title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Gravity and jerk"
] | [
false
] | Suppose I hold a ball above the ground. When I'm holding it, it has an acceleration of zero. When I let it go, how much jerk does the ball experience? I imagine it depends greatly on the air, and the way I drop it. Surely it doesn't instantaneously experience 1g of acceleration? | [
"'Jerk' is the fairly standard term for the time derivative of acceleration."
] | [
"There will be a short period of time when the ball is scraping along your fingers, because they are still touching the ball, but not applying enough pressure to hold it in place. This time is tiny, so the jerk on the ball is enormous."
] | [
"This is correct. There is no infinite jerk. Just really high."
] |
[
"With all the recent posts about atmospheric pollution clearance secondary to wide spread quarantining, is this having any effect on climate changes and temperatures? Or is it too small a time frame to see any real changes?"
] | [
false
] | null | [
" The current, temporary reduction in emissions (even if sustained for many more months beyond the present length) will basically do nothing and this would only have some longer lasting influence if it led to a real, and sustained change in behavior/emissions post COVID-19 (but even then, it would take decades to c... | [
"Note that \"pollution\" usually refers to emissions that have adverse health effects to humans and other organisms. Carbon dioxide, the main driver of the climate change, is pretty much neutral at atmospheric concentration. It also disperses quickly to be in a roughly homogenous concentration globally. The usual \... | [
"Thanks for having a short and a long answer"
] |
[
"Is what we call \"the observable universe\" the same as a Hubble volume?"
] | [
false
] | As I understand it, since the expansion of the universe is accelerating, there is a point at which objects in space begin to travel away from us faster than the speed of light, thus making the light that those objects emit impossible for us to see since it can never reach us. A Hubble volume is everything we can see in... | [
"The Hubble volume is the region in which objects are receeding from us at a rate less than the speed of light.",
"Objects outside of the Hubble volume are receeding faster than the speed of light, but we can still observe them. The photons from those objects leave and travel to us - they don't care how fast the ... | [
"Could it be that entropy is somehow decreasing and time is somehow reversing direction beyond the hubble volume?",
"It seems strange to say that the universe could be expanding faster than the speed of light. ",
"Are the implications any different if we say that the rate of time (rate of entropy increase) is a... | [
"Could it be that entropy is somehow decreasing and time is somehow reversing direction beyond the hubble volume?",
"No.",
"It seems strange to say that the universe could be expanding faster than the speed of light. ",
"Information is not being transmitted faster than the speed of light, so the laws of physi... |
[
"What could future earth look like?"
] | [
false
] | null | [
"Such hypothetical / speculative / open-ended questions are better suited for our sister-sub ",
"/r/asksciencediscussion",
". Please post there instead."
] | [
"Thank you. I'll be sure to do that. Should I delete this post?"
] | [
"Already removed."
] |
[
"Which car will win when 2 cars with same engine and configuration but in different gear collide?"
] | [
false
] | [deleted] | [
"Whichever car starts in the lower gear will have more speed. Whichever is in a lower gear when they collide will have more power, because it will not be able to shift up as quickly. I'd say the car that starts in first will be in a higher gear when they collide, but will have more speed. Unless the car that sta... | [
"If they are at the same rpm but different gears, the higher gear will be going faster, therefore more momentum."
] | [
"Thanks for the reply. Although I wasn't clear enough, I meant two cars remain in same gear and same throttle/engine power. As they are consuming same energy they should be equals when they collide. And nothing out of two can win. But that doesn't feel right."
] |
[
"Can the Earth ever become tidally locked to the Sun so one side is always facing inwards (like the Moon)?"
] | [
false
] | The titles pretty much explains it all. I understand how the moon is locked to the Earth but wondering if this could ever happen on a scale as large as the Earth/Sun. Bonus question: What would happen to the moon if the Earth was locked to the sun? | [
"The earth used to spin much faster millions of years ago and has been gradually losing rotational energy. Not sure of the exact details but it is caused by the interaction between the moon and the earth through ocean tides. A torque is set up which accelerates the moon and decelerates the earth. Here's the ",
"w... | [
"Anyway the earth will eventually be tidally locked to the moon so that 1 day = 1 month.",
"1 earth day = 1 lunar month?",
"Oh, and fun fact:"
] | [
"Oh wow imagine that humidity."
] |
[
"Are there any examples of cross species breeding in the wild?"
] | [
false
] | null | [
"Grizzly-polar bear hybrids have ",
"been confirmed in the wild",
"."
] | [
"Coyotes and wolfs form ",
"coywolf"
] | [
"They are different species. Ursus maritimus and Ursus arctos horribilis (Ursus being the genus).",
"Maybe you're thinking of grizzlies, kodiaks and alaskan brown bears which are all subspecies of brown bear."
] |
[
"Does a graviton \"shadow\" exist?"
] | [
false
] | For instance, if the Moon is "hidden" behind the Earth from the Sun, should there exist a graviton shadow? Does the Earth intercept gravitons that would have otherwise interacted with the Moon (which would, I presume, have at least some effect on the moon's orbit)? If this does in fact occur, are there laws that bala... | [
"Well, we haven't discovered gravitons (yet?). We also don't have a quantum theory of gravity.",
"If you're asking whether the gravitational pull on the moon from the sun becomes weaker when the Earth goes between them, the answer would be no. Such a thing would have an observable effect on the orbit of the moo... | [
"Well, not really. If there were an analogous force-carrier particle for gravity, the normal gravitational attraction between objects would be mediated by virtual gravitons. Real gravitons would pop up when you're discussing stuff like gravitational waves, disturbances in the gravitational field. This is analogo... | [
"I guess this is equivalent to say that gravitons are not absorbed by matter (while photons are). Is this correct?"
] |
[
"Is a circle with a radius of zero still a circle?"
] | [
false
] | The question on a chem report: when graphing the relationship between diameter and circumference of a circle, does the y-axis pass through (0,0)? On one hand, yes, because when r = zero then the circumference is also zero. But that got me thinking... is a circle with a radius of zero still even a circle? Is this just a... | [
"It is a point. The question is whether a single point still counts as a circle.",
"One way to state the definition of a circle is that it's the set of all points that are a distance ",
" from a given center point. If you set r=0, then your circle is the set of all points that are 0 distance from the center. Th... | [
"It's just a point then"
] | [
"I'm in higher mathematics and I consider it a circle. It's just an unsatisfying circle."
] |
[
"AskScience: What are the best science documentaries?"
] | [
false
] | null | [
"For biology and nature, you cannot beat the David Attenborough series.",
"I recommend Blue Planet, Planet Earth, and his \"Life\" series:\n- Life on Earth\n- The Living Planet\n- The Trials of Life\n- Life in the Freezer\n- The Private Life of Plants\n- The Life of Birds\n- The Life of Mammals\n- Life in the Und... | [
"Outdated, sure, but I watched it for an appreciation of the mentality involved. To watch someone so brilliant talk about something so passionately can teach you plenty, and I doubt that will ever be outdated."
] | [
"I like the Horizon series from the BBC, it covers a lot of specific subjects from different disciplines of science and is very well produced."
] |
[
"Are there any other species of ape that could learn to talk?"
] | [
false
] | I know that some gorillas have been taught limited sign language. Are there any specific reasons why they wouldn't be able to actually talk (brain development, vocal cords, tongue etc)? Also, are there any other apes that might be able to communicate with us? | [
"While the animals can learn to USE the sign language most of them cannot really understand it. There is a lot of debate on this matter. Some say it is as simple as association like your dog shaking hands for treats. While others (usually the trainers) believe that the animals are very funny and interesting to talk... | [
"Besides differences in their respective vocal (and manual) apparatus(es), there are cognitive differences between humans and other primates that prevent the latter from learning language like ours. What exactly this is is a matter of great debate. A popular answer (the mainstream one, I'd say), espoused ",
"here... | [
"so they physically cannot speak? "
] |
[
"Is there such a thing as true randomness?"
] | [
false
] | Is entropy random? | [
"So if the smallest unit is random is everything that occurs random?"
] | [
"Quantum processes are inherently random."
] | [
"To my understanding, yes. Radioactive decay, for example. ",
"In resistors, heat produces a very small amount of voltage. This fluctuates extremely randomly. Fed into an opamp it can provide entropy for encryption. "
] |
[
"What did the SapceX Falcon 9 rocket launch look the way it did?"
] | [
false
] | Why did it look like some type of cloud, is that just vapor trails or something else? (I also don’t really know what flair I should add so I just put the one that makes the most sense) | [
"A lot of folks noticed that the plume looked a lot like a contrail at first, then ballooned outwards later.",
"As the rocket reached higher and higher altitude, there's less ambient air pressure to push against the rocket exhaust coming out of the engine, so the plume is able to expand much farther - this is wha... | [
"You saw liftoff, stage one separation, stage two light off and leave great plume, sunlight reflection and then the fairing separation which many camera persons captured greatly trailing the stage two separation. Great view of Sunlight plume. Probably the best view people has ever seen of a rocket launch. You only ... | [
"No. Rocket launch times are driven by what orbit the payload is going to. This was a set of communication satellites going to ",
" low earth orbit (Thanks, ",
"u/kendrome",
" !) and the launch window for it just so happened to be right.",
"While you could theoretically move a launch time wherever you like,... |
[
"How do the cells of complex organisms know which direction to grow in so that they get the desired shape on a macro level?"
] | [
false
] | I was thinking about this while looking at a plant. I was wondering from where in the plant do the cells multiply to make it grow. But more interestingly, how do they know to multiply in a line stretching upwards and outwards along the stem rather than into a random blob of cells. Then I started wondering the same abou... | [
"As the other commenter said, there's an entire field devoted to answering questions like this, and there's ",
" that we still don't understand, but it's still possible to make some general statements.",
"So first of all - and sorry if this is review for you - every somatic cell (as opposed to gametes, i.e. rep... | [
"Answering this question is an entire field of science:",
" developmental biology.",
" A full explanation would fill an entire textbook, but if you're curious you can start reading one. I recommend ",
"this one",
" (also available on Libgen)."
] | [
"Let's put that in context now: You can actually take pretty much any plant material and, by exposing it to two types of plant hormones called auxin and cytokinin, turn it into a \"blob of cells\" called callus. (Unlike animal cells, plant cells can go \"backwards\" in development, essentially becoming less special... |
[
"Do antibodies get used up when preventing an infection?"
] | [
false
] | Suppose I have COVID-19 neutralizing antibodies from a vaccine. I get exposed to SARS-CoV-2, but neutralizing antibodies prevent the virus from reaching my cells. Does that lower my antibody levels, leaving me more vulnerable on next exposure? Would antibody levels drop for other reasons than this? Can the distinction ... | [
"Yes, antibodies get used up while preventing an infection. ",
"Antibodies also get used up when ",
" preventing an infection, and the difference in rates is pretty small. ",
"Antibodies normally only have a half-life of 2-3 weeks. The reason antibodies seem to remain roughly constant is that they’re being co... | [
"It’s normal, it’s ",
", for B cells to reduce in number after an antigen is no longer present. You’re exposed to literally millions of antigens throughout your life; if your B cells never reset their number after responding, you’d just be a thick gelatinous ooze of B cells by the time you were 20. ",
"The whol... | [
"I think there's some confusion here about antibodies. Antibodies are proteins that have a shelf life, just like any other circulating protein in your body. All proteins get degraded by proteasomes at some point. What's important is your cell-mediated immunity and your memory cells. These are the factories that pro... |
[
"How do we know a T-Rex sight was based on movement?"
] | [
false
] | A very specific thing to know about a species that's been dead for millions of years. | [
"Super late, but it is extremely unlikely that T-rex's visual acuity was based on movement. That was complete fiction from Crighton (I still love his book, though). If it were reality, the Tyrannosaurus would not have been near the predator it is reputed to be. ",
"In reality, the Tyrannosaurus Rex probably had ... | [
"Crighton didn't completely pull it out of his ass. There was a study done at the time which compared the brain of a T-Rex (made from a plaster cast of the inside of a T-Tex skull) to the brain of a frog, and found similarities in the visual cortex which they interpreted to mean that the T-Rex could only track mov... | [
"It is not actually. The myth was first made in Micharl Crichton's Jurassic Park. And made known in the film adaptation. An apex predator having a massive visual flaw like that would likely result in the extinction of said species."
] |
[
"How does the body obtain Vitamin D from Sunlight?"
] | [
false
] | null | [
"Vitamin D3 (cholecalciferol) is produced in the skin in a ",
"photochemical reaction",
" driven by UV light. Photons in this range add to and break the C9-C10 bond in the B ring of 7-dehydrocholesterol, shaded in pink in ",
"this figure",
".* ",
"Two additional hydroxylation steps then occur",
": C25 i... | [
"This is true. Mushrooms are rich in ergosterol, which can be converted to ergocalciferols (pro-vitamin D2) by UV B light. Upon consumption, these are similarly dihydroxylated to yield the active hormone (1,25-dihydroxycholecalciferol)."
] | [
"Thank you so much! Then I’ll keep sunbathing my mushrooms!"
] |
[
"Do plant enzymes play any role/benefit for the human body? Or, because plant-enzymes are created by the plants for their own metabolic processes, their role in human digestion is nil?"
] | [
false
] | Do plant enzymes aid human digestion, or help us absorb more nutrients aside from the role of the enzymes our body currently produces? EDIT: I did find by Stephen Barrett from . Here are some of his key points: | [
"You're asking if when we eat plants, the enzymes in the plant cells help us absorb more nutrients? ",
"No, the enzymes are all denatured and digested in the harsh environment of the stomach, anyway."
] | [
"Enzymes are proteins that speed up a reaction. When you eat a plant and it reaches your stomach gastric juices chop up the enzymes or proteins into bits called amino acids which are the building blocks of all proteins. Your body can use these to make its own proteins that it needs. This is especially important for... | [
"TL;DR Plant enzymes are not significant in normal, healthy digestive tracts. Some enzymes, however, such as papain and bromelain may aid in digestion with individuals who have abnormal digestive tract issues. Abnormal digestive tract issues can arise from taking antibiotics, proton-pump inhibitors, or other anta... |
[
"How are astronomers able to determine the spin of a black hole?"
] | [
false
] | I saw a post about a black hole 300 million l/y away spinning at 50% the speed of light, but how are they able to determine that? As far as I know we are barely able to see Sagittarius A*. Edit: Veritasium actually recently, check it out, it's a really nice video. | [
"First ask yourself this: How does something with no surface spin with an angular velocity measured in units of linear velocity?",
"When you realize the answer, you will understand where that number came from: <spoiler>bad reporting</spoiler>.",
"OK, but seriously, it's actually the estimated velocity of materi... | [
"That was very jargony, and I love it. But for the breakdown for non-astrophysics types: you can use the laws of motion (particularly angular momentum and the law of conservation thereof) to determine the speed of the disk of stuff the black hole is feeding on and reverse engineer the math to give you the rotation ... | [
"Also note: we can’t see Sag A* because of all the crap in the way (molecular clouds and silicate dust and such). But we can figure out its rotation speed but knowing the orbital velocities of the stars and such going around it and the mass within its gravitational influence "
] |
[
"Why wasn't ocean acidification a problem millions of years ago when the dinosaurs were experiencing extremely high levels of CO2?"
] | [
false
] | My friend and I were talking about the effects of CO2 and he brought up a good point that CO2 has been really high in the past, but the ecosystems didn't collapse like we think they might from the recent spike in climate change. He is pretty anti-climate change, and I usually lean toward the side of most scientists. I ... | [
"High atmospheric concentrations of CO2 that rise rapidly (like they are now) have most definitely been a problem for oceanic organisms in the geologic past. Specifically, ocean acidification caused by this phenomena is considered a contributing cause in the Permian-Triassic, the largest extinction event in Earth h... | [
"Records of past climate change are very useful for understanding how the climate system works (and interactions with the biosphere). However, caution is needed when using past climates as analogues for today and this question highlights why. To cut a long story short, ocean chemistry was very different during the ... | [
"Also particularly relevant for today is the Paleocene-Eocene Thermal Maximum. Just as mammals were gaining a strong foothold 55 million years ago, the planet saw a very sudden, very strong atmospheric carbon spike in less than 10k years, quickly followed by a +7 degree temperature excursion. (Coincidentally, that'... |
[
"If Energy cannot be created, and the Universe IS expanding, will the energy eventually become so dispersed enough that it is essentially useless?"
] | [
false
] | I've read about conservation of energy, and the laws of thermodynamics, and it raises the question for me that if the universe really is expanding and energy cannot be created, will the energy eventually be dispersed enough to be useless? | [
"Probably. In an infinitely expanding universe (which we think we have), you will eventually reach a point of maximum entropy where the energy is evenly distributed, and essentially nothing happens. This is called the \"heat death\" of the universe, and would occur in more than 10",
" (10 to the power of 100, for... | [
"I'm glad you pointed out that this assumes our current physical models are in fact perfectly correct. As a layman, who is simply interested in this, there would appear to be a lot of unknowns predicting this far out, so we really don't know. "
] | [
"My physics professor said that most laypeople see the field as unknowable predictions of irrelevant things to an unmeasurable degree of certainty. ",
"Of course, it isn't true. Predicting the heat death of the Universe is merely an interesting extrapolation of current models being tested. Theoretical physics wi... |
[
"Why isn't spiciness a basic taste?"
] | [
false
] | Per this and the guy explaining about wine and food pairing, spiciness is apparently not a basic taste but something called "umami" is. How did these come about? | [
"It qualifies as a sensation",
". As for why it's not a basic taste -- I don't know. That's not my department."
] | [
"Are you saying that the criteria for being a \"taste\" is that it activates taste receptors alone",
"No, that's not what I'm saying. Many \"tastes\" are not basic tastes, rather, they are additional stimuli (smell, pain receptors, carbonic acid, etc...) that change the ",
" of the basic tastes. They alter, on ... | [
"Warning: Threadjack ",
"How on earth isn't fat a basic taste? I can clearly taste the difference"
] |
[
"We know its possible for pets to become bored, but what about depressed?"
] | [
false
] | [deleted] | [
"Can you take her to the vet to see if she just does not feel good?"
] | [
"She's become sedentary, doesn't listen, and often hangs out under tables and away from people.",
"Take her to the vet, those might be signs that she is in pain or has some sort of medical problem."
] | [
"Hm. I would hope she hasn't been hurt. She isn't limping or showing any physical characteristics of pain, but I'll take her anyways. Thank you!"
] |
[
"Why are you not allowed to cross your legs when getting your blood pressure taken?"
] | [
false
] | How does it skew the reading and why? | [
"The mechanical compression from crossing your legs moves the blood from your leg veins toward your chest. This provides more blood to be pumped from your heart, resulting in an elevated blood pressure reading.",
"For the physiology-inclined –",
"The pooling of the blood towards the chest results in an increase... | [
"So hypothetically, if someone is losing blood pressure rapidly you could save their lives by crossing their legs?"
] | [
"Crossing legs theoretically would increase venous return to the heart, providing more blood to critical organs in the chest and head. But there are so many variables needing to be considered and addressed as to why blood pressure is falling rapidly - trauma? medication-induced? etc. As to whether this could hypoth... |
[
"How does a nuclear reactor increase power output without crossing into prompt criticality?"
] | [
false
] | I think my question stems from a misunderstanding of the balancing act nuclear reactors play. My understanding is that prompt neutrons comprise of almost all neutrons produced in a reactor (>99%), while delayed neutrons provide the rest (<1%). Due to how quickly prompt neutrons are created (on the order of a few nano s... | [
"Between subcriticality and prompt criticality, there's another option called ",
", where the prompt neutrons alone are not enough to sustain the chain reaction, but the combined prompt and delayed neutrons are.",
"Since the delayed neutrons are emitted over a much longer timescale than the prompt neutrons, the... | [
"The margin between overall criticality (Keff for all neutrons = 1) and prompt criticality (Keff for only prompt neutrons = 1) is small from a overall sense, but in the margins that nuclear reactors operate on that difference is relatively large compared to the magnitude of adjustments made by other reactor control... | [
"This is the bit I'm confused with. Reading your paragraph, it sounds like the criticality itself (the balancing point between an exponential increase or decrease in power) can be increased? I don't understand how, with a set arrangement of fuel rods, there can be an adjustable criticality. To my knowledge, no fuel... |
[
"How does 911 call your local police station?"
] | [
false
] | Since all police stations in the U.S.A. have the same number, how does it always direct you to your local station? | [
"911 calls on your PSTN provider are routed to a \"public safety answering point\", a call center responsible for routing calls to police, firefighting, ambulance services. The way PSAPs are set up differs from country to country/state, but they are generally statically set up depending on location & capability and... | [
"They also often get ANI/Ali data and approximate location from the cell phone carrier. (I help design PSAPS, Public Safety Answering Points) "
] | [
"They also often get ANI/Ali data and approximate location from the cell phone carrier. (I help design PSAPS, Public Safety Answering Points) "
] |
[
"Why do some places only have 2 tidal changes per day as opposed to 4?"
] | [
false
] | A friend of mine stays in thailand at the moment, and told me, that high and low tide only occured once per day. I was very doubtful and suspected false observation (tidal change during night time or something like that), since i know from holidays at the sea that two high tides appear each day. But she was insisting h... | [
"Tides are a dynamic phenomenon. Imagine a big, wide bowl partially filled with water. Now imagine tipping the bowl slightly back and forth (meaning: tip it very slightly to the right, then tip it very slightly to the left, and so on). This is analogous to tidal forces, you're changing where the \"flat\" level of t... | [
"Tides are complicated. ",
"Here is a map of the 12 hour cycle",
". White lines are places of equal time of high tides. The naive \"two bulges move around the globe\" would be a parallel set of vertical lines. As you can see that is not even a good approximation. Some places have their high tide when the Moon i... | [
"For another perspective: If the Earth had no continents, just a water planet with uniform depth, the variations in surface elevation due to tides would be a matter of inches. What the continents do is to make it ",
" in complex patterns.",
"Another way to look at it: Ever do your own oil changes without a lift... |
[
"If visible light is on the same spectrum as radio and other waves, what causes things to be \"bright\", and can radio waves be \"bright\"?"
] | [
false
] | null | [
"Like any sine wave, two characteristics can be measured from any light source- the Wavelength and Amplitude.",
"Wavelength determines where on the EM spectrum the radiation lies- from infrared to visible light to x- and gamma rays. On the visible spectrum, this value determines color. On a wave, this represents ... | [
"That makes so much sense. It's difficult (for me) to instinctively think of radio waves, x-rays, gamma rays as fundamentally the same as visible light, even though I know it intellectually, but your explanation really helped it to click!",
"I also never knew that amplitude of a wave was based on number of photon... | [
"Well, not quite. The amplitude of the wave is based on the number of photons and energy of the photons (wavelength). ",
"The intensity (power per area) of light can be found from the electric field strength (amplitude) by I = cnεE",
" /2 . The important part being the E",
" dependency, or the amplitude depen... |
[
"Why can a blue whale only dive 350ft, but a sperm whale can dive 8,200ft?"
] | [
false
] | null | [
"shamelessly stolen from wikipedia:",
"The sperm whale has adapted to cope with drastic pressure changes when diving. The flexible ribcage allows lung collapse, reducing nitrogen intake, and metabolism can decrease to conserve oxygen. Myoglobin, which stores oxygen in muscle tissue, is much more abundant than in ... | [
"Link to post - Sperm Whale"
] | [
"Probably evolution and habitus. Blue whales are suspension feeders; they feed on mostly surface dwelling zooplankton and the fish that feed on those. These will tend, as plankton do, to dwell nearer the surface. Thus, blue whales tend to inhabit the upper levels of the water column, and selective events have not h... |
[
"A question about the uncertainty principle?"
] | [
false
] | null | [
"Yes."
] | [
"So that's why we say quantum objects Don't have specific position and momentum? the uncertainty comes from physically possible state not the individual particles?"
] | [
"Correct."
] |
[
"What is a good explanation for the outcome of the following ball and ramp experiment? (assume no friction)"
] | [
false
] | My physics class is having a serious debate about the Galileo ball experiment. This is the experiment where there are two ramps with the same horizontal length but not the same length from start to finish because ramp B has a dip in it. Two identical balls are dropped from both ramps and the ball released from the dipp... | [
"I propose an alternative thought experiment to illustrate the solution:",
"You take your two ramps. One has a dip,like in your link, but does not actually come up again.",
"Now both balls start at a certain speed. When they reach the dip, both have the same X-position and the same speed. The dip, accelerates t... | [
"Am I right in thinking that in a frictionless world the balls wouldn't actually roll, they'd just slide? Because with rolling balls, rotational momentum is an important part of the system, so neglecting friction isn't just a simplifying assumption, I think it dramatically affects the behaviour of the system."
] | [
"wow, thank you, this makes sense!"
] |
[
"Is there a reason to why the sugar is less sweet in the past 5 years?"
] | [
false
] | I don't know if this is a local thing, but I've asked to many people around here and they have the same perception: the sugar is less sweet. It takes more sugar to sweet a coffee, for example. | [
"It was ",
"correct",
" the first time."
] | [
"Well maybe you are all just eating more sweet stuff, so you are used to it.",
"Since sugar is afaIk Saccharose, there isn't much you can change about it"
] | [
"You mean sucrose. "
] |
[
"Coworker asked me about the legitimacy this DNA study on Homo sapiens cognatus \"bigfoot\". Article says 3 \"bigfoot\" genmoes sequences in a 5-year study"
] | [
false
] | The article piqued my interest but i have no familiarity with the website or the journals through which this article was published. i read over the article but have no strong background with bioinformatics and have been out of the sciences for a few years now. Anyone have any background or followed this type of study? | [
"The first thing I did was click through to the paper at denovajournal.com. Pretty flashy site for a scientific journal. Not much there except for the 'bigfoot' study. So then I googled \"DeNovo Scientific Publishing.com\", the parent org, supposedly. Again, not much there except for this one 'study'.",
"I leave ... | [
"You don't need a scientist to tell you the website for the journal is fishy. They have only one paper. They appear to have created the whole thing just to publish this one paper."
] | [
"I don't have a background with bioinformatics, but as an anthropologist I think Bigfoot can be comfortably dismissed as non-existent. As such, I'd suggest these findings (that the hair is not human or animal) are much more probably incorrect or have misidentified some other sort of fibrous material. "
] |
[
"Why we can make plasma with a microwave if it uses non-ionizing frequencies?"
] | [
false
] | I've seen people putting a grape cut in half in a microwave and making plasma that i know is ionized gas, how could be possible if microwave uses 2.4GHz frquencies that are non-ionizing? | [
"Ionizing radiation is not necessary to generate a plasma. For example, you can use ",
"electron cyclotron resonance",
".",
"Even at relatively low temperatures, a gas will have some small degree of ionization, and some free electrons around. If you subject the gas to a static magnetic field, and shoot microw... | [
"Ions in a microwave or in a gas discharge lamp are not made from photon-electron collisions. You are correct that the photons required to do so would be in the x-ray range. Instead plasma is made by accelerating naturally occurring ions or electrons in an electric field, giving them enough kinetic energy to ionize... | [
"Thank you, so those free electrons could hit other atoms, also not of the same matter they come from, and ionize other things?\nIf that's true it could mean that every type of radiation, including light, in presence of air is not likey to but could cause cancer.\n(To everyone reading that: please don't take my ass... |
[
"Why do we get sick so fast after eating food, if it takes a couple hours to go through the digestive system?"
] | [
false
] | I remember seeing this question, but I am unable to find it. | [
"What do you mean by fast? It takes at least two hours for something like bacteria to get to a place where it can cause food poisoning symptoms. Although if it was a bacteria that releases a toxin (like S. aureus), the toxin may already be in the food or may be released earlier in digestion. This could cause a fast... | [
"Think about the scale of things. You can see the food that you're ingesting, meaning your body has lots of work to do in order for that food to be able to processed. First, the saliva breaks down carbohydrates. Food gets pushed into the stomach where acid breaks down proteins into component parts, as well as mecha... | [
"So can I have a TL;DR version of the answer?"
] |
[
"What is the effect of X-Ray radiation on gold?"
] | [
false
] | Hi I was wondering what is the effect of high energy ionizing radiation on gold. Does something 1000 grey of X-Ray irradiation cause gold to become radioactive? and if so what is the half life etc and what are the implications for health | [
"It depends on the energy of the x rays. If they are below a few MeV then there will be no activation of the gold: it will just heat up slightly. Above a threshold (don't have exact number on me, maybe 8 MeV) the x rays can start knocking neutrons off some of the nuclei, making them into radioactive isotopes. Th... | [
"the x rays can start knocking neutrons off some of the nuclei",
"If their energy is that high wouldn't they be gamma rays instead?"
] | [
"The definition of x-rays vs gamma rays varies from field to field. In medical physics and nuclear physics, there is no separation between the two based on energy. Instead, it depends on where they came from. Gamma rays come from nuclear decay or annihilation, and everything else is x rays. So just two differen... |
[
"What equations are used to demonstrate that an object moving at >c is also moving \"backwards\" in time?"
] | [
false
] | null | [
"The short answer is that you use the Lorentz transformations, which tell you how to translate from one frame of reference to another.",
"The precise statement that emerges is this: If you have an object that travels faster than the speed of light in one reference frame, there exist other reference frames -- whic... | [
"I believe it's from when you do a ",
"Lorentz transformation",
" you get a imaginary Lorentz factor (ɣ) if velocity v > c.",
"ɣ = 1/sqr(1-( v^2 / c^2 ))\n"
] | [
"Thank you for your reply! Looks like I'll be studying up on Lorentz transformations."
] |
[
"How is it that different breeds of Canis lupus familiaris (domesticated dog) can develop to be so different in specific individual populations around the world, yet not be subject to speciation?"
] | [
false
] | Distinct breeds exist that vary in size, shape, and other physical qualities greatly, and have evolved that way in specific populations across the globe. Does the way humans selectively bred the species have something to do with it? | [
"Dogs have likely only existed as a separate subspecies of Canis lupus for ~ 40,000 yrs at max, which is too short a time for speciation to occur from wolves, much less different breeds of dog, even with geographical or other isolation. Most dogs are not \"purebreds\", anyway, so there is little chance for genetic... | [
"It doesn't take much genetic difference to lead to dramatically different appearances, traits, and behaviors. This is part of the power of the genetic makeup of modern animals, it's a kind of \"meta-trait\" of modern organisms. Animals that didn't have the arrangements of genes and physiology which allowed for rap... | [
"Because the variation is overwhelmingly accounted for by changes in allele frequencies, not by novel mutations. While it's novel mutations, and more specifically incompatible mutations that cause species divergence.",
"This might be confusing because usual explanations of the way evolution works are more or less... |
[
"Is there any truth to native americans being less tolrant to alcohol?"
] | [
false
] | Stemming from a discussion in , I always took it for granted that natives were less tolerant to alcohol and a smaller amount had a much greater effect on them than say caucasians. Admittedly my workding was a little rough and people took it as a racist comment. So, is there any truth to this ethnic low tolerance? | [
"Yes, it's related to delayed breakdown of acetaldehyde caused by a genetic abnormality, however it is not ",
" by race; only more common in those of certain heritages. ",
"http://journals.psychiatryonline.org/article.aspx?Volume=160&page=41&journalID=13"
] | [
"Our acknowledgment of race is certainly a social construction.",
"However, the reason that people of similar heritage look similar, or have similar predispositions to diseases, etc. is because they come from, what is known as, the same \"breeding population\"- meaning population who live in the same geographic a... | [
"genetic abnormality",
"Sounds weird, it's a really common allele. 'Genetic abnormality' sounds way more ... large and less frequent. Like chromosomes fusing or something."
] |
[
"A scientific explanation for the enjoyment of unsavory pornography?"
] | [
false
] | null | [
"I can't delve into this too much right now, but just as a supplement to what others may give you as an answer: there is an interesting section regarding this in the book ",
"The Brain that Changes Itself",
". This is an awesome book in general if you are interested in the neuroplastic nature of the brain expla... | [
"I was under the impression that yourbrainonporn had been discredited as pseudo-science nonsense..."
] | [
"Not an answer, but a clarification which I think is worthwhile to point out - These are very common kinks, i.e. fetishes for specific things, which are often expressed in a few different ways. But they're very generic, hit up FetLife and most everybody shares these core tastes. So rather than frame the question in... |
[
"Why does the pH scale have 7 as neutral instead of 0?"
] | [
false
] | I understand that pH is determined using the negative logarithm, but wouldn't it be much easier if they stuck a "-7" at the end of the formula? | [
"Neutral in water is pH 7 is only \"neutral\" because there is an equal concentration of hydroxide ions. pH is really a shorthand for the ",
" or ",
"solvent-H",
" protonated cations",
". The point of pH 7 being \"neutral\" is dependent on the fact that the ",
" medium is water. In water, the concentratio... | [
"One small picky thing... remember, at room temperature ",
"Kw = [OH",
" ][H3O",
" ] = 1.0x10",
"and ",
"pH = -log([H3O",
" ]) ",
"Since the two concentrations are equal at neutral pH, ",
"[OH",
" ] = [H3O",
" ] = 1.0x10",
"and ",
"pH = -log(1.0x10",
" = 7.0",
"I agree with most of what ... | [
"pH is the negative log of the hydronium ion concentration (H+). Pure water happens to have a hydronium (and hydroxide) ion concentration of 1*10",
" moles/liter, which is really interesting... You may ask, how can PURE water (H20) have any ions in it???",
"The answer is cool: water is so polar, it actually spl... |
[
"Black hole question - What is a naked singularity?"
] | [
false
] | What is a naked singularity? I’ve heard it’s something like a black hole that’s evaporated completely from Hawking radiation, this is obviously trillions of years in the future, but where the only thing left is the singularity in the middle.? Is this right? And can you explain a little more? | [
"A naked singularity is generally a singularity that is not hidden behind an event horizon.",
"A black hole, on the other hand, is region of spacetime in which there ",
" a singularity and it is hidden behind an event horizon. So in these cases, it's not possible, for instance, to observe a particle actually fa... | [
"These are unphysical solutions. ",
" of the black hole's mass is due to rotational energy. So it's as if a massless, spinning star collapsed into a black hole. This is not physically possible.",
"Another such unphysical solution is one in which the mass M is less than the electric charge Q (with suitable const... | [
"To be clear, we're reasonably sure that naked singularities do not and cannot exist. They are the result of stretching the equations of General Relativity beyond the regime in which they provide accurate predictions, by plugging in values that are probably unphysical. This has nothing to do with black hole evapora... |
[
"If the neutrinos that were possibly going faster than the speed of light were travelling backwards through time, wouldn't they be seen as antineutrinos?"
] | [
false
] | [deleted] | [
"You seem to have a decent grasp on what FTL means according to special relativity. Most likely if this result holds we can't just naively interpret special relativity that way. If this result is correct (a huge if) it's much less likely that these neutrinos actually go back in time and violate causality than that ... | [
"The notion that a particle traveling forward in time is equivalent to its antiparticle traveling backward in time is one that depends on special relativity, as is the notion that traveling faster than light means going backwards in time. If this neutrino result turns out to be true, chances are that such a naïve i... | [
"From my very limited knowledge about the alleged speeds reached at CERN, (I read a lot, no specific knowledge or science education) I tried my best to explain to a friend (who has less knowledge again) that in this instance the neutrino was supposed to be travelling FTL and would in fact be going backwards in time... |
[
"In Grade and High School, I always heard about how Jupiter was a \"failed\" Star. Can it (under the right circumstances) eventually become a Star? If so, what process would it go through?"
] | [
false
] | null | [
"When people talk about \"failed stars\" they're referring to these fascinating little objects called ",
"brown dwarfs",
". Brown dwarfs are what happen when a star forms with so little mass - less than about 80 times the mass of Jupiter - that it doesn't have enough pressure from the inward pull of gravity to ... | [
"Odd question: ",
"When the sun starts to burn out (assuming we're quite technologically advance), could we \"throw\" Jupiter in there to buy ourselves some time? How much time would it buy us?"
] | [
"Wow, thanks for the info. Never heard of a Brown Dwarf either."
] |
[
"Is there a theoretical maximum for a how reflective a surface can be?"
] | [
false
] | I remember reading a while ago that household mirrors absorb around 10% of light that hits them. Is there specialised mirrors that are more efficient? If so, what are they used for? | [
"The theoretical maximum for reflection is 100%.",
"In theory, any ideal metal is 100% reflective. In practice, mirrors, coated with metallic layer on the back of a transparent glass, does not reflect 100% because even metal can absorb the incoming light slightly. Gold is a very good natural reflector with less t... | [
"You couldn't really use this to make a mirror,",
"Sure you can! They're called reflective prisms, and they're commonly used in binoculars."
] | [
"/u/isison",
" is close, though in the optical coating industry these are usually referred to as dielectric mirrors, not photonic mirrors. The simplest type is commonly called a \"quarter wave stack\". By stacking quarter wavelength [optical] thicknesses of material, you can achieve arbitrarily good reflection ... |
[
"Does free space have a Poisson ratio?"
] | [
false
] | I've been wondering since reading about the discovery of gravitational waves and how they 'compress and stretch' the earth. Does the compression of space-time along some axis correspond to an expansion about others? And like the title says, is there a Poisson ratio for space-time or free space? | [
"What a bizzarre way to put it... anyways when a gravitational wave passes, it only affects the two directions orthogonal to its motion. Moreover at any given time one is stretched and one is compressed so that the volume of a given region of space is kept constant. Since GWs are very weak, that means the relative ... | [
"Young's Modulus is a material property like density, color, melting point, etc. Space time is not a material so you're talking about completely different things."
] | [
"Young's modulus describes how hard it is to deform something. General Relativity describes gravity as the deformation of spacetime by mass. So the Young's modulus of spacetime would describe how hard it is to deform spacetime. It is a perfectly sensible notion, at least at some level. My question is whether it can... |
[
"I'm unable to spit out mucous no matter what I use(details as to why inside). What can I use to break down the phlegm so that I can swallow it instead?"
] | [
false
] | null | [
"What is the problem with swallowing it back down? It is coming from your respiratory system and swallowed down your digestive system... swallowing it doesnt \"send it back where it came from\"."
] | [
"I think you misunderstood my post. I am asking for a way to swallow the mucus as opposed to spitting it out."
] | [
"Right.... why don't you just swallow it?"
] |
[
"Black holes affect light; thus light is pulled by gravity. Does light exert its own pull in return?"
] | [
false
] | null | [
"Yep, light definitely does gravitate - everything does! In Einstein's gravity it's not just mass that gravitates, but mass and ",
" - and everything has energy.",
"When it comes to a black hole, the gravity of the light it pulls in is pretty much always negligible by comparison. But there are instances where t... | [
"There are also massive bosons like the W and Z bosons, and they obviously interact by gravitational force.",
"There is no reason why the spin state (i.e.fermion or boson) should play a role when interaction gravitationally."
] | [
"Oh whoops, my bad. Forgetting what I learnt years ago. "
] |
[
"When we eat, why is there such a long delay between being full and feeling full?"
] | [
false
] | null | [
"One of the key physiological regulators in appetite (note: I say ",
" rather than neurological) is the peptide hormone ",
". Ghrelin is released by the stomach into the bloodstream and is a noted appetite stimulant. When the stomach is full ghrelin release is inhibited (switching off the appetite, as it were) ... | [
"Ghrelin is not the only peptide responsible for appetite and is certainly not the only one responsible satiety signals. There is also CCK, NPY, leptin, cannabinoids, and to some extent cortisol, which act on multiple brain areas such as he hypothalamus and parts of the brain stem, the nucleus of the solitary tract... | [
"This is only part of the answer. The stomach's stretch mechanism results in the inhibition of ",
" (a peptide that stimulates the appetite). As circulating ghrelin levels fall, so does the desire to eat. This does take a little time though as ghrelin needs to be cleared from the circulation (it's a hormone that ... |
[
"Is the cardinality of the set of points in a number line the same as the cardinality of the set of points of a plane?"
] | [
false
] | null | [
"Technically they just show there's at least as many points on a line.",
"And obviously, there are at least as many points in a plane as on a line. So by the Schröder–Bernstein theorem, they have the same cardinality."
] | [
"Yep. See ",
"space filling curves",
" for examples of mappings between an interval and multidimensional spaces."
] | [
"Yes. The easiest way to prove this explicitly, IMO, is to make use of the ",
"Schröder–Bernstein theorem",
", which says that if A and B are sets and f:A->B and g:B->A are both injective functions, then there exists a bijection between A and B. This way, you can avoid finding an explicit bijection between R an... |
[
"Can we use Nuclear Magnetic Resonance to image modern semiconductor?"
] | [
false
] | Just like we can get brain scans/images with an MRI machine,Is it possible to get scans/images of a modern semiconductor microchip using an MRI machine Can the technique of Nuclear Magnetic Resonance be in some way used to image silicon structures? | [
"You can do MRI of semiconductors (and nanometer-sized objects), although not using a typical MRI setup...",
"170nm nuclear magnetic resonance imaging using magnetic resonance force microscopy",
".",
"We demonstrate one-dimensional nuclear magnetic resonance imaging of the semiconductor GaAs with 170 nm slic... | [
"Thanks a lot!! this is what i need to get started.",
"Can you please elaborate on your last statement \"There's also a lot of literature on the spectroscopy side of the house, of course\""
] | [
"You're welcome. ",
"Can you please elaborate on your last statement \"There's also a lot of literature on the spectroscopy side of the house, of course\"",
"Exactly what I said - there's been a lot of NMR spectroscopy (not imaging!) on semiconductors over the years. For example, optically pumped/detected NMR... |
[
"How sure are we that Proxima Centauri is indeed gravitationally bound to the Alpha Centauri binary pair?"
] | [
false
] | So therefore what are the odds that it is not? | [
"This study",
" concluded that there's only about a 4x10",
" (0.000004%) chance that Proxima Centauri is not gravitationally bound to Alpha Centauri AB."
] | [
"Good question! ",
"This paper",
" published in 2017 sought to answer this question by looking at the dynamics of the system directly. While in their abstract they say \"we show that Proxima and Alpha Cen are gravitationally bound with a high degree of confidence\" it is somewhat difficult to give an absolute p... | [
"Why are you guessing at a figure based on simulated orbits, when they already derive one from the relative velocity?",
"The observed velocity is therefore lower than the unbound velocity limit by −5.4σ, corresponding to a theoretical probability of 4×10",
" that the stars are not gravitationally bound."
] |
[
"Why do electrons pair up in superconductors?"
] | [
false
] | My limited knowledge keeps telling me that it doesn't make sense, opposite charges repel. | [
"Something that has been bothering me for a while about this subject: I've heard it explained that the reason Cooper Pairs have no resistance is that a Cooper Pair is a boson, so it follows Bose-Einstein statistics instead of the Fermi-Dirac statistics of a single electron. Why does this work? It seems there must b... | [
"Something that has been bothering me for a while about this subject: I've heard it explained that the reason Cooper Pairs have no resistance is that a Cooper Pair is a boson, so it follows Bose-Einstein statistics instead of the Fermi-Dirac statistics of a single electron. Why does this work? It seems there must b... | [
"Cooper showed, before the BCS paper, that if you have a non zero constant attractive interaction between electrons they will form bound state. In free space, of course they will repel, but put them in a system where this happens and they will always form a bound state. I do not believe he even mentions statistics ... |
[
"How do we know how old cave drawings are?"
] | [
false
] | A recent post showed cave painting approximately 30,000 years old. How do we know this? | [
"Cebus is correct in that we use other radiometric dating techniques to get \"absolute dates\" for some artifacts, but we almost always start with \"cross dating\" using other artifacts or ecofacts of known age. In the case of cave paintings we can also use chromatography to get the elemental composition of the pig... | [
"thanks!"
] | [
"Either you date the rock the painting is on or you date the layer of rock above and below using ",
"radiometric dating",
"."
] |
[
"Why is the periodic table called the periodic table?"
] | [
false
] | [deleted] | [
"The idea behind the periodic table is that if you list all of the elements in the order of the number of protons they have, there are repeating patterns in their behavior. These repeating patterns are called \"periods\", because they are periodic. The periodic table is what happens when you lay out the elements in... | [
"Mostly true (you flipped the right and left on the stable noble gasses that are on the far right and the reactive alkalis on the left)."
] | [
"The history is that John Newland noticed a periodicity of the chemical properties of chemical elements when arranged in the order of atomic weight. He called this the law of octaves in 1864. Gregor Mendeleev in Russia then started arranging the elements in a table in the 1870s, which, while different from the mo... |
[
"Can someone explain inverse-square law to me. I need to use it to work out the cutting measurements to build a pendulum wave."
] | [
false
] | It may be that you use inverse-square law to find the length of each pendulum. I am going to be building something . | [
"I'll allow it."
] | [
"Oh ok. I was confused because usually inverse-square law refers to something else.",
"He lines it out here: ",
"the length you are looking for is the length of the longest pendulum multiplied by the square of the ratio of the time periods squared. ",
"So when you figure out what you want the swing times to b... | [
"When a pendulum's swing is quite free",
"It's always a marvel to me",
"The each tick and each tock",
"Of the grandfather clock",
"2 pi root L over g",
"Note that this is the small angle approximation."
] |
[
"Why do distant mountains fade to blue?"
] | [
false
] | I recently saw a post from called "Welcome to America." One of the pictures showed a mountain range becoming a light blue as the mountain range became more distant. In a middle school art class, I remember being told this occurred, but I wasn't told why this happened. | [
"The phenomenon which makes mountains (and everything else) further away from us fade to blue is actually Mie scattering. Mie scattering is similar to Rayleigh scattering, except the particle size is different. With Rayleigh scattering, the particles are much smaller than the wavelength of the light (gas molecule... | [
"I think, and I may be mistaken, that it actually isn't Rayleigh scattering here. Or if it is, there's an enhancement. I feel like I remember reading something about the water vapor given off by trees and such that makes the atmosphere bluer in a shorter distance than standard atmospheric conditions.",
"Edit: her... | [
"So if the larger particles responsible for Mie scattering weren't present, would the blue haze be less or even nonexistent? I realize that it's not probable for these larger particles to be absent over a large distance, such as a mountain range. I guess it's more of a hypothetical."
] |
[
"Why does a sink get to a stable level after a while of water flowing?"
] | [
false
] | I tried for literal 20 minutes to draw a diagram on pen and paper with the forces I've considered and the ones I've dismissed, but nothing really worth scanning. This is what I'm thinking. 0) We have a sink of unspecified shape, volume V0, contact area at the top A0 and drain hole area A1. 1) In the empty sink, there's... | [
"The basic concept is that friction is directly proportional to velocity squared. The higher the water level, the higher the velocity in the pipe, the higher the friction. As soon as the friction gets high enough to restrict the flow, you will arrive at a stable water level. "
] | [
"Yes, the two forces that are balancing are the pressure due to the water level, and the resistance in the pipe. If you have pipe with no gunk built up, you probably won't have any resistance and the water will pass freely without water building up in the sink.",
"There is no restriction on the 'other side' of t... | [
"Wait. So ",
", rather than the air pressure from within the pipe system, is the counteracting force here? Air pressure from inside the tubes is negligible?"
] |
[
"How much do we really know about the likelihood of future earthquakes?"
] | [
false
] | I got an ad for earthquake insurance and it was super expensive. 3x my regular homeowners insurance and a deductable around 80k. Does the insurance company know something I don't? I also hear a lot about "overdue" earthquakes but how accurate is our knowledge on the subject? Can anyone say that an earthquake will ha... | [
"If you want to see some of the nuts and bolts behind the probability used by structural engineers, the USGS has a pretty good site. Go here ",
"http://earthquake.usgs.gov/hazards/apps/gis/",
" and enter your location to find out what your probability of exceeding a certain PGA will be over a given time period.... | [
"Haha \"overdue\" earthquakes. That's not how probability works. ",
"Event frequency is classified on a 1/x scale (1/2, 1/20, 1/1000), in this case measured in years. Generally speaking the severity of earthquake, as with cyclones, tidal waves, etc. increases inversely with the probability; severity from 1/1000 y... | [
"So... I didn't actually answer your second part very well. ",
"Yes, especially in urban or high-interest locations, geologists and risk analysts can assign a probability and a likely severity to future earthquakes. ",
"This is generally static, and will be the same risk profile for EVERY insurance company in t... |
[
"What makes it rain harder? Why do some clouds cause flash floods while others hardly drizzle?"
] | [
false
] | null | [
"This is a really good question and I'm not sure I've ever seen it asked in this sub before! The answer is pretty complicated and multi-faceted but I think I can get it down in the 20 minutes while I finish my morning coffee.",
"Clouds can form in a few different ways, but the most common and most important for p... | [
"Thanks for the explanation, you were great !\nHope the coffee didn’t get too cold ;)"
] | [
"Amazing answer!"
] |
[
"How are dams able to be constructed against the constant push of flowing water?"
] | [
false
] | Secondly, how exactly does a dam hold back a constantly accumulating amount of water without simply overflowing? I know they drain some water through spillways, but it seems like the vast majority of water is still trapped above the dam. Where does it all go? | [
"Usually the river is redirected around the site where permanent dam construction is taking place. A temporary dam may be used to assist the redirection.",
"A hydroelectric dam routes some of the water through the turbines within the dam to create electricity. Excess water exits through spillways.",
"When the l... | [
"http://www.hydroquebec.com/learning/hydroelectricite/construction-refection.html",
"I live in Quebec and our home power company has all you need to know with a nice animation."
] | [
"How on Earth do they build the temporary dam?"
] |
[
"A friend has a degenerative condition in her retinas; blindness is inevitable within a decade. Is there hope?"
] | [
false
] | null | [
"Right, I wasn't really looking for a diagnosis or case-specific information, rather just first-hand feedback from people who are working in the relevant fields, and what they anticipate as options for treatment for people with degenerative retinal disorders in the coming decade. "
] | [
"Right, I wasn't really looking for a diagnosis or case-specific information, rather just first-hand feedback from people who are working in the relevant fields, and what they anticipate as options for treatment for people with degenerative retinal disorders in the coming decade. "
] | [
"I understand, but it's a line we toe and when a specific person is mentioned we can't release the question. ",
"A ",
"quick search",
" on AskScience shows multiple recent questions on stem cells, most of which haven't garnered much of a response. ",
"This question",
" from a month ago is probably very si... |
[
"Water powered cars: Is this possible? Is there a catch?"
] | [
false
] | Hey, I saw , and I've seen other videos like it. Is this possible? Often I hear that more energy goes into it than can be taken out, does that mean that this car has a battery or something? How does stuff like this work? | [
"If it seems too good to be true, it probably is. The only sensible way to run a car on water is to split the water into hydrogen and oxygen (costs energy) then burn the hydrogen and oxygen back together to make water (runs your car). You could have the oxygen in the water react with something else to make energy, ... | [
"Apparently that Japanese company (Genepax) ",
"shutdown their website two years ago",
", and no information about what their supposed \"chemical reaction\" can be found. ",
"If their car really worked, it certainly did not use water as the energy source, it was probably using compound like potassium hydride... | [
"Is this possible?",
"No. I think that this can be, for all reasonable intents and purposes, completely ruled out.",
"At room temperature and pressure, or even anything close to room temperature and pressure, H2O is simply the most stable, and therefore low energy, chemical configuration of hydrogen and oxygen ... |
[
"What happened during Earth's \"Dark Age,\" or the first 500 million years after it formed?"
] | [
false
] | null | [
"Unfortunately, its quite difficult to tell exactly what was happening. The problem is, the earths tectonic plates are constantly undergoing subduction and deposition. Put simply, the entire surface of the earth back then has since been pushed underground, melted, and reformed. There are literally no rocks on the e... | [
"There have certainly been tectonic processes (and of course weathering and erosion) operating for a long time between 4 billion+ years ago and now, though it sounds like your initial sentence assumes this was happening in the actual Hadean, sort of erasing the early Earth as it went along. It’s not so much that te... | [
"Okay, I understand, but look to the root of the question. OP just wanted to know what was going down on our planet for the first 500 million years. I also understand that their are minerals (zircon in particular) from that time period (I might add, I'm not aware of a true rock, being comprised of many minerals, th... |
[
"How does SSL prevent the initial key from being stolen?"
] | [
false
] | Hi there, I've been looking for this answer on the web and here, but haven't found anything yet. The best I've seen so far is this article on encryption. In step one of how SSL works, it says "The web server sends its public key with its certificate." (article ) And from there on the browser and web server can use the ... | [
"The article is extremely bad in omitting crucial assumptions, on top of the actual method.",
"Let's have a look at the two variations that answer your question. I've found the sequences in ",
"this illustration",
" to be easiest to digest. Note they are referring to TLS 1.3. We are going to start with TLS 1.... | [
"I think your question is really about: how can 2 people share a secret when anyone could be watching?",
"Some algorithms are very easy to go in 1 direction, but hard to invert. For example:",
"\"Factor the number: 899 into it's prime components\" would take you a few seconds, but the results are 29 and 31.",
... | [
"The client encrypts it with the public key of the server certificate (assuming it's validated and valid) and sends it.",
"This answers OP's question, doesn't it? A user's web browser / operating system can already be sure that nobody's impersonating the web server, making it easy to prevent trivial MITM attacks.... |
[
"Would keeping large bottles of ice in the freezer save electricity? How much?"
] | [
false
] | I heard that keeping solids in the freezer like ice saves electricity because it doesn't escape when you open the freezer door like air does, but I found post on AskScience and I'm not as sure anymore. And even if it does save electricity, is it a significant amount? | [
"Seems like it would keep the temperature more constant by increasing the heat capacity of the stuff stored inside, but unless it was taking up a very large volume I think you would still get the same amount of air exchanged and thus total heat being absorbed. So, probably not."
] | [
"The less air a freezer has to chill every time you open the door, the less energy it'll take to run. Having stuff in the freezer excludes air so there's less air that can escape and less warm air that can get in. ",
"How much energy it saves depends on how big your freezer is, but rounding a lot, a full-sized ... | [
"So, If you have a small personal cooler and you put in the freezer, let the air inside the cooler chill to freezing then sit it out, with an open lid at room temperature, how long would the air inside the cooler stay cool?",
"Now, imagine that same cooler with filled with blocks of ice. Doesn't it seem logical ... |
[
"Are galaxies that are moving faster than light due to cosmic expansion going backwards in time?"
] | [
false
] | null | [
"I'm going to deduce that the spirit of the question is something like \"does this qualify as FTL travel, and if so, doesn't that mean these galaxies can travel through time?\" This is a good question!",
"The restriction that things cannot travel faster than the speed of light is a ",
" one. That is, locally (e... | [
"Slightly less technical response: the real restriction is on ",
" propagating faster than light. So if I can send a message from point A to point B faster than light can travel, then there's the possibility to wreak real havoc with cause and effect. But the expansion of the Universe can't be used to send informa... | [
"Well, I'm not sure that qualifies as an explanation so much as a statement of fact. My goal was to get at why an expanding universe implies that FTL travel is not occurring."
] |
[
"Why does my bathroom door randomly close out of nowhere? Every day the door is cracked a bit and then out of nowhere it'll SLAM closed. Any ideas?"
] | [
false
] | null | [
"Hi Theethanlong thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of the fo... | [
"There is a vent to the outside (usually a fan in the ceiling) in most bathrooms. If the door is open a small amount and the air pressure changes quickly (from other parts of the house, or wind outside), it'll suck or blow through the crack between the door and the frame and slam it shut (or blow it open wider, dep... | [
"I figured it out hahah. Thanks though!"
] |
[
"Why do we never forget how to ride a bicycle?"
] | [
false
] | People say this all the time when someone is about to do something for the first time in a while. Is it true that we never forget how to ride a bike, and why? | [
"I don't know anything about human learning, but I have read about bicycles. Once you get it above a certain speed, a well-designed bike is stable in its upright position. It doesn't want to fall over; it practically rides itself. Unfortunately, there isn't a simple explanation for why bikes are stable. The easy an... | [
"Did you really just disagree with him that he did not forget to ride a bike? There will always be exceptions. Don't be ridiculous. "
] | [
"I have to disagree.",
"COME ON, MAN"
] |
[
"In a discrete universe, what is the force exerted on an particle?"
] | [
false
] | Here is the situation, imagine a discrete universe. Two particles are in space. Particle A has a mass of 3kg and velocity of 5 meters a second in a straight line. Particle B has an unknown mass and velocity. Particle A and B collide. Since this is a discrete universe, the smallest unit of time is 1 second, so the colli... | [
"Well wouldn't dp/dt be Δp/Δt ?",
"It depends on what you take to be an axiom. ",
"Do you accept ",
"Hamilton's principle of least action",
"? ",
"My math is rusty on this, when you apply this principle to a discrete world, does it come out with a discrete equation of motion? "
] | [
"Yes it would. ",
"I think the least action principal is a bit too complicated for this problem. I think it's an exercise in Newtonian dynamics."
] | [
"Exactly, all you need is to go from continuous exchange of momentum to discrete exchange. ",
"Although it really isn't easier in this case you could also do this via action principles etc. In that case the action integral would become a sum, and indeed the equation of motion would change from a differential equa... |
[
"If I take a two dimensional object and rotate it through the third dimension, it appears that the object has become a mirror image of itself to a two dimensional observer. Is there an equivalent to reflect a 3D object via rotation in the fourth dimension?"
] | [
false
] | null | [
"Yes. In every 3d rotation, there is a fixed plane (the rotation plane) and a fixed line, the axis of rotation. This decomposition in rotation is required for galaxys, solar systems and atoms exist.",
"In 4d we don't have this asymmetric decomposition. Instead, every 4d rotation has two fixed planes. Solar system... | [
"Right. It's even weirder than that though, as every molecule of their body would be an enantiomer of their pre-4d-rotation self!",
"https://en.m.wikipedia.org/wiki/Enantiomer"
] | [
"I'm struggling to visualize this. Can you describe what it would look like if an object on my desk went through this?"
] |
[
"Is the sun at the same focus for all elliptical orbits?"
] | [
false
] | [deleted] | [
"Since an ellipse is symmetrical, there's no way to tell the difference between the two foci. If I rotate an ellipse 180 degrees, the \"left\" focus becomes the \"right\" one, but nothing has changed."
] | [
"I think you misunderstood the question. If you draw two ellipses with a single shared focus there is a difference. After pinning one down the angle between the two semi-major axes can be anything at all. I think you can rightly call it \"the same focus\" if the angle is less than 90 degrees",
"Doesn't the direct... | [
"Though precession might cause the same problem",
"It sounds like apsidal precession is exactly what ",
"/u/Seraph062",
" is talking about.",
"For nonexperts: while the orientation of the long axis of the ellipse remains fixed in a simple textbook orbit, the gravitational pull from other planets and general... |
[
"AskScience Open House [meta]"
] | [
false
] | The time is ripe to look back and see how things are going for AskScience, and to look forward and see how we want things to go in the future. Here's your opportunity to voice your opinions on things going on in AskScience, things affecting AskScience, and things that AskScience affects. Please bring up anything you wa... | [
"Brain Doc already said this, but I'd like to reiterate it. ",
" We do not control this. If your post doesn't show up, it's not because we're science Hitler. Message us with the link and we can fix it. Don't go on a tirade because the automatic bot automatically botted you.",
"For those of you who are new to as... | [
"People always thank the mods, but remember that AskScience would be nothing without the community at large! So, thank you!"
] | [
"I just want to say thank you for putting your time into one of the, if not the, most helpful and interesting subreddits :)"
] |
[
"Why doesn't fast food spoil, and should I care?"
] | [
false
] | Hi, I saw yet another "look, these hamburgers from McDonald's that I bought 2 years ago and left on the counter haven't spoiled or degraded!" post making the rounds on facebook. Basically, it's something like: The obvious subtext is "if nothing else will eat it, neither should you." Being a skeptical kind of guy, I am ... | [
"The problem is the cited experiment is bad science.",
"The fast food in the example doesn't \"spoil\" because it dehydrates. If you do the same test but put the McDonalds in a warm, moist, dark place then it rots just as well as anything else.",
"Here's an at-home experiment that actually tries to control seve... | [
"this same science also works for a variety of non fast food products"
] | [
"Yeah, people who post this stuff clearly haven't thought a bit about it. When you consider that the fries and burgers are ",
" at a ",
", there will be no to almost none bacteria or other microorganisms. If put in a sealed environment, it will not decompose because there isn't anything to decompose it. If you ... |
[
"Why doesn't your body heal cavities in your teeth?"
] | [
false
] | I was just wondering why ones body can't heal cavities in teeth. | [
"Dr. Weston Price",
" (who founded the American Dental Association's research section) is best known for having documented the oral health of indigenous populations, and compared/contrasted these populations based on what they ate. The result is his book, ",
"\"Nutrition and Physical Degeneration.\"",
" He wa... | [
"Very interesting! Thanks for the links and the future reading material!"
] | [
"Sucrose --> lactic acid.",
" Presumably other sugars and carbohydrates will work as well; lactic acid is a metabolic endpoint for a bunch of organisms.",
"Fat, interestingly, opposes this sort of thing; a combination of low sugars and relatively high-fat diets are probably why skulls recovered from pre-agricul... |
[
"Is there any reaction in the physical world caused by something else that is truly 'instant'?"
] | [
false
] | [deleted] | [
"Physics student here. The only thing that comes to mind that can be described as truly instantaneous would be the phenomenon of quantum entanglement, in which the quantum states of two (or more) objects depend on each other. Therefore, if two particles are entangled, and one is measured to have \"up\" spin, the ot... | [
"As you mention, it is convenient within some context to consider certain ohenomena to be happening instantaneously - but this is always an approximation rather than 'reality'. In general, when building a qiantitative model it is best to do what is most convenient; in this way the useability of your model will be i... | [
"I don't have flair, but I know for a fact that it is possible to entangle any number of particles (at least in principle). The entanglement of the three particles, for example, is the cornerstone of the ",
"GZHM experiments",
" which aim to show extremely stark contrast between quantum mechanics and classical ... |
[
"Can a black hole ever reverse itself; or can a singularity become normal matter again?"
] | [
false
] | Can a black hole ever lose enough energy through energy emission (Hawking radiation or the like) that it become unable to maintain the gravitational force needed to hold itself together? As always, forgive my username in this subreddit. | [
"No. Once it's a black hole, it remains a black hole. Hawking radiation ",
" its transformation into \"regular\" matter. Over time it evaporates away to nothing, in the process releasing all of these various \"normal\" particles. "
] | [
"It's a hot-cold thing. The mass (energy) of a black hole is proportional to the radius of the black hole's event horizon. The entropy is proportional to the surface area of the event horizon, which is in turn, proportional to the ",
" of the radius. So since temperature is internal energy over entropy, for large... | [
"When a particle is emitted through Hawking radiation it is emitted with sufficient momentum to escape the black hole. Otherwise, it would, as you note, fall back into the hole and not really be \"radiation\" ",
". So imagine you're a short distance outside of the event horizon and you gain (through a collision o... |
[
"How did natural selection cause the ability to fly?"
] | [
false
] | I don't have a hard time envisioning all the intermediate beneficial traits that took us from tree swinging to sentience but how did certain simple animals find their way from simple locomotion to something so complex and relatively scarce as flight? | [
"Flight is not scarce. Quite a lot of insects fly, bats fly, most species of birds fly, pterosaurs flew. Then there are gliders like flying squirrels and flying snakes and lizards.",
"There's a lot of conjecture about how flying evolved. Here's a ",
"link about vertebrate flight",
".",
"edit: Article about ... | [
"\"relatively\" there are many more crawlers and swimmers than flyers I would think.",
"Yes, but the point is that there are no less than four independent evolutionary origins of flight in the history of life: mammals, birds, pterosaurs, and insects. Further, it happened rather differently each time. Bats have ma... | [
"Instead of looking at flying as the end of a chain devoted towards flight, look at it as gliding with style. Creatures could potentiality start in trees, eating insects. Eventually they get more and more accustomed to living in trees till its pretty much suicide to be on the ground for any amount of time. So a few... |
[
"how can we know the half-life of isotopes with extremely long halflives"
] | [
false
] | how can we know the half-life isotopes like tellurium-128(wikipedia says its about 2.2 10 about a septillion years) when the universe isnt even that old. | [
"If you have a large enough collection of slowly decaying atoms, some will be decaying at any given time and you can measure the activity of this decay and extrapolate to find the half-life. However, in the case of Tl-128, it looks like the number is based on ratios of daughter products found in old rocks, accordin... | [
"https://hps.org/publicinformation/ate/q8270.html",
"In the case of 238U and some other long-lived radionuclides, one approach that has been used is to separate a pure sample of the radionuclide in a known chemical form, weigh the sample, and then measure the activity, A (disintegration rate). The half-life is th... | [
"The approach used, as far as I can tell, is to measure the ratio of Tl-128 to it's daughter elements in old geological samples of a known age determined through other geochronological means such as U-Pb, and infer the rate of decay from that. ",
"For this to work, you need extremely stable mineral material, such... |
[
"What happens if a mutation creates a codon that doesn't translate into an amino acid or stop codon?"
] | [
false
] | null | [
"From my understanding as a biology student, every possible combination of three bases codes for either an amino acid or a stop codon. Take a look at ",
"this chart",
". It shows what every possible combination codes for."
] | [
"Research over the past few years has suggested that these non-coding regions play a role in gene expression and regulation. "
] | [
"This is true. The four ",
"Nitrogenous Bases",
" that make up DNA arranged in any order code for an amino acid, or a stop codon. This includes the start codon AUG (see above chart), which codes for methionine.",
"Let me know if this makes sense!"
] |
[
"Is it even feasible to terraform mars without a magnetic field?"
] | [
false
] | I hear a lot about terraforming mars and just watched a video about how it would be easier to do it with the moon. But they seem to be leaving out one glaring problem as far as I know. You need a magnetic field so solar winds don't blow the atmosphere away. Without that I don't know why these discussions even exist. | [
" If you’re just joining us, read ",
"this",
" comment within this thread for a comprehensive answer.",
"This is a common question, and a common one to which ",
"/u/astromike23",
" provides a comprehensive answer. If they want to join in and provide more context, they're welcome, but I'll also spare them ... | [
"So, hypothetically assuming we had the ability to rapidly (even if by rapid we meant a few hundred years) add an atmosphere to Mars, it would take an extremely long time for it to escape.",
"Yep. Having the tech to add an atmosphere should also make it trivial to ",
" one, even if its loss rate were much highe... | [
"It’s kind of like saying “Why build a power grid if light bulbs all eventually burn out?”"
] |
[
"What would happen to a salt-water fish if you threw it into freshwater?"
] | [
false
] | Alternatively, can you season a freshwater fish by throwing it into saltwater to die? Ignoring ethical issues and all. | [
"Most fish species would die from osmotic shock, however evolution has equipped some to survive this transition. Salmon transit from fresh to salt and back again, and eels from salt to fresh, However many more species, if gradually equilibrated, can live quite well in the other environment. Guppies come to mind ... | [
"The key word here is \"osmotic\".",
"In the case of a freshwater fish in salt water, water would essentially leak out of the fish's tissues until the osmotic charge (or salt concentration as a rough estimate) is equivalent on both sides of the membrane.",
"So the fish receives a one-two punch of losing a lot o... | [
"What exactly causes the shock, and why is it so deadly?"
] |
[
"What are some of the newer theories on the nature of consciousness?"
] | [
false
] | Any names or links to recent or ongoing studies would be much appreciated. | [
"In spite of Postmodern_Pat sentiments, there is a healthy, active and growing literature regarding the phenomenon of consciousness studied from neural perspectives.",
"There is Baars' ",
"Global Workspace",
" model, for instance, as wells as Edelman's concept of ",
"primary consciousness",
", which would... | [
"Another interesting area of research is Dissociative Identity Disorder (DID), where some people can have more than one consciousness or personality existing in the same brain at the same time. Up until recently, there was little (if any) hard evidence to prove that it even existed, so the very idea of it was cont... | [
"I'll save you the time. With regard to the 'so-called' hard problem, nothing of any value has come along recently (or perhaps ever). These 'thories' people are citing really just recast the question in fancy new terms. For example, consciousness arises from integrated networks (Koch). Well, ok, but ",
"?"
] |
[
"uncertain re the uncertainty principle"
] | [
false
] | Okay, so I'm a determinist...I don't believe in free-will and I think everything has a causal relationship. Everything I've seen leads me to believe as much. However, I've read that the Heisenberg Uncertainty Principle has "disproven" determinism. Naturally, I went to for clarification...and it didn't help. Okay, so... | [
"This is a very subtle point, one that I only really got a solid grip on somewhere between my 2nd and 3rd quantum classes, so don't feel bad.",
"First, an explanation of what we're dealing with. In quantum mechanics, as I'm sure you've heard, things are described by wavefunctions. Now, a wavefunction is this ephe... | [
"I'd like to try to explain the fourier transform with a bit less mathematics here. The essential point I'm trying to explain: ",
"And it's a property of fourier transforms that \"narrower\" functions have \"wider\" transforms",
"The most familiar example of a fourier transform is \"equalizer\"-like visualizati... | [
"Just to add a bit of a more experimental way of thinking about this problem. To physically measure the particle (i.e. determine its position) you have to interact with it. It's not like a baseball where you can look and say \"well it's over there!\" With an electron if you hit it with a photon (so you can see it) ... |
[
"Is there a maximum frequency sound that air can support? What happens beyond that point?"
] | [
false
] | null | [
"In air, molecules go 68 nm between collisions on average. The speed of sound is about 330 ms",
" Dividing gives 4.8 GHz. That's the absolute limit though; you're not going to see practical transmission anywhere near that high."
] | [
"The maximum frequency is given by the space between particles. If the speaker was pulsing back and forth smaller than the distance between the particles in front of it, no phonons (waves) would be created. A more dense material (water or metal) will allow for higher frequencies. ",
"At some point you'll be putti... | [
"In air, molecules go 68 nm between collisions on average.",
"But that's in air ",
". If you would excite the air with high-frequency pressure waves, this may no longer hold. (The same goes for the speed of sound).",
"A few years ago I read a couple of books about sound propagation and if memory serves, in on... |
[
"Does bronze have any anti biological properties?"
] | [
false
] | I have heard that for some reason bronze can kill bacteria/viruses but have never heard of this material being used in hospitals, be it for doorknobs, bedframes or whatever else. Is there any truth in this? | [
"Copper has antimicrobial properties",
", so copper door handles, etc., may be useful in certain settings, though I've not personally seen it used that way in hospitals, for whatever reason.",
"Bronze is an alloy made of mostly copper. I've no idea how much the inclusion of other elements affects bronze's antim... | [
"From your interesting link: A 1983 report documenting the beneficial effects of using brass and bronze on doorknobs to prevent the spread of microbes in a hospitals remained largely unnoticed (18)."
] | [
"There is certainly reason to believe copper has anti-microbial effects on the basis of in vitro testing. However, data examining the ability of copper-containing materials to reduce contact transmission are rather sparse, but there is a nice open access article reviewing what has been published: ",
"doi: 10.33... |
[
"Where do 2048 bit long prime numbers come from? (e.g. as used in RSA)"
] | [
false
] | [deleted] | [
"To find a prime of legth 2048, simply generate a random odd 2048-bit integer and test whether it is prime by your primality test of choice, e.g. the Miller-Rabin test. If the test fails, generate another random integer, and repeat until you succeed. ",
"A slightly different approach is this: begin by choosing a ... | [
"To find a prime of legth 2048, simply generate a random odd 2048-bit integer and test whether it is prime by your primality test of choice, e.g. the Miller-Rabin test. If the test fails, generate another random integer, and repeat until you succeed.",
"This is true but it's important to note that the Miller-Rabi... | [
"This method wouldn't really help you generate a 2048-bit prime number, since you effectively need to generate every prime number less than the target magnitude."
] |
[
"How is pH calculated exactly? Wikipedia seems to state that -log[H+] is only an approximation."
] | [
false
] | null | [
"The Wikipedia article discusses the definition of pH more thoroughly a bit further down in its current incarnation. Namely, it involves the consideration of ",
"activity",
" and not just concentration.",
"You can also check out the IUPAC Gold Book ",
"entry for pH",
" if you'd prefer a non-Wikipedia sou... | [
"The pH of a solution is calculated approximately by ",
" pH=-log[H] (1)\n",
"where [H] is the concentration of hydrogen ions in moles/liter. If you know the molar concentration then this calculation is a decent approximation.\nAs mentioned, this only a rough approximati... | [
"Someone will want the long answer with equations."
] |
[
"Why can't I remember anything before age 5, but my 3 year old kid can remember things from last year?"
] | [
false
] | A local farm has a "fall festival" every year with a corn maze. We went last year, when she was two. This year, we went again. When I suggested going through the corn maze, my daughter systematically recalled some of the sights along the maze, including giant playing cards and a dark room full of disorienting spinning ... | [
"Childhood amnesia",
". (Not an expert, this is just the answer usually)"
] | [
"I'll have to find the source, but I do remember an article that somewhat dealt with this. (Might have been a Radiolab episode though.) The major changes the occur in us that allow the retention of memories are advances in defining the world around us. The first big component is language, or at least the ability... | [
"This sounds like speculation. If you are addressing these questions to an expert you should be clear of your intention, otherwise your response will likely be down voted at lay speculation."
] |
[
"Subscriptions to scientific literature without taking out a loan"
] | [
false
] | Does anyone know of scientific journals (for me personally subjects pertaining to nature, geology, astronomy) that will not destroy all my funds. I'm also of course not talking about stuff like National Geographic or Popular Science :). It's not that I'm a cheapass or lack money its just things like this: I'm not abou... | [
"Well, there's always the ",
"Public Library of Science",
", which is probably the most prestigious open-access journal, or ",
"arXiv",
", but many articles in arXiv are pre-print and thus unreviewed, so be wary.",
"As far as paid journals go, those are intended pretty much solely for institutional subscr... | [
"You can probably get a membership to a university library. At my alma mater, it's apparently 50 bucks a year."
] | [
"Thank you, arXiv is a good Astrophysics source it seems (although the rest doesn't strike my fancy). The Public Library of Science doesn't seem to have much of what I want or lack, since I already have full access to PubMed.",
"The thing is of course that I'm old fashioned and love to read actual journals in my... |
[
"What species has the most generations alive at one time?"
] | [
false
] | I've heard sea turtles can live something like 150 years, but I don't know how often they reproduce, and I know rabbits reproduce pretty quickly, but what I'm really curious about is what animal/bug/whatever has the most alive generations at a single time. Are there great-great-great-great-great-great-great grandparent... | [
"Turritopsis Nutricula",
", also.know as the Immortal Jellyfish. Upon reaching 'death', it reverts to polyp stage and goes through life again. "
] | [
"So theres probably no way to know just how many generations there would be, if that even counts as a generation."
] | [
"Do we count bacteria?"
] |
[
"Can the equations of fluid dynamics be used to describe/model the flow of electrons?"
] | [
false
] | null | [
"In low-Reynolds number flow (slow or constricted flow), fluid circuits can be treated the same way as basic electrical circuits, with pressure instead of voltage, flow rate instead of electrical current, and a fluidic resistance that is analogous to electrical resistance except depends differently on geometry. The... | [
"Add to that the fact that the pressure-voltage analogy only works in horizontal flow with no change in section area. That's because the energy of a fluid can be stored as gravitational and kinetic as well as \"pressure energy\" (which is actually work done at the boundaries). To solve a hydraulic circuit, we have ... | [
"Almost. The incompressible, Newtonian Navier-Stokes equations for fluid momentum are very similar to the drift-diffusion equations that govern the electron/hole density in materials. One major difference is that the drift-diffusion equations also require solving the Poisson equation for the electric field inside t... |
[
"Just watched \"Sugar: The Bitter Truth\", how much of what is said about the hazards of fructose in this lecture is strongly supported by scientific evidence?"
] | [
false
] | So I just got done watching . (Its about 90 minutes long.) While he seems passionate and knowledgeable about the topic, he uses "shock and awe" words, makes causation out of weak correlation, and frequently falls back on conspiracy and anecdotal evidence. So my questions is just how much is what he said actually suppor... | [
"http://www.alanaragonblog.com/2010/01/29/the-bitter-truth-about-fructose-alarmism/"
] | [
"Fructose may not elicit an insulin response but it's byproducts certainly do. ",
"Source: I'm a type I diabetic and also a biochemist. If you need sources I'll pubmed it in the morning."
] | [
"The rebuttal shifts the argument mostly to the total caloric content, but to be fair, there ",
" a marked difference between fructose and glucose. Whether it's as significant a difference as Lustig wants to have is another question, but I think Alan went a little overboard on dismissing it.",
"Here some key di... |
[
"Heard an 'alarming' statistic for the first time this weekend... can someone please untangle this mess and explain? Water Vapor as Greenhouse Gas?"
] | [
false
] | I can't really recall what I was watching that mentioned this. Basically they were referring to water vapor in the atmosphere causing a positive feedback loop and having global temps rise as a result. To be honest, I had never heard of water vapor being described as a greenhouse gas, but after thinking about it a bit... | [
"Water is an extremely strong absorber of infrared light. It is the bane of my existence. It is present in almost every infrared spectrum ever measured.",
"So basically warmer planet --> more water evaporation --> more water in the atmosphere--> more infrared light being trapped --> warmer planet.",
"But the pl... | [
"Yes, it's widely accepted that water vapour is a greenhouse gas, and probably the most potent in the atmosphere. ",
"Wikipedia",
" actually gives not too bad a concise summary.",
"You got it right when you say that water vapour is a feedback response to temperature increase caused by carbon dioxide. In fact,... | [
"Yeah, the complexity is what got me. I started to read up on all of this and got a headache :)"
] |
[
"Why is pig tissue used for human transplants instead of monkey tissue?"
] | [
false
] | My sister made a snide comment at dinner, "isn't that interesting" implying it was evidence that we did not share a common ancestry with apes/chimps. I'm curious for information on tissue evolution and why pig tissue might be more compatible than our closer relatives. | [
"From ",
"the Wikipedia on xenotransplantation",
":",
"Pigs are currently thought to be the best candidates for organ donation. The risk of cross-species disease transmission is decreased because of their increased phylogenetic distance from humans. They are readily available, their organs are anatomically co... | [
"Tissue engineer here - the main reason for the use of porcine tissue as a tissue source is historically based on the intial experiments and due to tissue availability. ",
"If you are refering to acellular matrices, then the cells and most immunogenic components are removed so the species should in theory have li... | [
"The other problem is not compatibility, but rights. There are several well supported movements (from scientific and political standpoints) that are ",
"pushing to grant rights of \"personhood\" to great apes",
".",
"Killing them simply to cut out a heart valve is considerably closer to murder than with pigs... |
[
"At the cellular level, what is happening when we get callouses?"
] | [
false
] | I've been rock climbing a lot and I'm getting callouses on my hands. What is different in those cells? | [
"Just for more specification. Your stratus corneum is the outer most layer of your epidermis. It is comprised of dead epithelial cells. Your epidermis is composed of 5 layers, the outermost of which is the stratus corneum. The stratus corneum is essentially made up of dead epithelial cells that are keratinized. Fri... | [
"Further specification/clarification: Skin cells are actively dividing down at the basal layer, where the cells directly touching the basement membrane (a layer of non-cell connective material, we have different kinds of this stuff around all sorts of different organs). So these newly created cells are then being p... | [
"The friction causes the strateus corneum to develop."
] |
[
"How does the \"I am not a robot\" checkbox know I'm not a robot?"
] | [
false
] | null | [
"Mouse position, clicks, scroll, keystrokes(not all), screen swipes in touch screen displays, ip address, os, browser, extensions, resolution, fonts installed, timezone, language and some other stuffs I can't remember from the top of my head are detectable by sites without any permission. Caches and cookies are nor... | [
"The verification is based on many different factors such as-",
"Mouse movements, clicks and keystrokes: Many of the bots work by directly generating a click on a certain position of the screen or requesting a browser to send a click to a certain element of the website (button, link etc); they don't bring the mou... | [
"Wait, so if i make erratic mouse movements, or take a while to click the box, then i won't have to identify busses and fire hydrants for the machine gods' amusement?"
] |
[
"I read that the fastest way to thaw something is cold running water. Why is this so?"
] | [
false
] | null | [
"Water has a very high heat of fusion. That is, the energy to freeze the liquid or melt the solid is quite large in magnitude. So even if the water is cold, it still has quite a bit of ice-melting energy on account of it being a liquid.",
"Why running water? Because by constantly replacing the water there is a st... | [
"Ah, I remember now! This was the reason Alton Brown gives in \"Good Eats\". Thank you!"
] | [
"Care to share the source? I would suspect hot running water would achieve the same results, but faster."
] |
[
"Does the Doppler effect have any noticeable consequences on wireless Internet connection?"
] | [
false
] | Let's say I'm downloading a file and run towards my router at significant speed, will that make the file download faster, or cause errors? Does it matter whether the signal is AM or FM? | [
"Yes it can actually have a pretty significant effect on communications. ",
"In particular, if S(f) is the spectrum of your original signal, S(",
"f) will be the spectrum afterwards (PDF).",
" Here ",
" is relatively close",
" to 1, basically 1 - v/c where c is the speed of light and v the velocity of the... | [
"so, this is shift from reflections being out of phase with the original signal, due to a longer path, and those reflections changing with time due to the source moving.",
"If there were zero reflections, say I'm just in an open field with a router and my phone, would this effect still occur?"
] | [
"This is not the doppler effect.",
"You know, you are right. That is not the doppler effect. Yeah my bad. But I am not saying other factors, the doppler effect in and of itself still reduces the capacity of a channel in a multi-path environment in a way that does not occur with LOS.",
"The doppler effect in mul... |
[
"Is it possible there is a super nova we don't see yet within our galaxy, that is close enough to our solar system, that once it appeared would be bright enough to illuminate the night sky for the rest of human existence?"
] | [
false
] | This of course assumes that the event happened several hundred thousand years ago, and light from the event has not yet reached Earth. Based on a program I saw on TV the other night, it seems quite plausible, though the program did not attempt to paint this scenario at all. | [
"Supernovae don't last very long. The initial burst of energy can be as brief as only a few hours, depending on the type of supernova, (edit: but will often take weeks/months to burn out entirely).",
"So, taking IK Peg as an example, which is only 150LY away, we can do a little maths with known values to figure o... | [
"For Spica I used a magnitude of -17, since that's the typical absolute magnitude of a type 2. I guess maybe I should've mentioned that detail."
] | [
"Related:",
"The nearest star that could go SuperNova is 150 light years way, though one at 260 is more likely",
"That would be entirely possible then, though there would be some lead up to the event that we would notice."
] |
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