title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"The probability of transmitting HIV is X% for sex acts of a type Y. How do scientists find X? I'm assuming there are no controlled, randomized, double blind trials here. Do scientists just use surveys?"
] | [
false
] | null | [
"It is through surveys. It is interesting however because these stats are likely based on a time when our current anti-retroviral regimens were not being used. An interesting question would be what are the chances of transmitting HIV when your viral load is X and you're on regimen Y, doing sexual act Z?"
] | [
"Interesting. It seems like there must be so many confounding factors though. Do people just estimate how many exposures they had? How do they know how long they had it? E.g. Someone finds out their partner of a year has HIV. They get tested and find out they also have it. How would they know if they got it in the ... | [
"As the other person said, it's through surveys. But there are some problems with this.",
"Here's an example why:",
"Throughout the 80s and the very early 90s, very very few heterosexual men had contracted HIV in NY. Men would get tested, get a positive result, and claim to be heterosexual. Counselling and back... |
[
"Could Earth's orbit change over time?"
] | [
false
] | [deleted] | [
"In a perfect, clean, two body system, there is no drift towards the sun. This is kept in check by the conservation of angular momentum. However, you have processes that could dissipate angular momentum. None of these are significant on astronomical timescales (meaning we'll probably die from something else before ... | [
"It's the opposite to what he is positing, though, the Earth is moving away from the Sun, not towards it. ",
"http://www.newscientist.com/article/dn17228-why-is-the-earth-moving-away-from-the-sun.html"
] | [
"It does, over astronomical time."
] |
[
"What conditions or assumptions are required for there to be a non-constant, time-dependent surface concentration in a diffusion system?"
] | [
false
] | [deleted] | [
"Could you please clarify your question? It's not clear what the \"perfect sphere\" is made of (i.e., is it empty or is it a material), what you mean by \"fluid with concentration C1\" (e.g., concentration within another material? density?), what the context is when you say \"it is normal\", or whether you're talki... | [
"Sure, I was just being general for simplicity. The sphere is a tumor spheroid. The bulk concentration around the sphere are monoclonal antibodies. Basically I'm analyzing a paper that in which they derive a function to describe the concentration of antibodies diffusing into the sphere as a function of radius and t... | [
"Ah, got it. You can only assume constant concentration at the boundary of the tumor if at least ALL of the following hold: "
] |
[
"What is the genetic basis for instinct? What do we currently know about how genes influence innate behavior?"
] | [
false
] | I'm very curious about this and information wasn't forthcoming after some internet searches. Can any behaviorists or geneticists weigh in? How is it that genes code for the instincts present in new offspring or what is our current level of understanding? | [
"I think it’s easier to use the term ‘innate behavior’ rather than ‘instincts’ because the latter has a lot of more metaphysical connotations in humans, at least. I can describe an innate behavior in a simpler organism, like a fly. ",
"Fly mating behavior is what we call ‘stereotyped’- given certain stimuli (like... | [
"This is a really big question you're asking, but I'll try to give a bit of a foundation for you. If you've ever taken a class in the life sciences you've likely heard the phrase \"structure determines function\". I first learned this in the context of proteins: the amino acid structure of a protein determines i... | [
"It's worth noting that innate behavior and learning often interact. For instance rats have an innate tendency to rapidly learn to associate nausea with foods and visual stimuli with physical discomfort. So a rat rapidly learns to avoid eating a food flavor that made it sick, and that a flashing light warns of a ... |
[
"How did phyla emerge rapidly following the Cambrian explosion?"
] | [
false
] | Following the Cambrian explosion, phyla began developing relatively rapidly: within 6-10 million years. What drove such fast emergence of biodiversity? | [
"For one thing, the phyla weren't nearly as genetically distant from each other as they are today; being only recently diverged. Biologists in the Cambrian would probably classify them several levels down, possibly even all as part of a single phylum or even order."
] | [
"One possibility is that life evolved shells or other features that were more easily fossilized and thus it appears lots of new species emerged when maybe there were not so many. Also keep in mind that suddenly in geological time is still a very long time and it also might be factors were present that caused specia... | [
"One possibility is that life evolved shells or other features that were more easily fossilized and thus it appears lots of new species emerged when maybe there were not so many. ",
"I see your point, but we’re talking about higher level classifications than species in that case. If an organism didn’t have hard p... |
[
"Why do humans 'enjoy' the musical notes that we do?"
] | [
false
] | Please bear with me, my music theory is terrible. Pretty much all music fits on a similar scale, ie every instrument plays the same notes and they are all tuned similarly (A, B, C, D, E, F, G). Why do we find these pre-determined frequencies 'pleasant' and frequencies in between not so 'pleasant'? If we had evolved dif... | [
"The intervals we enjoy are generally fairly simple ratios of frequencies.",
"For example, an octave (C to C) is doubling the frequency. A \"perfect fifth\" (C to G) is multiplying by 3/2. A \"perfect fourth\" (C to F) is multiplying by 4/3.",
"As for the notes in between, these actually differ between cultures... | [
"You may be interested in watching this, you can view it online.",
"Nova - Musical Minds"
] | [
"Not available in my region. Shit. Thank you though."
] |
[
"Can you bend light by passing it through a really small gap?"
] | [
false
] | As photons exhibit wave-like properties, and waves bend when passed through small openings, is the above possible? | [
"Yes! Light undergoes ",
"diffraction",
" at a slit."
] | [
"if you pass light through a small gap it will diffract. Essentially, you can forget the photon picture and consider the light as a wave for this problem. It will diffract, but obviously at any point on the non-source side of the gap the light will have a lower intensity than at the source. So while you can in a se... | [
"Is it still bending, or many minute angles, or is that thinking just pedantic?"
] |
[
"can a wave be longitudinal and transverse at the same time?"
] | [
false
] | if so, why and how? and what would be an example of such wave? | [
"Ocean waves have this. The bits of water move in circles so there's both transverse (uo and down) and longitudinal (back and forth) motion.",
"Similar waves in solids are called Rayleigh waves.",
"Either way, these waves are associated with a boundary between two different materials, for example water and air... | [
"To expand. Thinking just about mechanical waves, such as sound or seismic waves. For body waves, those that travel in the bulk of a material, the speeds of p-waves (longitudinal) and s-waves (transverse) are given by",
"vp = √((K + 4u/3)/p)",
"vs = √(",
"u/p",
")",
"K and u are the bulk and shear modulus... | [
"P-waves are fastest. S-waves travel at around 60% of the speed of P-waves, Rayleigh waves travel at around 90% of the speed of S-waves and Love waves marginally faster than Rayleigh.",
"EDIT Corrected."
] |
[
"Why does ionizing radiation cause harm to DNA/lead to cancer?"
] | [
false
] | Pretty sure this is chemistry but I'm not positive. I know practically nothing beyond that radiation causes cancer and harms DNA. | [
"I can explain from the DNA damage side. The radiation itself doesn't cause cancer. DNA damage causes the cancer. ",
"When you get damaged DNA, your cellular biochemistry can sometimes repair the damage. If it can't, it leads to permanent changes in the DNA of that cell as well as all progeny of that cell. Potent... | [
"To get a bit more specific, radiation causes DNA damage which is seen as single stranded breaks, double stranded breaks, and weird changes such as pyrimidine bridges (pyrimidines side by side will form covalent bonds with one another). Through these damages, the cell will try to repair the problem through homologo... | [
"When you talk in terms of radiation (specifically, \"ionizing\" radiation), you need to refer to the type of radiation, and the dosage absorbed by the body, and consider the short-term (acute) and long-term (chronic) effects of such a dose. ",
"Your cells are constantly in motion - being created, managed, and d... |
[
"Is right now the warmest time it has ever been over the human occupation of earth; if not, when was it the warmest?"
] | [
false
] | null | [
"Anatomically modern humans have existed for about 200,000 years. If we take a look at ",
"this graph",
", we see that the Eemian was a bit hotter than Earth is now. I don't know what caused them, but there were several global melts between 400 and 200 thousand years ago, all of which were hotter than it is n... | [
"I'm not debating climate change. I want more a chronological perspective on when did we see comparable high temperatures, regardless of cause."
] | [
"I'm not debating climate change. I want more a chronological perspective on when did we see comparable high temperatures, regardless of cause."
] |
[
"Can statisticians control for people lying on surveys?"
] | [
false
] | Reddit users have been telling me that everyone lies on online surveys (presumably because they don't like the results). Can statistical methods detect and control for this? | [
"Yes. It's easier to do in a large (read: lots of questions) assessment. But we ask the same question a few different ways, and we have metrics that check that and we get a \"consistency score\" ",
"Low scores indicate that people either aren't reading the questions or they are forgetting how they answered simila... | [
"They do exist and if they know what to look for can game the system, but that's true of just about any system. Inside knowledge makes breaking things much easier."
] | [
"what about liars with good memories?"
] |
[
"Is it me or does the word for \"No\" or other general negative words start with the \"N\" sound in a huge number of languages? If so why?"
] | [
false
] | [deleted] | [
"Which languages do you know? If the sample set you are examining is mostly comprised of Indo-European languages, the similarities in negation can be easily chalked up to the languages being related to each other to some extent. But the Indo-European family is not representative of the world of languages, and the W... | [
"English, German, and Japanese.",
"At first I thought it might be localized to the European languages which would make sense, but at the same time I was able to find cases such as Persian, Japanese, languages originating from India, and a few Native American languages as well.",
"I also know of some exceptions,... | [
"Persian and many languages in India are also Indo-European so there's that. Many of the major world languages today are IE, so people tend to have a skewed view about what is and is not common cross-linguistically. Languages like Hindi, Persian, English, Russian, Spanish, and hundreds of others are all related t... |
[
"Would suction cups not work in a vacuum?"
] | [
false
] | I was thinking about how if you suck all the air out of a sealed plastic bag, like a beach ball, it's nearly impossible to pull it apart so that there is a gap between the insides of the plastic. This got me wondering, is this the same phenomenon that allows suction cups to stick to surfaces? And then I got to thinking... | [
"I was thinking about how if you suck all the air out of a sealed plastic bag, like a beach ball, it's nearly impossible to pull it apart so that there is a gap between the insides of the plastic",
"That's because there's an external air pressure that attempts to squish the sides together. ",
"The air pressure ... | [
"Yes.",
"Basic concept but fascinating to think about. I thank you for making me think about it."
] | [
"So if I deflate a beach ball and put it inside a vacuum, can I pull the sides apart, even with no air to fill it?"
] |
[
"Do other people see you or your flipped image (camera flip)?"
] | [
false
] | null | [
"The camera flips you to make you look like you do in a mirror because that's how you are used to seeing yourself. Your webcam does this also. However, the front-facing camera on your phone doesn't do this and you don't appear flipped to the people watching your webcam. That is how they normally see you in the real... | [
"This is extremely misleading. An image is upside down on your retina relative to an outside observer. Your brain doesn't do any \"flipping\". It just receives input the eye. The bottom part of the retina just corresponds to the upper part of the visual field / world. There's no need to flip anything. anything. Th... | [
"Your eyes flip all images upside down. Your brain flips it."
] |
[
"Why do we have trouble instantly counting larger groups of objects (say, 7+), while we can instantly identify the number in smaller groups?"
] | [
false
] | null | [
"An excellent post on the matter.",
" ",
"One amusing theory in the comments: When you're facing down predators, and you go from one to two predators, that represents a 100% increase in predators that dramatically changes the game. When you're faced down by five predators and a sixth joins the bunch, you're sti... | [
"An excellent post on the matter.",
" ",
"One amusing theory in the comments: When you're facing down predators, and you go from one to two predators, that represents a 100% increase in predators that dramatically changes the game. When you're faced down by five predators and a sixth joins the bunch, you're sti... | [
"In this case you'd feel slightly better, rather than slightly worse, but the degree of change is about the same."
] |
[
"Is there any real natural connection between all of the animals that we call \"dinosaurs\"? Or are they all just called that because they lived within the same time period?"
] | [
false
] | In movies/shows depicting the different eras when dinosaurs lived, the wildlife seems to consist entirely of scaly somewhat lizard-like animals. Was life really that much less varied then than today? edit: I understand that a number of two-legged carnivorous dinosaurs are suspected/known to have had feathers. I have to... | [
"Yes, all dinosaurs shared a common ancestor that was not shared with any non-dinosaurs. There were other types of animals that lived in the same era that were not dinosaurs, including reptiles, mammals, amphibians, and fish. Mammals were pretty small at the time though; most of the large animals were dinosaurs or ... | [
"Furthering this discussion - the Dinosauria was sort of a vaguely defined group that was named in the mid 19th century, named to group very large Mesozoic reptiles with an apparent upright gait; it wasn't until the late 20th century that a solid definition of the Dinosauria was developed, and there are a number of... | [
"Most biologists/zoologists tend to avoid the term \"reptile\" these days because of the vagueness that is inherent to it when you look at modern phylogeny and taxonomy. We prefer to say \"non-avian sauropsids.\"",
"http://en.wikipedia.org/wiki/Sauropsida"
] |
[
"I sat in an old burnt out car for a photo, now everybody is saying I'm gonna die from mesothelioma. Are they right?"
] | [
false
] | [deleted] | [
"Mesothelioma is a very rare type of cancer, caused mostly by prolonged exporsure to asbestos.",
" It's symptoms don't even set in for a good twenty to fifty years. I think you'll live. "
] | [
"To reiterate, can you get mesothelioma from a burnt out car?"
] | [
"The car wouldn't even have asbestos in it unless it was manufactured twenty plus years ago, and even then you need prolonged exposure to it. So the short answer is no, unless it's a really old car and you decided to move in to it as a permanent home. "
] |
[
"Is there any known way to \"Optimize\" sleep, so that our body requires less?"
] | [
false
] | null | [
"An indirect answer:",
"Some people have sleep apnea. Stopping sleep apnea helps those people (and their partners) actually sleep.",
"Snoring can interfere with sleep, so stopping snoring is useful. Unfortunately, that's easier said than done. There's a link to overweight and snoring.",
"Then there's a bun... | [
"Yes, check out this article. With the Uberman Cycle you can sleep for 3 hours a day and get your optimal REM sleep once your body is trained to do so. Read the blog of the man who tried it. It is very interesting. ",
"http://www.highexistence.com/alternate-sleep-cycles/"
] | [
"There is a thing called ",
"polyphasic sleeping",
" where, for example, you sleep for 20 min every 4 hours. It takes a while to get used to (it's like staying up for a week straight) but once you do you pretty much go directly in to REM sleep. Using this technique, you can go with only sleeping 2 hours a day. ... |
[
"How do our bodies produce electricity with electrolytes? What are these electrolyte cells made out of? When the iron gates of these electrolytes open, to flip the charge inside and outside the cell, how does it make sure the wrong charge doesn't go to the wrong place?"
] | [
false
] | [deleted] | [
"When you think of \"electricity\" you probably think about electrons moving in metal wires. But more generally \"electric current\" is when anything with a charge (like electrons) move (in wires or anything else). Electrons have a negative charge. But in the body, the things with charge that moves are ions (not ir... | [
"To add on to this, one of the key features of your cells is that they ",
". They have special channels to allow them through, which can be opened and closed based on various signals. On top of this, every cell in your body has \"pumps\" to push out sodium (Na+) and pull in potassium (K+). They need energy to do... | [
"No, we completely understand how the body makes voltages. There is nothing vague about it. It's just that you're asking about \"electricity\" and \"electrolytes\" which aren't scientific terms. As I say, The explanation is simple: the body makes it so there is a high concentration of potassium ions inside the cell... |
[
"Why do manufacturer to consumer direct business models often fail?"
] | [
false
] | I work in an industry where manufacturers sell product to wholesale distributor at markup, then distributors sell to retailers, then retailers sell to consumers. The markup from wholesalers to retailers alone is 100%. Why don't manufacturers sell directly to consumers at a lower price, but higher profit? | [
"Access to consumers directly requires a differentiating business model that most manufacturers don't have or want. Logistics and the ability to capitalize on choice is a speciality that many companies also don't want to focus on. They'd often rather focus on innovation and brand quality in their own space."
] | [
"Regional differences are also a factor. Knowledge of where to place the retail location, how to price the product, hours, marketing, ect. These are all things that can affect how well a business does, and require intimate knowledge of an area. It's cheaper and quicker into expand into an area, for the manufacturer... | [
"One of the simplest reasons is just logistics honestly.",
"You have distributors that warehouse your product and take the burden of logistics off the manufacturer.",
"Logistics is a huge cost and is quite frequently a cost people don't associate big numbers with.",
"So in turn what manufactures tend to do is... |
[
"If an object acquires near-light speed and its observed mass increases manifold , will its interaction with other objects through gravitational forces change as well ?"
] | [
false
] | lets suppose for example the object is a HUGE starship and the other object is a rogue planetoid with significant speed of light | [
"The actual mass does not increase.",
"It just get's harder to get it to move faster and faster ",
".",
"But the object does not gain mass in its own (or anyone else's) perspective (reference frame)."
] | [
"True, and I would continue to add that although the mass doesn't increase, gravitational effect is based on ",
" (and other stuff), which does increase. In other words, there's no distinction between mass energy and other types of energy. So yes, a fast-moving object has a greater gravitational field than the sa... | [
"gravitational effect is based on energy",
"Whoa, there. No, no, no, no. Please don't tell people that. Saying \"gravity is based on energy\" is semantically identical to saying \"gravity is based on relativistic mass\" which you just correctly denied. Curvature is due to the stress-energy tensor, which includes ... |
[
"Since gravity is the curvature of space, would a static universe have gravity?"
] | [
false
] | Poorly worded, but I mean since gravity is the curvature of space, then would it have any effect if nothing was moving through that space? If we imagine a universe consisting solely of two bodies, say stars, that were stationary in space, would they be attracted to each other? | [
"No. The bodies' masses (or more honestly, their energies) would cause spacetime to curve, and that would in turn cause them to move towards each other. They wouldn't sit there static unless there were some force acting against gravity to hold them there."
] | [
"Nope. Gravity is what happens when spacetime is curved. The fact that we're including time is important, because ",
" is moving through spacetime. Even if you're at rest, you're still moving through the time direction. So every object has a spacetime path.",
"Now, curvature means that the shortest path between... | [
"No, it's more that in a curved space (or spacetime), actually straight lines ",
". Think about the surface of the Earth. What does a straight line look like on the Earth's surface? There aren't any - the best you can do is a path called a ",
" (or a segment of one), which is a path that goes all the way around... |
[
"How is it that we cannot use vegetable oil to power all vehicles since diesel engines are able to combust with it? Would this be a sustainable fuel source outside of solar/wind power?"
] | [
false
] | null | [
"It is sustainable in that vegetable oil is produced from plants, and we can control how many of these plants we grow. As I understand it, the problem with using vegetable oil to power all vehicles is that there is only so much land that could potentially be used to grow the plants that produce vegetable oil, and m... | [
"The U.S. uses around 133 billion gallons of GASOLINE alone per year. ",
"You can get around 3 gallons of ethanol per bushel (of corn) and can grow about 145 bushels per acre.",
"145 x 3 = 435 gallons per acre.",
"133 x (10",
" / 435 = 305,747,126.4 acres of corn.",
"The U.S. uses around 400 million acre... | [
"Biofuel Controversy",
"Also, WVO is not a very good fuel in an unrefined state. It's difficult to use in cold climates because it's so thick. It really doesn't work well in modern diesel engines causing incredibly high cost and frequency of maintenance. The cost to ",
" convert existing vehicles is quite high(... |
[
"Is there scientific evidence that has determined whether protein supplements are healthy or not?"
] | [
false
] | I'd also be intrigued to know how other supplements are viewed by the scientific community, like vitamin or fish oil. | [
"Well like I said, it's basically powdered milk. It's a fine source of dietary protein and might have some therapeutic uses.\nsee",
"Hulmi JJ, et al. Effect of protein/essential amino acids and resistance training on skeletal muscle hypertrophy: A case for whey protein. Nutr Metab (Lond). 2010 Jun 17;7:51.",
"X... | [
"That's based on studies on full body nitrogen balance and doesn't apply at all to people who want to maximize muscle growth or even spare muscle in a deficit. Full body nitrogen doesn't tell us anything about muscle loss/gain because the body can prioritize nitrogen away from muscle and just because an amino acid ... | [
"If you're looking for scientific information on supplements, examine.com is a great resource. "
] |
[
"How high can birds fly?"
] | [
false
] | null | [
"An ",
"article from last october",
" reported a new 'record holder', the bar-headed goose, who they observed at heights up to 7290 meters, although they normally didn't fly that high.",
"Of course, other birds might fly even higher but haven't been observed doing so yet."
] | [
"Take a look at ",
"this",
".",
"The authors indicate that birds generally stay under 500 feet, but birds migrating long distances are often found between 5000 and 20000 feet.",
"They also say this:",
"Perhaps the most impressive altitude record is that of a flock of Whooper Swans which was seen on radar ... | [
"Wow that's crazy! Thanks!"
] |
[
"Does color on the electromagnetic scale exist outside of the human brain?"
] | [
false
] | [deleted] | [
"color is a neural phenomenon, it exists only in brains. we can understand color as one way the brain tries to estimate surface properties. it is ",
" a property of light or electromagnetism - we do not have perceptual access to these things, outside of special physical analyses requiring tools.",
"the brain an... | [
"I find it odd that I couldn't understand op's question until I saw your answer."
] | [
"Does color exist outside of our brains",
"It depends on what you mean by \"color\". Light definitely exists independent of human psychology. Furthermore, light of different frequencies definitely exist on their own and have a logical, independent, physical existence. How you personally experience a certain frequ... |
[
"Do candle flames cast shadows?"
] | [
false
] | I have wondered this for a long time: Does a candle's flame cast a shadow? I mean in this context: I have a single candle in a completely dark room with a blank wall behind it. I place a very bright light (read much brighter than a single candle flame) pointed at the candle. When I look at the wall behind the candl... | [
"The flame of the candle is filled with a mixture of vaporized resins, burned carbon fibers, aerosolized wax, and hot ionized gas molecules. This fundamentally changes the nature of the medium (air) that the bright light is trying to propagate through. It will partially block some of the light, a very small will ... | [
"It seems to me that you could have a definitive answer for yourself fairly easily, at least to the \"Does it...\" part of your question. As to the \"Why or why not...,\" well, see c_is_4_cookie's answer."
] | [
"A ",
"sunspot",
" is one kind of example. They are still extremely hot plasma that emit lots of light, but they're 2000-3000 K cooler than the surrounding photosphere of the sun, so when the sun is viewed at an appropriate relative brightness scale, the sunspots appear black. A candle could be considered anal... |
[
"Is it possible that PI is irrational because of our difficulties in making a perfectly round object?"
] | [
false
] | null | [
"No. The definition of pi has nothing to do with our ability to draw a circle."
] | [
"These are extremely commonly asked questions whose answers can be found by some simple sub searches. Rationality is not dependent on the number base. The base is just a way to represent the number symbolically."
] | [
"No. Whether a number is rational has nothing to do with the number base. Again, these are extremely commonly asked questions. They are in the FAQ and readily available via a sub search.",
"https://www.reddit.com/r/askscience/search?q=pi+rational&restrict_sr=on&sort=relevance&t=all"
] |
[
"Why does the shingles vaccine work?"
] | [
false
] | My understanding of the way vaccines work is that it gives your body a chance to create antibodies so when it comes in contact with the actual virus it knows how to fight it. So, why is it that you can get shingles more than once but a vaccine exists? Wouldn’t having the virus originally give you the antibodies that yo... | [
"Shingles is an unusual vaccine and it's aimed at an unusual virus.",
"Varicella Zoster virus (VZV), the virus that causes both chicken pox and shingles, is a member of the herpesvirus family. Herpesviruses are an enormous group of viruses; virtually every vertebrate species probably has one to ten or so specific... | [
"About a third. ",
"We can say that because about a third of the population will have shingles, and almost everyone carries VZV -- as I said, these are incredibly well adapted viruses, and no one escapes being infected with them. ",
"Over 95 percent of people are infected by the varicella zoster virus (VZV), du... | [
"With shingles, once youve had it once, the virus is always dormant inside you. Typically your immune system does a good job at keeping the virus dormant but over time as you age the immune system \"forgets\" the antibodies and gives the virus a chance to flair up. The shingles vaccine doesnt permanently prevent sh... |
[
"Once the body's defences against cancer have failed and a tumour starts, does the body have any natural defences to fight it?"
] | [
false
] | Essentially what I'm asking is, without treatment and intervention, would everyone who contracts cancer die from it unless the cancer itself didn't spread? | [
"Yes, the immune system will still fight the abnormal cells but usually they are almost indistinguishable from normal cells. Once a malignant tumor forms that can't be effectively targeted by the immune system the person will eventually die without treatment.",
"The immunesystem is extremely strong once it acquir... | [
"The immune system can still react to the cancer, in some cases. When a tumor forms, that is the immune systems defenses FAILING. Most malignant cells are forced to die whwn detected. But when one mutates to resist those signals it can expand, and the potential for more mutation comes, for growth signalling and an... | [
"Tumors mostly start out as cells whose replication regulation mechanisms fail, for whatever reason (exposure to radiation, chemicals, certain viruses, etc.). All human cells have systems that check whether this has occurred, and either try to repair the damage, or destroy the cell to preserve the organism. ",
"S... |
[
"Are planetary orbit models accurate?"
] | [
false
] | Do the planets of our solar system actually orbit in a disc like ellipse all in the same plane or is that just how they are modeled? And if so, why do we use that type of model? Also do planets of other systems orbit in the same manner as ours? It seems logical to me that planets would orbit a sun as electrons do a nuc... | [
"Planets do orbit that way (which was one of the reasons pluto was demoted, since it's the only one that did not). Electrons however don't do what you think and are far more abstract than being actual physical objects that orbit. "
] | [
"Do the planets of our solar system actually orbit in a disc like ellipse all in the same plane or is that just how they are modeled?",
"Each planet has its own orbital plane. However their inclinations are not very big, e.g. Mars is 1.85º, Venus is 3.4º. Mercury has a particularly high inclination at 7º.",
"An... | [
"Very interesting, thanks. It almost seems weird to think they all orbit more or less on a flat plane though. "
] |
[
"If evidence of the Higgs is released on Tuesday and follow up observations prove its existence, will we finally have a Theory of Everything?"
] | [
false
] | null | [
"No. The Higgs would be the last piece of the ",
"Standard Model",
" of particle physics to be discovered experimentally. The Standard Model is one of the two pillars of modern theoretical physics, the other being ",
"general relativity",
" (GR). The Standard Model is a quantum theory describing the known p... | [
"There was a small period of time (in the 50's was it ?) when people were ready to abandon quantum field theory. The theories were throwing up infinities left and right even for quantities that should give reasonable answers on experimental measurement.",
"They then realized that their theories were taking into a... | [
"Mathematically nonsensical - infinities and such for physically observable quantities. Quantum mechanics may seem nonsensical to you but it is mathematically well-defined and gives quantitative answers which we can test, and turn out to be correct. So in an objective sense it's ",
" nonsensical."
] |
[
"How do scientists calculate that a star is xy billion light years away?"
] | [
false
] | What the title says, I can't figure this out. If, for example, a star is x billion years away, obviously sending a signal or something which would bounce back isn't an option. So how do they do it? | [
"I've already seen the answers posted but I wanted to post these Khan Academy videos that I found helpful when learning about this topic.",
"This is about calculating stellar distance using ",
"parallax",
".",
"And this one explains ",
"red and blue shifts",
".",
"I could write a long block comment bu... | [
"Stellar parallax (khanacademy.org)",
"edit: oops, didn't see it was already posted"
] | [
"That's completely irrelevant and off-topic. Why would you even bring fundamentalists into this?",
"Atheists on Reddit are always bringing religion into science discussion. It's pretty ironic to me, because I ",
" see any Christians do it."
] |
[
"Could something similar to a shark evolve on Europa?"
] | [
false
] | null | [
"It's impossible to answer this question without speculation, but I suppose that giving links is probably fine.",
"Richard Greenberg (author of the recent book “Unmasking Europa: The Search for Life on Jupiter’s Ocean Moon”) has said that",
"the concentrations of oxygen would be great enough to support not only... | [
"Did you accidentally a letter or did I just miss the joke?"
] | [
"Did you accidentally a letter or did I just miss the joke?"
] |
[
"When viewed from earth with the naked eye, Venus currently looks like one big ball of light, brighter than any star. Does that mean if viewed from Venus (or elsewhere), the earth looks like a shining star?"
] | [
false
] | When I think of pics of the earth taken from, the moon for example, the earth doesn't appear to be "glowing" at all. Obviously I understand we're talking about significantly different distances, but I'm just curious if the earth would ever look like a glowing star if viewed from the right place. | [
"The Earth is significantly less reflective than Venus, and being further from the Sun is also less brightly lit, but other than being dimmer at the same angle it will look about the same from a distance, yes, as do the other planets (Mars and Jupiter in particular are pretty obvious from the Earth, for example). Y... | [
"Yes, any planet will appear like a point of light like stars. You should check out ",
"stellarium",
", if you're curious about the views of the sky from any planet/moon. ",
"At this current moment, from earth, venus is at -4.15 magnitude, and jupiter is at -1.88. If we are at venus right now, and say that we... | [
"No, Venus is so bright because it is covered in thick clouds that reflect much of the light from the sun. You should read ",
"this",
" for more information"
] |
[
"Do paper bags really create more pollution than plastic?"
] | [
false
] | I often hear the claim that paper bags supposedly create more pollution than plastic bags during production, and are therefore more harmful to the environment. But when I try to find scientific research supporting this claim, I can only find studies funded or conducted by people in the the petroleum and plastics indust... | [
"I agree. Paper bags, however, eventually become fertilizer if they wind up in a stream or ocean. I really think the long-term effects of plastic are far more harmful to the environment."
] | [
"They're both bad. Paper factories emit a ton of air pollution - definitely more than the factories that make plastic bags. It costs more energy to make paper bags. Paper bags are also not as degradable as you'd think. Plastic is terrible for the environment that's for sure, and personally I prefer paper over plast... | [
"Wait, there are no toxic gases released in refining crude oil for polyethylene?"
] |
[
"Is there a \"frame rate\" for reality? More specifically, is there a point in time where there is no motion whatsoever even at the quantum level?"
] | [
false
] | I've read that a zeptosecond is the shortest unit of time measured to this date. Does all motion cease at 0 zeptoseconds or is time like a number line with infinite numbers between each value? | [
"Is there a \"frame rate\" for reality? More specifically, is there a point in time where there is no motion whatsoever even at the quantum level?",
"There is currently no evidence to suggest this, no — for both questions.",
"Both of our best current models of physics — general relativity for gravity and the st... | [
"As far as I am aware, in the standard model there is nothing which prevents there from being subdivisions smaller than that, nor does anything prevent measurement of them.",
"However when accounting for general relativity, no physical apparatus could measure smaller length scales without itself becoming a black ... | [
"Um what about subdivisions less than One Planck Time?"
] |
[
"In a future where a large Mars colony exists, how might we implement an interplanetary Internet?"
] | [
false
] | [deleted] | [
"Previous sighting: ",
"Using current technology, would it be possible to have a shared internet network between Mars and Earth?"
] | [
"People are working on this right now.",
"https://en.wikipedia.org/wiki/Interplanetary_Internet"
] | [
"The main issue with implementing this kind of system would be:",
"Predictive caching: Send info to Mars because you know people there will want it soon, and you don't want to wait an entire round trip time to retrieve a webpage.",
"Connection less protocols: Currently when you go to reddit.com, you create a DN... |
[
"What happens to electrons in a circuit?"
] | [
false
] | I've always had a really hard time understanding how electricity really works. I'm trying to understand how a circuit works but here is what I don't understand: Does electrons or charge get "lost" during the process thanks to resistance or do all electrons all eventually make through from on pole to the other? If they ... | [
"For the purposes of circuits, electricity works a lot like a pneumatic system. With wire there will be electrons in all the places at the same time. If power gets used up, to useful work or to resistance it does so in the form of a 'pressure drop' but the electrons are still around.",
"The actual net movement ... | [
"So in metals, there is a large amount of electrons in the \"conduction band\" (the outer electron shells), and these electrons can freely move throughout the whole metal. They are doing this all the time, just whizzing around randomly like molecules in a liquid. When you apply a Voltage (say, using a 9V battery)... | [
"My answer is from a chemistry background so might not be 100% accurate. Electrons can act as waves as well as being particles, so through a long metal wire the electrons transfer energy by acting like one big wave which transfers energy down the wire similar to making water waves (the wave travels across the pool.... |
[
"Electric currents travel through water, so could electricity travel through water droplets in the air in a thick enough fog?"
] | [
false
] | I was influenced by the film The Day After Tomorrow as a kid (ooo Daddy Dennis Quaid) so I’ve always enjoyed thinking about theoretical environments capable of extreme calamities. Would moisture levels in the area become thick enough to where humans couldn’t breath before electricity from a lightening bolt is able trav... | [
"A lightening bolt is electricity traveling through air. If the potential of the electric source is big enough (ie high enough voltage) then it can travel through an air space. I'm guessing what your asking is could the moisture content of the air be high enough for the air to become 'electrified' in the same way a... | [
"I was under the assumption that it's not the water that conducts electricity, but the ions from dissolved compounds (like NaCl into Na+ and Cl-, which makes a lot more sense in terms of allowing current to pass). So no, since water vapor doesn't have enough of these ions and close together this wouldn't be possib... | [
"moisture levels in the area become thick enough to where humans couldn’t breath",
"This is not actually possible. Depending on air temperature, humidity can't be higher than up to about 5% (at 40°C). Air is about 21% oxygen, so adding 5% humidity can only dilute that down to about 20.5% oxygen, still quite breat... |
[
"The specific heat of water ... I'm told it's marvelous, why?"
] | [
false
] | [deleted] | [
"It's pretty high, meaning it is hard to change its temperature. That means hot water stays hot for longer than other liquids and cold water stays cold. This is awesome for keeping us warm as well as keeping the atmosphere at a fairly constant temperature. ",
"It also means we can use it to dissipate heat for ins... | [
"If you are asking why physically does water have a high specific heat -it's because of the molecular forces associate with water molecules. H20 hydrogen bonds with itself, so when you heat water you must provide additional energy to disrupt the extensive hydrogen bonding network."
] | [
"It's not that a high specific heat capacity makes it necessarily ",
" to change something's temperature, it's more that it can absorb a lot more energy without changing its temperature. ",
"For example, Iron has a low specific heat capacity of around 450J/kg°C, while water has a rather high specific heat capa... |
[
"Special relativity says that all observations from any reference frame are valid. How do you make observations from a rotating reference frame?"
] | [
false
] | I know that, for example, if an object is moving right relative to me at 1mph less than the speed of light (c), and another object moves to the right at 2mph relative to the first object, the second object would still move approximately 1mph under c from my viewpoint. How can we then explain and describe, for example, ... | [
"You have to go to General Relativity to handle accelerating reference frames",
"Sorry, but that's a misconception. SR is perfectly adequate to describe accelerating reference frames, in the same way that Newton's classical mechanics are. In classical mechanics, the three laws still apply, although you must use t... | [
"Special relativity says that all observations from any reference frame are valid.",
"No, special relativity says that all ",
" (i.e. non-accelerating) frames are equally valid. A rotating reference frame has centripetal acceleration and is therefore not inertial. You have to go to General Relativity to handle ... | [
"That is what he is saying. In order for there to be some rotation there must be some (linear) acceleration this is distinct from angular acceleration which changes the rate of rotation."
] |
[
"Do the proteins and phospholipids of cell walls and organelles have to be repaired often?"
] | [
false
] | And does this produce a waste that has to be excreted or does it recycle the material? | [
"Proteins are turned over fairly constantly - they're actually thought of as not particularly stable entities. They can be re-folded by chaperone proteins like GroEL, or if they are very damaged/no longer required, they are targeted to the proteasome for degradation. As far as I know, the resultant peptides are rec... | [
"Since the other guy focused on proteins, I'll focus on phospholipids.",
"The answer is not necessarily repaired, but regenerated. The phospholipids of the cell membrane (cell walls are only found in plants and are made of sugars, not phospholipids) regularly get used to do things like endocytize a receptor-liga... | [
"It also depends on the environment and the type of protein. Some proteins are incredibly stable. The protein in your eye will last until you get cataracts or past your death even. While other proteins may have a fleeting life time. It really depends on the function and location. But our bodies use proteins like pe... |
[
"Why does the baby does not get exact same immunity to diseases as a mother?"
] | [
false
] | Babies are ill all the time because they don't have a lot of "memory" cells to fight diseases. Slowly with a help with vaccines babies build up their immune system. So nature does not pass already built up immunity from mother's system to babies? Just trying to think of any good reason why it does NOT happen. | [
"To a certain extent, babies do inherit some immunity. ",
"Certain genes are linked to immunity to certain diseases. ",
"Babies inherit their mother's microbiome during childbirth and breastfeeding, which helps build immunity by inheriting symbiotic microorganisms. ",
"That being said, the exact composition o... | [
"The development of acquired immunity is quite complex, among other things immune cells need to not react to the persons own cells/proteins etc. This is achieved through a process of negative selection when those immune cells are developing. ",
"A baby and its mother have different genetics. If a mother was able ... | [
"To a very limited extent, some immunity is temporarily conveyed to an infant from the mother's breast milk in the form of Immunoglubulin G, or IgG. IgG is the most common antibody found in the blood, and its transference to an infant allows them the same level of coverage that the IgG would provide within the moth... |
[
"Can animals see the stars?"
] | [
false
] | Humans can see under good circumstances maybe 6000 stars. Have other animals this capability? My guess is not too many. Can we count ourselves lucky to be able to experience this sight? | [
"As ExplosiveWombat pointed out, any animal with the right kind of eyes can ",
" the stars, but whether they pay any attention to them is a different question. But at least three groups of animals (besides humans) ",
" known to look at the stars: some ",
"birds",
", some ",
"seals",
", and ",
"dung be... | [
"Thank you, I enjoyed this answer. :-)"
] | [
"Glad to help! :)"
] |
[
"Is it possible that there were organisms in our ancient history whose DNA replication processes were less prone to errors/mutations, but because of this efficiency the organism lacked the ability to adapt to changes and died out?"
] | [
false
] | null | [
"Actually, our predecessors were far more efficient at DNA repair and therefore had a lower mutation ",
" -- the bacteria. However, far from having 'died out', they're by far the most dominant lifeform on the planet and are doing quite well. I feel queasy about evolvability as it's a fairly high order phenomenon,... | [
"It sounds like you might be talking about ",
"evolvability."
] | [
"It seems possible to me. How could you ever demonstrate it to have happened though? No descendants of those individuals exist today, so how could we study them."
] |
[
"Where does the relativistic mass of photon come from?"
] | [
false
] | null | [
"Relativistic mass is just E/c",
". So for a photon, it's p/c."
] | [
"So if i use E2 = p2 c2 + m_rest2 c4 for photon, m_rest=0, therefore E=pc. Does it mean that it’s correct to write E=m_rel c c for photon as you said m_rel=p/c?"
] | [
"Sure, that's fine. As long as the relativistic mass is defined to be the energy of the photon divided by c",
"."
] |
[
"How strong are the blood vessels, nerves and other pipe/thread like structures inside the human body?"
] | [
false
] | I always have this bad feeling that nerves and blood vessels are thin and fragile structures which are very very easy to snap/tear/break. Is that right? Is there some easy to understand reference to compare their strengths to? | [
"It depends on size. Small blood vessels like capillaries can be quite fragile. Heavy coughing, vomiting etc. can burst blood vessels in the eyes, face and upper chest just due to pressure. These small bleeds are called petichiae, you can get similar bruises carrying a heavy bag strap directly on skin, for instance... | [
"If a smaller vessel like the one in the eye bursts, does that mean death?"
] | [
"No it's harmless, you can get a small ",
"bruise",
" under the conjunctiva that goes away on its own."
] |
[
"Why do we feel a pain in the center of the chest area when we are emotionally hurt and/or embarrassed?"
] | [
false
] | Whenever I remember something embarrassing I did sometime earlier in the day or week, I feel a dull pain in the center of the chest area, and it gets worse as I start to remember more embarrassing things. This also happens when someone insults me. Why is that? If this has already been discussed, please give me the lin... | [
"Emotion scientist, here.",
"I'm not exactly certain which plays a more prominent role, but it's a combination of your parasympathetic and sympathetic nervous systems responding to the situation. Your parasympathetic nervous system withdraws its regulation of the heart via the vagus nerve and your sympathetic ner... | [
"Here you go. Information."
] | [
"why exactly do we cry when we're upset? what evolutionary, if any, aspects play into this also?"
] |
[
"Can you have a nucleus that is orbited by muons instead of electrons? If so, what similarities/differences would the atom have chemically and physically?"
] | [
false
] | null | [
"Yes, these can be made synthetically. They are not known to occur naturally. Muonic hydrogen and muonic helium are the two that we have worked with. The former can be used for low-energy nuclear fusion, because the muons allow the two protons to get closer together. The latter is interesting because if there is bo... | [
"Yes. Muonic hydrogen - a proton orbited by a muon instead of an electron - has been studied a good deal. Muons live for an average of about 2 microseconds before decaying, though, so these atoms aren't stable and have to be studied quickly. In particular, it would be hard for these atoms to form chemical bonds ... | [
"What I find interesting about this is the the muon replaces an e- in the 1s orbital but orbits closer. The orbital density apparently changes in a compressed manner. I’d love to see what it looks like and how muons could affect MO theory."
] |
[
"If Matter and Antimatter behave very, very similar, can we be sure that distant galaxies aren't made of antimatter?"
] | [
false
] | To my recollection, recent tests have shown that Anti-Hydrogen reflects light very similarly to normal hydrogen. Can we still tell them apart over astronomical distances? | [
"The issue is that there really isn't any \"empty space\". Even in the space between galaxies you have on average 1 atom per cubic meter. That's not much, but it's enough that if different galaxies were made of different types of matter (anti- versus regular) there would necessarily be some bright, easy to observ... | [
"Yes.",
"When matter comes into contact with anti-matter, they annihilate in a flash of gamma radiation.",
"We can see many, many galaxies that are the result of collisions. If this ever happened between a matter and an anti-matter galaxy, it would be by far the brightest object in the universe, and it would bu... | [
"That makes a lot of sense. ",
"Thanks!"
] |
[
"(1+2+3+...+n)^2=1^3+2^3+3^3+...+n^3. Why?"
] | [
false
] | null | [
"Let's prove it (by induction), the \"why\" is a neat algebraic trick that will pop up.",
"First note that it holds in the base case n=1 (1",
" = 1",
" )",
"Now suppose the statement is true for some integer k, we want to show it is true for k+1.",
"((1+...+k)+(k+1))",
" = (1+...+k)",
" + 2 (1+...+k)(... | [
"Let's examine the difference between (1 + 2 + ... + n)",
" and (1 + 2 + ... + (n + 1))",
"Let a = 1 + 2 + ... + n, and b = 1 + 2 + ... + (n + 1).",
"b",
" - a",
" =",
"= (b + a) * (b - a) =",
"= (2a + (n + 1) ) * (n + 1) =",
"Recall that 1 + 2 + ... + n = n * (n + 1) / 2:",
"= (n * (n + 1) + (n +... | [
"Someone posted a very nice pictorial demonstration of this on ",
"/r/math",
" awhile back:",
"https://www.reddit.com/r/math/comments/27sjq7/last_week_there_was_a_beautiful_visual_proof_for/"
] |
[
"Is dyslexic people's sight affected while doing anything other than reading?"
] | [
false
] | Is it only words that are switched up by their brains or does dyslexia affect perception of other everyday things? | [
"Folks, please don't post anecdotes here. They're not allowed and are being removed. Thanks. "
] | [
"Please don't post non-science. There is valid research on this topic. People with dyslexia DO NOT have trouble interpreting non-linguistic symbols. (See Vellutino, F. R., et al. \"Differential Transfer in Poor and Normal Readers.\" Journal of\nGenetic Psychology 126 (1975): 3-18; and ",
"Snowling 1980",
") "... | [
"Please don't post non-science. There is valid research on this topic. People with dyslexia DO NOT have trouble interpreting non-linguistic symbols. (See Vellutino, F. R., et al. \"Differential Transfer in Poor and Normal Readers.\" Journal of\nGenetic Psychology 126 (1975): 3-18; and ",
"Snowling 1980",
") "... |
[
"How many different atoms are theoretically possible?"
] | [
false
] | [deleted] | [
"Scientists aren't sure.",
"Some think it ends at the atomic number of ~130.",
"Others say that there might be an infinite amount of different atoms.",
"What we do know now, is that the heavier atoms get, the shorter half-lives they have, down to milliseconds. (Not exactly a linear decent though.)",
"But sc... | [
"There is also a difference between saying atoms and nuclei. Atoms are predicted to end around 130. Nuclei on the other hand are predicted to end around 170-190. That is the limit of boundness for nucleons."
] | [
"Are we talking atoms, or stable atoms? For the latter, Strukkstars answer is great, for the former, well, neutron stars are basically atomic nuclei with sizes measured in kilometers, so the limit is pretty far up."
] |
[
"If you combined carbon and hydrogen in a way that they would bond, what hydrocarbon would you make?"
] | [
false
] | And how are the rest of the hydrocarbons made | [
"In what way are you combining them? You build hydrocarbons when your body makes phospholipids and triglycerides in a manner similar to ",
"this lovely process",
". Hydrocarbons in the form of oil is made when massive amounts of organic matter (mostly algae I think) is subjected to intense heat and pressure.",
... | [
"There is no such thing as molecular carbon",
"How do you define ",
"? I think it's perfect valid to refer to graphite and fullerenes as molecules."
] | [
"I mean the generally referred to \"molecular\" atoms. Two hydrogens, two oxygens being molecular hydrogen and oxygen respectively. I didn't mean to say that those things aren't molecules."
] |
[
"Why is/was there a tendency for like minerals to collect together on earth?"
] | [
false
] | It seems that the original source for minerals was random and that they should be randomly, and relatively homogeneously spread over the surface of the earth. Yet minerals like iron oxide, sodium chloride, gold, silver, (and most others it seems) have had a significant tendency to be found concentrated in various area... | [
"2 parts to this (admittedly insufficient) answer.",
"Sodium chloride stands out on this list. Sodium chloride build up is often due to sea water being trapped or secluded from fresh water. Over time the water will evaporate leaving the salt concentrated in that area.",
"As for concentration of other elements, ... | [
"To elaborate on this, minerals (by definition) are comprised of elements distributed throughout the Earth. \nObviously, not all elements are in equal abundance; For instance gold (Au) is much less abundant on Earth than Oxygen (O), Silicon (Si), Iron (Fe), or Magnesium (Mg). Like Karbon was saying, these elements ... | [
"It seems that the original source for minerals was random and that they should be randomly, and relatively homogeneously spread over the surface of the earth. ",
"When everything is molten then yes it starts out homogenous. Although it's not clear if Earth was ever completely molten, it was very probably ",
"... |
[
"How does the specific heat capacity effect the performance of heatsinks?"
] | [
false
] | So the specific heat capacity is the amount of heat energy required to heat up a substance per unit of mass. I get that. But how does it relate to heat sinks? is it that the lower the specific heat capacity, the better it is cuz it takes less energy to heat it up therefore it's easier to transfer the heat away? Please ... | [
"\"Heat up\" is very vague. Specific heat capacity is the amount of heat (in joules) needed to increase the temperature (in Kelvin) of 1 kg of substance by 1 K (or 1°C).",
"So, heat sinks should have high specific heat capacity so they can \"absorb\" more heat for each increase in temperature, since the heat tran... | [
"So, heat sinks should have high specific heat capacity so they can \"absorb\" more heat for each increase in temperature, since the heat transfer needs a temperature gradient.",
"Except they don't need to absorb anything, as \"heat sinks\" as we call them aren't actually heat sinks, but heat conductors. Zero hea... | [
"“Better” is subjective here. The mass, specific heat, and heat rejection ability all play into choosing a heat sink for a specific load. ",
"More to your specific question. The greater the thermal capacity of a heat sink the generally slower the transient response of the system. The shedding of the heat load is ... |
[
"Genetic scientists will often include a gene that codes for a green fluorescent protein in combination with a desired gene. How does the glow tell scientists that the desired gene was inserted correctly?"
] | [
false
] | null | [
"GFP-fusions aren't really intended to tell you that a gene was inserted correctly (though I guess it tells you that too). You could just as easily tell if your gene is being expressed with qPCR or a Western blot or something. ",
"Usually the purpose of GFP-fusions is to easily track the cellular location of GFP ... | [
"Plasmids are kind of an \"extra\" piece of DNA that bacteria can have. Usually the plasmid contains whatever gene you intended to insert, and the GFP gene, as well as regulatory sequences such as a promoter region to push along the expression of GFP. This promoter basically allows markers to bind to them which sig... | [
"https://en.wikipedia.org/wiki/Green_fluorescent_protein#Reporter_assays",
"I might have misunderstood you, but the GFP doesn't bind to the target protein, and therefore doesn't really get treated/moved to the same cellular locations as the target protein. The purpose of GFP is that the regulatory sequence that c... |
[
"What's the lowest theoretically possible stable orbit around Earth?"
] | [
false
] | [deleted] | [
"Depends what you mean by stable. The ISS has to periodically adjust its orbit because of drag from the latent atmosphere."
] | [
"But it will eventually fall out of orbit with us since it's moving away.",
"Wikipedia claims (with citations) that ",
"lunar orbit around Earth will stabilize",
" in about 50 billion years, assuming that sun lets it go that far (which it won't)."
] | [
"What if the question was revised to say \"orbit around the moon?\" Is there an arbitrarily low altitude where orbit could be maintained without adding energy to the system, now that atmospheric drag is negligible or nonexistent?"
] |
[
"In places where nudity is the norm, do people who go through puberty have the innate sexual attraction to other peoples primary and secondary sex characteristics or is that a learned trait?"
] | [
false
] | null | [
"There is an ",
"r/askanthropology",
" you may want to check out where some variation of this question is often asked and answered. Short answer is that it is at least partially a learned trait - other cultures where exposed breasts are the norm don't sexualize breasts to the same extent that we do in western ... | [
"As a Senegalese woman explained to me when I asked why they go to such lengths to keep their thighs covered but not their breasts: \"This [gestures to the area between waist and knees] is for your husband, and these [gestures towards breasts] are for your kids.\""
] | [
"I find faces attractive and I see them all day. Why would other body parts be different?"
] |
[
"I'm having a bit of a hard time understanding how if one travelled close to the speed of light for 20 years, when they stopped, they'd be 1000 years in the future. Anyone care to explain to an idiot?"
] | [
false
] | [deleted] | [
"The universe would brake if this happened. ",
"Probably a typo, perhaps a clever pun. Either way, good one."
] | [
"haha i wish it was a clever pun, sadly its a typo, but i suppose also true"
] | [
"Have you already considered why, since speed is a relative thing, we cannot just say that the earth is speeding away from the traveler? Because if that were the case, the earths time should have slowed down.",
"Meet ",
"the twin paradox"
] |
[
"As a reformed creationist I am now thoroughly convinced that evolution is true. I do have one question though."
] | [
false
] | [deleted] | [
"You get duplication of genes. These duplicate copies made either by mutations or transposons (jumping genes), can then be mutated to have new properties. This is essentially how organisms become more and more complex."
] | [
"The issue is that the word \"information\" has a subtler meaning than you think. How much information would you say there is in a megabyte of random noise? It's not correlated with anything, it's not useful, it doesn't contain knowledge, but it's also completely impossible to predict - so, on the one hand, it cont... | [
"This is one of the proposed mechanisms by which there is evolution of new genes; here is a press release on such events ",
"http://www.scripps.edu/news/press/2012/20120503polleux.html",
" and a paper ",
"http://www.sciencedirect.com/science/article/pii/S0092867412004618",
".",
"One thing to note as well ... |
[
"In humans, is the milk produced by lactating males just as nutritious as the one secreted by females?"
] | [
false
] | Is the paternal milk exuded by lactating human males chemically indistinguishable from its maternal counterpart? | [
"Both types come from the same tissue, so there should be no difference. Interestingly, ",
"Darwin speculated that",
" \"both sexes may have nursed young in early mammalian ancestors, and subsequently mammals evolved to inactivate them in males at an early age.\""
] | [
"How about some male hormones? Couldn't they percolate into the milk?"
] | [
"Really couldn't help imagining a coffee maker after I read your comment haha"
] |
[
"What is the worst disease, poison, sting or bite a human being can suffer?"
] | [
false
] | null | [
"Blue ringed octopus poison is some nasty fucking shit. It's a neurotoxic agent around 10,000 times more powerful than cyanide, and usually causes complete paralysis within minutes of being stung. While thats nasty in its own right, the worst thing is that you're pretty much suffocating in your own body because you... | [
"The Bullet Ant.",
" It is said that the pain from a single sting lasts for 24 hours. "
] | [
"I didn't forget, just figured the info in the link covered that base well enough. One fun fact is that there exists an ",
"amazonian tribe",
" that uses the ants in a very painful rite of passage. "
] |
[
"If hormonal contraception stops eggs being released, how do they eventually come out?"
] | [
false
] | Most oral contraceptives stop eggs being released. But after you stop taking them, do they come out in gluts or staggered over a longer period of time? And of gluts, why aren't former contraceptive users more likely to have twins and multiple births? | [
"Women start off with ~ 1 million eggs, most of them will never be used at all, and they don't ever ",
" to come out. You seem to be imagining sort of a backed up conveyor belt a la Lucille Ball, but eggs are only viable after full development (which happens to 1 egg right before ovulation) for a limited time. So... | [
"My understanding of most hormonal birth control is it tricks the body into thinking it's already pregnant and there is no need for a new egg."
] | [
"It's more like it tricks the body into thinking it's in the phase of the cycle where it's already ovulated"
] |
[
"Other than light, what is the fastest thing we have ever observed?"
] | [
false
] | null | [
"That would be the ",
"Oh-My-God particle",
", which from what I can gather was traveling at 0.9999999999999999999999951 c. Although the source I got that from said it's a proton, and Wikipedia says it's an iron nucleus",
", so that would be a bit fast."
] | [
"If you were traveling as fast as that particle you'd see yourself reach ",
"Andromeda galaxy in 3.5 minutes",
".",
"Actually you'd hit a hydrogen atom and die. No one is sure how even something as small as an atom could avoid slowing down due to collisions with photons over intergalactic distances. The best ... | [
"Time passes more slowly in a moving reference frame. So in the reference frame of the OMG particle, only 3.5 minutes have passed. In our (Earth) reference frame, the OMG particle still takes close to 2.5 million years."
] |
[
"How did Mars become red?"
] | [
false
] | I know that the reason it appears red is a result of abundant iron oxides on its crust, but how did those oxides form? I do know a bit about chemistry and don't rust-red iron oxides require abundant oxygen to form. Otherwise, without exposure to oxygen, wouldn't the iron be more grey as it would be in a more reduced st... | [
"The current working hypothesis is:",
"Mars used to have water. Maybe a ",
" of water, like an ocean-worth.",
"Unlike on Earth, evaporation means clouds and water vapor can rise very high in the early Martian atmosphere, reaching heights where hard UV light is prominent. That light can split water vapor molec... | [
"Yes, exactly.",
"And for an added twist: we think something similar might have happened on Venus, too. It's tougher to see under the sulfur-yellow clouds, but the surface of Venus is also very oxidized, there's an even-more-crazy deuterium enrichment there, and there's rocks we think only form in the presence of... | [
"Also the earth's magnetic field helps protect the atmosphere from being eroded by solar wind, and Mars doesn't have one.",
"So this whole \"magnetospheres shield atmospheres\" idea is popular in layman literature, but really doesn't hold up to scientific scrutiny. ",
"After all, consider that Venus has no intr... |
[
"How to calculate position of an object moving under gravity towards another bigger fixed object, taking into account the change in gravity as it gets closer."
] | [
false
] | suppose a small body is placed at a distance from a bigger object. How can I calculate the position of the small object after,say 2 seconds assuming the big object is big enough to pull the small body towards it. I know the equation s= ut+.5at but here 'a', accelaration is not a constant as the gravity increases as the... | [
"Yes, but you need to do some calculus to get there. Use the expression F = -GmM/r",
" for the force on your falling object, which gives you a = -GM/r",
" for its acceleration (F is force, G is the gravitational constant, m is mass of falling object, M is mass of massive object that it is falling towards, r is ... | [
"This is a perfect time to use energy instead of forces (we are, of course, assuming that there is no air resistance. Side note: we are also assuming that the large object is not moving at all, even though officially it is being pulled ever so slightly towards the small object, but whatever). However, you're going ... | [
"Potential energy is -GMm/r, not -GMm/r"
] |
[
"How does your \"state of mind\" affect the quality of your training?"
] | [
false
] | It seems to be popular to "multitask" during training - for example, watching TV while using an exercise bike. I wonder if this has any noticeable impact on the results of your training, compared to if you do the exact same exercise but put all your concentration on it. How could the brain affect your training? Well, i... | [
"One important concept here is Central Fatigue (or supraspinal fatigue). This states that exercise capacity is limited by the brain. In classic exercise physiology, we learn that as we become fatigued, glycogen stores in the muscle and liver and glucose concentration in the blood diminish, and lactate concentrati... | [
"I tend to think that all exercise behavior and physiology is governed centrally to a certain degree. Because much of this work comes from the sports science literature, the information we have is skewed toward exercise to the point of exhaustion. The ",
"Central Governor Theory",
" includes a theoretical fra... | [
"Muscle building certainly has a hormonal component which is controlled centrally, but you are describing an \"exercise pill\" which does not yet exist (but look at the ",
"irisn wiki",
", which does not build muscle, but might trigger some of the positive effects of exercise). To my knowledge, drugs such as a... |
[
"Does blue and yellow make green, or just confuse our eyes/brain into thinking it is a green wavelength?"
] | [
false
] | null | [
"We can experience many different combinations of wavelengths as the exact same color. See ",
"metamerism",
"."
] | [
"Right. My question is if you mix blue and yellow paint, is it reflecting some blue light frequencies (still) and some yellow light frequencies (still) (which our eyes interpret as \"green\"), or does the mixture itself cause the frequency of light reflected to be in the green frequency range."
] | [
"Paint mixing is ",
"subtractive",
". It is reflecting a narrower range of wavelengths. It is not the same as mixing two light sources. That is ",
"additive"
] |
[
"Why do the females of a species tend to live longer than the males?"
] | [
false
] | Specifically in mammals, but I'm also wondering if this is true in the other kingdoms of life. | [
"Here is quite a nice review detailing female longevity in animals"
] | [
"Any free articles on the subject?"
] | [
"Oh sorry, didn't realise it was behind a pay wall. How's this? ",
"http://www.filedropper.com/j1469-185x1989tb00635x"
] |
[
"Does a photon emitted by a black body have a pure quantum state, with Plank's law describing the distribution of the ensemble? Or do they have a mixed quantum state, in which Plank's law describes the superposition of an individual state?"
] | [
false
] | Of course, I may simply be mistaken in trying to describe a mixed state of non-quantized energy levels. The question may be clarified by considering the outcome of the following thought experiment: If I collect a single photon from the sun, clone it's quantum state (ignoring the no cloning theorem), and then measure th... | [
"You cannot consider a single photon from a blackbody spectrum. In general you cannot pick a photon from a state of the EM field. Blackbody radiation is a mixed state of the EM field.",
"I mean the sentence \"the state of a photon from blackbody radiation\" does not make sense.",
"You can perform measurements o... | [
"You can position photodetectors around your black body and measure various types of photon counting statistics. This would allow you to measure single photons. You can use Fabry-Perot Filters to detect photons of specific energies, et cetera. I agree that you cannot extract the full wave function of one of these p... | [
"Of course, whatever you do in quantum physics, you always measure observables, so I do not really see your point here. What would you in general consider a measurement of \"anything of the state of a given single photon.\"?",
"In fact a blackbody state isn't even a photon number eigenstate.",
"Your black body ... |
[
"Is it possible to know if a molecule is harmful or not by only looking at its structure?"
] | [
false
] | null | [
"We can mostly tell whether things are corrosive, flammable or explosive by looking at their structure. But telling whether or not they are poisonous or otherwise bad for our health is difficult.",
"There are definitely some things that will be an immediate sign that something is likely to be bad for our health s... | [
"Then you have the fun molecules where the one chirality is non harmful and the other chirality is. Such as that morning sickness medicine where one chirality was really good at preventing morning sickness, but we found out the hard way that the other chirality caused horrible bitrth defects."
] | [
"The second hard lesson of the thalidomide story was that a pure enantiomer racemized in the body..."
] |
[
"Why doesn't my stove fill my kitchen with CO and kill me?"
] | [
false
] | null | [
"Carbon monoxide results from the incomplete combustion of hydrocarbons. The fuel mixture in your oven and gas stovetop are sufficiently close to the stoichiometric point (even mixture) or lean (oxygen-rich) enough that this isn't a significant issue. If you notice that the flames are orange-red, that's an indica... | [
"Some numbers on the levels of CO emitted by kitchen ranges if you are curious. Most ranges are turned to produce safe levels of CO.",
"Carbon Monoxide Poisoning: Gas-fired Kitchen Ranges"
] | [
"If you leave it on without the burner being lit, it won't produce any CO at all. It could indeed kill you, however, by causing an explosion."
] |
[
"Inquiry on global warming and (pre)historic temps?"
] | [
false
] | [deleted] | [
"You are correct that there have been significant variations in global temperatures over the last 500,000 years, as shown in your graph. These variations are thought to result from ",
"Milankovitch Cycles",
", having periods from around 20,000 years to upwards of 100,000 years. I would say these are explainab... | [
"There have been observations where sometimes CO2 levels rise after other factors (Milankovitch forcing) have increased temperature. This lag reflects positive feedbacks, such as the ocean out-gassing CO2 as it warms. I am less familiar with CH4 records in the lead/lag context of temperature change. "
] | [
"That link was just the information I was looking for. Very appreciated. I was curious that maybe the 100,000 year cycle was decreasing temperature by negative feedback, though precession seems to be the real cause. Although, as a follow up, it seems global temperature has a strong correlation with CO2/methane leve... |
[
"Why can't the immune system prevent shingles outbreaks, since it already has antibodies for the virus?"
] | [
false
] | What I got from reading some articles online is that if you get chickenpox, the virus remains dormant even after you get better. Then sometimes it somehow wakes up, and you develop shingles. My probably stupid but unanswered question is: aren't you supposed to have developed antibodies for varicella zoster? Why does th... | [
"My professor explained it as a cellular vs humoral immunity question.",
"Antibodies do a great job of stopping spread in humors (blood, interstitial fluid, etc.) -- hence antibody immunity is called humoral immunity. But, Varicella Zoster Virus (VZV) survives in the nerve (dorsal root ganglia, to be specific), ... | [
"To add on this, VZV remains cell associated and is transmitted on cell-cell interaction, except for terminally differentiated epithelial cells in the lungs and the keratinocytes of skin lesions. The antibodies can limit its humoral spread but not the cell-cell interactions."
] | [
"I have a bit of a follow up question, since I've seen some commercials with Terry Bradshaw advertising a vaccine for singles how does that work? Is it separate from the chicken pox vaccine? Can someone who had chicken pox still get the shingles vaccine (and expect the efficacy to be reasonable)? "
] |
[
"What would happen if we trained just one side of our body?"
] | [
false
] | For example, lifting weights with just one hand all the time. Would one side of the body be extremely muscled, but the other one-very weak? Or would the effect kind of even out and we’d have an averagely trained body? | [
"You'd get something like this:",
"http://www.dailymail.co.uk/news/article-1220536/German-armwrestler-shows-single-Popeye-esque-limb.html"
] | [
"You grow both sides, but not nearly to the same level. You end up disproportionate; in some cases the counter muscles will not develop properly and the subject will end up with posture/flexibility issues. "
] | [
"Rafael Nadal/Furcal might be able to shed some light on this"
] |
[
"If one cask of wine, or other aged spirit were to be constantly agitated over the course of it's aging, how would it differ from a normally aged cask, if at all?"
] | [
false
] | Hopefully my wording isn't confusing. | [
"The reactions that occur while barrel ageing liquor are extremely slow - it takes on the order of 8 to 12 years to got 90-95% conversion of the cogeners. Agitating the cask would speed the process slightly, as it would constantly refresh the fluid near the barrel walls, but given that mass transfer is clearly not... | [
"Well there are lots of things in play here. If you're aging something that has been fermented but not distilled (cider, wine, and beer fall into this category), keeping the cask still during it's aging period will allow yeast and any other sediment to settle out of solution and end up clearer. So by agitating the ... | [
"Yes its the contact with the air itself. And yes, thats also why aeration is used to accelerate bacterial growth. Once again not a biochemist but that is how I understand it. "
] |
[
"Is there a material that will allow ultra-violet light pass but reflect infrared?"
] | [
false
] | null | [
"http://search.newport.com/i/1/nav/1/q1/Optical%2520Filters/q2/Bandpass%2520Filters/q3/266%2520nm/x1/section/x2/chapter/x3/facetValue05",
"In optics bandpass filters like that are fairly common. They are usually made by a combination of the material itself acting as a filter and a special film coating that acts ... | [
"Does the infrared reflect or does it get absorbed by the coating, I'm looking for something that reflects."
] | [
"Generally if its a coating its reflective but I am not sure for that specific optic."
] |
[
"Why are certain chromosomal translocations so common?"
] | [
false
] | There are many chromosomal translocations that commonly occur in humans. Some are completely benign -- inv(9)(p11q12) -- while others can cause cancer -- t(9;22)(q34.1;q11.2). Many of these cancer-causing translocations are so common, in fact, that there are specific genetic tests for identifying certain translocations... | [
"Most chromosomal anomalies are similar in how they arise. The reason some are more common is because they are not selected against as heavily as the others. Without specifically knowing much about these translocations, the most logical answer would appear (to me) to be that they don't kill that many of the affecte... | [
"Sort of like how lots of autosomal dominant diseases don't present until later in life, which is how they are able to be passed on to offspring before the parent is even aware of it.",
"I've got part of the answer now, but I still don't understand all of it. For example, most cancer-causing translocations aren't... | [
"There are definitely \"hot spots\" for chromosome breakage, for reasons we don't fully understand - probably to do with chromatin type and protein binding. 9;22 is also called BCR-abl. BCR stands for breakpoint cluster region."
] |
[
"Is electricity affected by gravity?"
] | [
false
] | null | [
"It is, in principle; electrons have mass and energy, and hence they are pulled by gravity.",
"In practice, the strength of gravity on an object with a mass of something like 10",
" kilograms is imperceptible, especially in comparison the relatively huge effects of electric fields on electrons. So in almost eve... | [
"Yes! It’s nearly imperceptible in local conditions, but at large scales it is quite apparent that electromagnetism is subject to the force of gravity. For the clearest visualization of this look at images of galaxies that are far away, and notice how they appear warped. This is called ",
"gravitational lensing",... | [
"In a real circuit, electrons would have to flow uphill and then downhill so the net gravitational effect on the flow of electrons would be zero. "
] |
[
"Is Evolution (by which I mean genetic mutation) Really Completely Random?"
] | [
false
] | EDIT: Yes, the title of this IS complete rubbish. Let's pretend it wasn't 3 AM when I wrote it, and see name as, "Is genetic mutation truly random in the context of evolution?" I'm just trying to get a better grasp on how genetic mutation plays into evolution. I've heard and read some conflicting things, and I want to ... | [
"I think it's necessary to make sure all of the words we're using here are clearly defined and being used scientifically!",
" means changes in the gene pool over time; it is a combination of random and non-random factors, it is NOT the same thing as genetic mutation, and I don't think it's what you're asking abou... | [
"They're not 'truly' random in the sense that mutation rates can differ with exposure to different carcinogens or even depending on where you are on the planet (one of the research topics of astrobiology). Moreover, there is evidence to suggest that mutation rates may even differ between areas of the genome. Last... | [
"Evolution is a long term \"optimization\" effect that you get by combining mutation and natural selection.",
"But isn't natural selection the result of genetic mutation?"
] |
[
"My grandpa died from multiple myeloma secondary to Agent Orange exposure in Vietnam. My grandma was diagnosed with Parkinsons a couple years after he died. I have a question...(x-post from AskReddit)"
] | [
false
] | [deleted] | [
"I am thinking along the lines of when people or things are exposed to high levels of radiation, they emit this radiation and can contaminate other people or things.",
"But they don't. Radiation exposure does not automatically make you radioactive - that can only happen if the individual carried some radioactive ... | [
"Well I fully admit right up front that I don't know a lot about this and hopefully someone else can provide more details, but until then I'll say this:",
"First of all Agent Orange isn't a radioactive substance and emits no radiation. It's a toxic chemical. If AO can cause Parkinson's (which I don't doubt), then... | [
"They have shown a link between Agent Orange and Parkinson's:\nFrom the ",
"VA",
": Veterans who develop Parkinson's disease and were exposed to Agent Orange or other herbicides during military service do not have to prove a connection between their disease and military service to be eligible to receive VA dis... |
[
"Why does my microwave interrupt my wireless internet?"
] | [
false
] | I ask this question for a couple of reasons. First, I assumed my Wireless-G/N home networking would run on a wavelength that wouldn't be on the same wavelength as a microwave and that my wireless network could identify data vs noise. Second, I assumed my microwave is shielded and not emitting radiation into my home. ... | [
"A few points need to be made:",
"Microwave ovens do not operate at exactly one frequency. They are designed (and required by the FCC) to operate ",
" 2.45 GHz, but the radiation created by the microwave oven typically involves frequencies spanning between 2.4 and 2.5 GHz. You have to realize that a microwave o... | [
"Some developers place devices in closed microwaves to simulate disconnection from Wi-Fi and see if their app responds correctly. This type of signal-blocking is called a Faraday Cage.",
"Just to clarify, in case someone were to try it at home: They place the devices in the closed microwave oven ",
"."
] | [
"Additional fun facts that are slightly less relevant, but still related:",
"Some developers place devices in closed microwaves to simulate disconnection from Wi-Fi and see if their app responds correctly. This type of signal-blocking is called a Faraday Cage.",
"Wi-Fi routers and many other wireless devices op... |
[
"Why can I start/stop torrents and still have them complete, but can't do it with other downloads off the internet?"
] | [
false
] | null | [
"You can do it with HTTP downloads, as long as server supports it and you have downloader that makes use of that support. Years back, I used a download manager that run multiple downloads of same file, because the server limited maximum upload for a connection, so multiple connections cheated this limitation. This ... | [
"You can resume normal http downloads,",
"$ wget http://releases.ubuntu.com/16.04.3/ubuntu-16.04.3-desktop-amd64.iso\n(...)\n(abort)\n(...)\n$ wget -c http://releases.ubuntu.com/16.04.3/ubuntu-16.04.3-desktop-amd64.iso\n(...)\nHTTP request sent, awaiting response... 206 Partial Content\nLength: 1587609600 (1.5G),... | [
"I think there are no options because most downloads take a few seconds if not a minute. Not many people are downloading full gig movies off of a browser or something.",
"HTTP supports range requests if wanted. The client can ask for a range of bytes to be transmitted, so it can in fact download a file in many pi... |
[
"How do asymptomatic people (who don’t cough) transmit COVID-19?"
] | [
false
] | null | [
"You're still producing new virions if you are asymptomatic. Most likely happening in your mouth/throat. If an asymptomatic person touches their mouth and then any other surface, it is contaminated for several days. Also, most people clear their throat on a daily basis or has a one off cough every now and then, tha... | [
"The science looks to be inconclusive but you can read up on it here: ",
"https://www.wired.com/story/how-long-does-the-coronavirus-last-on-surfaces/",
"It looks like several days does seem possible.\nFor transmission I assume talking face to face is also a factor as everyone emits particles while speaking."
] | [
"I wouldn't say that it is fear mongering. Asymptomatic people do seem to be able to spread COVID-19. That's probably the second biggest reason why we have gaps in knowing how some people got infected without contact with another known infection. The biggest reason being the lack of testing in the US."
] |
[
"AskScience: What is the most useful thing we now have because of Optical Fibres?"
] | [
false
] | Apart from telecommunications, what do you think are the greatest things we can now accomplish because of optical fibres? I'm having a bet with someone who doesn't think they've done us any good. I have no idea where to start but I'm sure he's wrong given how fast they can transmit data. | [
"Finally! An AskScience question that is right up my street.",
"Optical fibres are used in literally hundreds of different applications. These fall into roughly 2 broad categories, as described below.",
"(1) The first category is the most obvious, that is applications where the fibre is simply used to transmit ... | [
"Why apart from telecommunications? That's like apart from automobiles, what's the wheel ever done for us."
] | [
"Endoscopes. You know those little tube-like things they use in surgery, to be able to see things inside the human body? Those use fibre optics.",
"I remember they could also be used for lasers, but I can't remember in which regard."
] |
[
"Do countries with higher rates of infant mortality have correspondingly higher rates of depression?"
] | [
false
] | null | [
"As far as I'm aware, no work has ever been done to find such a correlation. It would be prohibitively difficult to find one, both because such countries tend to have many confounding factors that would lead to depression, and because such countries would tend to have poor mental health infrastructure. The result o... | [
"The hypothesis I would want to see tested is exactly the other way around than the OP's proposal. Early death and frequent death is and has been the normal condition of humanity. ",
" in developed countries are the anomaly, our expectation that people should survive until they die of old age is thoroughly modern... | [
"Generally speaking I believe countries with circumstances that significantly lowers life expectancy (e.g. war) are generally less burdened by such things on an emotional level as far as grief goes due to a certain level of learned stoicism. People simply get accustomed to death.",
"Obviously war in particular wi... |
[
"A closed volume is filled with 50% water, the rest is air. What does the pressure curve inside the volume look like when it's heated up to, say, 2000K?"
] | [
false
] | The volume remains constant, the vessel is not affected by the temperature increase. I thought I'd read up on phase diagrams, but as usual, the on phase diagrams can only be understood by people who could have written it themselves. | [
"Do correct me if I am wrong, but wouldn't we need a starting temperature to be able to describe the curve?"
] | [
"Just pick any reasonable temperature. Let's go with 274K."
] | [
"Expansion of the liquid would dominate 0",
" - ~60",
" , which would be a slow linear increase. Then there would be a steep hyperbolic incline from about 60",
" until 100",
" C (possibly long depending on the rate of increase) where you have liquid turning into gas, increasing in rate of rising because the... |
[
"How do interlocking basalt columns, such as those seen in \"The Giant's Causeway\" in Northern Ireland, form?"
] | [
false
] | [deleted] | [
"First, you need to form an even layer of hot molten rock. The two best ways of doing that are either a lava flow, or a sill (a sill being an intrusion of magma along a bedding plane between sedimentary rock layers).",
"That then gives you a hot flat plate of rock, which begins to cool.",
"Any cooling liquid, g... | [
"The reason that the columns form is quite simple. As the basalt cools from its lava state into rock, it begins to contract (liquid to solid, particles become closer together). As it contracts, cracks form in the rock in multiple areas on the surface that propagate downwards. These cracks occasionally connect to on... | [
"Sandypeat in that thread provides the following explanation:\n\"Geologist here: The columns form when lava comes into contact with something very cod ie water/ice. The hexagonal pattern forms because the pattern is the most efficient way to cool the rock. Now ya know.\""
] |
[
"Is boredom harmful for the mind?"
] | [
false
] | I've tried searching online for answer to this question and come up with a bunch of conflicting reports (mostly by news sites which I don't really trust for scientific questions). Is the habitual boredom many of us experience from a 9-5 job harmful physically or mentally? Of course, most people also (hopefully) experie... | [
"Boredom can be good or bad, depending on the individual. It turns out that there is constructive boredom (the kind you experienced as a little kid during summer breaks that led you to go outside and poke the mud with a stick), and there is destructive boredom, the kind that is so crippling that the individual beco... | [
"and there is destructive boredom",
"Like when you're forced to do nothing and have no option to go outside or be free in any way."
] | [
"Just throwing this out there: the ",
"wiki article on boredom",
" has some information.",
"[R]esearch on boredom suggests that boredom is a major factor impacting diverse areas of a person's life. People ranked low on a boredom-proneness scale were found to have better performance in a wide variety of aspect... |
[
"Is my assumption about gravity, antipodes, and spatial orientation correct?"
] | [
false
] | Gravity boggles my mind and confuses the hell out of me no matter how much I read about it. So here's my question: A person is standing in Argentina, and another person is standing at the first person's antipodal point in China. Even though Earth is round, both people are standing upright with the help of gravity, and ... | [
"Basically, yes. \"Down\" points toward the center of the Earth, wherever you happen to be. That's how \"down\" is defined for us."
] | [
"For you, a present: ρ."
] | [
"It's not zero orientation at all. It's a very rigidly defined orientation. \"Down\" means \"toward the center of the Earth\" to anyone who's on or very near the Earth's surface. That's how that direction is defined.",
"Maybe what's troubling you is the fact that you can't define orientation in space without maki... |
[
"What happens to the tooth socket after we lose a permanent tooth?"
] | [
false
] | Does the socket smooth over with new bone tissue, or does it get filled with gum tissue? Or is it a combination of both? To what extent? | [
"After tooth extraction, first the socket is filled with blood that coagulates. The socket will then fill in with bone over the course of ~8 weeks. However, the bone in the area where the tooth was will slowly undergo resorption both horizontally and vertically over many years, complicating the restoration of the... | [
"This. I wish I knew this would happen. After 10 years of waiting I no longer have enough bone material for an implant and bone grafting is out of the picture. Can only get a bridge. People. Do not wait to get dental implants! "
] | [
"This. I wish I knew this would happen. After 10 years of waiting I no longer have enough bone material for an implant and bone grafting is out of the picture. Can only get a bridge. People. Do not wait to get dental implants! "
] |
[
"If I can't hear anything above 20khz, if a super loud sound occurred at above 20khz would it eventually damage my hearing?"
] | [
false
] | Basically if I slept next to a bat that was chirping in my ear all night, would that damage my hearing in some way. I'm a little fuzzy on the actual mechanics of hearing damage, like how the hairs in the cochlea get damaged and why the higher frequency ones get damaged first. Could I listen to a super loud 17khz tone (... | [
"Well you are talking about mechanical damage vs. sensory damage. If you can't hear a frequency, you aren't going to receive any 'sensory' damage (damage to the hair cells, the type of hearing that gets worse over time) because you have no receptors for that particular frequency. If the intensity is high enough to ... | [
"The distinction between sensory and mechanical damage is a bit misleading, since damage to hair cell cilia is mechanical in nature (the cilia are snapped due to the force of the cochlear traveling wave) as well. Most literature I've read on the matter typically differentiates between mechanical and neurological da... | [
"The way I remember it is as de-",
"-ly, \"I agree without limit\". As a scientist, I'm sure you know how to spell finite :)"
] |
[
"I don't understand \"moles\" as in chemistry or physics(?) at all. Is it just an arbitrary number?"
] | [
false
] | Thank you everyone for all the responses!!! | [
"Yes, Avogadro's number (approx 6.02 x 10",
" is just a number. You can think of it like a dozen - you can have one molecule, two molecules, a dozen molecules, or a mole of molecules. The number was defined so that the mass of the molecule in amu (atomic mass units) is equal to the mass of a mole of those molecul... | [
"High school AP chem student here. This is how i always explain it to my friends in regular chem. (yes, 6 months into the schoolyear and they're just now learning moles.)",
"Avogadro's number is the conversion factor between atomic mass units and grams. So Avogadro's number of AMU is equal to one gram. This is co... | [
"Not all constants are numbers. ",
"The speed of light c is not a number, but has units m/s. g is an acceleration m/s",
" and the planck constant h has units Js. "
] |
[
"Today we can use lasers to measure distance of things, so can we point a huge laser to distant object to measure the distance?"
] | [
false
] | null | [
"This is regularly done with ",
"the Moon",
" but required the installation of reflectors on the surface so that we can observe the laser beam being bounced back. Without that, the laser scatters so we can't observe anything and can't use it to measure the distance to objects very easily.",
"Radar ranging",
... | [
"The echo strength is proportional to (1/distance)4 (two applications of the inverse-square law, there and back)",
"Why wouldn't it be (1/(2×distance))",
"?"
] | [
"No, each application is a proportionality. On your way out the intensity drops as (1/distance)",
" which I think is the easy part to understand. On the way back though, you have the reflection of the source and the intensity of that reflection will drop as (1/distance)",
" as well. That means that I_1 = I_0 / ... |
[
"What do our sensory nerve impulses actually look like?"
] | [
false
] | Ok, I actually have a few questions regarding the nervous system. 1.) Are the signals in a "digital" 1 0 format or are they more analog, like a sinusoid? 2.) How does, for example, the eye, determine what signal to output based on what it sees? So if we hook up a very sensitive voltmeter/ammeter, what image would corre... | [
"I can answer your first question. For an individual neuron, creation of an action potential is an \"all or nothing\" event (1 or 0). As long as a stimulus exceeds a certain threshold, the signal is sent. A stronger stimulus creates more frequent action potentials, but the action potentials themselves are identical... | [
"It's even more complicated than that. Some neurons don't use action potentials at all, but instead communicate via graded (analog) potentials. An example that is relevant to the OP's question are the photoreceptors in the retina. These do not produce action potentials, but rather constantly drool neurotransmitter.... | [
"Oh yes, how could i forget! Then there are ",
"gap junctions",
" too. So maybe the 'all-or-none' action potential covers more like 70%..."
] |
[
"Health differences between animal protein and plant protein?"
] | [
false
] | As I look around the health food section I can see that all of the protein bars and powders use a mixture of plant protein as well as whey and casein protein. Is there any nutritional difference between the protein that comes from plant matter and the protein that comes from animals? Would I be better served eating ste... | [
"Animal protein is a complete protein. It contains all nine essential amino acids that our bodies need. Vegetable proteins do not generally contain all nine amino acids. However, by combining foods you can make a complete protein. Rice and beans are an example."
] | [
"This is not true, but is a very common misconception. Vegetable proteins contain all amino acids.",
"http://en.wikipedia.org/wiki/Protein_combining"
] | [
"I'd suggest you read the referenced paper, it doesn't support the conclusion provided by that quote. The paper explicitly lays out that each of the foods contain all of the amino acids, some of them are just lower.",
"You need to eat more mass of vegetables to get the same protein as from meat, but all the amino... |
[
"What roles do wasps/hornets/killer bees play in the ecosystem?"
] | [
false
] | null | [
"Taken from ",
"Wikipedia.",
"Role in ecosystem",
"Pollination",
"While the vast majority of wasps play no role in pollination, a few species can effectively transport pollen and therefore contribute for the pollination of several plant species, being potential or even efficient pollinators;[4] in a few cas... | [
"\"Killer bees\" or africanized honeybees, play essentially the same role as other honeybees - pollination specialists. The main difference (at least in terms of why people fear killer bees) between killer bees and the generally more desirable varieties of honeybees is that European honeybees have largely been sele... | [
"On wasps, they do a tidy job of keeping caterpillars in check. They use them as food for their young. A wasp nest near your garden is a good thing, as long as its out of the way of being disturbed. Mud dauber wasps prey on spiders. ",
"http://fourstringfarm.me/tag/wasps-killing-caterpillars/"
] |
[
"How can a 3D printer render movable parts? I am having a \"sun revolves around the earth moment\""
] | [
false
] | [deleted] | [
"I'm pretty sure there is some funny business going on there with the wrench. They appear to have just scanned it with a light-based 3D scanner and somehow ended up with all the internal workings of it. I'm guessing they skipped the less sexy step of manually editing the computer model to add internal and back-faci... | [
"Hey doipeste, \nI am a lab tech at Uni and my main job is to maintain and operate the two 3D printers we have in the lab. What are you having trouble grasping?"
] | [
"The machines I work with are called PolyJet printers. There is no laser. It has a head with long row of very small jets that dispense liquid plastic on the print tray as the head moves past. There are two heads (more on fancier machines) one for build material, this is what makes the part, and one for support mate... |
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