT: Also, animals do not have photosynthesis. Darkness has nothing to do with sleep, it's just convenient for diurnal predators and gatherers."
] | [
"Largely incorrect. Most plants that I have tested (dozens under different conditions) grow just fine under 24 hour lighting in the early vegetative stage of a plant's life. There's distinct advantages to 24 hour lighting in the early stage of plant development such as reduced stem elongation.",
"It's flowering w... | [
"I mean animals in general."
] |
[
"How do hackers get information from unsecure sites?"
] | [
false
] | I was sent to an 'Apple' refund page. Logged in using apple id. Was surprised b/c I always forget the password. Then it started asking for sensitive information and it became clear that the page was not secure. Plus there's the little box in the corner on Chrome. My concern is that I started typing in info. I did not s... | [
"Websites can indeed read individual keystrokes. Think of how Google will autocomplete with search suggestions as you're still typing. They couldn't do that if they couldn't intercept your key presses before you hit the \"submit\" button.",
"In Javascript, for example, there is the OnKeyPress event. ",
"As oth... | [
"The website can indeed be configured in either way. Recording keystrokes is a bit more sophisticated and less trivial to implement than simple HTML form methods, but nothing crazy. A little bit of JavaScript will do. Hopefully you didn’t put in any real sensitive information. I think that if Apple asked for your S... | [
"Yeah that was the red flag. I'm thinking like wtf. And then I realize it's a scam. I didn't finish typing it out, but stuff like date of birth and address. SSN wasn't blacked out, so that also stopped me. I don't think I typed the full thing, but I am somewhat concerned. And there's basically nothing I can do. "
] |
[
"What prevents a tower crane from toppling over?"
] | [
false
] | I’m just astounded by the engineering marvel of cloud-breaching skyscraper construction and the assisting tower cranes that make it possible. Hoisting significantly heavy materials from ground to top level, and such a skinny build, what are the design measures that balance it? What balances the center of mass? | [
"So... For one thing, they have a big 'ol counterweight on the back end of the crane, so that when they lift heavy things, the heavy things put less stress on the metal truss structure that holds the train. They also make said truss structure super sturdy so that it can withstand the tremendous forces it is subject... | [
"The bases are actually pretty small, but well anchored to the building foundation. Maybe 30-40 feet square, but made from massive beams. The steel company I work for has made a lot of them, and we usually get them back afterwards since the GC has no more use for them, so it's win/win for us. They pay for it, and ... | [
"You don't know how heavy that counterweight is, or how heavy the load they're intending to lift with the crane is. The simple balance for any crane is that the counterweight times the distance from the counterweight to the center has to be equal to the load weight times the distance from the load to the center. Th... |
[
"Are our bodies optimized for a certain elevation (specifically breathing)?"
] | [
false
] | [deleted] | [
"Our bodies are able to dynamically alter their respiratory efficiency, so we're sort of optimized for lots of elevations, really. ",
"One basic way that we do this is to change the number of red blood cells in circulation; increasing the number means more oxygen can be extracted from the air, and decreasing the... | [
"Your blood has a system of regulators to it that help adjust what level of oxygen pressure in the air will result in it being absorbed by the blood.",
"There are multiple mechanisms used to adjust this system, each being used for different degrees of extremity. ",
"When you change elevations dramatically you n... | [
"I think ",
"yes",
".",
"Research on humans at high-altitudes contributes to understanding the processes of human adaptation to the environment and evolution. The unique stress at high altitude is hypobaric hypoxia caused by the fall in barometric pressure with increasing altitude and the consequently fewer o... |
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