title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Can ducks glide in the air? I've never seen it, they're always flapping. If they can't, why not?"
] | [
false
] | null | [
"It's a matter of ",
"aspect ratio",
", the relationship between length and 'depth', i.e., the size of the wing at right angle to the length.",
"Short stubby wings have relatively low lift and as a result low drag, like a fighter aircraft. ",
"Ducks are fast",
", like fighters, and while technically both... | [
"I wonder how they migrate. Constant flapping must require extreme amounts of energy."
] | [
"From the evidence i can find, ducks don't have the right wing shape to glide, so they have to flap to stay in the air...\nthey can of course glide when they land, but only for short periods of time, they don't have an aerofoil wing so it is really mostly for slowing down that do it."
] |
[
"Does it honestly take more energy to make a solar panel than it will ever collect?"
] | [
false
] | I've heard countless rumours surrounding this and really would like to know what the reality of it is. I'm interested in the energy used in collecting resources, manufacturing, transporting and installing them. Strong references would be appreciated! | [
"What you are referring to is known as ",
"; how long it takes the solar cell to produce as much energy as it took to manufacture/install it.",
"Modern solar panels pay back in ",
"as little as a year",
", but ",
"estimates vary",
". ",
"However, solar cells are ",
"increasing in efficiency at a rem... | [
"Great help, thanks. Needed to justify a design involving solar panels to someone who insisted they took 20 years to do this! There's a lot of dodgy info on the internet surrounding this.."
] | [
"Needed to justify a design involving solar panels to someone who insisted they took 20 years to do this!",
"A consumer making a purchasing decision has a slightly different decision to make. If they are concerned about the environmental impact then the manufacturing payback might be intellectually interesting, b... |
[
"When they dropped 2400 tons of lead into the Chernobyl reactor, was there a \"breaking radiation\" (Bremsstrahlung) effect and why or why not?"
] | [
false
] | null | [
"Anytime you have fast electrons moving through matter, bremsstrahlung will occur."
] | [
"Adding lead doesn’t increase the total amount of radioactivity. Lead is a good material for shielding, although certain types of radiation will produce secondary radiation within the shielding. Lead also shields against bremsstrahlung, so it’s somewhat self-shielding.",
"Bremsstrahlung is a side effect of the de... | [
"If that's the case, when they threw the lead into the reactor to cool the temperature, didn't they also cause a lot more radiation? Is this where the elephant's foot came from?"
] |
[
"Is birth order romantic compatibility pseudo-science?"
] | [
false
] | null | [
"You can rest assured that there is no science to this. It is one step away from horoscopes and numerology."
] | [
"Well, yes and no. I tried looking up some studies to check this out, and there are plenty of studies that examine the effect birth order can have on individuals. However, they are hugely vulnerable to selection bias, small sample sizes, lack of experimental controls, etc. ",
"This was the only one I saw that add... | [
"Maybe not romance per se, but some studies have suggested a role for birth order in ",
"sexual orientation",
". All of them are to be taken with sizable grains of salt."
] |
[
"If amino acids can only be recycled, how were the first ones created?"
] | [
false
] | null | [
"I am not sure who told you that amino acids can only be recycled, but it's not true.",
"http://en.wikipedia.org/wiki/Amino_acid_synthesis",
"Humans can only synthesize 12 of the 20 we require, maybe that's what you're thinking of?"
] | [
"It depends on what you mean by \"the first ones.\" The first ones you are I ever had were provided through nutrients given to us by our mothers. The very first ones ",
" on the other hand, is a different matter. And it goes back to the origin of life hypotheses, which I'll give you a brief rundown of through a p... | [
"Just to complete this: Humans synthesize 13 of the 22 aminoacids that we use (though only 21 are used in proteins, and only 20 are encoded in our genetic code). The remaining 9 (which are called \"essentials\") are either recycled or obtained from diet. Plants, for instance, are able to synthesize all of them. "
... |
[
"We know the universe is (very nearly) flat. Does this imply it is infinite and, if so, why?"
] | [
false
] | Does the knowledge that the universe is flat make it more likely that it is infinite? If so, why and to what extent? Are we certain that it is infinite, or is it just an assumption that makes the math easier without deviating from the experimental evidence? I understand that flatness refers to a lack of geometric cur... | [
"It's not an assumption of math but one of philosophical input into our science. We choose to believe that physics doesn't change with location in the universe because to assume otherwise is unnecessary complication. We haven't seen any evidence that the laws of physics vary, and we philosophically choose to keep t... | [
"If it can't be measured, even in principle, it's simultaneously not in our universe and not scientific. If you want to believe in other universes, you are free to do so, but it's not a belief supported by science.",
"Why is it unreasonable to assume the laws of physics of this universe do not hold outside this u... | [
"Thanks so much, this helped immensely!"
] |
[
"Is it possible to use other hadrons to catalyze nuclear reactions akin to photocatalysis of chemical reactions?"
] | [
false
] | A bit of background: My quantum mechanics course was in the chemistry department and pertained specifically to interactions within electromagnetic force. Sometimes photons are used to put reactants into an excited electronic, vibrational, and even rotational state that has the lowest kinetic (as opposed to thermodynami... | [
"This is usually done either with proton beams or the neutrons from nuclear reactors, often to produce medical isotopes. You can read about some of the processes ",
"here",
"."
] | [
"However we can certainly populate excited states in nuclei.",
"Can you clarify? Do you mean like a population inversion, or in a more chaotic way? You can produce excited rotational modes in CO by heating. If you use a laser, you can selectively excite the entire population exclusively in rotation such that 100%... | [
"However we can certainly populate excited states in nuclei.",
"Can you clarify? Do you mean like a population inversion, or in a more chaotic way? You can produce excited rotational modes in CO by heating. If you use a laser, you can selectively excite the entire population exclusively in rotation such that 100%... |
[
"Why do we feel pain after a few seconds rather than instantly?"
] | [
false
] | For example, when I stub my toe I feel my toe come in contact with the object instantly, but the pain only hits in after a few seconds. Are there different receptors, and if so, how much of a delay does pain have? | [
"Pain impulses travel at 0.61 m/s. So, if you are 6 ft (1.83 m) tall, the pain impulse takes about 3 seconds to reach your brain. Other impulses, such as those for touch, travel more than a hundred times faster, so you notice touch virtually immediately. ",
"(Source at the bottom)"
] | [
"That's kind of incorrect. Your pain nerves synapse in the spinal cord as part of the reflex response. When burned you pull your hand back faster than you realize you are in pain b/c as soon as the pain sensation reaches the spinal cord it sends a signal through interneurons to the motor neurons of the affected lim... | [
"That's kind of incorrect. Your pain nerves synapse in the spinal cord as part of the reflex response. When burned you pull your hand back faster than you realize you are in pain b/c as soon as the pain sensation reaches the spinal cord it sends a signal through interneurons to the motor neurons of the affected lim... |
[
"Can Carbon Fiber be Recycled?"
] | [
false
] | null | [
"In principle you probably could. But with recycling questions it's usually a matter of whether it can be done economically. I don't really have any specific knowledge here, but offhand I'd lean towards \"no\". Because to do so, you'd have to destroy/dissolve the epoxy resin they get baked in, which'd be complicate... | [
"Carbon fiber is made up of carbon fibers embedded in a resin. To recycle it, you must first separate the carbon from the resin (extremely difficult because the resin completely impregnates the fiber cloth like water on cotton), then you must somehow recycle the resin bits left over. The resin is cured epoxy, so it... | [
"Yes it can. ",
"While it is difficult as stated by previous comments, Trek has already started it's recycling plan. ",
"http://www.cyclingnews.com/news/trek-embarks-on-ambitious-carbon-fiber-recycling-program",
"*** sorry for the full link, I'm on a mobile at the moment. ",
"I also remember Specialized doi... |
[
"How real are \"biorhythms\"? Can individual people be \"nocturnal\"?"
] | [
false
] | Is it true that some people are just more active at night, or is it most strongly tied to behavioral things that can change over time? | [
"Biorhythms",
" have no scientific support whatsoever. For those unfamiliar with the idea, it was a pseudoscientific fad that claimed to predict your \"physical\", \"emotional\", and \"intellectual\" state, assuming that the three factors oscillated with 23, 28, and 33 day periods, respectively, beginning at your... | [
"Just want to add that while the regularity of the circadian rhythm can remain stable in the absence of exogenous cues, it will be altered in their presence. The suprachiasmatic nucleus interprets retinal signals to determine the time of day, and either inhibits or allows pineal melatonin production accordingly. W... | [
"Inability to \"fully adapt\" is usually due to people with monday-friday night shift schedules wanting to participate in daylight (\"normal people\") activities during the weekends, being exposed to sunlight on their drives home, and other cases of not fully adjusting to the schedule in the first place. ",
"Blue... |
[
"Why were some satellites and inter-planetary spacecraft deployed from the space shuttle, while others were launched alone?"
] | [
false
] | It seems like taking a satellite up in the shuttle would be a very inefficient way to put it into orbit, compared to simply launching the satellite on its own rocket. I understand why the shuttle is necessary for servicing missions, and also why it could make sense for releasing very small satellites (when the economi... | [
"At least at the beginning, the Space Shuttle could carry bigger payloads than most carrier rockets (except the Saturn V, for example, which was prohibitively expensive). In fact, the payload bay was designed specifically to accommodate a ",
"spy satellite",
". As other rockets improved in capacity and reliabil... | [
"I guess we just have greatly varying intuitions about the cost of developing a rocket which could lift 24,400 kg to LEO--but is otherwise conventional--when the Titan IIID (12,300 kg to LEO) and Saturn V (119,000 kg to LEO) already existed. In particular, I still can't see why you wouldn't develop the rocket dur... | [
"The intention of the space shuttle was that being re-usable it would be cheaper per launch.",
"The practice is that it was designed by committee (DoD had specific requirements for it (as linked above)) and with the overhead of carrying people and the refurbishment required for turnaround it was an incredibly exp... |
[
"Have I really messed up my gel?"
] | [
false
] | null | [
"I must preface this with the fact that I have never left a gel overnight so this is what I think might happen. First, what kind of data do you need to get from the gel? Are you simply checking for confirmation that the PCR worked? Or do you need to be able to tell the size of the bands? If it is the first you migh... | [
"My only experience is with Gel Red, but I assume this holds true for everything else.",
"1) Even if it has kinda died, you don't need to start over - you can just restain the gel. If you work in a lab, someone will know how to do it; if not/you can't find anyone, protocols should be online.",
"2) That said, 99... | [
"did you load your entire PCR reaction? If not, just make a new gel/run it, it should only take an hour tops."
] |
[
"How often is obesity actually caused by genetics?"
] | [
false
] | null | [
"Obesity is strongly influenced (not caused per se) by genetics and epigenetics (gene-environment interactions), and I certainly wouldn't say that the differences are marginal between \"obese genes\" and \"skinny genes\". Witness the stronger correlation of BMI and fat mass between an adoptee and their biological ... | [
"It's almost too obvious to mention, but of course another environmental factor is that no amount of obesity genes will cause obesity if you live in an environment where calories are limited. Whether one focuses on genes or environment as the \"cause\" of obesity really depends on what group one is looking at. Wh... | [
"Appetite certainly is regulated by environmental factors; however, the complex biochemical mechanisms that underpin it are delicately balanced and prone to dysruption. For example, maternal high-fat feeding during pregnancy induces fetal resistance to leptin (a key \"satiety\" molecule), disrupts the opioid and d... |
[
"What does the yoke on Boeing planes do while landing?"
] | [
false
] | Watching many landing videos on Boeing planes (737MAX, etc.) it looks like the pilots are moving the flight yoke as if they are playing an arcade racing game (in and out, left to right); yet the planes themselves are flying straight. What’s with all the yolk movement? | [
"At low airspeeds, larger control inputs are required to affect a change in direction. As such, the pilot's actions seem much more exaggerated.",
"Additionally, in slow flight the aircraft's speed is controlled by attitude (pitching up or down). Altitude is controlled with the throttle. When landing, precise cont... | [
"There are a number of factors that may make it appear that big control movements don’t appear to do much (but they do). ",
"First, our perspective is typically smaller vehicles, like cars. Turn the wheel on a car and it responds right away. The tires are also physically contacting th ground, so there is lots of... | [
"They are dining all those control inputs so the plane keeps flying straight. If you were to watch the control surfaces instead of the plane you could see them move a lot. Also b because of the low airspeed larger adjustments are needed for a desired effect, there is a lot less air being deflected, so the deflectio... |
[
"Why is sound-proofing so much harder than light-proofing? Both are waves, right? KINDA?"
] | [
false
] | Like why isn't there a paint that does to sound what does to light? Why can a sheet of tinfoil block basically all light but there isn't a material that does the same thing to sound? Is sound just higher energy than visible light and I am comparing sound waves to the wrong types of EM radiation? | [
"Why can a sheet of tinfoil block basically all light but there isn't a material that does the same thing to sound?",
"It's known as an ",
". If you look at one you'll see the walls, floor, and ceiling are covered in foam points that act to absorb the sound, not unlike the nanostructure of vantablack. But those... | [
"Sound waves are pressure waves while light is electromagnetic wave. \nSound requires medium to propagate and that medium exerts pressure on whatever it strikes. Hence you need very efficient dampers to completely absorb all pressure exerted on it. In case of light, it is just absorbed in form of energy by electron... | [
"Microwave or radio wave radiation is the same size as or bigger than sound and it can travel through walls. If it didn't you couldn't listen to a radio or get WiFi, bluetooh, or LTE unless the source was in the same room. "
] |
[
"Why can you only recharge lithium-ion batteries? Why can't you recharge alkaline batteries?"
] | [
false
] | What is preventing the opposite redox reaction from occurring in alkaline batteries in order to restore their chemical potential energy? Any links to articles are also helpful. | [
"You actually ",
" recharge alkaline batteries a few times, but they have an annoying tendancy to blow up, and you can only do it a few times anyway (with rapidly decreasing capacity each time).",
"Most chargers won't do this correctly, though - ",
".",
"Edit: I just discovered that chargers specifically f... | [
"It is worthwhile to note most batteries can blow up, not just alkaline ones. Batteries are really scary, don't mess with them too much"
] | [
"If you think about it, really anything that has high potential energy is dangerous"
] |
[
"What would be the effects of creating a room temperature super conductor?"
] | [
false
] | I've heard that a super conductor that can operate at room temperature is a sort of "holy grail" in physics, but what ramifications would it have on the world if one was to be made? | [
"If we had wires that could carry practically infinite amounts of current without heating up we would be able to build incredibly strong magnetic fields, much stronger than those created by the liquid-helium-niobium-titanium-superconducting-magnets that are used in tokamaks or experimental fusion reactors.",
"You... | [
"It would pretty much revolutionize science and engineering as much as the discovery of electricity. Room temperature superconductors have applications almost EVERYWHERE in the realm of electricity. Some of the advantages would be:",
" We would have ZERO losses in power transmission. This would eliminate the need... | [
"Well, you are implying that the superconductors would be as cheap as normal conductors today, and it is way more likely that they will be much more expensive, which changes how it could be used (e.g. I don't think we would use it for power transmission for a long time after discovering it)."
] |
[
"What is the placenta and umbilical setup in mammals that give birth to multiple young and how does it vary from single pregnancies?"
] | [
false
] | This photo over on had me realising I have no idea how animals like dogs have their fetus lifelines arranged. | [
"In mammals with larger litter sizes, ",
"uterine horns",
". However, the blood vessels flow through the entire length of the uterine horn before going back into the rest of the mother's circulatory system. This has an interesting consequence.",
"But first, a word on sex differentiation. The basic model for h... | [
"With twins, each one has its own umbilical chord, have separate amniotic sacs but identical twins share the same placenta, and non-identical twins have separate placentas. Although it is possible for identical twins to share an amniotic sac, in which case they are referred to as Monoamniotic twins. Even the mono... | [
"so in all possibility it wouldn't account for all cases of animal homosexuality (and maybe even not all female homosexuality), am I interpreting this correctly?",
"Yikes. Well, I didn't really say anything about homosexuality, per se. I don't think we have a very well-studied animal model for consistent lifelong... |
[
"when I get a muscular spasm, is it my brain sending bad information, or my muscle just tired of doing nothing ?"
] | [
false
] | null | [
"In general, your brain is sending bad information. However, there could be multiple causes. All that is needed is a sufficient buildup of potential somewhere along the nerve pathway to the muscle in question. This will trigger a nerve impulse and cause the muscle to twitch.",
"The root cause could be your tired ... | [
"When you are low on magnesium, acetylcholine production is not inhibited in you neuromuscular junctions and it is ACh that is responsible for initiating a muscle contraction. So you have too much ACh and your muscles start spasming/cramping. \nIt can also be psychological (and often is)."
] | [
"So why do I twitch a lot when I'm stoned? Especially around my legs"
] |
[
"Why do objects further away from us look smaller?"
] | [
false
] | null | [
"Because the angle of observation is much smaller than with a near object. This is especially important since our high-tech 3D eyes are very close to each other and fail to give you an accurate feeling about objects that are further away. So the brain relies on two kinds of information; the first is what you know, ... | [
"I believe the term for that is called \"Parallax\" if i'm not mistaken. Pretty cool concept of physics."
] | [
"No, parallax is an apparent change is position that has not actually occurred. Perspective would probably be more appropriate."
] |
[
"How is fractal compression different from how a normal file lie a jpeg is compressed?"
] | [
false
] | I really have a poor understanding on what fractal compression is doing, and how such a method of compression can even be done, and why isn't it being done more. | [
"Fractal compression is largely a fad that is over. The idea was that self-similar portions of images could be used to describe functions that would render the image and that the remaining noise could be tolerated or encoded with fewer bits [for lossless codecs].",
"The problem is it was slow and didn't really p... | [
"JPEG uses a 2 dimensional 8x8 DCT transform. This stores DC components in the top left (0,0) part of the 8x8 block and high AC components towards (7,7). ",
"It turns out for photos most of the information we care about is in the low frequency portions of the DCT output (which defines the tone of the 8x8 block)... | [
"Essentially if you work out that a bunch of bits of an image look similar you could generate a fractal codes which are then used to recreate the image later.",
"Its compressed because you save the fractal code rather than the data itself. When viewing it again you just work generate the image again with the code... |
[
"Can putting a hot spoon on a mesquito bite denature the protien to lessen the allergic reaction?"
] | [
false
] | [deleted] | [
"According to ",
"this paper",
", immunoglobulins (specifically IgG), the stuff that binds to the antigens introduced by a mosquito and cause swelling, start to denature at around 60°C (see page 401), which is probably not a safe temperature to expose your skin to.",
"As for your second question, it would tak... | [
"Antibodies (or immunoglobulins) don't cause the swelling, and you wouldn't want to denature them since they help your body neutralize the foreign agents introduced by a mosquito bite. AFAIK histamine (what causes the itch) is pretty heat-resistant. That's why heat ",
"doesn't inhibit",
" histamine-induced itch... | [
"Good answer, thank you.",
"I am unsubscribing from ",
"r/LPT",
"... Good idea, but garbage in practice."
] |
[
"Why is silver used for mirrors? Does it have a color?"
] | [
false
] | Other shiny things reflect, but tinted in the color of the material (I guess), like the Vietnam Veteran's Memorial. Chromed things are like mirrors, why not chrome? Also, what's the glass for? | [
"Also the glass acts as a cheap substrate. Before the technique of silvering glass was discovered, you would have just polished a flat piece of silver, which would have to have some thickness to keep it flat. Even if you tacked it onto a flat piece of wood it would still have to be thicker than foil to be any good.... | [
"most metals reflect really well because the free electrons in the metal can vibrate in response to a lot of different wavelengths of light that are incident. That's why most metals are some sort of neutral color. ",
"Next, light bounces off of any surface, especially if the surface is opaque(so that some light c... | [
"The glass is prevent tarnishing/oxidation."
] |
[
"When did the first sexual reproduction take place, and between what kind of organism?"
] | [
false
] | [deleted] | [
"First sexual reproduction and thinking doesn't really go hand in hand. It was 100% more instinct like, since it there were barely any nerve cells in those organisms. If I recall correctly, I think that first sexual reproduction was with subregnum Thallobionta, with Algaes. To be specific, first evolved were probab... | [
"Sexual reproduction is thought to be ancestral to all eukaryotes, so it would have evolved sometime before 1 billion years ago. The ancestor of all eukaryotes would have been unicellular, so there definitely wouldn't have been any thinking involved."
] | [
"We don't know for sure how sexual reproduction came about, nor which organisms where the first to do it. However, I can assure you that it was nothing like two organisms just deciding they could bang. ",
"I mean, think about it, sexual reproduction is an incredibly complex process, there's a million thing that n... |
[
"What is the meaning of negative and positive current?"
] | [
false
] | [deleted] | [
"Conventionally, the direction of the current is given by the direction that positive charge would flow, even if the charge carriers relevant to your system are negative (as is often the case).",
"My question is, is the current negative because of the sign of the charge or because it flows in the opposite directi... | [
"It is a convention that everyone agrees to use to avoid ambiguity. At some level it is arbitrary. Just like the \"dq/dt\" notation, if a different person was more famous, we'd write it in a different way but it would mean the same thing."
] | [
"Ultimately, it comes down to the fact that charges were named before we knew what they were. Benjamin Franklin was actually the one to originally propose our definition of positive and negative, based on the charges separated by rubbing silk on glass. ",
"It just happened that the main charge carriers in metals ... |
[
"Does the human eye see in pixels?"
] | [
false
] | null | [
"In a sense yes in that you have a ",
"mosaic",
" of ",
"photoreceptors",
" that are sensitive to photons much like the sensor in a camera (see also ",
"this",
" and ",
"this",
" image). However, the photoreceptors do not send signals directly to your brain. In front of them (i.e. closer to the fron... | [
"I know you're a real scientist because you called the figure \"a cartoon\"."
] | [
"If you say \"cartoon\" you are acknowledging in the talk that the figure you are about to show is simplified, and misses out key details for the sake of ease.",
"Not that it stops some pompous knob from saying \"I noticed in your figure that the mixing propellers were cylindrical, is this the actual set up of th... |
[
"Does sociopathy exist in other species than humans?"
] | [
false
] | null | [
"I think that would largely determine what criteria you used to define sociopathy. It's such a vague concept it's next to impossible to quantify. ",
"Narcissism as a defining trait is beyond the capacity of most animals (though cat lovers might disagree). But killing or maiming without the burden of empathy is la... | [
"I was thinking about the like of not feeling empathy for animals from their own species. Like a Lion killing another Lion without any reason (no food to steal, no female or anything), or animals deliberately torturing another animal?",
"Because I think most of the time the killing without empathy is \"justified\... | [
"First, sociopathy is not considered an actual disorder in the current DSM (i.e., the DSM-5). Yes, we can argue all day about the new DSM but let's just move on for now...",
"The primary cluster I think you are interested in is Personality Disorders under which you will find Antisocial Personality Disorder, Avoid... |
[
"Since antimatter is matter made from the corresponding antiparticles for protons and quarks can exotic antimatter exist hypothetically?"
] | [
false
] | null | [
"Any kind of exotic atom you want to make with regular matter, you can replace each particle with its antiparticle, and you can in principle make that too."
] | [
"Exotic antimatter can certainly exist."
] | [
"great! but could you elaborate on that?"
] |
[
"Why arent flywheels used more to store energy for electricity?"
] | [
false
] | Flywheels have many attribute which make them suitable for storage of energy, theyre better than batteries in many ways - The possible applications to store intermittent renewable energy got me thinking about this. Does anyone know why they arent used more to even out intermittent electricity grid supply/demand? | [
"Cost and mass. Everything is about cost but the mass required to have the same stored energy as the chemical energy in a battery would require it to move very fast. Fast moving heavy objects introduce significant stresses and if a failure occurs its like a bomb going off. Also these things cant be carried aroun... | [
"Safety limits their application. When they fail catastrophically, all their energy is released, and there's no way to avoid that. A 16 gallon tank of gasoline has 2.1GJ of energy, equivalent to half a ton of TNT, not what you want released all at once. ",
"A practical flywheel application is storing the electri... | [
"Also these things cant be carried around like a battery simply due to velocities required and stresses induced for any amount of energy in a small package.",
"would the gyroscope effect be an example of this?"
] |
[
"how random is genetic recombination?"
] | [
false
] | so, in meiosis, two homologous chromosomes get shuffled together into two new chromosomes. all the same genes are there, and in the same order, just randomly on one or the other chromosome. i know there's some stickiness involved, so bits of DNA located next to one another on a chromosome are likely to stay together du... | [
"For an individual meiotic event, there are relatively few recombination events per chromatid (it varies by organism, but something like 5 is reasonable). They will occur at mostly random intervals along the chromosome. It is random enough that genetic mapping is able to assume randomness to calculate distance be... | [
"Recombination hotspots exist. These are lengths of DNA in which recombination is far more likely to occur than in surrounding DNA. This cuts down the randomness of the process."
] | [
"/u/Sluisifer",
"'s response is good, but in this case a picture is worth a thousand words. ",
"Recombination events in a single human sperm cell.",
" As you can see, most chromosomes only have one or two crossovers. This is true for all people, but the specific position of the crossover is almost random.",
... |
[
"Came across this \"fact\" while browsing the net. I call bullshit. Can science confirm?"
] | [
false
] | If you have 23 people in a room, there is a 50% chance that 2 of them have the same birthday. | [
"Well, if there are 23 people, there is actually a 50.7% chance that 2 of them have the same birthday, assuming that the 365 possible birthdays (not counting February 29) are all equally likely. But 23 people are the minimum number of people required to have at least a 50% chance.",
"This is the famous ",
"birt... | [
"The unintuitive nature of the problem goes away when you consider that while there are only 23 people in the room, there are actually 253 unique pairs of people in the room.",
" ",
"/u/midtek",
" is correct that each trial is not independent, which also needs to be accounted for to calculate the exact proba... | [
"This is absolutely correct. It's called the ",
"Birthday Problem",
" and it's a well-known counter intuitive result. The reason it's counter intuitive is that since there's 365 days in the year, there's only a 1/365 chance that a random person has a birthday on a particular day; so, if you look pick a random p... |
[
"Are spiking artificial neural nets and integrate-and-fire neural nets the same? What about firing rate neural nets?"
] | [
false
] | Am absolutely baffled trying to find this out - my current guess is that integrate-and-fire is a subset of spiking and different to firing rate but am desperately confused. Any help guys? | [
"Typing on phone, but this question has been unanswered for two days.",
"In short, your intuition is correct. Integrate and fire (int) neurons sum up spike inputs, perhaps with a weight attached, and fire if their inputs over a time window exceed some threshold. Thus, they are a subset of spiking neurons/neural ... | [
"(posted to save my work, continuing here)\nRate based networks use the rate of firing as their preferred form of informational output. The contrast with spikes is the use of spike rate rather than the spikes themselves. In a noisy system, this can be more reliable."
] | [
"Some good sources if you need guidance would be:",
"http://www.izhikevich.org/",
" \nThis site features some good model examples and comparisons, and I think links to some of his papers detailing single neuron models.",
"Rieke et al., ",
"\nHighly regarded text on spikes and the information they convey.",
... |
[
"How do we know if radioactive decay is random?"
] | [
false
] | I've been thinking, how do we know if something is random? For example 20939, 2189203, 192190 may seem random, but the pattern could be +2168264, -1997013, +1 and the next term is 192191 | [
"If you model a truly random, independent process, the histogram of the frequency of that process occurring should be a Poisson distribution. ",
"If you watch a large chunk of radioactive material for a sufficient time, it tends asymptotically towards a perfect Poisson distribution. ",
"I don't know if that's p... | [
"Bell's Theorem proves that there aren't unseen local variables. There could be non-local variables, but I am unsure how those could ever be tested for. \"Non-local hidden variables\" include things like a guiding wave function intrinsic to the universe or an omnipotent god deciding all outcomes. While none of the... | [
"Doesnt Bells theorem prove that there cant be unseen variables affecting it?"
] |
[
"How can it be that electrically neutral atoms can have any electron affinity at all?"
] | [
false
] | It's something that really puzzles me. I know that without some kind of electron affinity, chemistry would be impossible, but when you consider that atoms in their natural state are already neutral, (i.e. they have satisfied their protonic hunger for electrons) it seems counter-intuitive to think that they would want e... | [
"The best explanation for the octet rule and the trend for electron affinities involves an understanding of effective nuclear charge. An approximation to calculate effective nuclear charge is the nuclear charge (atomic number) - core electrons (number of non-valence electrons). We can think of this as the \"effecti... | [
"The overall atom might be neutral, but the nucleus is still positive and an electron's net energy release from being put near the nucleus outweighs the extra electron repulsion that this creates. On the other hand, second electron affinities are typically negative because the electron must approach an atom that al... | [
"So can I think of it like the following then: The outermost electrons don't experience the full charge of the nucleus, because of the shielding effects of core electrons, and by conservation laws the nucleus does not feel the full negative charge. As a result, the +ve nuclear charge is not completely 'quenched' by... |
[
"Does lying to a patient about survival rates of a disease affect said survival rate?"
] | [
false
] | e.g. for a cancer with a survival rate of 15%, would telling the patient they have a survival chance of 90% improve their odds of survival through the placebo effect or otherwise? | [
"I've never seen any research into this particular topic because it would be completely unethical, but the research on positive thinking and breast cancer says there is no relationship between positive thinking and survival rates. Positive thinking might improve your quality of life while you are dying, but it can'... | [
"I’m not sure if this scenario has been studied, but that Pygmalion effect is similar to what you’re talking about. One of the most famous studies around this has to do with teachers with higher expectations for certain students then caused those students to perform better, like self-filling prophecy.",
"https://... | [
"If I’m not mistaken it’s illegal, due to Doctor-Patient Trust. You cannot lie to a patient about what disease they have, their treatment plans or survival rates. No matter if it affects their survival rates or not.",
"Basically it breaks Ethical boundaries and is frowned upon."
] |
[
"How would we know if time rolled at different speeds in some parts of space?"
] | [
false
] | Let's say something dilates time through its gravity, could the time dilation be tracked and measured somehow? I'm a complete layman, so don't take anything I say as deliberately offensive or misinterpreting or anything, but could we see if a faraway planet distorts time through a Doppler shift that doesn't correspond ... | [
"Doh, I didn't read your full question before replying. I shouldn't be allowed to play out when I'm tired. Feel free to download vote the ass out of my reply, as it doesn't really address the question. ",
"In regard to your actual question... I don't think you could measure time dilation this way. Although I ... | [
"Don't know who downvoted you, this stuff seemed related enough to my question...",
"Anyway, yeah my headache returned so I can't remember what I wanted to ask next. Thanks for the info for now!"
] | [
"I down voted myself for not paying attention "
] |
[
"How do you estimate the age of the oldest live organism on the planet?"
] | [
false
] | Every time I read of such a coelacanth or whatever marine creature is 200 years old, I cannot help wondering what is the science behind it. How can you know how old that thing could be with external observation and what I would expect to be quite simple models (I may be wrong). I could understand a few ways if the orga... | [
"They don't understand the question.",
"To determine the age of a LIVING organism, there are probably any number estimates used depending on what is already known about the species. For example, you might be able to look up how big a certain kind of shark \"usually\" gets over a certain amount of time, and then m... | [
"That makes sense for trees. I was daft. Of course we could get a core sample and do something with it. Maybe they use ash cloud deposit as for ice samples. ",
"Thanks for the reply."
] | [
"If you use carbon dating, or any other other atoms which isotope ratio gives you the right accuracy based on your prior regarding the age of the organism , how do you know this element was in the organism since its birth?"
] |
[
"If you were exposed to a fatal dosage of radiation, would you be able to feel any effects immediately?"
] | [
false
] | After reading about criticality events and other radioactive accidents, I was curious if the human body would be able to "feel" large amounts radiation entering and affecting the tissues at the time of exposure | [
"Yes you would. Depends on the dose. I will refer you to a past answer.",
"Past Answer"
] | [
"Wikipedia reports a few Immediate effects",
"\nincluding nausea and vomiting, Diarrhea, Headache, Fever and Nervous system impairment within an hour.",
"In terms of instant effects, there seems to be reports of a Metallic taste, though I can't find any explanations of why this is. If this fatal dose is deliver... | [
"Nationl Gorgraphic has a documentary on sub disasters, and they talk about this. On a russian sub, two sailors who had went to fix a leaked reactor immediately showed signs: vomitting, skin burns, etc.",
"The doc is on netflix."
] |
[
"why cant PH be greater then 14?"
] | [
false
] | why cant ph get above 14? as i understand it ph is just the inverse log of the number of hydrogen ions. for example in water a hydrogen ion occurs 10 of the time, with the inverse log of that being 7 so it gets a 7 on the ph scale. if something had a hydrogen ion occur in say 10 wouldn't it be 15 on the ph scale? | [
"You are correct, pH can go higher than 14 as well as lower than 0, we just use the 0-14 scale since most solutions fall into that range."
] | [
"That's just wrong.",
"First of all: the \"leveling effect\" only describes that a acid in water cannot be a stronger acid than \"H3O+\" itself. This has nothing to do with the pH of a solution.",
"2nd: If you have a 1N HCl solution you have a pH of about 0 (and a pOH of about 14). If you are >1N the pH is bel... | [
"Corrected the misinformation, my apologies."
] |
[
"Is there an understood neurological difference between imagined vision ( mind's eye ) and actual sight?"
] | [
false
] | How can I see something with my visual cortex and simultaneously imagine a different image? Where in the brain does the imagined image reside if my visual cortex is occupied by having my eyes open? (I apologize for any misconceptions I probably have about the neuroscience of vision...) | [
"There are some recent studies that indicate that imagery seems to activate similar populations as actually seeing the object, at least in higher visual areas (e.g., ",
"Stokes et al., 2009",
", ",
"Cichy et al., 2012",
"). In both of these articles, if I recall correctly, they are seeing to what extent act... | [
"I believe in the second paper I cite, they find some comparable activation in early visual cortex when imagining as when actually seeing. ",
"Cells in early visual areas (e.g., V1, V2) have small and highly selective receptive fields. Higher-level visual areas are more categorical in their responses. For example... | [
"I'm curious about similarities to sensory and motor cortex. Brain-computer interfaces are based on the fact that motor imagery elicits a nearly identical motor cortical response, and there has been work using other sensory imagery as well; for example, I worked with patients with subdural electrode grids placed ov... |
[
"If someone becomes incredibly obese, does their body create more nerve cells to cover their increased skin surface area?"
] | [
false
] | I hope that question makes sense. Basically, at normal weight I have nerve cells evenly dispersed across my body. However, what happens to those cells as I gain weight/more surface area? Does it just make more of the same cells? | [
"I am no expert in the field by any measure, however I distinctly remember hearing something about neurons stretching as an individual gains weight. ",
"Based on some information I have located the answer is yes. While I imagine that there is some neuro-genesis that takes place to create a few new neurons - they ... | [
"Typically neurons in the peripheral nervous system are finite and the human body doesn't grow new ones after a certain point in development. Injured neurons can regrow in rare circumstances, but usually take a long time if they succeed at all.",
"Most of these neurons synapse in nuclei inside your spinal chord a... | [
"What about the converse? Do you suppose that if they rapidly lost a lot of weight, would those stretched-out neurons be packed into a tighter space, and then would that equate to more sensitivity? "
] |
[
"What makes surfaces shiny?"
] | [
false
] | What creates the difference between matte surfaces and shiny surfaces? Is this just a physical aspect, or is it also something molecular? | [
"There are two main things (both of which you point out, but I am going to define them differently).",
"1.) The first is what I believe you mean by \"physical aspect.\" This is essentially roughness. Imagine that the surface is made up of a whole lot of very tiny mirrors. When a ray of light hits the little ti... | [
"There was a thread last week where this was discussed. I am not sure how successful this will be incomparison, but I'll try. It gets confusing because reflections is difficult to describe using the \"light as a particle\" approach as opposed to \"light as a wave.\"",
"Essentially, the photon strikes a surface ... | [
"Thank you for your detailed explanation! ",
"But, I'm also curious about the mirror effect itself; what makes photons reflect off surfaces? What causes this mirror effect? Not just in shiny surfaces, but also in mirrors themselves."
] |
[
"Could genesis have happened more than once on Earth? Could it still be happening?"
] | [
false
] | null | [
"I assume you mean ",
"Abiogenesis",
", the formation of life from non-life, in which case: Yes and yes.",
"Of course, we first need to ask the question: What is life? Which is a sufficiently difficult question that there is not, as yet, a generally agreed upon definition.",
"Furthermore, we have absolutely... | [
"That's a difficult question to answer. Technically the answer is yes to both questions, because the 'building blocks' of forming 'life' are all around, probably more so now than ever. The problem is that when 'life' (I use quotes because what originally existed probably wouldn't be what we traditionally consider l... | [
"Existing life making it hard for new life to survive for very long is only after it happens, so it doesn't really make it impossible, just very shortlived.",
"The current atmosphere being different is not really relevant, for several reasons:"
] |
[
"Why do different molecules affect the brain in the same way?"
] | [
false
] | [deleted] | [
"The simplest explanation is thinking of it as a “lock and key” mechanism. The target protein in the brain is like the lock, but it will accept a bunch of different shapes of keys (and will have the same effect) as long as the functional part of the key that fits is there"
] | [
"That's right. Basically, there are receptors that are looking for certain patterns and accept anything that meets certain criteria, which is usually a range of molecules.",
"\nThis is basically just like in chemistry, where a molecule might be accepting of all kinds of atoms because of its electron count. For ex... | [
"In addition, meth and Adderall don't have exactly the same effects. Just very similar."
] |
[
"Why do birds dive-bomb in front of my tractor while I cut grass?"
] | [
false
] | null | [
"Speculation, so feel free to delete with my full understanding mods. My hypothesis would be that the tractor is disturbing insects just ahead of it and driving them out of the grass - so you have an invisible bow-wave of bird-attracting tasty morsels just ahead of you.",
"But this a hypothesis you could test, wi... | [
"That makes sense to me!"
] | [
"Catching insects?"
] |
[
"Why we don't fall in love with the people we grow up with?"
] | [
false
] | I'm doing a research on incest and I remember reading a scientific phenomenon that prevents siblings from developing feeling with each others but I can't recall the name of the law. Can someone help me with that? | [
"I actually don't know much about it myself, but Redditors much more intelligent than myself have brought up solutions.",
"-I've read someone mention the \"Westermarck\" effect, which causes someone to become psychologically unattracted to those they spend long amounts of time with in childhood.",
"-Another Red... | [
"http://en.wikipedia.org/wiki/Westermarck_effect#Westermarck_effect",
"That one?"
] | [
"does this possibly explain why certain people also seem unattractive because they remind you of family? I can't look at girls with brown, curly hair without thinking of my sister, so i dont' think i'll ever be attracted to them. It's always seemed weird to me."
] |
[
"Gravity and space-time are often demonstrated in three dimensions using masses rolling on an elastic sheet. Is this analogy accurate? Where does it break down?"
] | [
false
] | Here's of a science teacher demonstrating the warping of space-time with a sheet of lycra. He explains many phenomena: orbiting bodies, why the planets orbit in the same direction, dark energy, and so on. How closely does this analogy model the true effects of the curvature of space-time? Where does this analogy brea... | [
"There is a problem using the elastic sheet to explain gravity as being a curvature in spacetime, because that analogy assumes that gravity is pulling down perpendicular to the sheet.",
"It's easy to understand, but is there a way to understand gravity as curvature of spacetime without using gravity, so as to hav... | [
"As long as you're taking it as an analogy, it's MOSTLY good. Obviously it's only two-dimensional instead of three.",
"The main point of breakdown is that lycra has physical properties of its own. ",
"For starters, there's friction between the masses and the lycra. When he puts two heavy masses on the sheet, th... | [
"Thanks for a very thoughtful reply. "
] |
[
"I often hear people refer to the phenomenon of \"purging toxins\" from their body, usually in reference to changes in diet (ex. VLCD) or beauty regimens. Is this accurate?"
] | [
false
] | null | [
"The idea of purging toxins is largely BS, at least with respect to diets and new age treatments. If you actually were poisoned by something, the treatment would have to be tailored to the specific toxin. Is it water or fat soluble? Is it a heavy metal or some organic compound? Is a mycotoxin or bacterial toxin... | [
"If you want a cheaper form of colonic irrigation, try an all-you-can-eat Indian buffet."
] | [
"This might be of interest: ",
"Long article on various \"detox\" methods on The Skeptic's Dictionary.com"
] |
[
"What happens if you make a solenoid out of solenoids?"
] | [
false
] | Solenoids are usually a wire curled around and around. What if you make a solenoid, and curl that around? What will the magnetic field produced look like? | [
"It sounds like you're describing a toroid. They are used to make transformers and inductors. ",
"This ",
" is what the magnetic field looks like. "
] | [
"Just to avoid confusion: The magnetic field is the black dots and + in the toroid, the field follows the torus. The thick lines are the vector potential, they magnetic field in that region is zero.",
"Here is a sketch of the magnetic field",
"."
] | [
"/u/whitcwa",
" describes a solenoid bent into a loop, but if you're talking about a solenoid bent into a helix, then remember that the magnetic field outside a solenoid is almost zero. This will still be true after you bend it into a helix: the magnetic field will be mostly confined to the interior of the origi... |
[
"What are the significance of The Schwarzschild Radius and The Dirac Equation?"
] | [
false
] | This may be a bit odd, but recently a major gaming figure (known for being very cryptic) released a picture of a character for his new game (Norman Reedus) that character has "dog tag" like things on his necklace with equations on them The top equation is clearly The Schwarzschild Radius and the second appears to be T... | [
"The Dirac equation is particularly interesting because it started out as an attempt to find a first order quantum wave equation that included special relativity (previous attempts were second order and weren't terribly useful) and ended up as an equation that fully accounted for spin effects and predicted antipart... | [
"Could a negative energy particle instead approach 0? In a strictly logical sense I see how trending towards 0 energy as opposed to the lowest energy could be realistic, especially when we are talking about already \"exotic\" scenarios. In my mind I'm looking at it like we see the top half of a sinusoid wave, just ... | [
"Could a negative energy particle instead approach 0? In a strictly logical sense I see how trending towards 0 energy as opposed to the lowest energy could be realistic, especially when we are talking about already \"exotic\" scenarios. In my mind I'm looking at it like we see the top half of a sinusoid wave, just ... |
[
"Does a perfect sphere have zero, one, or infinite faces?"
] | [
false
] | Does a face have to be flat? Then it would be zero, right? If not, I would think the answer is one. But if you had an approximation of a sphere, like a polygon but 3d, the more faces you added, the closer to a sphere it would be. So along that line of thinking, infinity faces would yield a prefect sphere. Help. T... | [
"It doesn't have any faces (i.e., 0) because a face is a part of a plane, therefore flat. Infinite faces would yield a perfect sphere--with faces of zero area--but infinity is not a number, so you can't really get there. If you've the mathematical interest to pursue it further, the concept you're brushing up agains... | [
"In a context where the surface of a sphere can't be considered a plane (that is, the explanation I was referring to), I fail to see how a mobius strip could possibly be one."
] | [
"It all depends on your definitions. For instance, if you are considering the word \"face\" in its strict, mathematical definition, a sphere has 0 faces since as a continuous surface it has no edges. If by \"face\" your intended meaning was the mathematical definition of a \"surface\" then the answer is either 1 or... |
[
"How much caffeine do you get by sucking on a whole bean rather than grinding and brewing coffee with hot water?"
] | [
false
] | I tried Google and only got Yahoo! Answers, and the sources provided in those answers weren't the best. Right now I'm led to believe that you hardly get any caffeine from them, but I see chocolate covered coffee beans offered in shops so I figure there is some point in it besides taste. Is it the hot water which extrac... | [
"Its a mixture of surface area, heat and moisture. Theoretically, I would think a whole bean would give you a higher overall dosage, however it would be like a time-release pill. The bean, during digestion, would have \"all\" of the caffeine within it rendered out. You would have t chew the bean and hold it in y... | [
"You might try googling decaffeinating techniques, since that involves remove (much of) the caffeine from the beans and should discuss that issue specifically."
] | [
"I've tried that as well. I see that the common technique is to take the raw bean (not roasted, which is what everyone except the self-roasting connoisseurs would likely be buying at the store) and use either specialized equipment such as a carbon filter, chemical extraction with various solvents such as ",
"dich... |
[
"Found this clouds image on line. Can someone explain what's going on from meteorological point of view."
] | [
false
] | null | [
"Fallstreak hole"
] | [
"Because of their rarity and unusual appearance, fallstreak holes are often mistaken for or attributed to unidentified flying objects.",
"Yep. Aliens. ಠ_ಠ",
"Seriously though: I never heard of that one. Thanks!"
] | [
"No worries! I saw one a few years ago and looked into what it was. I was working at an airport with a lot of turboprop activity and I was at work when I saw it nearby. Here's this article from Wired Science linking turboprop activity and the formation of fallstreaks, from just last year:",
"Strange Hole-Punch Cl... |
[
"What is the difference between Pathology, Pathogenicity and Pathogenesis of a virus?"
] | [
false
] | null | [
" relates to the disease (specificially, the effects on the host) caused by the virus.",
" describes the potential of a virus to cause disease.",
" is the process by which the virus causes disease."
] | [
"Almost. I tend to think of ",
" purely as a scale of how likely a pathogen can cause disease. A virus with low pathogenicity is less likely to cause disease, etc.",
"Viral characteristics themselves influence pathogenicity, but I would put a description and study of such characteristics under ",
"."
] | [
"Pathogenesis is an umbrella term that includes the specific mechanisms, (e.g. binding strength and affinity, tropism, immunomodulation, cleavage...)."
] |
[
"If methane levels rise to 5% it can explode, which makes sense. But why will it not explode above 15%?"
] | [
false
] | null | [
"Fire happens when something rapidly oxidizes. That is to say that some substances, when exposed to oxygen and heated enough will, combust/burn. The heated air expands. If the air is contained, the pressure can build to the point that the container explodes.",
"Some things like methane react very quickly and c... | [
"CH4 + 2 O2 -> CO2 + 2 H2O.",
"Oxygen has a concentration of about 20% in air. With 10% methane you can burn all the oxygen. Adding methane beyond that point means it won't react fully to CO2 and H2O and you are left with some reactions that release less energy or no energy. It also means you displace some oxygen... | [
"Methane is CH4. For complete combustion, you would need 4 oxygen atoms or 2 oxygen molecules of O2 to produce CO2 + 2H2O. You'd want to generate enough heat from combustion to initiate combustion in adjacent molecules. Wikipedia lists the combustible range as 4.4-17%, which would mean 15% should still be fine. As ... |
[
"If a square foot of water was pushed from all sides inward, would it become ice?"
] | [
false
] | null | [
"Yes, if the pressure is high enough. \n",
"http://upload.wikimedia.org/wikipedia/commons/thumb/0/08/Phase_diagram_of_water.svg/700px-Phase_diagram_of_water.svg.png"
] | [
"Has anyone ever tried to make this non-ice solid pressure cooked water you speak of? If so, what does it look like and how is it physically different from ice?"
] | [
"Has anyone ever tried to make this non-ice solid pressure cooked water you speak of? If so, what does it look like and how is it physically different from ice?"
] |
[
"Does the sun really produce enough energy in one minute to power the planet for an entire year?"
] | [
false
] | [deleted] | [
"The sun outputs more energy in a second than humanity has used in its entire history. By several orders of magnitude."
] | [
"See here: ",
"http://en.wikipedia.org/wiki/Orders_of_magnitude_(energy)",
"5.0x10",
" J is the total world energy consumption in 2010",
"1.5×10",
" J is the total energy from the Sun that ",
" each day. ",
"So 300 times more energy reaches the earth each ",
" than we use in a year.",
"The ",
" ... | [
"Of course we're never going to harvest the entirety of solar energy reaching the surface of the earth - a lot of it isn't even in the visible spectrum, and we wouldn't want to harvest it all anyway. The point is that it is a direct comparison between energy levels, and is a useful indicator of how rich an energy s... |
[
"Why is soap effective against viruses?"
] | [
false
] | [deleted] | [
"Germs stick to the oils and grease on our hands (sounds yucky, but it's totally normal). Water alone won't remove much of the germs on our hands because water and oil don't like each other, so they won't mix. But soap likes both water and oil. That's because soap molecules are a type of surfactant, which means the... | [
"That, and it has a lipid (fatty) shell which soap can break down which destroys the virus, given enough time. Corona and influenza viruses have a lipid shell but cold/rhino viruses I think all have protein shells. \n(Probably oversimplified. I’m not in this field but read this multiple times during the pandemic..... | [
"Yes, that's basically it. That lipid \"shell\" can easily be broken down by soaps and without that they cannot produce an infection, most of the one that have that lipid \"shell\" are also broken down in your gut with some exceptions (like Corona, that's with Corona also can cause diarrhea and other symptoms). The... |
[
"How would a meteorologist calculate or estimate the TOTAL amount of precipitation that falls in an area/state/country?"
] | [
false
] | If you look up the rainiest states in the U.S. for instance it goes by average precipitation. It says 22 inches of precipitation fell in California, which is obviously some kind of average. What’s the TOTAL amount of rain/snow that fell in California? Surely it would be much more than a smaller state like Hawaii, which... | [
"I think you'll need to provide a little clarification on what you're asking for specifically, i.e. are you asking how a spatially averaged estimate of rainfall would be calculated? Are you asking about volume? Something else? ",
"When we talk about precipitation, we have two key components, the depth (e.g. the 2... | [
"Hi thank you for the great response! Yes as your 2nd to last paragraph points out, I’m looking for the total amount of precipitation (not average) that fell over a given area (say the state of California), over a given time frame (2020? Could also be 5 or 10 years, or 100 years). I’m trying to find out which state... | [
"First, people don't get water from rainfall. We either pump it out of visible bodies of water such as lakes, rivers, etc., and this is called surface water. Or we pump it out of wells, and this is called ground water. About 60% of irrigation water is from surface water (on average, over the nation) and the remaind... |
[
"I keep reading that the universe is 'flat'. Can someone explain this idea to me? I see stars all around."
] | [
false
] | [deleted] | [
"So you may know that gravity is the result of mass (and other forms of energy) curving spacetime.",
"But what does that mean? The easiest way to think of it is in terms of triangles. So on a sheet of paper, if you draw a triangle, the angles add up to 180 degrees. However, if you draw a triangle on a sphere, thi... | [
"We don't directly measure triangles. We do this by measuring the properties of the cosmic microwave background radiation.",
"Whether the universe is flat or not depends on the density of the universe -- too much (triangles have more than 180 degrees), too little (triangles have fewer than 180 degrees) , or just... | [
"Well, the sheet is still metaphor. First, of course, it's only two dimensional, but even more to the point it is two dimensions of space, whereas the geometry of the universe has four dimensions, three which are spacelike and one which is timelike.",
"Second, in the flat sheet picture, the masses are on top the... |
[
"Regarding the biological processes of pregnancy"
] | [
false
] | I was having an argument with my fundamentalist christian father. He has no understanding of science at all and chooses to play word games instead. He was talking to me and asked me "When a sperm hits the egg cell and the cell splits, what is that called?" Me not knowing the actual name said that it doesn't matter but ... | [
"Of course it's not a human being, it's a zygote and then an embryo and then a fetus.",
"Is a zygote the beginning of life? Who knows. It's not really something you can define. It is alive? Yes. Does it represent a future baby? Not necessarily -- between 50% and 70% of zygotes never result in established pr... | [
"Beautifully explained.",
"It's a compelling thing for the father to say that apart from all those other sperm and egg cells that \"failed\", those were the ones that \"made it\" and are therefore to be protected.",
"Compelling, yes. Heart-warming, also. But other than that pretty arbitrary. The question when a... | [
"If life is sacred, ask him to please refrain from eating burgers from now on. Or any kind of meat.",
"\"Life is sacred\" my ass. As long as that clump of cells doesn't have a nervous system, it's just a clump of cells. It starts to become a human being when a nervous system starts to form - but there's no clear ... |
[
"Are there ways to chemically suppress emotion?"
] | [
false
] | [deleted] | [
"Well, what AgentAsterisk is suggesting happens isn't really what Lamictal does by design (though it is used as, but is not formally, a mood stabilizar), but most of our \"mood stabilizers\" have different primary functions like Lamictal, so it's not too far off.",
"Emotions are we know them seem to have two prim... | [
"is there a way to alter the human mind so it mostly ignores emotional responses to stimuli and instead just analyzes things rationally?",
"Most people think that there is a neurotransmitter for \"happiness\" and one for \"memory\" and one for \"sleep\" and one for etc. etc. etc. While numerous, there are a fini... | [
"Although this isn't what you're asking, I thought you'd be interested in the personality trait called ",
"alexithymia",
" where one has difficulty becoming aware of, processing, and expressing emotions. ",
"I'm not aware of a medication which would cause individuals to be alexithymic, but if we understood th... |
[
"What specifically is cancerous about cigarettes? Is it the tobacco leaf, the chemical nicotine, or just inhaling smoke into the lungs?"
] | [
false
] | null | [
"Smoke in general is carcinogenic, as evidenced by increased lung cancer rates in various situations around the world where indoor open fire cooking is prevalent (a ",
"general overview",
"). Tobacco has specific chemicals that are specifically carcinogenic (see various nitrosamines on ",
"this list",
"). N... | [
"There are two major factors involved. The cannabinoids that get you \"high\" also tend to inhibit cancers. However, smoking marijuana involves inhaling combustion products that can produce cancer. Also, cannabinoids tend to be immunosuppressive, so they could inhibit your immune system that is responsible for reco... | [
"There are two major factors involved. The cannabinoids that get you \"high\" also tend to inhibit cancers. However, smoking marijuana involves inhaling combustion products that can produce cancer. Also, cannabinoids tend to be immunosuppressive, so they could inhibit your immune system that is responsible for reco... |
[
"Why does/would Global Warming cause a rise in sea levels?"
] | [
false
] | null | [
"This is a very common question. Try looking at some of the previous good threads on this topic using the search function: ",
"http://www.reddit.com/r/askscience/search?q=global+sea&restrict_sr=on"
] | [
"Melting sea ice would not cause a rise in sea levels. It would affect ocean currents etc, but that is not your question. What does cause a rise in sea levels is melting land ice. And antarctica is covered in kilometers worth of land ice\n",
"http://hypertextbook.com/facts/2000/MaySy.shtml"
] | [
"While it isn't directly the melting of the ice that causes the sea levels to rise, it does play a part. The larger issue is thermal expansion, which states that water expands as it warms. ",
"See: ",
"http://www.grida.no/publications/other/ipcc_tar/?src=/climate/ipcc_tar/wg1/013.htm#b4"
] |
[
"What happens to moving electrons when they hit the ends of a wire?"
] | [
false
] | So electrons move in a wire even without a current flowing, but when they hit the end of the wire do they `bounce off'? | [
"The speed of electrons in ",
" is on that order, if you were to translate their kinetic energy into a classical velocity. Electrons are always in motion.",
"There's no real boundary to an atom, and no real boundary to a wire either. I'm not sure what you're asking about. Why don't electrons go flying off into ... | [
"Thinking of them as particles in a box (or even mathematically modelling them that way) has its uses, although its usefulness depends on what aspect you want to understand. If you want to understand how/why electrons remain stably bound to their atoms, then that's something that ultimately requires quantum mechani... | [
"Think of it more like water in a vessel. The water molecules are moving about, but confined by the walls of the container. No current flowing implies no voltage, so it would be like a water vessel with very low water pressure."
] |
[
"What are the causes of diarrhea and constipation? Looked around on r/askscience and haven't found a concise answer."
] | [
false
] | Since I was a kid I always had some minor pooping issues and so I spent a lot of time on the toilet pondering these things. The theory I've had since I was little was that diarrhea was caused by an excess of gas pressure churning the poop into it's liquid-y form but I'm starting to realize that's probably not the case... | [
"http://www.webmd.com/digestive-disorders/digestive-diseases-diarrhea"
] | [
"All depends on water, and your large intestine. Diarrhea is a lack or fluid retention. That's pretty much why cholera kills. You lose so much body fluid from diarrhea you die.",
"Constipation is a bit more complex, but can also depend on lack of water, fiber, stress, and other internal factors."
] | [
"This is one of the best written explanations for diarrhea that I've seen on askscience.",
"\n",
"http://www.reddit.com/r/askscience/comments/pk8cj/why_if_i_eat_problematic_foods_do_i_get_diarrhea/c3q2yh3"
] |
[
"Why don’t more recent rockets have fins for stability?"
] | [
false
] | null | [
"Engine gimballing can be more effective for maintaining correct flight attitude compared to fins. The engine can tilt by a few degrees to change direction of thrust and attitude of the rocket. Additionally fins can only work lower in the atmosphere where air pressure is high enough for control. Abovethis they are ... | [
"What are you referring to? There are a wide range of failure modes that can happen right after launch. Some can be guidance related, sensors installed incorrectly or upside down which happened on a Russian launch earlier this decade.",
"You can have all sorts of problems with the engines or fuel systems.l that c... | [
"That could be due to all the things a mentioned: problem with a sensor, could be a computer glitch, could be a mechanical failure of the engine gimbal."
] |
[
"What substance has the lowest known biologically active concentration?"
] | [
false
] | Some substances has such low active concentrations that I begin to wonder what is the average interval between interactions of a receptor site and a even a single molecule of the substance. | [
"The lethal dose of Botulinum toxin is 90-270 nanograms (10",
" grams). 4 kg could potentially kill the entire human population.",
"The threshold dose of LSD is 25 micrograms (10",
" grams)."
] | [
"Ok, botulism is a good contender. That's in the parts per ",
" and this is a lethal dose. A \"biologically active\" dose (e.g cosmetic botox injections) would be even lower.",
"LSD is in the parts per billion range."
] | [
"Tetrodotoxin has a LD50 of 25 micrograms / kg when given intravenously, 334 ug / kg when given orally. Therefore, 25 milligrams orally would be expected to kill a 170 lb person. ",
"TTX MSDS",
"LD50 is the dose required to kill half the members of a tested population after a specified test duration.",
"Saxit... |
[
"What is the legitimacy of CO2 increases in the atmosphere causing increases of vegetation in arid regions?"
] | [
false
] | I stumbled upon this article outlining this as the premise, but I'm not familiar with the legitimacy of the source or the science behind it. As always, sources in support or against this thesis would be greatly appreciated. Thanks for your time, all. | [
"Few points.",
"First, this is one study and many more will need to be done in order to know for sure the impacts of CO2 on vegetation growth. Although they have tried to account for other factors, that simply isn't fully possible with a single study like that.",
"Secondly, it does make sense in theory. Desert ... | [
"the world's most arid environments are more likely to become drier",
"So, in effect, a compounding effect/cause of desertification? It just seems that yes, this may cause this specific group of vegetation to be more receptive to growth in these environments, but the underlying cause of this growth is detrimental... | [
"the world's most arid environments are more likely to become drier",
"So, in effect, a compounding effect/cause of desertification? It just seems that yes, this may cause this specific group of vegetation to be more receptive to growth in these environments, but the underlying cause of this growth is detrimental... |
[
"How is it that we know that the \"singularity\" that started the expansion of the Universe was extremely tiny?"
] | [
false
] | I get that our Universe is expanding and by reversing that expansion we come back to where everything was crushed together in a single point. How do we know that the size of this was extremely tiny, smaller than a grain of sand? Why not the size of a baseball? Is it reasonable to assume that this point was so small tha... | [
"You have to understand that it's not that everything was \"crushed\" together. It's that all spatial coordinates were infinitely close together. The expansion of the universe is an actual expansion of metric space (For example, that means that the Milky Way's current location and any other galaxy's current locatio... | [
"In current models the universe is infinite. That wouldn't change as we go back in time. Everything becomes closer together, but for any given distance, there's still things that are further away than that. The density changes even though the size doesn't. "
] | [
"Thanks for the reply. I knew I was using the wrong words just couldn't think of the right ones to use at the time. I am a lay person extremely interested in cosmology. It's mind-blowing!"
] |
[
"Why do atoms in a solid state stick together?"
] | [
false
] | So, there are a lot of things at play here, right? Temperature, malleability, charge, etc. How does this all fit together? When I hold a rock, why does it stay intact? Aren't there multiple element there? They aren't bonded right? So what's going on? | [
"Ultimately atoms get stuck together by electrostatic attraction.",
"The attraction between two adjacent atoms can be represented by what is called a ",
"Lennard Jones potential",
".\nIt basically describes the attraction felt by the two atoms as a function of distance.\nIf in a positive region (i.e above the... | [
"Thermodynamics says that all systems tend to minimize their ",
"thermodynamic free energy",
". There are a few different ways of measuring this, depending on which system variables are controlled, but in its most basic form the free energy is [(internal energy) - (temperature)*(entropy)]. We'll use the Helmh... | [
"I have a lot to learn, but that does help. Thank you!"
] |
[
"How consistent is sea level across latitudes?"
] | [
false
] | Sea level is basically the standard for measuring altitude, and I'm sure it's easy to account for tides when determining zero. But am I wrong in assuming that the rotation of the Earth would "throw" more water to the equator making sea level there a bit higher? Am I wrong for thinking this, do we account for this, how ... | [
"Sea level is basically the standard for measuring altitude, and I'm sure it's easy to account for tides when determining zero.",
"Yes. \"Sea level\" is really short for \"mean sea level\", the average level of the ocean -- or the level the ocean ",
" be at, if there were ocean in some particular spot.",
"But... | [
"So how is the tallest mountain on Mars calculated? Did they pick an arbitrary sea level?"
] | [
"It is somewhat arbitrary. Atmospheric pressure is used. The ",
" on Mars is the elevation at which the mean atmospheric pressure is 610 Pascals. Altitudes are measured from that."
] |
[
"Why doesn't anyone use the human appendix as an example of evolution?"
] | [
false
] | So, this is probably going to be a really basic question, but: When I was in school I remember learning that the appendix is basically useless as it's just a vestigial version of an organ humans needed long ago. So in light of this, it seems that the human appendix would be a great example of evolution, but I haven't s... | [
"wisdom teeth seem more apparant to laymen"
] | [
"Thanks. I know it's a self centered view, but I hadn't seen it before in various conversations about evolution - so I wanted to see if I was missing a key piece of info."
] | [
"Personally I think the giraffes vocal nerve is even more compelling."
] |
[
"Do we have any idea what our solar system's previous star was like?"
] | [
false
] | I've read our sun and planets formed from the remnants of an exploded star that was here before. Can we tell anything about it from the material composition of our solar system? | [
"A huge number of stars contributed to the material that makes up our solar system. There is no \"previous star\" as individual object."
] | [
"Our sun and solar system formed in a giant molecular cloud (",
"http://planetfacts.org/wp-content/uploads/2011/03/Giant-Molecular-Cloud.jpg",
") with thousands of other stars. It formed at least 10-50 million years after the initial explosion of high-mass stars. These high-mass stars only live a few million ye... | [
"It was a high mass star if it made our sun which is a medium mass star also we know high mass stars don’t live very long and make most of the elements when they explode, and the sun and solar system could contain debris from multiple supernovae so we could have more than one parent star"
] |
[
"We know how elements react on an atomic level. Why can't we throw it into a computer simulation and brute force new substances?"
] | [
false
] | I have a feeling it to do with us not fully understanding something rather than lack of computing power, but I can't figure out what. | [
"At the state of the art in computational chemistry, it's still quite difficult to make your calculations line up with known experimental data, so predicting the result of an unknown reaction is usually done with some hesitation. ",
"As for building new substances on the computer, I do that all the time. Time i... | [
"At the bottom, chemistry is quantum mechanics.",
"After you calculate from QM, for the first time in your life, the orbital of a single hydrogen atom (the simplest there is out there), you realize how tricky it is to properly and truly simulate chemistry on a computer.",
"To the OP: The quantum mechanics calcu... | [
"For me the real realization came when trying to even approximate the orbitals of a 2 electron atom. Hydrogen is ",
" but it can be done analytically. Once you need to take electron-electron interaction into consideration it becomes straight up impossible on paper."
] |
[
"Would it be possible to communicate from inside a black hole by changing its rotation rate?"
] | [
false
] | Black holes are roughly spherical but rapidly rotating black holes are oblate spheroids. If you were inside a black hole and somehow could survive and change the black holes rotation rate could you then change the shape of the black holes gravity field and thus communicate by sending out signals using gravitational wa... | [
"Your angular momentum is exactly canceled out by the angular momentum of the reaction mass fired from your engines."
] | [
"When you are on the inside, you contribute to the total mass of the black hole. You've brought whatever mass you had outside to now be part of the black hole. The same is true of angular momentum. You can add to the angular momentum in some way but once you are inside the event horizon, that angular momentum now c... | [
"Good question! That's an open problem since this is a treatment purely from General Relativity. See the ",
"black hole information paradox"
] |
[
"Is it more efficient to breathe through your mouth or your nose when exercising?"
] | [
false
] | It seems to me that during vigorous aerobic exercise there is an urge to open your mouth in order to breath. My housemate was arguing that it is actually more efficient to breath through your nose during exercise. So which is it? And if it is more efficient to breath though your nose, than why do we have this overw... | [
"I looked this up on the internet rather extensively a while ago and wasn't able to find any sources that were tested scientifically. Both ways appear to have benefits, so I don't think there is a consensus to which is better. ",
"The information that I found on running websites(not reputable scientific sources... | [
"About.com has a medical review board??"
] | [
"This is kind of right... ",
"When you get into high intensity exercise, you are utilising your entire lung capacity and breathing rapidly, so you use your mouth to move a large volume of air. That said, yes the nose is still importan for exactly the reason that it humidifies the air. Doing something like a maxim... |
[
"If the light omitted on the far side of a galaxy is significantly older than that of the front side, why isn't the shape distorted?"
] | [
false
] | I can't wrap my head around this. In a galaxy that is, say, 100,000 light years across, why do we still see it as a "perfect" formation? | [
"It takes 2500x as long as that (250M years) to rotate around the galaxy. So, in 100k years, the stars only shifted 0.144° . ",
"So, there is distortion, but it's not enough to ruin the seemingly \"perfect\" formation."
] | [
"Others have addressed that, in principle, there is ",
" distortion. But since there are billions of stars and you don’t have a point of reference it’s not really noticeable that they are differentially offset in angle slightly. ",
"However, you may be interested to know that the stars on one side of the galaxy... | [
"The stars in the galactic center revolve much faster than we do.",
"Not true. The galactic rotation curves are different to normal orbital systems.",
"https://en.wikipedia.org/wiki/Galaxy_rotation_curve",
"The rotational/orbital speeds of galaxies/stars do not follow the rules found in other orbital systems ... |
[
"Does NASA have a plan to save astronauts that are stranded on the ISS?"
] | [
false
] | Could NASA save astronauts, or are they just crossing their fingers and hoping that this situation won't happen. | [
"There are at all times enough spacecraft docked to take all astronauts back to Earth. These are the same spacecraft that are used to take astronauts up to the ISS."
] | [
"More people would physically fit into Dragon, but without a seat the return to Earth would be quite dangerous. I expect that \"staying on the ISS until another spacecraft arrives\" would be the default plan if something happened to a Soyuz. The ISS has kept people alive for 20 years now.",
"Normally new crewed s... | [
"No way with the Soyuz as only 3 bodies could physically fit in there. (",
"https://www.nasa.gov/sites/default/files/styles/side_image/public/thumbnails/image/edu_exp35_iss.jpg?itok=Br7zYTcG",
")",
"But with Dragon, they might seriously consider stuffing everyone in a single capsule in an emergency. It has a... |
[
"Does Viscosity have anything to do with Mass of a liquid?"
] | [
false
] | null | [
"There have been experiments done on pitch to determine it's viscosity. It has been found in some cases to have a viscosity 230 billion times that of water, while the density is very similar. If it were based on mass, you could expect the ratio of the density to be similar to that large figure. In reality, the visc... | [
"Yea, I think I was mistaken about that. I suppose what we have are more appropriately called models. They aren't matching reality perfectly. I know that simulations can be run which make assumptions about molecular interactions. But you are right, that is far from a rigorous expression."
] | [
"It depends on what kind of viscosity you are talking about, but in general yes. There is both the dynamic viscosity (often represented by the Greek character eta) and the kinematic viscosity (represented by nu and equal to eta/density). You are probably interested in the dynamic viscosity, which you can use to cal... |
[
"What exactly happens between the alpha particles and the air to cause clouds to form in a cloud chamber?"
] | [
false
] | I understand the basic premise of a cloud chamber - the air is supersaturated, so even the tiny alpha particles are enough to cause the clouds to form. But how exactly are the alpha particles interacting with the air? If they are travelling in straight lines, it makes it seem like they just passing through without inte... | [
"The alpha particles cause ionization in the gas. Ionized particles act as nucleation points for droplets of liquid to condense out of the supersaturated gas phase.",
"What you're seeing a bunch of small droplets, forming something similar to a cloud in the sky.",
"This makes the trail of ionization caused by t... | [
"Yes, each alpha particle causes ",
" ionization events.",
"Alpha particles from typical alpha decay sources have energies of around 5 MeV. The W-value (the average amount of energy to cause ionization of one gas molecule) for a gas like this is on the order of 10 eV. So if the alpha particle comes to rest in t... | [
"Just a follow up question: does each alpha particle cause multiple ionisation events? I can't seem to understand why the trails seem to cause a series of many nucleation events along the path of the radiation."
] |
[
"If you attached a multimeter to your spinal cord, what kind of voltage would it show? Would it have any negative effect on body function?"
] | [
false
] | null | [
"Whilst I'm not sure about the effect of a multimeter, most nerves operate at between -70 and 40 millivolts (across the membrane)."
] | [
"Electric potentials in nerve fibers and neurons are regularly measured by scientists using a variety of ",
"electrophysiology techniques",
". You'd likely need something more sensitive than a typical store-bought multimeter to see much, though. I mostly know about electrophysiology in the brain, but perhaps ... | [
"That is the voltage across a single neuron's membrane. Unless you were to place your multimeter's probe inside the neuron's membrane (which scientists actually do with very very tiny electrodes), this isn't the relevant quantity. The local field is more likely what you'd be measuring with a consumer multimeter."... |
[
"Why can we see the colours of lasers?"
] | [
false
] | Why can we see lasers when they go through dense gases (and not with a naked eye)? Is it possible to change the colour of a laser by changing the gas you are using to see it? | [
"You certainly can see lasers with the naked eye! It's just very dangerous to look at them directly, because they can damage your retina irreparably.",
"You need to think about the light coming out of a laser like a stream of bullets from a rifle. They go completely straight, and once properly focused form a tigh... | [
"Edit: It's Rayleigh scattering, not Reighley.... but who cares about British aristocrats anyway?",
"The visibility of the beam is mostly due to ",
"Mie scattering",
", i.e. tiny particles (dust or liquid droplets) in air that are larger than the wavelength of the light. It has no strong wavelength dependence... | [
"On a much weaker level you have Reighley and Raman scattering, where photons interact with individual molecules/atoms. Those have a strong material dependence (because here resonances matter), and can actively shift the spectrum of the scattered light. ",
"Two corrections: (1) It is spelled Rayleigh scattering, ... |
[
"Why don't we remember dreams for very long?"
] | [
false
] | I normally have a really good memory. When I wake up in the morning and remember a dream from the previous night, why do I immediately forget everything about it, even normally memorable things? | [
"It has been shown in mice that the order of firing of place cells* while running a maze is repeated while they sleep",
"--Kind of interestingly the order is actually repeated backwards and very quickly. Its not always perfect, but much more likely to be in backwards order than would be predicted by chance.",
... | [
"It has been shown in mice that the order of firing of place cells* while running a maze is repeated while they sleep",
"--Kind of interestingly the order is actually repeated backwards and very quickly. Its not always perfect, but much more likely to be in backwards order than would be predicted by chance.",
... | [
"This was asked yesterday on AskReddit by the looks of it ",
"THIS",
" post seems informative. I do remember reading articles that suggested that you don't remember it because dreams aren't exactly stored in memory and we only remember them because as we wake up we think about what it was and then store it in o... |
[
"Why do you need glasses/contacts? Can't the brain just correct the image as it receives it?"
] | [
false
] | null | [
"This suggests to me that they are perceiving their vision as sharper than it actually is",
"They're just not perceiving it as a deficit. When I was 8 and 9 years old, I had to keep moving closer to the blackboard to be able to read it. I didn't perceive my vision as sharper than it was, I just didn't know it was... | [
"Myopia (for example) is often caused by a corneal defect that causes incoming light to focus just in front of the retina. This causes a loss of clarity simply because of the optics of the situation. Your brain cannot add any information that it is not physically receiving through the optic nerve.",
"It is worth ... | [
"That and to an extent the eye can focus [adjust] for the deficit. That's why myopic people aren't typically completely blind.",
"I also had the same experience but it took till around age 9 or 10 or so before I realized it wasn't normal to not be able to read the board from anywhere in the class."
] |
[
"Is it theoretically possible to make a light source bright/intense enough to blind someone even if their eyes are closed, without causing severe damage to the eyelid itself?"
] | [
false
] | The title pretty much says it all. | [
"First off, I'm not an expert, I just happen to know a little bit about laser safety.",
"One of the reasons that bright light damages the retina before it damages other skin is because it can be focused by the lens of the eye onto a very small region on the retina. When the eye is closed, the eyelid will do a de... | [
"If I can use \"light\" in the sense of electromagnetic waves, then a beam of hard X-rays directed at the optic chiasm should do it. Even from the side, while completely avoiding the eyelids."
] | [
"presence of chemicals that are susceptible to photo-chemical breakdown (is my lack of biology training showing?)",
"The term would be \"photolysis\" if anything (photo = light, lysis = breakdown), so you weren't too far off ;)",
"Just to add, the chemicals in the eye which allow us to see ",
" actually alter... |
[
"how can an infinity be bigger than another infinity?"
] | [
false
] | so i saw this video on youtube . now in my logic doesn't make any since infinite is well infinite and thus there should not be a difference between of different infinitys | [
"The only thing stopping this from being intuitive to you is what \"bigger\" means. ",
"You're used to judging the sizes of things by counting each of them and comparing the numbers. That is, if I gave you two bunches of apples, you might count and see that there are 10 apples in the first bunch and 14 in the sec... | [
"That's just limit behavior on an unbounded domain. The formal formulations of those concepts rarely invoke infinity as anything other than convenient shorthand.",
"It is rather different from the concrete instantiations of infinity in set theory."
] | [
"There are several notions of size when it comes to infinity. The most common is ",
" which in lay terms asks whether one infinity can be fit (or more formally, mapped) into another.",
"For example, if you have a list of the positive integers, there is a way to place a rational number next to each positive int... |
[
"How can a human hold a collection of U-325 pellets without getting radiation sickness?"
] | [
false
] | null | [
"The naturally-occurring isotopes of uranium aren’t that radioactive. They have pretty low specific activities. Before they go into the reactor, you can hold them. However ",
" fuel will contain lots of fission products which are much more radioactive. You wouldn’t want to hold that."
] | [
"Aha! But when splitting the U-235 atoms, its not actually U-235 but rather Thorium and other elements down the chain of decay that's dangerous?"
] | [
"No, when the fission chain reaction is occurring, that’s a totally different situation. You don’t just have some material undergoing radioactive decay, you have a chain of induced reactions, occurring at a much higher rate than the fuel decays."
] |
[
"What happens to endorphins after they're released?"
] | [
false
] | I know that endorphins are released from the brain in moments of pleasure, stress, relaxation or various other activities, but I don't know what happens to them. Do they explode and then reform? Are we using the same endorphins every time we copulate? Or do they exit through our pores...? I don't know why I want to kno... | [
"I'm sort of surprised that I don't know more about this, and that endorphin catabolism hasn't been a very easy search to find good info on. But here's what I do know:",
"ß-Endorphins are small peptides (only 31 amino acids). So, most likely they are broken down by some sort of peptidase, and the amino acids are ... | [
"Thank you! I appreciate your efforts. I'm not well versed in anything scientific and had no idea what to look for. And like I said, it's just this niggling question I've had- I'm glad I've piqued your interest!"
] | [
"http://aids.hallym.ac.kr/d/kns/tutor/medical/endo.html",
"Once the endorphin molecule has served its function which was mediated by receptors, the endorphins are rapidly inactivated, experiencing a relatively short life. Enzymatic degradation of endorphin molecules appears to be the principle mechanism for inact... |
[
"Can focused electromagnetic power be used to reduce/eliminate pain signals to the brain?"
] | [
false
] | Here is my question: Is it possible to create a medical device that can diminish/eliminate pain by electrically disrupting the electro-chemical impulses that are transmitted to the brain via our nervous system. I know that sound waves can cancel each other and radiowaves can disrupt each other, is the same true for ele... | [
"Is it possible to create a medical device that can diminish/eliminate pain by electrically disrupting the electro-chemical impulses that are transmitted to the brain via our nervous system.",
"Yes. It's called a ",
"spinal cord stimulator",
". "
] | [
"Sure. ",
"Transcutaneous Electrical Nerve Stimulation (TENS)",
". Only somewhat effective in cases of severe chronic pain. Much better for minor or mild pain (some argue mostly through placebo effect)."
] | [
"This device doesn't seem to zero in on pain specifically and appears to just be a general application of electricity to muscles",
"Actually, no. In contrast to electrical muscle stimulation, TENS is specifically designed to disrupt the signals of pain by interfering with the nerve signal transmission. Again, t... |
[
"How old could the average rock be, how young? Are most very old? How old? How long does it take to make an average round rock? How does it happen?"
] | [
false
] | null | [
"How old could the average rock be, how young? Are most very old? How old?",
"This will depend a lot on where you are. As an example, lets take a look at a super simplified geologic map (a type of map that shows the type/age or rocks at the surface in an area) of the ",
"USA",
". The colors here are keyed to ... | [
"One small addition to this otherwise comprehensive answer, at the very old end of the scale there are also meteorites formed in space independently of the Earth and subsequently fell to the ground. The oldest meteorite found is believed to have formed something like 7 billion years ago, so is significantly older ... | [
"Meteorites are pretty rare (and hard to find in most environments). The vast majority of them are the same age as the Earth, i.e. 4.56 billion years old, and in fact ",
"meteorites are what we have used to date the formation of the Earth",
". There, to my knowledge, has never been an entire meteorite that has ... |
[
"[Physics] Could understanding gravity be a gateway to learning how to manipulate the 4th spacial dimension?"
] | [
false
] | null | [
"what 4th spatial dimension?"
] | [
"Spacetime? I'm a bit uncertain on the details. The one that bends from gravity and allows wormholes."
] | [
"Spacetime is the thing you're in right now. It has one time dimension and 3 space dimensions."
] |
[
"Why isn’t HIV always transmitted, when having unprotected sex with an HIV positive person?"
] | [
false
] | null | [
"Answered previously for other viruses."
] | [
"But could you please answer for HIV."
] | [
"Same answer. We don’t expect the experts who answer questions here to waste their time repeating answers"
] |
[
"If Earth were represented as one single pixel in size, how large would you have to make Antares for illustrating to scale?"
] | [
false
] | Edit #1, for details: The calculations of Antares' ratio to Earth seem to differ. Some say that Antares' radius is 88,000 times that of earth, others 160,000 times, and my own collected info had said that it's 96,247 times the size of earth. However, at 96 dpi, that would appear to require anywhere from 17 meters to... | [
"Pixels are two-dimensional while planets are three-dimensional, so that doesn't really work. Assuming you just want a cross-section, we can say that ",
"the diameter of Antares is about 160,000 times that of Earth",
", so you would need a circle 160,000 pixels across, or about 20 billion pixels total."
] | [
"If you used 720p HD TVs, it would be Earth as one pixel on one TV and a giant array of thousands of TV all a solid color representing Antares that was\n83 TVs wide by 148 TVs tall"
] | [
"Just done the calculation for Antares and Earth, and my pixel size of around 0.27mm and I get 43.2 meters. So I think you are correct!",
"I should read the question in the future."
] |
[
"What happens to the matter of a meteor when it burns up in sky? Does it rain down, go back to space or stay in the atmosphere?"
] | [
false
] | Or maybe all at once? | [
"Depends what it's made of. Most of it will sprinkle to the ground very slowly, basically as dust. If it has a component that's ice or frozen gases, then that would evaporate and be incorporated into the atmosphere. There's really no way it could go back to space."
] | [
"Well actually depending on a few factors like composition and part of the atmosphere where evaporation occurs, i.e. thermosphere, some of the gas could escape back to space via photodissociation. But like I said, this would only occur with the elements light enough to freely escape (H, He). "
] | [
"If the meteor is massive enough (this is also highly dependant on the meteor's elemental composition), it may hit the ground. But if it burns up like in your case, again, dependant on its elemental composition, it may totally evaporate, or pieces that are very small may still fall down scattered. Although the firs... |
[
"How do the asteroid miners plan to use water as fuel? Why can't we do that here on Earth?"
] | [
false
] | null | [
"We use hydrogen and oxygen as propellant for rockets on Earth all the time. They would have to use electrolysis to separate the water into hydrogen and oxygen, necessitating a separate power source, likely nuclear power or solar panels.",
"For most applications on earth simply using the electricity required to ... | [
"Also, you can build a solar electrolysis plant in space and spend months filling tanks with H2 & O2. Then the ship docks, fills up its tanks, and flies off. ",
"(PS I don't disagree with anything you said, just wanted to add the time element to it)"
] | [
"There is no need to strap a rocket to a car.",
"\nIf you want to use hydrogen as a fuel source there are hydrogen fuel cell cars that utilize the fact that two Hydrogen atoms and an Oxygen atom react resulting in energy and Water(H2O). The energy is then used to power a set of electric motors."
] |
[
"How to scientists manage to hit two particles in such a large particle accelerator?"
] | [
false
] | null | [
"They don't aim one particle at one particle. ",
"The beam consists of billions of particles. When the beam hits a beam coming in the opposite direction (or a stationary target, depending on the experiment) the vast majority of particles will go straight past each other, but with so many particles in the beam yo... | [
"How do they isolate and accelerate protons alone? I'd guess they accelerate protons with negative magnets?"
] | [
"If you want to use just protons in your accelerator its actually quite easy. The source is just a bottle of hydrogen gas. The actual acceleration is performed with electric fields, in most accelerators actually RF fields, but its always the electric field that does the accelerating. Magnets are used to steer the p... |
[
"The LHC created quark-gluon plasma. How long did it last for? and are there any implications that can be drawn?"
] | [
false
] | [deleted] | [
"Quark gluon plasma was first created in the Relativistic Heavy Ion Collider in 2010 and also by the Large Hadron Collider since then. What is new about the story in the news is that it was accomplished in a collision between two protons, whereas before it was done with large nuclei.",
"To answer your question, i... | [
"That's what's happening in the LHC. Except it's not really \"pass through\" and more \"splatter into a mess of particles.\""
] | [
"I'm not sure what there is to elaborate on. Any particle interaction that leaves \"extra energy\" lying around can produce new particles out of that energy, it's the way the universe works. At low energies, this means photons - it's why fires produce light.",
"If you can get enough energy in one place, you can p... |
[
"If Shark attacks are typically blamed on sharks confusing humans for seals, then why don't surfers wear wet suits with loud patterns (like polka dots or stripes) to clearly distinguish themselves from typical shark prey?"
] | [
false
] | Sharks are color blind, so bright orange won't help. | [
"Mostly because shark attacks are ",
"extremely rare",
". The average surfer barely even considers the possibility of a shark attack, and certainly won't sacrifice style for it."
] | [
"Those same studies ",
"which suggest that sharks may be color blind",
" (only few species have been tested yet) say that you'd want to reduce contrast to not attract attention, not increase it."
] | [
"Not sure why you're getting downvotes- shark attacks are exceedingly rare. There have been less than 2500 recorded unprovoked shark attacks in the last 400+ years. Compare that to ",
"this study",
" which examined over 1200 acute surfing injuries in just over a year, none of which were caused by marine life.",... |
[
"What are, in order, the membranes of the eye?"
] | [
false
] | null | [
"Homework question?"
] | [
"Yep.\nI dissected an eyeball in class today and we were given a sheet to fill out. One of the questions wanted to know the order of the membranes. I've looked on the Internet for it and couldn't find it anywhere."
] | [
"Does ",
"this help",
"?"
] |
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