title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Do all brains throughout the animal kingdom work in similar ways?"
] | [
false
] | Do all brains work with the same nuero-transmitters e.g. serotonin, dopamine etc. Or are there many different ways for a brain to fuction? | [
"In a way, you're asking the wrong question. If you want to know how similar our brains are to those of other animals, neurotransmitters are not what's important. What's important is whether other have the same brain structures as we do, serving similar functions, and containing similar circuits. ",
"Within the r... | [
"Within the realm of mammals, at least, the answer is certainly yes",
"To add on that, some neurotransmitters are found in nearly all animals. Glutamate receptors, for example, are found in mammals, amphipians, insects, and even sea cucumbers. And Proteins very similar to glutamate receptors are even found in pla... | [
"Well I guess the obvious follow up question is, what makes us different then?"
] |
[
"Is the universe’s rate of acceleration increasing, decreasing, or steady?"
] | [
false
] | So I know the current scientific consensus is that the universe is expanding at a rate that is accelerating. My questions are: Is this rate of acceleration steady? Would a decreasing rate of acceleration suggest that some day the universe may start condensing? Do we have this information, or do we even have a way to ca... | [
"Per current evidence, the universe's rate of acceleration is increasing. Large scale stuff is expanding away from each other at ever increasing rates. Of course science hasn't really answered the why and how of the mechanism behind this. This has lead creation to the construct of dark energy. Again, what exactly t... | [
"Per current evidence, the universe's rate of acceleration is increasing.",
"It depends on how you measure it. Our observations point to a future where distances increase exponentially. If you calculate r(t) - the distance as function of time - then all derivatives of it are increasing. If you calculate the deriv... | [
"In short, yes.",
"https://en.wikipedia.org/wiki/Scale_factor_(cosmology)#Dark_energy-dominated_era",
"https://en.wikipedia.org/wiki/Vacuum_energy",
"Sorry for mostly posting links to other sources, this quickly gets beyond my ability to explain it. "
] |
[
"If particles cant traven faster than the speed of light, shouldn't there be a absolute max temprature?"
] | [
false
] | Since the hotter a particle is the more it vibrates, and that vibration should only be able to vibrate as fast as the speed of light? Im thinking of a absolute max temprature as there is a absolute minimum. | [
"You also have to consider the Lorentz factor when calculating the kinetic energy at velocities near c. The faster a massive object moves, the higher its momentum and its kinetic energy.",
"http://en.wikipedia.org/wiki/Lorentz_factor",
"http://en.wikipedia.org/wiki/Tests_of_relativistic_energy_and_momentum"
] | [
"Temperature depends on the average kinetic energy (not the speed) of the particles, and kinetic energy goes to infinity as speed approaches c. ",
"Links that may be of interest:",
"http://en.wikipedia.org/wiki/Absolute_hot",
"http://en.wikipedia.org/wiki/Negative_temperature"
] | [
"Oh cool, ill try to understand this!\nThanks"
] |
[
"Is it a coincidence that countries closer to the equator are generally poorer?"
] | [
false
] | null | [
"if you look at ",
"The Equator",
" you see it pass through, Rainforest\n, Desert\n, Archipelago\n, and Ocean.\nNow if you're talking about North Africa, East Indies, and Central/South America in general that's a different story. Europeans developed shipbuilding/navigation techniques and began to explore the wo... | [
"Let me point out that Brazil has one of the fastest growing economies on earth, and with-in 20' of the equator sits Saudi Arabia, India, and Mexico's fast growing or strong economies. But The R. of Congo, or Indonesia make good examples. ",
"I could offer up my thoughts, but I don't really have the back-ground (... | [
"Its perhaps something to do with the fact they they were all conquered. ",
"Missing out on the Industrial Revolution.",
"Equatorial weather, lots of vegetation, better climate made it easy to survive & multiply. There was never a need to explore or venture out into the oceans in like the European nations did. ... |
[
"are sound waves affected by gravity?"
] | [
false
] | null | [
"Yes.",
"Sound waves need a medium to travel through (air or water as an example) and the density of those materials will be affected by gravity. ",
"The density of a medium absolutely affects how sound travels in that medium."
] | [
"This isn't entirely accurate. Although we commonly teach that gravity is a force, the study of general relativity tells us that objects with some mass actually ",
" spacetime itself. So, while sound waves do not have any mass, they are still affected by the curving of spacetime around such objects.",
"For exam... | [
"Related question: Do phonons have mass, and are they affected by gravity?"
] |
[
"If there's a lottery with a 50% chance of winning, and you buy one ticket per week for an infinite number of weeks, are you guaranteed a winning ticket."
] | [
false
] | note - spinoff from thread. | [
"The question is not well-formed because there's no such thing as \"after an infinite number of weeks\". "
] | [
"The probability approaches 1.",
"You can pick any number less than 1 and find a week where your chances are better than your given number, but the probability is never 100%."
] | [
"And yet you're still not guaranteed to win."
] |
[
"Wouldn't it be greener to produce green power for homes and manufactures and still be on gas-powered cars instead of electric cars?"
] | [
false
] | Hello there, I have always had this question on my mind that if electric cars are mostly using power that is produced by fossil fuels, what is their purpose? I mean, electric cars make more pollution in manufacturing process than traditional cars, their batteries are bad for the environment and are produced out of rare... | [
"You're making a lot of faulty assumptions here.",
"if electric cars are mostly using power that is produced by fossil fuels, what is their purpose?",
"EVs can use power from either fossil fuels and renewable sources, while ICEVs are stuck with only fossil fuels. But even when they're using electricity generate... | [
"I would like to challenge OP to read ",
"this",
" it’s only one case of how EVs vs ICE cars are produced. Sure EVs use may pollute more being made but over the lifetime of the car it is better for the environment"
] | [
"That would take fossil fuels off the table - I think Norway is getting there",
"The Norway Paradox.",
"On one hand the 15th biggest exporter of oil and 8th largest global exporter of natural gas. It is growing it's oil & gas sector and created new laws to facilitate drilling in the Arctic.",
"On the other h... |
[
"What kinds of negative effects does farming have on the environment and the planet as a whole?"
] | [
false
] | null | [
"We can address this in parts:",
"1) Farming requires lots of clear land. This has led to enormous amounts of clear cutting and burning of other vibrant and old ecosystems to install a man made one. See the Amazon.",
"2) Monoculture. To maximize automation, we plant large swathes of identical crops. While this ... | [
"The question was what affect does it have on the environment. Whether it's banning led to starvation in Africa or not is irrelevant to the fact that it had a negative environmental impact.",
"As I said later, there are long tail, complicated issues to discuss arising from farming and consumption, I just didn't w... | [
"DDT",
"You should do some research before putting that statement out there. The fertilizers they used caused thousands of times more damage than DDT did. Also, the ban on it is directly responsible for hundreds of millions of dead children in Africa."
] |
[
"How do Astronomers 'Know' that Gas Giants are Different than 'Normal' Planets? What if Gas Giants are just Planets like Earth but with Thick Atmospheres?"
] | [
false
] | I hope my question makes any sense. I know that no one knows what really is inside of a gas giant, but there is a difference. I remember in grammar school we learned that there were gas giants and 'normal' planets like Earth with solid cores. How do we know this difference? | [
"For starters, current theories on planet formation are very difficult to reconcile with very massive Earth like rocky planets. Past a certain point, a rocky protoplanet in a protostellar disk will begin accumulating Hydrogen and Helium, which will always represent the majority of the disk. When that starts happeni... | [
"In a way, gas planets are the result of an Earth-like object gaining too much of an atmosphere, if we assume the core-accretion model of planetary formation (i.e. that the gas planets started out as solid cores, and that these gained enough mass to trap significant amounts of hydrogen with their gravity) is correc... | [
"The wording of your last sentence is confusing. Reading it seems like you're saying Uranus has a larger mass and smaller radius, not Neptune. You change subjects within the sentence, so it took me a second to parse what you were referring to. ",
"Something like \"because Neptune has higher mass and is a smaller ... |
[
"Is it possible that human couples share each other's internal electricity?"
] | [
false
] | null | [
"What is internal electricity?"
] | [
"http://health.howstuffworks.com/human-body/systems/nervous-system/human-body-make-electricity.htm",
"It was quite vague. I got thinking about what people can share other than any physical connection. I landed on electricity. I own a restaurant and have seen a lot of people pass over the years and, in elderly cou... | [
"Yes, neurons communicate via electrical impulses, but that has nothing to do with colloquial notions of \"electricity between people\"."
] |
[
"How is colour change and movement emulated in case of video games?"
] | [
false
] | null | [
"So electron guns existed in CRTs. The electron beam from the electron gun is magnetically (usually) deflected to scan the phosphor screen in a sawtooth (Z) pattern. See ",
"https://en.wikipedia.org/wiki/Raster_scan",
" and the page on CRTs. For a 60 Hz refresh rate, it really does do this scan 60 times in one ... | [
"ok, one focused beam is launched from one point, yes? I saw that, but how, without movement, is it possible to have this beam deflected so it flls the entire screen with proper colours>",
"",
"Also with modern Liquid Crystals, what exactly makes the color change if nothing is moving? This is exactly what fasc... | [
"This",
" site has an excellent explanation and demo of how magnetic fields (in the demo, depicted as little magnets, but actually the result of passing electricity through two, unmoving electromagnetic coils) can affect the direction of the beam. Changing the magnetic field is as easy as changing the amount of e... |
[
"How can brains (human or otherwise) accurately keep time? What do we use as a \"clock signal\"?"
] | [
false
] | I'm referring to a person's ability to keep a rhythm over time, which can be highly accurate with practice. Edit: for clarity, I mean really short term timekeeping, like less than 10 second intervals. | [
"There's a constant cycle of protein breakdown within your brain that gives your body an internal \"sense\" of time; it appears that it is regulated/kept \"tuned up\" by factors such as light exposure: ",
"http://en.wikipedia.org/wiki/Circadian_clock",
" (and see also ",
"http://en.wikipedia.org/wiki/Circadia... | [
"KingSloth's explanation works for seconds or hours",
"KingSloth is specifically referencing circadian systems which refer to those of \"about a day\", by definition.",
"Furthermore, while it's conceivable that there are purely protein-protein interactions that could potentially keep time on fast time scales, t... | [
"We have a three phase clock running into our hippocampus. The three waves are heterodyned to give a unique \"address\" for each moment since you woke up. (Adrenaline increases the frequency, leading to more addresses per time interval). ",
"The rest is entrainment using the thalamus as a delay line and the phono... |
[
"My father and I want to conduct an experiment to determine if our cat can count. How can I go about this?"
] | [
false
] | I found a paper that seems to be just what I need for this (Quantity discrimination in felines: a preliminary investigation of the domestic cat), but couldn't find a free version on Google Scholar. Neither of us are scientists, so I have no idea how to go about setting up an experiment like this. | [
"Apparently children have to rewire their brains to think about numbers linearly (instead of logarithmically). Before they do, kids can easily distinguish one from a few and/or many, but not, say, 7 from 8. I would guess cats would be similar -- very interesting question!"
] | [
"Wow, thanks dude! I only regret that I have but one up-vote to give."
] | [
"Wow, thanks dude! I only regret that I have but one up-vote to give."
] |
[
"Does it require more, or less energy to climb stairs two steps at a time as opposed to one?"
] | [
false
] | null | [
"From a physics standpoint as long as you are going up to the same height you are always doing the exact same amount of work. ",
"If you lift one pound ten feet in 10 seconds or in 10 minutes you still do the same work. ",
"From a physiological standpoint it might be different. "
] | [
"but there are so many things to consider! its not an easy question to answer.",
"i would assume it would require more energy. if you think of each step being 20 centimeters tall, your leg has to lift you 20 centimeters twice. if you do two steps at once, your leg has to lift you 40 centimeters once. still follow... | [
"The muscles that flex the leg (quads, sartorius, etc.) generally stretch along the front of the thigh from the pelvis down to attach at the bottom of the femur or the top of the tibia/fibula. That is, they run vertically when you are standing straight up. Right when you raise your foot off the ground, the thigh is... |
[
"Hey AskScience, Will you help educate me?"
] | [
false
] | [deleted] | [
"Check out MIT's ",
"OpenCourseWare",
"."
] | [
"There's a ",
" website here, which I think you'll find as awesome as I do: ",
"http://khanacademy.org/",
" "
] | [
"I doubt you'll get someone to personally mentor you, but good luck anyway. However, you might want to check out ",
"Academic Earth",
" for some free university level education."
] |
[
"If I am traveling through space at the speed of light then how fast is the light from my spaceships headlights moving?"
] | [
false
] | null | [
"The light from your headlights will propagate at exactly the speed of light, as for you and for any outside observer. The Problem with your argumentation is the same with which any relativity discussion starts, that time is a fixed thing. According to Einsteins theory however, this is not true. The only thing that... | [
"The speed of light. See: Theory of Relativity. "
] | [
"My hypothesis is this: If Light moves at a constant speed then I believe that if the source of light is moving than the photons emitted from it move at the speed of light relative to how fast the source is moving.",
"The way it works is that the measured speed of light in a vacuum will be the same, for all obser... |
[
"How did astronomers determine the mass of the rogue planet SIMP J01365663+0933473 if it’s not orbiting a star and has no known natural satellites?"
] | [
false
] | I heard about this planet yesterday from this post over at and haven’t got an answer yet According to the post / article, the free-range planet is said to be 13 times the mass of Jupiter but does not orbit a star and no moons have been found yet. If this is the case, how could have astronomers determined its mass with... | [
"It sounds like a statistical correlation. Kind of like how if you know how long a blue whale is, you can guess it’s weight because you’ve measured the length and weight of thousands of other blue whales and have noticed a correlation."
] | [
"I don't think we've ever used a laser \"ping\" to measure any distance in space for extrasolar objects."
] | [
"Yes, but we know the new species is an aquatic mammal with fairly similar habits, but an intermediate size between other known whales. Which, in real life, would work well - there's only so much the density of an animal like that can vary and still be made up of warm-blooded meat.",
"To pull back from the metaph... |
[
"A person falling into a body of water from a high altitude can get seriously injured or even die due to the impact against water's surface tension. What happens if they fall into a liquid that has less surface tension, like rubbing alcohol?"
] | [
false
] | Can they survive the impact from a further distance than they would if they fell into water? Bonus: Is there a way to calculate the furthest distance a person could fall into a liquid without hurting themselves for different types of liquids? I was just curious because I don't think I've ever seen someone dive into a p... | [
"It's actually not due to the surface tension of the water, it's due to the fact that water really isn't compressible. Basically, if you jump into the water from a small height, you aren't moving as fast and the water has time to \"move out of the way,\" and therefore you can jump into the water. If you jump from a... | [
"Good answer. ",
"One way to get a more compressible liquid is to put air bubbles into the water. This is what they do for some high divers. They pump compressed air to the bottom of the pool and release it."
] | [
"Cool! Wow I had always thought it was because of surface tension. So what are some examples of fluids that are more compressible? "
] |
[
"Is there any validity to this article regarding the Fukushima radiation spread? If so, what can be done to truly prevent radiation absorption in our food supplies/daily life?"
] | [
false
] | Samples of milk taken across the United States have shown radiation at levels 2000 percent higher than EPA maximums. The reason that milk is so significant is that it is representative of the entire food supply. According to an article published on Natural News, “Cows consume grass and are exposed to the same element... | [
"Ok, first off this link is not science at all. ",
"secondly, now that I'm home and have had more time to look at the article, allow me to start debunking stuff directly from it.",
"babies born with thyroid issues linked to radiation are rising quickly ",
"A rooftop water monitoring program managed by UC Berk... | [
"Nope. There are a number of red flags, but probably the best one is common sense.",
"When the FDA suspects beef to be tainted with e. coli they recall all the beef.\nWhen the FDA finds listeria in food, the perform a recall and again all food that might be tainted is removed.\nIf the FDA found dangers levels of ... | [
"at levels 2000 percent",
"Smells like fearmonging. The author should have written \"20 times\", but of course, \"2000\" is better from a journalistic perspective.",
"Also, that's just a comparison to some other value. What's the absolute number?",
"If all those figures come from a random number generator, d... |
[
"Do ice breaking ships speed up the rate that the arctic ice melts?"
] | [
false
] | It is clear that if I put in one large lump of ice in my cola, it will take longer to melt than if I put several lumps whose combined volume equals the single lump. More and more ships are now crossing the arctic ocean, breaking through "thin" ice as they do so. They are effectively chopping up the ice into smaller lum... | [
"When you crush an ice cube you increase the surface area which allows the room temp/outdoor air/cola (which is usually above 0C and cola always is) to exchange heat more effectively with the ice thereby melting it faster.",
"With ice in the arctic while if you do break it up the temperatures are below freezing w... | [
"Probably not, that thin of ice should have no problem freezing over again. Luckily melting ice that's afloat in the ocean doesn't effect sea levels much anyway."
] | [
"As others pretty much note, yes, it does make the ice melt faster ",
" it also makes the ocean itself colder faster (you increase the rate of heat transfer, but not the amount), so it'll freeze faster.",
".",
"When water at 0C loses heat, it turns into ice when enough heat (the heat of fusion) is lost. By in... |
[
"If everyone had to go to the doctor once a year, would this result in more or less work for the health service?"
] | [
false
] | null | [
"Preventative medicine is well known to reduce health care costs and improve health and quality of life.",
"An annual trip to the GP might not be the best way to achieve this but measures such as regular screening for certain condtions and vaccinations help."
] | [
"Or, to add to the question: if not a year, what would the ideal frequency be on average?"
] | [
"\"Due to\"?"
] |
[
"Can a person test negative for COVID, but still be contagious? (Assuming that person is in the process of being COVID positive)"
] | [
false
] | null | [
"Yes, if you test too early and your viral load is too low you may not test positive. In addition too this, there is also always the chance of a false negative or false positive with any test. No test is 100% accurate and incorrect results could come from things as simple as mislabeling of a specimen or some othe... | [
"That is true, but I'm not sure that answers the question fully. If you test negative because your viral load is too low, are you contagious (assuming you are already infected)?"
] | [
"Depending on the timing, yes.",
"https://www.hackensackmeridianhealth.org/HealthU/2020/12/03/exposed-to-covid-heres-when-to-get-tested/"
] |
[
"How would a nuclear reactor setup fare in space?"
] | [
false
] | My main question is about the heat dissipation in space. Since space is generally very cold, would it be more efficient for a nuclear reactor to be cooled in space or would it be less efficient to rely on heat radiation without any air vs an air or water-cooled system as they're designed to work in an atmosphere? | [
"They work. There are several satellites that actually use nuclear reactors to generate electrical power. Wikipedia has a list: ",
"https://en.wikipedia.org/wiki/List_of_nuclear_power_systems_in_space",
" (which also includes RTGs, they are a different thing, but still nuclear).",
"My main question is about t... | [
"Okay, I didn't have any hint that OP was asking about megawatts but it's still answerable. There aren't any MW-scale reactors in space as of today, but there are some designs that have been proposed for nuclear-electric propulsion, which would have power requirements of this order of magnitude.",
"The spacecraft... | [
"The mass budget for that concept certainly seems to make the accountants sweat blood.",
"Still better than using huge fuel tanks for chemical propulsion"
] |
[
"As fish, like Koi, grow larger do the rods and cones in their eyes become larger or increase in number?"
] | [
false
] | ...or both? I am curious to learn if an older and larger Koi would have greater ability to see fine details and/or better light sensitivity compared to its younger and smaller self. | [
"What does this have to do with fish?",
"And you are wrong. Adult humans have larger eyes than babies."
] | [
"What does this have to do with fish?",
"And you are wrong. Adult humans have larger eyes than babies."
] | [
"They increase in number.",
"The growth occurs in the ciliary margin, which is the bit of the retina closest to the iris."
] |
[
"If different races aren't like different dog breeds, what are they and is \"race\" even real?"
] | [
false
] | null | [
"but outside of that the difference is just skin color",
"Not true.",
" There are DNA differences between the races. The DNA from neanderthals can effect ",
"blood cholesterol levels, schizophrenia, eating disorders, and rheumatoid arthritis."
] | [
"The caveat \"other examples\" meant that there are other conditions I do not know about."
] | [
"There is no genetic difference that all \"black\" people have vs all \"white people\" for example.\nThere is NO such scientific thing as race. It is a social construct. Yes, there are genetic mutations that are common in different societies, I am not positive why, but a guess would be due to breeding and passing i... |
[
"Does the human body heal injuries / repair itself faster while sleeping?"
] | [
false
] | null | [
"In terms of say, tissue repair, lack of sleep does not seem to matter, at least in rats (",
"study",
", ",
"study",
"). However sleep is implicated in the functioning of your immune system (",
"review",
"), so your ability to fight of an infection for example, could be compromised by lack of sleep, but... | [
"Unfortunately, there doesn't seem to be too much current literature on the topic. Most of the papers I found discuss sleep in the context of ICU care, so it's more an issue of chronic sleep deprivation rather than the difference between sleep/wake cycles.",
"This",
" paper says ",
"Sleep is an essential res... | [
"Related, I imagine some wounds would heal faster simply because you'd stop picking at them."
] |
[
"FTL Signalling with Entangled Photons - Why Doesn't it Work?"
] | [
false
] | Hello wonderful people of AskScience. I've been thinking through a notion for faster than light signalling. It's based on a fairly simple demonstration. Set up two polarizing filters, one rotated 90˚ relative to the other, and notice that light is not transmitted through them. [ GENERIC LIGHT SOURCE ] ---> [ FILTER at... | [
"The photons that are transmitted are not transmitted unscathed; they are forced (so to speak) into a vertically polarized state. so its polarization state has been measured, and so it is no longer entangled with the other photon.",
"If you had N mutually entangled photons and measured the polarization of one of ... | [
"There are several errors here.",
"First, in your initial set-up, only 1/8 of the light is transmitted; it gets cut in half when the natural light hits the 0",
" polarizer as well as when it crosses the other two polarizers.",
"Second, in your second set-up, whether you wave the 45",
" polarizer in or out o... | [
"This is one of the features of quantum measurement. If you have a system in a mixed state, a measurement will force that state to shift into a state in which the observable measured has a definite value; this is what is meant, in fact, by a measurement. (As to what happens at the time of measurement: this is a s... |
[
"Can a vaccinated adult get pertussis?"
] | [
false
] | [deleted] | [
"The answer is absolutely. The probability is going to be hard to determine. Remember that we vaccinate of course to protect ourselves, but also to protect one another. ",
"Herd immunity",
" works best such that if a vaccine happens to fail in me, it's not a big deal because it worked in you and you won't get m... | [
"Vaccine efficacy for pertussis vaccines is around 70-90%, so a significant minority of vaccinated people are potentially at least partially susceptible. (Most of the susceptible people do have some degree of immunity, reducing severity and/or transmissibility of the disease.)",
"Two other points: Immunity for j... | [
"Except herd immunity doesn't work with the acellular pertussis vaccine. The old whole-cell vaccine (TDP) did protect against transmission, but all the new-fangled ones (the -aP ones) unfortunately don't. "
] |
[
"How do you weigh something in space?"
] | [
false
] | [deleted] | [
"For starters, landing the rocket is done with computers using sensors to measure the rocket's position and acceleration (search for IMU for a better idea of the type of measurements). It's a less error-prone method to just measure the position of the spacecraft and adjust than try to work out the kinematics using ... | [
"The simplest method I can think of (which may not be how they do it!) is to see how quickly something accelerates when you apply a force. Quite simply, if you apply the same force to a heavy object and a light one, the lighter one will accelerate more quickly, as described by ",
"Newton's second law",
" (F=ma)... | [
"Space travel is generally a closed system. You pack out what you pack in, to borrow terminology from hiking. Even biowaste will have the same initial and final mass unless you jettison it, in which case, you probably won't really care since it is going to be ejected at a low velocity and already low mass. Plus if ... |
[
"How do yeasts contribute to flavour in beer, wine and bread making?"
] | [
false
] | As a keen homebrewer I am very aware that the yeasts you use can have a huge impact on the flavour profile of anything you make. However, my crappy school-level biochemistry and some cursory searching and wiki trawling only seems to discuss the fermentation of sugars into alcohols. Clearly that can't be all that's goin... | [
"Well yeasts (all cells really) take up all sorts from their environment and release all sorts of chemicals and proteins too. As well as sugars they take up any micronutrients they need. These are appropriately metabolised and some of the metabolic products will be released to the environment, some will be excretor... | [
"Awesome, thank you so much. That metabolome database is a phenomenal resource."
] | [
"Also, several of these compounds are actively avoided in brewing. Some by allowing the yeast to continue metabolizing (they'll resorb and digest some of the things they secrete as the sugar is used up), and some by adding finings to bind and precipitate certain components.",
"Don't remember all the details exact... |
[
"I just mixed some Acetone and Water and the beaker warmed up. Why?"
] | [
false
] | [deleted] | [
"No thats not corret. You're right there is no reaction, but it has to do with the delta G of mixing."
] | [
"I think the answer to this question is going to be complicated, depend on the ratio of water and acetone, and ultimately have to do with the thermodynamics of how the acetone and water molecules arrange themselves. But to be overly simplified, I think you could just state that the acetone/H2O molecules fit togethe... | [
"You can have heat release even with mixing. For most mixtures it is just so small that it isn't noticeable. "
] |
[
"What determines the radius of curvature of a rainbow?"
] | [
false
] | null | [
"See ",
"this",
" thread for a pretty good description, with diagrams, of what causes rainbows.",
"However, I think it's clearer to think of a rainbow not as a \"circle,\" or a curve at a fixed ",
" position in space, but rather as an entire ",
", with the vertex at your eye. It makes sense to talk about... | [
"But there is also the fact that the rainbow is formed due to reflection, refraction, and dispersion caused by water droplets. These droplets have to be in the atmosphere at some distance away from the observer. Not one exact distance, for sure, but some range of distances - the droplets aren't at all distances alo... | [
"Here is a simple fact that helps explain the shape: It is a ring at 42º centered around the antisolar point. Guess what the antisolar point is? The shadow of your head. ",
"It illustrates the fact that not everyone in a group of people is seeing the same rainbow, and helps you realize that light is being scatter... |
[
"\"Perhaps most mind-boggling of all is the math that shows that at any given moment, each of us has at least a million atoms in our body that were once in the body of every person who has ever lived, from Moses to Lady Gaga, from Marcel Proust to Newt Gingrich.\""
] | [
false
] | I've heard this, or some variation, quite a few times. Is this possible and, if so, how? EDIT: Words. Can't brain today; I got the dumb. | [
"So, not \"Every single atom.\" as you said above."
] | [
"I think it's mostly a statistics trick to make this kind of a claim, based on people having ~7e27 atoms in their body (according to wolfram alpha) and less than 7 billion people alive at a time (7 billion times 1 million is only 7e15, so our bodies would at least consist of 99.99999...% unrecycled material, since ... | [
"What about hydrogen? Isn't all, or a vast majority, of hydrogen primordial?"
] |
[
"Why can you rename, or change the path of, an open file in OS X but not Windows?"
] | [
false
] | null | [
"The Windows filesystem identifies files by their paths (including the file names)—if you change a file’s path, applications and the operating system will perceive it as a new file with no connection to the original.",
"The OS X filesystem identifies files by an independent file ID, which remains fixed if the fil... | [
"I've taken a class in Operating Systems. The simplest answer is probably this:",
"In this case specifically, there may not be many repercussions. However, let's consider an extrapolation of these two mindsets. Windows is keeping things simple, but disallows some operations like the one that OP asked about. OS X ... | [
"Follow up question,..what's the pro/cons of both method ?"
] |
[
"As a ball's velocity approaches the speed of light, does the Higgs field effect on the ball increase because the mass of the ball increases?"
] | [
false
] | . | [
"(1) We no longer talk about mass increasing as speed does, because it is a misleading concept. We instead just talk about momentum no longer being a linear function of momentum.",
"(2) The Higgs is not responsible for most mass. It is responsible for the mass of individual particles like quarks, but in fact that... | [
"As i understand it, the faster it goes, relative to some other inertial reference frame, the more it will interact with the higgs field, relative to that inertial frame, thus making one in the other frame measure it as heavier. But i dont think it actually aquires particles."
] | [
"Thanks, that's certainly a better, and accurate, way of putting it."
] |
[
"Can a parasite get parasites?"
] | [
false
] | null | [
"Yes; there's even a word for it, ",
"hyperparasitism",
". Depending on the definition of parasite you choose to work with, some examples of hyperparasitism may or may not apply, but an example that I think would fit most definitions is ",
", a parasite genus that lives in insects, particularly parasitic flea... | [
"Yes!",
"The Chestnutblight fungus, ",
" is susceptable to a mycovirus which lessens the damage that is done to the tree."
] | [
"Yes, there is an example in the disease Diphtheria. It is caused by a bacterium, a parasite that is itself the victim of a bacteriophage virus, a parasite. ",
"The gene for the toxin in Diphtheria is not in the bacterium's genome, it is encoded by the virus."
] |
[
"Angular momentum question."
] | [
false
] | I'm not sure if his is a dumb question or not but why does angular momentum follow the right hand rule? You know the rule that says if you point the fingers of your right hand in the direction of rotation your thumb points in the directon of angular momentum. Was 'God" right handed? Is it the same in the Southern He... | [
"It's just convention. There are only two options. I suppose more generally it follows from the right hand rule for cross products."
] | [
"It doesn't matter which hand you use, as long as you're consistent. If you change all of our right hand rules to left hand rules everything works out the same."
] | [
"You could use a left hand rule for ",
" without changing physics. Whether it is the right or left is arbitrary. ",
"What is true of angular momentum, and must be addressed in our rules is that angular momentum appears to be opposite in a mirror. ",
"Take a bottle cap, or a frisbee...or anything disklike. ... |
[
"Evolution: Do all current \"versions\" of a species derive from one single individual?"
] | [
false
] | [deleted] | [
"Well, for this question:",
"Does this mean that, since all sharks now have this ability, that they are all ancestors of one particular shark?",
"Yes, assuming you mean descendants rather than ancestors.",
"But for this question:",
"Do all current \"versions\" of a species derive from one single individual?... | [
"I'm not familiar enough with this to speak for all animals, but there are two relevant common human ancestors (because of sexual reproduction): ",
"Mitochondrial Eve",
" and ",
"Y-chromosomal Adam",
"."
] | [
"But it didn't happen in one stage, so your \"one shark\" example isn't that realistic. ",
"It would also probably be a mistake to call the creatures that started the process as \"sharks\". They were ancestors of sharks, but not sharks.",
"And we needn't feel sorry for those who didn't contribute to the shark t... |
[
"What percentage of a person's mass is made up of up quarks, of down quarks, and of electrons?"
] | [
false
] | Wiki has an article on , but it got me wondering, what is the composition of the body in terms of elementary particles? Also, is the mass of photons, gluons, Higgs', and other particles statistically insignificant when calculating this? | [
"I want to make note to anybody playing at home with their calculator, the measured masses of the quarks are ",
" lower that what you'd expect when considering the mass of the protons and neutrons—this is because the majority of the mass results from binding energy in what's oddly enough a special relativity effe... | [
"Assuming we have roughly even numbers of protons and neutrons (which is pretty close to true, although we'll have an excess of protons due to the large amounts of water in the human body, since hydrogen atoms mostly consist of a single proton and no neutrons), we're 50% up quarks, 50% down quarks, and a fraction o... | [
"I think that would really depend on what you consider a characteristic. The binding energy will pretty much always be present anytime you find a quark. However, the binding energy being there is based on conditions that aren't necessarily mandatory given or current knowledge of physics. But then again, the same th... |
[
"Why do atoms need to fill up their orbitals?"
] | [
false
] | I am an undergrad doing first year chem and I was wondering why atoms need to fill up their electron orbitals, even if it means creating an unbalanced charge? Do we know why particles do this or were theories created based on observations made from experiments? | [
"Good question! Because they actually ",
" create an unbalanced charge. What I mean is that if you were to (somehow) take a single NaCl molecule and pull the two atoms apart in a vacuum, you would ",
" end up with Na",
" and Cl",
" but with two electrically neutral atoms; Na",
" and Cl",
" (asterisks he... | [
"Thanks for your answer!",
"If I understand correctly, you're saying atoms never ",
" get an unbalanced charge, and if they do, there is a way to balance the charges? (e.g. NaCl in water)",
"And are you referring to electronegativity in your second last paragraph?",
"Can you explain, even if briefly, why at... | [
"No, I'm saying that two atoms in a molecule won't break apart into charged fragments in a vacuum, because separating two charged particles like that costs too much energy. If there's a way to ",
" the charges (lower the energy of having a situation with separated charges) ",
" you can get two atoms to separate... |
[
"Why is there (at least) three space-like dimensions and only one time-like dimension?"
] | [
false
] | null | [
"What do you mean \"why\"?"
] | [
"Wow, this is surprisingly difficult to answer. I guess I mean why is it presumed or why do we only work with one time-like dimension? ",
"I am sort of thinking aloud here and I hope that is ok. Is it a result of our experience in a way similar to how it was presumed that there are three space-like dimensions ",
... | [
"Why do we work that way and why is it that way, if that's even the case, are two diffrent questions. That is unless you belive in a strong anthropic principle, and therefore think that the universe not only is the way to is because we are here and require it to be this way, but ",
" because we are here and obser... |
[
"What does a 1kW solar panel realistically produce in average?"
] | [
false
] | What is a solar panel rated at 1kW realistically going to produce in average? Not when only the sun shines, but all year round, night and day. So if we took all the power it produced through a year, and calculated the average, what would it realistically be? | [
"The rating for the panel is produced through testing by a company in Florida (there are others but the one in Florida does most of the testing) where the average insolation is about 5.25 kWh per square meter per day which is high, but not the highest on Earth. In these conditions, a solar panel will produce elect... | [
"It really depends on where the panel is located and many other factors. ",
"This",
" is a great tool to find out. I just checked my area in Portland, Oregon, and a 1kW system would produce 1018 kWh in one year."
] | [
"It generates more than 1 kWh per hour in the day, due to the stronger than normal sunlight."
] |
[
"Why do most earthquakes have a magnitude between 4.0-4.9?"
] | [
false
] | When I looked at the amount of earthquakes each year it was very weird to realise that atleast 90% of all earthquakes have a magnitude between 4.0-4.9. What is even more weird is that magnitudes could increase because the spin of earth is slowing down. So I was wondering if that 4.0-4.9 could also change in 5.0-5.9 or ... | [
"Luckily for everyone, it is ",
"not true",
" that most earthquakes are magnitude 4.0-4.9. It just ",
" that a majority of quakes are in that range because lists of earthquakes normally don't include smaller quakes, even though there are ",
"vastly more of them",
" (play with the \"all magnitudes\" settin... | [
"That's not exactly true. The number of earthquakes increases with lowering the magnitude. So the most earthquakes have a very little magnitude. Maybe the list of earthquakes that you've been seen just have the minimal magnitude of 4.0 so it is the most widespread magnitude because it is the lowest."
] | [
"The ISC is usually good, ",
"ANSS catalog",
" is one of the other big global datasets. Most global catalogs, especially ones that are populated with a lot of teleseismic data (i.e. info on earthquakes relatively far away from contributing stations) will have magnitude of completeness well above Mw 1. Local net... |
[
"How do other animals see television? As a series of still images, a blur, or like we do (as motion)?"
] | [
false
] | I realise this may depend a lot on the animal - so lets says a a cat, a dog & a bird of prey. **Lets assume it's it's either a movie or a tv show, so 24 frames per second or above. | [
"ultraviolet"
] | [
"Related: The red, green and blue displayed by TVs correspond to the cones in our eyes. Turtles have four types of cones, so the color on a TV doesn't look like real life to them."
] | [
"AskScience discussion about how dogs see television"
] |
[
"What is the mechanism for antimicrobial behavior of silver or copper?"
] | [
false
] | How does putting these materials in the fabric of my shirt so anything to kill microbes? | [
"Copper and silver ions disrupt bacterial membranes and viral protein coats which can lead to them spilling their contents out into the world, killing them. One of the ways they do this is by reacting with thiol (sulphur containing) groups on membrane proteins. ",
"If this disruption isn't enough to kill the micr... | [
"Silver also has the ability to denature key enzyme systems within bacteria."
] | [
"Silver also has the ability to denature key enzyme systems within bacteria."
] |
[
"Ask Anything Wednesday - Economics, Political Science, Linguistics, Anthropology"
] | [
false
] | Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical post? No question is too big or small for AAW. In this thread you can ask any science-related question! ... | [
"Is there any substantive evidence to suggest ranked choice voting significantly changes electoral outcomes vs. winner-take-all?"
] | [
"Somewhat to the contrary, fairvote.org lists ",
"some data",
" that seems to suggest the impact is minimal:",
"A FairVote report on incumbency in the Bay Area of California shows that incumbents are re-elected at the same rate both with and without RCV.",
"There have been 15 RCV races in the U.S. which wer... | [
"Interesting! Thank you"
] |
[
"Why do insects trapped in amber look the same as insects today? Is there anything in particular about modern insects that distinguishes them from insects that lived 250 million years ago?"
] | [
false
] | From an evolutionary perspective, it seems on the surface that bugs looked the same today as they did back when dinosaurs roamed the earth. Amber of frozen insects don't immediately make apparent that millions of years of evolution separate that trapped insect with insects in 2019. Is there anything, perhaps internally... | [
"I'd argue they aren't really any more similar to modern insects than ancient vertebrates are similar to modern vertebrates, it's just that you do not see the differences as readily because your eye is trained to look at vertebrates and notice details it just misses when looking at insects. Many modern insect group... | [
"it's just that you do not see the differences ",
"This. I imagine that entomologists are screaming as they read the original question. Insect species today might be visually differentiated by a pattern of hairs or the veins in their wings, things that a lay person (like myself) don't register. I was recently on ... | [
"Aside from perhaps size I can’t think of much, I’m no expert in insect biology and evolution but usually when an animal does not further change in physiology it is because they’ve no need to adapt, they are already evolved to fit their purpose and survival needs. That would suggest that in earths state for the las... |
[
"How do mathematicians discover more digits to pi?"
] | [
false
] | [deleted] | [
"No. Mathematicians aren't particularly interested in the digits of Pi. I know 3.14159, and that's it. Digits are not an important property of a number, we try to ignore them as much as possible. ",
"But most formulas for Pi are in terms of infinite sums, which means you can add up a finite number of them to get... | [
"usually a fairly ",
"convoluted formula",
" derived from an identiy by Ramanujan is used, because it converges ",
" quickly"
] | [
"Actually, supercomputers discover the digits of pi using polygons. Think of an hexagon. It tends to be a circle. Now add more sides. Think of a polygon with 1,000 sides. Think it with even 1 million or billion sides. It certainly is very close to a circle. From these, supercomputers calculate the perimeter and the... |
[
"Does relativity imply that gravity is a pseudo-force?"
] | [
false
] | null | [
"\"Force\" is not the best-defined term in physics. We tend to call it a force more often than not, but you're right that it's different than all the other forces because it's not an effect particles have on each other, but rather an effect of particles moving on natural paths through spacetime itself."
] | [
"That's correct, the appearance of the downwards force of gravity is just an artifact of the fact we are working in an accelerated reference frame with respect to spacetime geodesics. So in that sense, it's a fictitious force, in exactly the same way as centrifugal force, with which people are familiar. ",
"(Of c... | [
"Depending on what the correct quantum theory of gravity looks like, that may well end up being a reasonable interpretation."
] |
[
"If electric is transferred via electromagnetic waves and the speed of these waves are near the speed of light, why does the type of conductor matter?"
] | [
false
] | null | [
"Conductors matter for how efficiently the wave is transmitted (how much energy is lost in the wires), but they don't matter for speed as you say."
] | [
"Fiber optics lets you send more data at once with higher frequency without it getting attenuated or scrambled as much over distance. It has nothing to do with how fast the signal travels.",
"Think about it as the difference between ping and bandwidth if you are familiar with networks. The ping stays the same, th... | [
"Ahh I get it now. But when we are using ways of communication such as internet, why are we using fiber optic cables? They transmit it at the speed of light but, isn’t a normal cable doing the same too? How is it faster?"
] |
[
"Is there a critical time window for puberty? If you gave a eunuch, who was castrated pre-puberty, hormone supplements late in development would he undergo puberty or gain a sex drive?"
] | [
false
] | null | [
"Would a male with only one testicle mature more slowly than regular?"
] | [
"It wouldn't affect height, but it would certainly affect penis enlargement. A trans man, a person transitioning from female to male, will take testosterone. One of the things this causes is a large amount of clitoris growth. The clitoris will elongate, become more penis-like. A length of 1-2 inches is common. This... | [
"It wouldn't affect height, but it would certainly affect penis enlargement. A trans man, a person transitioning from female to male, will take testosterone. One of the things this causes is a large amount of clitoris growth. The clitoris will elongate, become more penis-like. A length of 1-2 inches is common. This... |
[
"Ask Anything Wednesday - Physics, Astronomy, Earth and Planetary Science"
] | [
false
] | Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical post? No question is too big or small for AAW. In this thread you can ask any science-related question! ... | [
"Why are most fruits spherical or oval? And what about bananas? "
] | [
"The rotation of the earth doesn't change the gravitational acceleration itself, but rather introduces a second force that counteracts part of it. It results in an apparent outward force that varies from 0 at the poles to a maximum at the equator. This force reduces the apparent gravity at the equator by ",
"~0.0... | [
"It is. It's just rotating at the same speed as it is going round the earth - once every 28 or so days. So from the earth, it looks like it's not rotating."
] |
[
"What is the logic behind a retailer pricing its sole two items $1 apart? Why would the consumer buy the cheaper item when it seems like a bad deal?"
] | [
false
] | [deleted] | [
"This is known as \"decoy pricing\" [1] [2] [3].",
"[1] ",
"http://en.wikipedia.org/wiki/Pricing_strategies#Decoy_pricing",
"[2] ",
"http://en.wikipedia.org/wiki/Decoy_effect",
"[3] ",
"http://conversionxl.com/pricing-experiments-you-might-not-know-but-can-learn-from"
] | [
"The retailer wants you to purchase the $9 juice and not the $8 juice. The pricing is done so that the consumer will think the $9 is a better deal. It's the same logic as 1.99 vs 2.00 people see 1.99 and think, oh it's only a dollar when it's really two dollars but it feels cheaper. "
] | [
"To use your juice as an example.... The juice guy makes an extra dollar, however the time taken to make a small compared to a large is the same, his overheads are the same. The increase in ingredients would cost very little as would the increase in cup size. ",
"Most people would look at those prices and feel t... |
[
"Are elements organized in periods by energy level? Period 1 has two elements, and the first energy level also has 2 elements. But Period 3 has eight elements, while the third energy level can hold 18 electrons. Are period and energy level related at all?"
] | [
false
] | Edit: Assuming this is a stable atom of course... | [
"Yes, the period corresponds to the principle quantum number for the s and p blocks. The d block is in the n+1 period due to the way the orbitals are filled, ie the 3d is in period 4.",
"The principle quantum number is directly related to energy levels."
] | [
"They are correlated, but things get a bit tricky when you hit the fourth energy level. I'll give the simpler explanation first.",
"Once the third energy level hits eight electrons, the fourth energy level starts filling up. Then we hit the part of the periodic table where the third and fourth energy levels get a... | [
"Periods are related to ",
"orbitals",
" and orbitals are related to ",
"spherical harmonics",
". Electrons are actually waves, and when electrons \"orbit\" an atomic nucleus they actually form standing waves (which take the form of spherical harmonics) centered on the nucleus. This is a minimum energy conf... |
[
"How does lactose (milk sugar) metabolize compared to sucrose (table sugar), and do they affect health differently?"
] | [
false
] | I know that sucrose is glucose+fructose and lactose is glucose+galactose, and I know fructose is primarily metabolized in the liver, but I don't know anything about what happens to galactose when it enters the body. There have been lots of studies and reports on the harmful combination of glucose and fructose consumed ... | [
"To my knowledge, there is little evidence that galactose is any more dangerous than glucose to normal, healthy people. Galactose is metabolized to glucose efficiently, so lactose ultimately becomes two glucose molecules anyway. Glucose tends to trigger the insulin response better than fructose. This inhibits appet... | [
"one thing about glucose that makes it special is that it makes you feel much more full than other sugars. this is one of the dangers of high-fructose corn syrup—while its calorie content per mass is the same as glucose, it makes you feel much less full, causing you to consume much larger quantities of it"
] | [
"Ah okay, that's what I was looking to find out. I wasn't wondering about lactose as an alternative sweetener, more like wondering if drinking lots of milk is \"as bad\" or \"worse\" as eating food with the equivalent amount of regular sugar."
] |
[
"How can tube/cones make sounds \"louder\" without any input energy?"
] | [
false
] | see: how does this not break the laws of thermodynamics? i understand the answer must be loudness=/=energy but its still confusing | [
"The total energy is still the same, but it comes out more concentrated in a certain direction. "
] | [
"Your ear does the same thing, in order to overcome the density change from the tectum (ear drum) to the cochlea sound is 'focused' (by way of some cool level action too) by lowering the surface area from one side to the next"
] | [
"hm, i guess i just never observed this. thanks :D"
] |
[
"How do quarks interact inside a proton?"
] | [
false
] | null | [
"The force that binds quarks together to form a proton is called the strong force, and perhaps the most distinctive feature of this force is something called ",
".",
"The strong force acts on a property of quarks that is rather fancifully called ",
" (although it has nothing to do with actual color). There a... | [
"Up would only annihilate anti-up.",
"A particle/antiparticle pair can form a particle that decays after a short amount of time. An electron and positron, for example, can form positronium (sort of like a hydrogen atom, except with a positron replacing the proton), though it will quickly decay, typically into ph... | [
"Here is a good picture of the model",
"."
] |
[
"Can high amount of concentrated electromagnetic waves warp space like gravity does?"
] | [
false
] | null | [
" Yes.",
" Mass warps spacetime. That's Einstein's theory of general relativity. But that's not all. ",
" energy warps spacetime. Remember, E=mc",
" - mass and energy are basically the same thing, packaged different ways. ",
"This means something weird. For example, suppose you had two identical planets - e... | [
"So suppose the sun was 1 million Kelvin all throughout. Not a bad assumption, it's about 15 million in the core, and about 5,000 K at the surface.",
"The kinetic energy of a proton in a 1 million Kelvin gas is found from 3/2 k T (k is the Boltzmann constant). That's 0.0001 MeV. Compare that to the mass-energy of... | [
"So suppose the sun was 1 million Kelvin all throughout. Not a bad assumption, it's about 15 million in the core, and about 5,000 K at the surface.",
"The kinetic energy of a proton in a 1 million Kelvin gas is found from 3/2 k T (k is the Boltzmann constant). That's 0.0001 MeV. Compare that to the mass-energy of... |
[
"Why don't stem cells manage to replace cells lost to cell death as the body ages?"
] | [
false
] | Cell death is a good thing. Getting rid of broken cells is necessary, and stem cells react by replenishing the the tissue, at least until adulthood. What makes the stem cells less effective with age, so that tissue deterioration and plaque buildup occurs? | [
"... wat...."
] | [
"... wat...."
] | [
"Cell death is a good thing. Getting rid of broken cells is necessary, and stem cells react by replenishing the the tissue, at least until adulthood. What makes the stem cells less effective with age, so that tissue deterioration and plaque buildup occurs?",
"Hm, there's a couple of things I'll try to elaborate o... |
[
"Why do chimps have nearly twice as many genes as humans, while having nearly the same genome size?"
] | [
false
] | [deleted] | [
"They don't. Where are you getting your numbers from? All placental mammals that I know of have around 20-25 thousand genes, and the difference between humans and chimps is around a hundred."
] | [
"It's a misprint."
] | [
"I got the number from a ",
"biochemistry textbook."
] |
[
"Question about relativity, a long pole, and black holes."
] | [
false
] | I hope I can word this in a way that makes sense. So as I understand it, relativity dictates that the laws of physics work the same in any inertial reference frame. So if we take out our telescopes and look at an object, we should be able to measure its mass and size. The results should vary between reference frames, b... | [
"This is really tough to solve, but I'm going to go out on a limb here and guess that you're neglecting the momentum term in the stress energy tensor; ie, mass doesn't inform General Relativity alone, but so too does momentum. The Schwarzschild metric is for a spherical mass at rest. I'm not sure what the solution ... | [
"This is an outdated way of teaching relativity. An object in relative motion may act ",
" it had an increase in mass, but its mass has not actually increased.",
"Consider that Newton defined momentum ",
" = m",
". Well, he was right for sufficiently small speeds. But relativistically, we find that ",
"= ... | [
"The answer is given here:\n",
"http://math.ucr.edu/home/baez/physics/Relativity/BlackHoles/black_fast.html",
"In short, shavera is correct that you're neglecting the fact that you no longer have a static spacetime; things like momentum and angular momentum become important. "
] |
[
"When two photons are emitted in two exact opposite directions, what is their speed relatively to each other?"
] | [
false
] | [deleted] | [
"There is no such thing as \"speed relative to a photon\". When we say \"speed relative to something\" we mean the speed as measured in that something's rest frame of reference. Photons do not have a rest frame of reference. This is a foundational pillar of relativity. Therefore you can never measure a speed relat... | [
"There cannot be a reference frame for a photon because the fundamental postulate of special relativity is that light/photons travel at c in all reference frames. If there were rest frame for a photon, its speed in that frame would be 0, not c by definition. So no such frame exists. "
] | [
"At rest is a relative term to describe in relation to something. When you are at rest with the earth, the net velocity between you and the earth is zero. "
] |
[
"There's no such thing as a perfect vacuum. But what's the closest to a perfect vacuum in nature? In the least dense part of space, how far apart are two atoms?"
] | [
false
] | [deleted] | [
"Does a defect inside a metal, i.e. a missing atoms, count as perfect vacuum? If so, would there be any special properties?"
] | [
"Does a defect inside a metal, i.e. a missing atoms, count as perfect vacuum? If so, would there be any special properties?"
] | [
"Does a defect inside a metal, i.e. a missing atoms, count as perfect vacuum? ",
"It shouldn't. ",
"The mean free path for a molecule in air at STP is about 70 nm",
". If you have a single-atom defect in, say, a block of iron, the gap between two adjacent atoms is at most on the order of 2*the lattice param... |
[
"How does circular polarization work?"
] | [
false
] | I understand how linear polarization can give two orthogonal signals completely independent of each other, but I don't see how this could be the case for circular polarization. | [
"You can think of circular polarization as the sum of two linear polarizations that are 1/4 of a wave out of phase. That is to say, take two in phase waves that are linearly polarized (one vertically and one horizontally) and then shift the phase of the vertically polarized wave by 1/4 wave. The horizontal wave w... | [
"It's a bit more complicated to explain how a ",
"circular polarisation filter",
" works than a linear filter, but basically the key is that it's possible to change the components of polarisation in different directions with a crystal called a ",
"wave plate",
", and the thickness affects how the components... | [
"The reason they use circularly polarized light is probably so the contrast between the two images is good when you tilt your head a bit.",
"This is correct, but it isn't a complete solution because your eyes need to be pretty level for the optical illusion to work. ",
"It might also be done so the lenses don't... |
[
"How similar are other mammals taste buds to ours?"
] | [
false
] | Also, if other mammals only eat to survive, why do my dogs drool over steak and things like that when they've already been fed that night? | [
"I'm not versed in all the tastes across species, but the T1R family is key for sensing sweet and umami flavors. Combining T1R2 and T1R3 proteins allows transmission of sweet flavors, while T1R1 and T1R3 together transmits umami. The T1R2 receptor is ",
"structured differently in mice",
" and ",
"missing in d... | [
"The taste ",
" is the \"tasting\" part of the taste bud. Taste receptors are proteins, and are therefore coded by specific genes. This means that we can compare the genetic sequences of taste receptor genes across many species. For bitter taste receptors, for example, it is possible to identify similarities acro... | [
"Pointless to put it that way. All it means is they sense certain chemicals. It just so happens when our tongue senses those chemicals, it sends specific signals to the brain that we experience as flavors. ",
"You could theoretically make an infinite variety \"flavor receptors\" that send \"flavor signals\" to th... |
[
"On a bicycle, do fatter tires = more friction?"
] | [
false
] | Assuming same tread patterns. Bonus question: How much of an aerodynamic penalty is there with fatter tires? | [
"Rolling friction does generally go up with increased surface area in contact with the road. So yeah, if a fatter tire has a larger cross section radius it will result in slightly more rolling friction. But it probably depends on a lot of different things, like tire pressure, your weight, road properties etc.",
"... | [
"This is a fairly complex area of dynamics, but I think I can get it distilled down for you.",
"Rolling resistance is related to the length of the contact patch. The area of the contact patch is controlled by tyre pressure. So at the same pressure, a 26x1.75 will have the same contact area as a 26x2.35.",
"Beca... | [
"What you're after isn't friction, but rolling resistance.",
"23 mm tryes were standard in bicycle racing for a long time. Smaller contact patch, less rolling resistance, right!",
"Actually it gets more complicated. If you fix the carcass construction, and pressure, different sizes have the same size contact pa... |
[
"How far are we to companies growing organs in labs for transplant (kidneys, livers, hearts, etc.) and what is standing in the way?"
] | [
false
] | for what is standing in the way, I mean technical, and medical terms. Also, what fields would make this possible? Stem Cell researchers? Any citations would be awesome | [
"Simple organs, like a trachea, have already been ",
"made and transplanted",
" into people. ",
"A ",
"beating rat heart",
" was made from a rat stem cells seeded into the leftover extracellular matrix from a dead rat's heart -- a similar process to what was done in my first example, except not quite as a... | [
"Depends on what type of organ you are talking about and what methodology is used.",
"The presently most advanced method is decellularization: take a donor organ, strip its cells, repopulate with the patient's cells. That doesn't really count as growing a new organ, and you still need the donor. It is still a mas... | [
"I'm commenting on your post since I'm not really answering the question but rather adding more info on your answer.",
"In relation to the 'obstacles' part, one of them might be that there are potentially other more efficient (perhaps easier to commercially manufacture) alternatives: machines.",
"I happened to ... |
[
"Can you someone please debunk this silly 'hollow earth theory' for me?"
] | [
false
] | It just seems entirely ridiculous to me. This doesn't seem to be how gravity or planet formation works. I would just like some examples of how unlikely it might be. That, or if it can be disproven - would also be nice. Thanks! | [
"As someone in geology, the hollow earth theory is a painful theory to discuss. Just the shear volume of complete lies and mis-interpreted facts shoved into those arguments is awful. I'll try to work through some of the points on that web-page, but discussing the theory is an unpleasant experience for me so I may n... | [
"There's a load of response you could have, starting with something like Occam's razor: there is no real reason to suppose that the earth could be hollow, so why try and create a massive implausible system to justify the hypothesis.",
"Secondly, it's not supported by evidence:",
"We can work out the relative ma... | [
"The varying density of the inside of the earth causes differential diffraction of mechanical waves produced by seismic events. We can use this to map the inside of the earth, and we have done so.",
"http://en.wikipedia.org/wiki/File:Earthquake_wave_paths.svg",
"Also, a hollow planet would collapse in on itsel... |
[
"Is there a way in which a person can increase their mental ability / IQ?"
] | [
false
] | [deleted] | [
"100 IQ is calibrated to average human intelligence. Theoretically you could kill or mentally impair people of above average intelligence and readjust the average thereby improving your own IQ."
] | [
"According to ",
"some research",
", cognitive training with ",
"dual n-back",
" can potentially increase working memory and IQ scores. Here is a ",
"Wired article",
" on the topic. "
] | [
"This is a big question. First of: There are multiple ways to improve cognitive functions once you lose them. Old people can increase their cognitive functions through a number of means, such as ",
"Physical activity",
". But that's not really what's you're asking.",
"What you're asking is if a normal, health... |
[
"CRT displays show weird colors in presence of a magnet due to deflection of electrons. Why does the effect last even when the external magnet is removed?"
] | [
false
] | null | [
"Colour CRTs have three electron guns which are directed using magnets. There is also a metal plate with holes just in front of the phosphor screen that prevents electrons from hitting the wrong colours. When you place a magnet near a CRT, you are redirecting the electrons, producing weird images. If you use a stro... | [
"My dad was a TV/AV engineer up until he retired about 5 years ago. When I was about 12 (waaay back in the 80's) we learned about this affect on CRT's at school. I had a nice big magnet - a CB radio antenna mount, and tried it on our TV at home. Got into a lot of trouble, as the magnet was powerful enough to WARP t... | [
"The shadow mask (or aperture grille, depending on design) in color CRTs is often made of steel-- the magnet you're holding is turning the shadow mask itself into a permanent magnet."
] |
[
"What happens to the fishing/game population if there was/is no fishing/hunting?"
] | [
false
] | I often read and hear about how hunting is allowed in some areas to control the population and fishing is regulated to make sure we don't over fish. What happens to the population of these animals if fishing/hunting were to stop or never existed. I also have kept in mind that some of the reason why hunting is needed i... | [
"Well if you include the natural predators in this question then our backyards would be quite a bit wilder. But if we were killing the natural predators out of fear and necessity for farms and ranches then we would have an overpopulation of deer and other prey type animals. "
] | [
"Then that overpopulation would cause the animals to starve to death when the environment can no longer support their increasing numbers."
] | [
"Without hunting or fishing, populations would be much higher. Fish populations in particular are vastly smaller (both in number and individual body size) than they were before extinsive commercial fishing. There used to be schools of fish so thick boats could hardly sail through them. On land, flocks of birds t... |
[
"From seeing the supermoon tonight it made me curious, is there ever a night with no moon?"
] | [
false
] | To clarify I don't mean a new moon, but it more like on the other side of the planet. | [
"Yes, roughly half the month, every month there is no moon in the night sky. And in the same token, for about half of the month the moon is visible during the day, something which apparently routinely surprises people who have presumably lived on this planet their entire lives. ",
"This can all be made pretty cle... | [
"When the Moon is on the far side of the planet at night also happens to be during a New Moon!",
"The closer the Moon is to the Sun in the sky, the more the Moon is up during the day and the less the Moon is up at night. But the closer the Moon is to the Sun in the sky, the more we're seeing the shadowy side of t... | [
"If you are far enough north or south, then there will be at least one day a month when the moon never rises, and another when it never sets. It's for the same reasons that the midnight sun happens.",
"The tilt of the moon's orbit compared to Earth's equator varies on an 18.6 year cycle, so how far north is \"far... |
[
"What is “personality” and how does it differ from a “personality disorder”?"
] | [
false
] | null | [
"The definition of when a personality becomes 'disordered' is a social construct. There is no accurate yardstick, and often the diagnosis is highly subjective with psychiatrists disagreeing about cases.",
"Generally disorders are diagnosed when behaviour is seen as dangerous, outlandish, or eccentric from the po... | [
"From an animal behavior perspective, personality is any set of behaviors which an organism consistently exhibits."
] | [
"This is a biiiig question. But I'll try to simplify it for you.\nPersonality is basically how a person interacts with their environment. For better or for worse. It is how somebody prefers their environment to be structured, and how they view their environment. I'll take two big personality characteristics and giv... |
[
"Are there any health risks to saving plastic take-out containers to use as tupperware (and microwaving them)?"
] | [
false
] | Title says it all. | [
"Yes. Those containers are designed to hold hot food once. The most immediate health risk is burning yourself because the plastic breaks or melts and you spill hot food on yourself.",
"But dioxin or bpa in those containers? Not likely. That doesn't mean ther are no carcinogens or that it is a good idea; they ar... | [
"There is no such thing as \"Cl\". There is Cl",
" and there is Cl₂, but not plain Cl."
] | [
"There is a difference between plastic that has not been broken down to plastic that has been broken down. Same reason why NaCl in moderate quantities is harmless, but Cl by itself is toxic."
] |
[
"Due to the conservation of energy, if you had a pendulum in a vacuum would it continue on forever reaching the same height each side every time?"
] | [
false
] | null | [
"There would still be friction at the pivot point. The friction dissipates energy as heat, even in a vacuum. The pendulum would slow down and eventually stop."
] | [
"You can do a lot of things to reduce friction, but you'll never get rid of it completely. You could get the pendulum to swing ",
" all the way back to where it started, but not quite all the way. You could get the pendulum to swing for a ",
" time, but not forever.",
"The friction might be negligible (in t... | [
"Friction could be very small, but as long as it is non-zero, it will stop the pendulum. Second, I haven't seen it mentioned here, but materials that you make the pendulum with aren't rigid. Everything is vibrating and wiggling and that will sap energy from the pendulum."
] |
[
"What makes the timbre of an oboe different from that of a violin?"
] | [
false
] | I'm a musician and composer in school and I'm wrangling together a music theory class for the University of Reddit. I fully expect this question to come up - and it's a really good one, I think. If I understand correctly, it has to do with the harmonic series. Certain instruments emphasize certain partials, and what we... | [
"You've got it right. The characteristics of a certain instrument or sound is defined by what harmonics that instrument produces and emphasizes, and when you can identify different instruments, this is how you do it. ",
"A sound without harmonics, such as a clean sine wave, does sound dull.",
"If you want to ac... | [
"The answer lies largely in the acoustics.",
"It is a combination of harmonic series and resonances.",
"A string excited with a bow will generate a particular harmonic series, typically plus a nice chunk of noise, particularly at the start of the note. The excited reeds of the oboe generate a different harmonic... | [
"A reed instrument produces ",
"sine waves",
", while bowed instruments produce waves that are more ",
"saw tooth",
" -like in character.",
"Furthermore (as you suggested), the conical shape of the oboe's cavity lends to the tone, as it allows for complex (both odd and even) overtones. Cylindrical cavitie... |
[
"What happens to detergents and soaps after they go down the drain?"
] | [
false
] | I recently bought a bottle of Costco environmentally friendly dish detergent that claims it biodegrades 70 percent in 28 days after cleaning. I think this is a plant based detergent (or soap) and I understand that many detergents are made from petroleum based chemicals. For a few years now, I have only used Dr Bronner... | [
"Everything that goes down your drain goes to a waste water treatment plant. They have ",
"ways to treat water with detergents",
", but biodegradable makes it a lot easier. What's bad is soaps with antibacterial agents like triclosan. Triclosan degrades into dioxins in sunlight, and there are limits to how succ... | [
"Now antibacterial soap is fine, just not antiMICRO-bacterial soap.",
"Wat? There is no such thing as \"anti-micro-bacterial\" soap (or \"micro-bacteria\" for that matter). Do you mean \"anti-microbial\" soap? That's the same thing as anti-bacterial soap; all bacteria are ",
"microbes",
". Are you really an E... | [
"Some soaps and detergents are petroleum based, does bacteria still chew on those? Or is other stuff added at the waste water facility to remove it?"
] |
[
"How unhealthy is smoking 1-2 packs of cigarettes a month?"
] | [
false
] | [deleted] | [
"According to ",
"this study",
", \"Light and intermittent smoking carry nearly the same risk for cardiovascular disease as daily smoking\" \nand \n\"the risk of ischemic heart disease in light-smoking men and women aged 35 to 39 years who smoke 1 to 4 cigarettes per day is ",
"\""
] | [
"Reading further on... ",
"in that study",
" you can say that your risk of cancer is a lot less than 20+ cigarettes per day smokers. Normally, the risk of lung cancer is very low for most people: it's one of the rarer cancers, but very often fatal. Many cancers can be cured now, but ",
"lung cancer still has ... | [
"I don't think this particular anecdote should be considered due to the large biological differences between individuals, as well as damage that may not be evident and ex-smokers who live healthily possibly doing better than non-smokers who live unhealthily."
] |
[
"Of we were to send mirrors into space in all directions, would we be able to look back in time once the mirrors have travelled far enough?"
] | [
false
] | null | [
"Yes and no. ",
"If you send the mirrors away at 70% of the speed of light, then after 10 years they will be 7 light-years away. Light reflected at that moment will have been travelling for 7 years... and will have to travel another 7 years to get back. In other words 17 years after you sent the mirrors away you ... | [
"If you can go faster than the speed of light you don't need mirrors to see the past. You can visit it. Which is one of the many reasons why faster than light travel is silly."
] | [
"Travel to the future is easy. Travel to the past is not."
] |
[
"8 glasses of water per day?"
] | [
false
] | [deleted] | [
"If you feel that way you should see a doctor rather than assume its just dehydration.",
"Those symptoms can fall under a long list of ailments which can have different causes. Dehydration is just one of many."
] | [
"If you feel that way you should see a doctor rather than assume its just dehydration.",
"Those symptoms can fall under a long list of ailments which can have different causes. Dehydration is just one of many."
] | [
"That entirely depends on the person. A lethargic person in a high humidity environment who eats high moisture food might actually not need any water per day. ",
"A marathon runner might consume 1L/hr during training (~4 glasses). That doesn't even include what the person consumes the rest of the day. "
] |
[
"What makes a phobia a phobia?"
] | [
false
] | [deleted] | [
"That is ostensibly irrational by virtue of the inanimate, abstract nature of a number. In direct opposition to this, I have acrophobia, or, a fear of heights. To me, this is not a real phobia as a significant fall may result in loss of life or serious injury and is therefore perfectly rational.",
"Part of the cr... | [
"One of the central ideas in diagnosing a mental disorder is the level of impairment it causes. Nearly every diagnostic criteria seen in the DSM-IV or 5 is something also seen in most people, but often to a lesser degree. (I guess I would compare this to regular medical symptoms and how everybody always jokes about... | [
"Also, phobias significantly interferes with normal functioning. It is a sub-type of anxiety disorder. Specifically, it is known as an \"",
"Axis I",
"\" disorder. That is, it is not a pervasive personality disorder that generally affects all thoughts.",
"The initial diagnosis of anxiety disorder are pretty d... |
[
"Can we change our ways? For an example, could someone who's lazy become a super motivated person, or are we just genetically wired to be certain ways?"
] | [
false
] | null | [
"We can change our actions, yes. Whether or not we can change our inclination towards certain thoughts is less likely. For example, you can't prevent being a homosexual, but you can definitely refrain from homosexual acts. (A whole different topic is the damage to yourself vs damage to others these decisions cause)... | [
"Whether or not we can change our inclination towards certain thoughts is less likely.",
"Actually I have found that if you make a consistent conscious effort changes, even in inclination can change. Personally I have found it usually takes a minimum of 30 days.",
"For example",
"I have radically changed my ... | [
"But you still crave food, right?"
] |
[
"How does obesity affect the procedure of surgery? If the patient carries excessive body fat, how much does it hinder the surgeon?"
] | [
false
] | This is mainly referring to surgeries done in places with typically more body fat, such as stomach or chest area. | [
"Yes we do.",
"A lot",
"Bigger incisions, more complications, poorer visualization, more complications (did I say that 2x?), longer surgery times, takes longer to close wound, harder to position implants, and they're a work out.",
"Obesity can be a code 22 modifier, but it's a pain to justify. (code 22 is a b... | [
"Great answers!",
"Also, I would like to add that post-operative complication is relatively high in the obese and morbidly obese.",
"First of all, the anesthesiologist has to use more medication to maintain sedation during surgery. Due to the weight-based dosing of these drugs but the variable nature of individ... | [
"Great answers!",
"Also, I would like to add that post-operative complication is relatively high in the obese and morbidly obese.",
"First of all, the anesthesiologist has to use more medication to maintain sedation during surgery. Due to the weight-based dosing of these drugs but the variable nature of individ... |
[
"How is it possible to generate light from mechanical energy?"
] | [
false
] | There are these juggling balls which at the moment of impact with the ground or your hand thy emit light. These balls have no batteries. How is this possible? | [
"Most likely a piezoelectric effect, but I can't really say I've never seen those balls you speak of. ",
"http://en.wikipedia.org/wiki/Piezoelectricity"
] | [
"I'll let a physicist give you the indepth explanation but the simple one is: ",
"Band gaps",
".",
"Most balls, when compressed from the force of falling and impacting the ground, generate energy in the form of heat. But your juggling balls most likely have florescent material in them, that absorbs some of ... | [
"Piezoelectric crystals maybe?"
] |
[
"What was the environmental impact of the opening of the Suez Canal? Did the connection of two biomes (Mediterranean and Red Sea) result in the mutual introduction of exotic species and a disruption in the food chains?"
] | [
false
] | null | [
"As you predict, there was substantial biological interchange as a result of the Suez canal. The two seas are slightly different: the Red Sea is saltier, has fewer nutrients, and is generally considered a \"tougher\" environment to live in. It's also at a higher altitude, so water naturally flows from the Red to th... | [
"There was talk of digging a sea level canal between the Atlantic and Pacific in Nicaragua, although last I heard it had sort of dissolved due to financial issues. The current canal involves a freshwater section which reduces passage of life between the oceans, a sea level one would have a much bigger impact, bu... | [
"Thanks for the detailed answer. That sounds pretty devastating. I suppose nowadays, a project like that wouldn't pass the Environmental Impact Analysis part of development without some major alterations."
] |
[
"Are there bicellular organisms?"
] | [
false
] | [deleted] | [
"I’m not aware of any organism that is limited to two cells. Some bacteria, the ",
"Cocci",
", come in relatively small packets but without strict size limit. Among the eucaryotes, the ",
"Placozoa",
" are the simplest and smallest muticellular organism.",
"\nThe ‘idea’ behind multicellularity is that of ... | [
"There was a ",
"recent question",
" that is somewhat related to yours which I took a shot at answering. The smallest organisms which I think can be truly considered multicellular had four cells; to quote the relevant part:",
"You may have seen the relatively famous ",
", which contains a few hundred or th... | [
"However, this does start to get into the argument of whether such an arrangement should be considered a true organism or simply a colony of single cells (though the paper I cited above does seem to argue the former). ",
"In my opinion, that question is just as problematic as asking for an exact species definitio... |
[
"If a bowl of fresh strawberries is sprinkled with sugar, and a few minutes later the berries are covered with juice, how does that happened?"
] | [
false
] | [deleted] | [
"It's called ",
", and it works through osmosis.",
"A solvent \"wants\" to move from a region of lower solute concentration to a region of higher solute concentration. In this case the solvent is the water in the strawberry, and the solute is the sugar. ",
"When you sprinkle a strawberry with sugar, there's a... | [
"Diffusion. Water (which makes up the majority of strawberry juice) always moves to even out a diffusion gradient. More sugar on one side than the other of the cells in the strawberry draws out the juice to even the gradient."
] | [
"Technically yes, since all osmosis is diffusion, but not all diffusion is osmosis."
] |
[
"Is 3 spatial dimensions optimal for life? I know 2D life would be hard, but would life be possible in a 4 spatial dimensional universe?"
] | [
false
] | null | [
"Obviously any answer to this would be theoretical because we can't do experiments in higher or lower dimensions, but in greater than three spatial dimensions you have an issue where gravitational fields no longer lead to stable orbits, which makes it hard for planetary life as we know it to form. You can read abou... | [
"Something to note: In three dimensions, there's a property of any system that the angular momentum can always be resolved into one direction, with an axis and the whole thing rotating closckwise or anti-clockwise. ",
"This ends up meaning that the momenta along that axis cancel out for everything in the densely ... | [
"It can't be explained visually because you can't see 4 dimensional things."
] |
[
"Why do some genes skip a generation? Is this True?"
] | [
false
] | Do genes usually skip generation's? You often here people saying that you pick up trait's, diseases, and tendencies from grandparents such as Alcoholism. Why is this?' Edit. Oh by the way thanks people. Answered my question's. | [
"Genes cannot skip generations (they would be lost) but traits can if that trait is caused by a recessive allele. A recessive allele is a version of a gene is not expressed if the other allele in the individual is dominant. A recessive trait might skip a generation if:\ngrandparent's genotype is a/a (both recessi... | [
"Most addicitions, while they exhibit strong genetic influences, also exhibit strong environmental biases as well.",
"See here.",
"I can't find the study I can remember at the moment, but the general gist was this:",
"Foster Children with alcoholic parents who grow up in a home free of alcohol have less risk ... | [
"Yes that was the point I was trying to make sorry if it was not clear"
] |
[
"How are radio stations able to broadcast silence and have it not sound like static?"
] | [
false
] | For example, in MC Hammer's , what is going on between the radio station and my car stereo that makes it so that there is a pause between "Stop" and ". . . Hammertime" rather than the random noise I'd hear if I tuned to an empty station? Thanks. | [
"Let's back up a little bit and talk about how the radio station sends ",
" over the air. If it's an AM radio station, the transmitter broadcasts a constant radio-frequency tone at (say) 1.000,000 MHz, but ",
" that tone: it makes the broadcast slightly stronger or slightly weaker depending on where the speaker... | [
"Sorry to take so long to get back to you... No, there's no AGC for modern FM units. There was in the early days. FM is, of course, ",
" modulation - the station tunes itself to a slightly higher frequency when the speaker cone is supposed to move outward a little bit, and lower to move it in. In the old days,... | [
"The Cosmic Microwave Background is only a small percentage of the total radio background (around 1%).\n99% of it comes from the thermal noise in the atmosphere (which is hotter than the CMB and thus noisier)."
] |
[
"Vehicle Tech of the Near Future: What are the (dis)advantages of hydrogen fuel cells versus Lithium-ion batteries, when used on a large (e.g., nationwide) scale?"
] | [
false
] | Five or so days ago various media that Japan intends to focus on using hydrogen as the energy storage medium of choice for its nation's vehicles. On a purely technological and pragmatic level, what are the advantages and disadvantages of doing so? Aspects worth mentioning might include: The efficiency of the hydrogen p... | [
"Hydrogen tends to leak through containers. Storing it as a gas limits the density. Storing it as a liquid is prohibitively expensive and not all that much of an improvement anyway. Storing it as a metal hydride tends to require exotic metals. However, it's fast and usually easy to refuel, and there's no shortag... | [
"The proper and thorough answer to your question would be several pages long, I will mention a few things only:",
"Hydrogen production: Currently the most economic source of hydrogen is natural gas, but it makes little sense to convert natural gas to hydrogen rather than using the gas itself. For renewable energy... | [
"Also note that electricity would be used to generate the hydrogen, which would still come from the same power plants used to charge an electric car."
] |
[
"What is this? Neither Space or Geology could tell what it is. Maybe you can?"
] | [
false
] | [deleted] | [
"Looks to me like a lot of broken glass cast in some resin. Perhaps part of an old sculpture or other piece of art, abandoned years ago?"
] | [
"What area did you find it in?"
] | [
"The only thing I can think of is bauxite, an aluminum ore: ",
"http://product-image.tradeindia.com/00179034/b/0/bauxite.jpg",
"but the red inclusions (crystals?) in your sample are much more rectangular as opposed to rounded. It would help if you could break it open with a hammer."
] |
[
"In terms of evolution, why are glasses a thing?"
] | [
false
] | null | [
"There is currently a myopia epidemic going on. This article discusses incidence rates and current thoughts about causes: ",
"https://www.nature.com/news/the-myopia-boom-1.17120"
] | [
"This is actually an interesting read and answers my question fairly well. I was under the impression it was related to genetics (article states this was believed in the past). I always scoffed at my mother when she said staring at the TV all day would ruin my eyesight but it turns out while she wasn't exactly righ... | [
"I should clarify that this is not settled science. There is evidence in favor of the sunlight exposure theory, but this is an active area of research."
] |
[
"How old is the ISS REALLY?"
] | [
false
] | GPS satellites have to regularly reset their clocks to stay accurate to earth surface time due to the relativistic time difference between the satellite and the earth surface. How much younger than its Earth surface age is the ISS due to the fact it’s been spinning around since 1998? Do they have to reset their clocks ... | [
"Orbital velocity: ~8km/sec",
"\nSeconds since original launch date: ~765,849,600",
"\n",
"Seconds at observer",
": ~765,849,600.27268 ",
"So to answer your question, the original section of the ISS is about a quarter of a second younger than it would be if the parts had stayed on Earth."
] | [
"GPS clocks are not reset. They run at adjusted frequency. In general in a satellite mission you want to avoid resets and be prepared to do adjustments not only for time dilation. In a satellite mission I worked we had an onboard clock that was the source of mission time in \"milliseconds\" since the satellite was ... | [
"Thank you for answering the question."
] |
[
"Would it be possible to change somebody's blood type by draining their body completely of blood, and then replacing it with a different blood type?"
] | [
false
] | This is assuming you have all the necessary equipment to keep someone alive during such a process. We know a person with type A blood can only receive blood from people with types A or O. Their body will reject types B and AB. But if you completely removed the type A blood from their body, could you replace it with typ... | [
"No. In short, blood is created in the bone marrow, and if you just replaced someone's blood, eventually it would die out (erythrocytes live only around 120 days on average) and be replaced by the original blood. However the immune system of the recipient will act much faster and destroy the donated blood much fast... | [
"It should be noted that this is exactly what happens in stem cell transplants used to treat leukemia and other blood diseases. The bone marrow is completely destroyed as described. The donor stem cells are introduced into the blood stream and find their way to the bone marrow where they begin producing blood cel... | [
"That's \"host-vs-graft\", wherein the recipient's body rejects the transplanted organ. In \"graft-vs-host,\" it's the opposite. The new blood cells reject some parts of the host. Like 7-sidedDice said in another comment, nothing is 100%. When used to treat blood cancer, the patient can experience both host-vs-... |
[
"Does cloud cover affect the power output of solar panels?"
] | [
false
] | If cloud block the sun light, would electrical output fall to 0? would it stay the same because the UV radiation still goes through the clouds? | [
"Solar panels get most of their energy from the visible part of the spectrum, not UV, so the output drops a lot. Not to zero though, because there's still some diffuse light getting through the clouds (it's not pitch black out).",
"Here's one set of graphs of how much power some panels produced over days with di... | [
"thanks those graphs are helpfull"
] | [
"For maximal efficiency solar panels should try and use the whole spectrum of sunlight. Most of the energy in sunlight is in the visible range, it would not be that useful to design panels that would work best on wavelengths other than what the sun provides."
] |
[
"If the theory of parallel universes is real, in the infinite possibilities of universes would exist one where the theory of parallel universes is not real?"
] | [
false
] | null | [
"To see this easily, consider the set of odd numbers. Clearly, there are infinitely many odd numbers. However, this is not all numbers. The same can be seen with the set of all numbers except for 7, or the set of negative numbers, or the set of prime numbers.",
"Even if there are infinitely many universes, that d... | [
"No.",
"I think you might have a wrong idea how \"parallel universe\" is used in this context.",
"In Quantum Mechanics, particles may be described by a mathematical tool called the \"Wave Function\".",
"In QM, the sum of two solutions to a given problem is also a solution. This is sum is called \"a superposit... | [
"What you're describing is the issue of defining a ",
"Level 4 multiverse",
", as outlined by Tegmark, in a manner consistent with ",
"Godel's incompleteness theorems.",
" It's still entirely speculative, so there's not yet a way treat it scientifically."
] |
[
"From an engineering standpoint, how plausible is this \"Phonebloks\" concept from a video that keeps floating around my Facebook?"
] | [
false
] | I keep seeing YouTube video in my Facebook feed. It is a three minute video suggesting that we should start using interchangeable parts on our cell phones. It seems all well and good in theory, but is it really plausible for phones to be this flexible? Edit: Also, is this a computing or engineering question? | [
"It was discussed",
" pretty thoroughly a couple days ago on ",
"/r/askengineers",
". ",
"The overwhelming consensus is \"not at all\""
] | [
"It's a very plausible way of getting gullible people to give you free money through kickstarter, however."
] | [
"It's not easily possible at all. It's probably possible (with some design concessions) but there are ",
" engineering hurdles to be overcome. Off of the top of my head, some of the problems are:"
] |
[
"Since the earth orbits in an ellipse, and sometimes the distance between it and the sun can differ by thousands of miles, why does a slight tilt affect climate and seasons so much?"
] | [
false
] | [deleted] | [
"Axial tilt affects the season because it affects the duration of a day and the \"altitude\" of the sun in the sky. It's not simply because some parts of the earth are closer to the sun.",
"Longer day means more exposure to the sun. When the sun is \"higher\" in the sky, its heat and radiation have less atmospher... | [
"I think it's also due to the same amount of sunlight being spread over more surface of the earth due to the tilt. This site explains it better than me:",
"http://www.loc.gov/rr/scitech/mysteries/seasons.html"
] | [
"Because the length of time an area is exposed to sunlight on a given day can be drastically different depending on time of the year and latitude.",
" There is far more seasonal variation near the poles than at the equator. "
] |
[
"Why are there so many acidic fruits, but few if any alkaline ones?"
] | [
false
] | null | [
"Fruits are \"designed\" by natural selection to lure animals to help spread their seeds in exchange for a nutritious snack. Therefore fruits must be apetising to the target animals. Most animals use acids as a part of their digestion and therefore alkaline substances, which react with acids can, at least make dige... | [
"Ascorbate (anion of ascorbic acid/\"vitamin C\") is used in a lot of metabolic reactions in plants.",
"Citrate (citric acid) helps oxidize macromolecules like fats, proteins and carbs.",
"Acetic acid comes from the bacterial breakdown of sugars.",
"Tartrates (tartaric acid) comes from the breakdown of ascorb... | [
"Isn't coffee very acidic though?"
] |
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