title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"I bought salsa the other day and it just exploded in my face when I took it out of the fridge... why...?"
] | [
false
] | So I bought a combo of salsa and bean-dip at costco the other day. The bean-dip container was stacked on top of the salsa contained and the two were wrapped together with plastic wrap. Anyways, when I took the salsa and bean dip out of my fridge, two weeks after buying them, I noticed that the salsa was bulging from it... | [
"When something starts to decompose, it releases gasses. So in the closed jar of salsa built up pressure. So when you released it all of the pressure released, Salsa was pulled along with the escaping gasses."
] | [
"If your salsa was contaminated, bacteria could produce gasses which would build up in the container. "
] | [
"Thank you!"
] |
[
"Are the Hubble \"deep field\" photos in true color or false color?"
] | [
false
] | I can't find any information online but I would really like to know the answer. I would assume it is a false color photo but I want to be positive. If they are in "false color", what would I really see if I hypothetically had superhuman vision which granted me the ability to see what Hubble captured for myself? | [
"Nothing except your eyeballs are in true color. \"Color\" is purely a human perception."
] | [
"The Hubble deep fields have been released many times in slightly different variations and depending on the one you're referring to, the wavelengths used vary -- but for all deep fields the images are false color.",
"In ",
"this version",
", as referenced on ",
"the HubbleSite page here",
", all of the li... | [
"The ones I saw were corrected for red shift. So it wasn't a \"straight out of camera\" image but each galaxy was supposed to have been corrected (within the limits of the amount of red-shifting) so it looked like what it would look like in an inertial reference frame."
] |
[
"Aside from the light from the sun, does the moon emit light?"
] | [
false
] | [deleted] | [
"Yes, but it's much less radiation than that emitted by most objects on Earth.",
"It's also immensely dimmer compared to Earthshine, light reflected from Earth to the Moon and back, that occasionally makes the silhouette of the night side of the Moon visible in front of a dark sky."
] | [
"But it ",
" produce light, correct? It's not visible, but it does shoot off light, right?"
] | [
"No. The surface of the night side of the moon is pretty cold, too cold to emit in visible light by blackbody radiation. Consider that the night Earth is much warmer and still it's completely dark.",
"You need to be at least several hundred degrees before you start glowing in visible.",
"Anything with a positiv... |
[
"Why do stars seem to \"twinkle\" at night, even on a really clear night?"
] | [
false
] | null | [
"Planets do not twinkle the way stars do. In fact, this is a good way of figuring out if a particular object you see in the sky is a planet or a star. The reason is that stars are so far away that they are essentially points of light on the sky, while planets actually have finite size. The size of a planet on the s... | [
"Stars twinkle because of turbulence in the atmosphere of the Earth. As the atmosphere churns, the light from the star is refracted in different directions. This causes the star's image to change slightly in brightness and position, hence \"twinkle.\" ",
"Source"
] | [
"As others have mentioned, it is atmospheric distortions.",
"If you are interested, we actually have a method to ",
" stars called Adaptive Optics. Basically we use a small scope to view stars near the target object of our main telescope. A computer observes the twinkle and deforms a small mirror in realtime ... |
[
"Why are electrons attracted to protons and through what medium do forces of attraction propagate?"
] | [
false
] | Why are electrons attracted to protons? What forces drive that interaction? I've always been told in science classes that positives are attracted to negatives, but why? | [
"Okay, not \"why\" in that sense of the word. Maybe ",
" is a better question to ask. ",
"If I asked you why gas pressure increased when (all other things being equal) temperature increased, you'd be able to give me an answer to that question.",
"Now, I'm not trying to conflate quantum physics and the gas law... | [
"Okay, not \"why\" in that sense of the word. Maybe ",
" is a better question to ask. ",
"If I asked you why gas pressure increased when (all other things being equal) temperature increased, you'd be able to give me an answer to that question.",
"Now, I'm not trying to conflate quantum physics and the gas law... | [
"Here's Feynman's response to more-or-less your question",
"."
] |
[
"Do humans heal at different rates?"
] | [
false
] | If yes, what is the range of difference? | [
"Yes, of course. You need only look at an older person and a younger person to see the difference in rates of healing. There's no real 'range' as it depends on a myriad of factors, such as nutrient availability, collagen deposition, clotting, immune response, chronic disease states, and so forth, all of which wi... | [
"I would think it has a lot to do with nourishment. If your body has all the tools it needs to rebuild and repair it will do so quicker than if it doesn't. If you're asking \"all nutritional factors being equal\" then I have no idea."
] | [
": Yes. Wounds in the mouth heal faster than skin cuts."
] |
[
"If we can not travel faster than light, how can we image the early universe?"
] | [
false
] | I am always amazed by the early universe images and by the cosmic microwave background radiation images. However, I don't understand how can we detect now those radiation? so at t(0) (i.e. Big Bang) we have a rapid expansion. Radiation emitted from this event should be traveling at the speed of light. 13.7 billion year... | [
"This is an analogy one of my astronomy professors used, and I think it works pretty well:",
"Imagine you are in the stands of a soccer stadium. Now imagine everyone in the stadium cheers once, all at the same time. What do you hear?",
"You would first hear the people closest to you, they are loud, and then t... | [
"This is an analogy one of my astronomy professors used, and I think it works pretty well:",
"Imagine you are in the stands of a soccer stadium. Now imagine everyone in the stadium cheers once, all at the same time. What do you hear?",
"You would first hear the people closest to you, they are loud, and then t... | [
"The photons we see from the Cosmic Microwave Background comes from when the universe was about 400,000 years old, this was after inflation. Before an age of 400,000 years the entire universe was opaque and photons couldn't travel very far without being absorbed. The only way to understand the universe before it be... |
[
"What percentage of Earth's diameter is solid?"
] | [
false
] | null | [
"Not sure what you mean by this, but an interesting note on earth's diameter. The highest mountain on earth is 8km, the lowest crevice about 15km that's 23km of up and down. the diameter of earth is around 6000km...",
"If earth was shrunk down to the size of a bowling or pool ball it would be the smoothest one in... | [
"haha wouldn't know, you try measure :P"
] | [
"Everything is more-or-less solid except the ",
"outer core",
". Calculating the solid percentage is left as an exercise to the student. Edit: To be fair, you need to know the total radius (not on the figure) or 6371 km."
] |
[
"Is there an organism that could go extinct and have no repercussions on the ecosystem?"
] | [
false
] | null | [
"This was the answer I came looking for. Mosquitoes seem like one of the few species on the planet whose detrimentality exceed their benefits. Aren't there actual efforts to try and bring them to extinction? ",
"Edit: Out of the dozens of replies I've received commenting on the potential environmental impact of t... | [
"This was the answer I came looking for. Mosquitoes seem like one of the few species on the planet whose detrimentality exceed their benefits. Aren't there actual efforts to try and bring them to extinction? ",
"Edit: Out of the dozens of replies I've received commenting on the potential environmental impact of t... | [
"a lot of flagship species, that is species that organisations and charities can rally behind as a symbol and to gain support (like pandas for the WWF), are often not very important when compared to other endangered organisms. Also the spotted owl is a good example of a threatened animal that really wouldn't have a... |
[
"If we were able to stand next to the Curiosity rover on Mars while it sang happy birthday to itself, would it sound different than it would sound on Earth?"
] | [
false
] | null | [
"The main change would be the fact that the sound wouldn't travel nearly as far, due to the lower atmospheric pressure. I've heard conflicting things about the pitch change, but according to ",
"this",
" article, you'd just sound larger, with a slight high-frequency accentuation due to the reduced air density.... | [
"Assuming you mean an alien with human-like speech, or a human that can somehow survive lead-melting temperatures and crushing pressures... then I'm not sure about the specifics of the vocal cord structure, but they would definitely sound much higher-pitched here than there. Assuming their voice sounded like ours w... | [
"Very, very interesting. Question: what would 'someone' from Venus sound like on Earth? Would their vocal chords be substantially different from ours? How would they react to our atmosphere?"
] |
[
"What's the difference between using a 12V car battery and a 12V duracell battery when powering electronics?"
] | [
false
] | [deleted] | [
"If you put the two batteries in ",
"series",
" and there is no or minimal resistance between them, then you will get 12V. However, the amps from the duracell batteries will be reduced. Power is Voltage*amps, so depending on the cell size then you can figure out how long you can run the monition (if at all). Ca... | [
"When you say that a car battery has 500 amp hours, that means that even though the potential of the car battery is at 12V, it has enough material inside it to support 500 hours of supplying 1 amp to a 12V load? So that would be the main difference between a lamp battery and a car battery (both at 12V)? That is, th... | [
"Thévenin's theorem doesn't say anything about how actual batteries perform in the real world, it's a way to abstract out some complexity in circuit calculations.",
"If you try to draw 2 amps from a 12v deep cycle battery (pulling that out of thin air), you'll get a sustained 24W-ish output for days (depending on... |
[
"Do post-lead elements retain their unstable-ness even after forming compounds? If so, why?"
] | [
false
] | Hi, title really says it all. I tried searching online for an answer but I'm taking my GCSEs next year, and so far my teacher hasn't gone through anything about it as far as I could recall. Could I request that the answer and reasoning be simplified for me to understand? Thanks! | [
"Are you referring to stability in terms of radioactive decay? If so, then there is almost no effect on radioactivity whether the atoms are bonded to other atoms.",
"The energy associated with nuclear activity is much higher than that associated with chemical bonding, so the effect of bonding activity is minimal ... | [
"A quick chemistry-based way of explaining it is that radioactivity is almost exclusively a \"nucleus thing\" while chemical bonding is almost exclusively an \"electron cloud thing\". ",
"The stability or instability of a nucleus is a property of the nucleus itself and doesn't depend on other nuclei that may be \... | [
"It is likely that the molecule breaks apart due to the decay or does some other chemical reaction afterwards."
] |
[
"Why does hair stop growing?"
] | [
false
] | Like why does our arm hair stop at a certain length, same with any kind of bodily hair, even the hair on our head stops eventually | [
"Our hair follicles go through growth and dormancy cycles. Basically an anagen phase for growth, a catagen phase to stop growth, a telogen phase for resting (where the hair generally remains intact until growth starts again).",
"All of the hair on our bodies basically grows at the same rate (0.5 inches per month)... | [
"Why do arm hairs or embarrassing lip hairs grow and stay blond at the base, but turn dark at the ends, making them more visible."
] | [
"How does it know when to stop growing? Like if you trim your beard it will grow back to the length it was. Not that I have one worth trimming."
] |
[
"What gives lightning its color?"
] | [
false
] | What gives lightning its color? I know that lightning bolts are essentially plasma. So does it have to do with the argon concentration in the atmosphere? Thanks :) | [
"Hey that's a good question. I don't know much about lightning, but argon effects will not be enormous because argon is only about 1% of the gas in the atmosphere. Most of the gas is nitrogen, so you would expect nitrogen effects to dominate. ",
"All colors, infrared, x-rays, red, blue, are photons with a specif... | [
"Not Argon, but the more common gasses that make up our atmosphere, primarily Nitrogen.",
"I answered this with more depth in this thread a while back so I will cite it instead of pasting the response here: ",
"https://old.reddit.com/r/askscience/comments/c6dgoi/what_gives_the_purple_tint_to_lightning_bolts/"
] | [
"Color is actually determined by wavelength. Brightness is determined by the amount of radiation"
] |
[
"What varieties of memory are there and how do they work?"
] | [
false
] | FormerlyKnwnAsPrince informs me that "There are MANY types of memory, and this skill learning is a specific type of memory called implicit or procedural memory. Long term memory generally refers to declarative memories" This leads me to believe there are several types of memory and not just STM and LTM. In fact I know ... | [
"Very detailed question, but i'll take a stab at it. I majored in Neuroscience and am now a first year medical student so I know a fair bit about this but I'm no expert.",
"The cerebellum helps to coordinate movement and accounts for one type of memory. This structure has an extraordinarily repetitive/simple neur... | [
"Yeah awesome example of how memories are processed differently. This question starts getting at the various ways we recall previously stored info. I remember in one class we watched a documentary video about people who can recall everything they did, every day, prompted just by the date. There's actually a fair nu... | [
"How does autobiographical memory remain distinct from factual memory e.g. how can an amnesiac forget his life but not what a car is?"
] |
[
"Do you know any fun, hands-on, science activities (in any science discipline) that uses commonly found or inexpensive materials?"
] | [
false
] | null | [
"See this recent reddit post on askreddit: ",
"http://redd.it/q5jfa",
" -- lots of ideas here."
] | [
"I do a DNA extraction with school groups that uses household things. It is normally done with strawberries, but I'm sure that any fleshy fruit could be used. Here's how it works:",
"Materials:\n* Lysis buffer (900 mL water, 100 mL shampoo, 2 tsp salt)\n* Ice cold ethanol (we use everclear and it must be ice co... | [
"I worked in a lab on a university campus taking ",
" down to just DNA, and these are pretty much the important steps."
] |
[
"Are you able to target a specific element in a compound using EM waves at a resonate frequency of that atom?"
] | [
false
] | If so, how would if effect the atom? I have a hunch that it'd either heat up or release an electron. Just thought there would be many interesting applications for such technology. | [
"An electron in an atom resides in an atomic orbital. However, if the atom is part of a compound, the electron will reside in a ",
" orbital - meaning that being in a compound changes the energy landscape of that atom.",
"What this means is that you're now looking at the ",
" to absorb a photon, as opposed to... | [
"Microwaves work via dielectric heating, not any resonance coupling with water. Water just happens to be both ubiquitous, quite polar, and mobile as to respond strongly to the changing electric field."
] | [
"I'm pretty sure that that's how microwave ovens work. The wavelength of the microwaves has been selected to excite the water molecules in food."
] |
[
"Tissue rejection in the case of limb/organ transplants. Can someone explain to me how tissue rejection is overcome, ultimately, in the case of transplants? Do they take anti-rejection drugs forever? Does the transplanted limb or organ ever become genetically identical to the recipient's?"
] | [
false
] | Excerpt from article: Marrocco is taking anti-rejection medication, which can lead to side effects like infection and organ damage. But he's received an infusion of the donor's bone marrow cells to further prevent rejection of his new arms. That infusion allows him to take only one anti-rejection drug instead of the us... | [
"There are several types of transplant rejection. Let's review them!",
": This occurs immediately after the transplant. It's a type of hypersensitivity reaction (type II, or antibody-mediated, to be specific), which occurs because the recipient already has antibodies against the donor tissue. This occurs, for exa... | [
"Best response IIT. I would like to add to answer the OP's questions:",
"tissue rejection is overcome with immunosuppressive drugs. These drugs act mainly on T-cells and NK cells that recognize host from foreign.",
"Yes, transplant recipients are an these drugs indefinitely. ",
"No, the transplanted organ onl... | [
"i'd like to point out that the body may initially accept a transplant, but it may reject it sometime in the future (months to years) via the indirect pathway of chronic rejection. Foreign dendritic cells will travel to secondary lymphoid tissues (lymph nodes), where they will eventually undergo apoptosis. cellul... |
[
"I am a traditional photographer and have a solution of Ferrous Sulfate for development. If I dilute it, will its shelf-life be reduced?"
] | [
false
] | For full disclosure, I know next to nothing about chemistry. I'm in a remedial course this semester, but most of it is going over my head. HOWEVER, I'm using the Wet-Plate Collodion process to make photographs, and a lot of the chemicals used in the process are strange and bizarre to me. I've looked over my notes, goog... | [
"Also try cross posting to ",
"/r/photography",
". It can't hurt. "
] | [
"Any exposure to oxygen will hurt you here. Obviously an airtight container is a must, but water itself has a substantial amount of dissolved oxygen (this is how fish breathe under water) so you are certainly going to reduce the shelf life by diluting it. Perhaps not by much, the easiest way to determine this would... | [
"If you put it in an airtight container, it will oxidize very slightly from the oxygen trapped between the bottom of the lid and the surface of the solution, but once that oxygen is exhausted it will be stable."
] |
[
"Do scientists have the capability to integrate \"upgrade\" capabilities into spacecraft years after they launch?"
] | [
false
] | Since missions for spacecraft take years to begin collecting data from launch to target, the technology aboard the craft is only as up-to-date as it was prior to launch. In the years following launch, there could be so many advances and breakthroughs which could have been a better option for the mission. Do scientists ... | [
"Although that would be cool to be able to send updates and patches to spacecraft, unfortunately it cannot happen. Much of the way data is collected depends on the physical instruments. Luckily, our analysis and collection tools on Earth can easily be upgraded. For example, to boost the signal from Voyager, the sat... | [
"Although that would be cool to be able to send updates and patches to spacecraft, unfortunately it cannot happen. ",
"Wasn't there a craft that had an issue with its transmitter after launch which meant sending back full resolution pictures would take way too long, so they upgraded/changed the software to use so... | [
"Thanks so much for taking the time to explain. I see it I terms of how I work in graphic design. If the client doesn't provide images that are high enough resolution, there isn't much I can do to sharpen them, even with the latest editing software. "
] |
[
"Combining Light for a specific wavelength?"
] | [
false
] | Greetings AskScience, I was wondering if you could explain what happens when you take 2 coloured light sources, and combine them for a different perceived colour. Take using a Red and a Blue LED and ending up with a Purple/Violet colour, or using an RGB LED with a Red and Blue die. What I guess I am getting at, is this... | [
"Thanks for the info. I will have to figure out a way to generate a variable frequency. I am wondering if maybe using a white light source, most likely something like a Halogen, and then using something like a colour filter wheel would work.",
"As for the nonlinear thing, is that an example of say firing a red la... | [
"Long story short, you need the exact emitter.",
"Pretty much every optical system you're likely to encounter in day-to-day life is linear. Linear systems preserve frequency: if you put in a 500 THz sine wave, you get out a sine wave at 500 THz and only at 500 THz. Send in both 600 nm and 520 nm light, and out wi... | [
"Yeah, a white-light source and some sort of filter is the easiest and most versatile way to generate a good variable-wavelength source. A ",
"diffraction grating",
" working as part of a monochromator gives you the most control. If you can get a nice large grating, then the rest of the monochromator basically ... |
[
"Why does someone get more drunk if they don't eat beforehand? Even if the food \"soaks up the alcohol\", assuming the same amount, wouldn't all the alcohol still get absorbed by the body?"
] | [
false
] | Of course, I would love to see studies and maths and other such explanations behind this. Also anything about eating after drinking alcohol is also helpful to answering the question. | [
"Peak concentration is not solely related to bioavailability but also to rate of absorption."
] | [
"Alcohol is also eliminated from the bloodstream more quickly when food is eaten.",
"Source"
] | [
"That kinda makes sense. So it's not the total amount over x period of time, but amount over x time divided by absorbtion rate?"
] |
[
"How can Einstein's theories be used to predict the orbit of Mercury?"
] | [
false
] | [deleted] | [
"I think what you're getting at is that Newtonian gravity didn't correctly predict the ",
"precession of the perihelion of mercury",
"'s orbit. And General Relativity did correctly retrodict the measured value."
] | [
"Yes. A lovely word. Particularly as we do invent theories that ",
" make predictions of measurements had those measurements not already been made. "
] | [
"retrodict? ",
"Is that word in common usage in physics? I've never seen it before. Quite a useful word though."
] |
[
"How many different antibiotics are there?"
] | [
false
] | I have wondered this for quite some time: How many different antibiotics are there that I can theoretically "switch between" if I develop a resistance to one of them. I know there is a on Wikipedia. Can I count every single one on there as an alternative? Is the resistance dependent on how they are grouped ? Also, is t... | [
"How many different antibiotics are there that I can theoretically \"switch between\" if I develop a resistance to one of them.",
" resistance is not what you need to be concerned about, it's the bugs'. You can pretty much look at each of the classes there and say that a bug that's resistant to one of those drugs... | [
"Some are, some aren't. I'm working with a startup to develop an antibiotic right now, but it's not for phase trials. Even if we get the next round of the grant, which is roughly 8 times what we got for the first round, it's nowhere near enough to run phase trials. They are expensive, time consuming, and risky. And... | [
"Do the drug companies not get given grants by the government if they're in low demand, a la if they were developing an orphan drug?"
] |
[
"How much can DNA tell about a persons ancestry?"
] | [
false
] | null | [
"Mitochondrial DNA is often used as an ancestral lineage tracer in that is is inherited solely down the maternal line. Upon formation of the zygote, male mtDNA is ubiquitin tagged and subsequently degraded within the cell. This means that, bar random mutation, your mitochondrial DNA should be a perfect replica of y... | [
"This means that, bar random mutation, your mitochondrial DNA should be a perfect replica of your mother's. ",
"This is actually a pretty huge assumption, too. mtDNA lacks typical repair mechanisms and is, therefore, more prone to mutation than nuclear DNA. The reason mtDNA is so great for tracing lineage is beca... | [
"Which grandmother of two, great-grandmother of four, etc.? Oh, never mind, I see what you're saying. It's always from mother to mother, so all of the mtDNA of the mothers who produced the boys in all of the past matings was lost in your matrilineal line. It's only conserved if they produced girls, and only if thos... |
[
"Was the salinity level of the ocean the same during the eras of the dinosaurs?"
] | [
false
] | I found an article claiming it was twice as salty but it was from the daily mail so I'm not taking that on faith. Do we know how the salinity level of the ocean has changed over the last 200 million years? Has it remained relatively constant, has it slowly increased or decreased? Do we know if major specific (relativel... | [
"Do we know, yes, and with some accuracy. Evaporites (does what it says) provide a snapshot of salinity. The percentage salinity varies from a maximum of about 5% 300mya to around 3.5% today. It has both increased and decreased during that period, the main driver being glaciation effectively removing water from t... | [
"Fascinating, thank you"
] | [
"It’s an interesting thought isn’t it? The Earth is over 4 billion years old, so why aren’t the oceans completely saturated with salt? ",
"There are two main sources of oceanic salinity, erosion and tectonic. The latter consisting mostly of deep sea vents out gassing chlorine and sodium. However, the rate of ... |
[
"How are genes for disease resistance in plants identified and extracted for use in crop plants?"
] | [
false
] | null | [
"While I cannot speak for disease resistance in particular I can speculate that it follows a model, much as has been done in the search for genes that can make crops drought resistant. In which he model species Arabidopsis thaliana is used, picked because it is itself drought resistant. The plants genome has been... | [
"Well you don't at first, this is where testing is done. ",
"The gene is isolated, using PCR and specific primers, and then transferred into a plasmid (a piece of non-genomic DNA used by bacteria) which is then put into a specific bacterial species called agrobacterium which then transfects the DNA into a plant.... | [
"Genes for disease resistance can be roughly split up into three classes based on the proteins that they encode: Pattern recognition receptors (PRRs), Signalling Components (SCs), and Transcription Factors (TFs). PRR genes (also called R-genes, for Resistance-genes) encode receptors that are localized at the cell-s... |
[
"How NASA chooses where to point Hubble?"
] | [
false
] | null | [
"For Hubble (and just about any other telescope), time allocation - and hence the targets observed - is based on proposals by the astronomical community. These are submitted in response to a \"Call for Proposals\".",
"Each proposal must justify why the requested observations are worth doing, and also that the exp... | [
"NASA delegates the job to the ",
"Space Telescope Science Institute",
" (or STScI). It's an organization formed from various Universities. They have a governing structure and whatnot. Anyway, astronomers make various proposals on research to be done with Hubble and then those are reviewed, judged, and prioriti... | [
"Thank you so much for your answer, this was really clarifying. :D"
] |
[
"Is it possible to make metallic hydrogen on earth?"
] | [
false
] | I am just wondering if it would be possible to make metallic hydrogen on earth, or is this beyond our capabilities right now? If so are we close? I read that metallic hydrogen would be a good alternative fuel, as the only by product would be water. | [
"Hydrogen is the simplest element, consisting of one proton and one electron. In atomic form, the electron is in the simplest atomic orbital, the spherically symmetric 1s orbital, the only orbital in which the wave function can be calculated exactly analytically. Hydrogen is the most abundant element, accounting fo... | [
"References: "
] | [
"I did a project on this and there has been a few claims of creating metallic hydrogen over the years. These use methods which should produce the pressures required for metallic hydrogen. The problem is when you are dealing with such high pressures, there are lots of things that can go wrong to give false positives... |
[
"Why are humans the only creatures (to my knowledge) that care about covering up with clothing?"
] | [
false
] | From some light research it's easy to tell that humans are the only creatures that wear clothing to cover their bodies up almost completely. Why is this? There are times when it can be cold, and wearing something warm is better, but a time ago, I'd imagine people simply didn't care. What changed, and why did we change?... | [
"Yeah, pretty much.",
"Clothing was originally just for warmth but eventually we got the idea in our heads that covering up was appropriate. Its not a natural feeling though. If you took a child and raised it in a naked environment (like parents raising a child nudist) they would have no bashful feelings about nu... | [
"No other vertebrates habitually wear clothes, as far as I know. ",
"But there are examples of invertebrates creating or using things in the environment for shelter and cover. Whether they 'care' about it or not is another question.",
"The best known is probably the caddis-fly larva, or the hermit-crab; but arg... | [
"I read somewhere that even the children of nudists go through a phase where they want to cover up their bodies, related to puberty. The shame they feel seemed to be coming from the children, not society. Can you expand on this?"
] |
[
"When a geological event is \"overdue,\" does it actually have a higher chance of happening soon, or does that conclusion come from a misunderstanding of statistics?"
] | [
false
] | People will say things like "that volcano is overdue for an eruption" or "California is overdue for an earthquake." what exactly does that mean? Does the probability of an event continue to increase over time, or is it a gambler's fallacy--they assume that because it hasn't happened for X years, and it on average happe... | [
"Yes ",
" no. You're quite right that, when scientists talk about something happening \"on average every <foo> years\", they are implying a model of uniform, time independent probability - so \"overdue\" just means that it's been longer than the average since the last one. ",
"But some geological events (like... | [
"As a general trend, yes. But specific earthquakes are all over the board, of course. It depends on exactly what moves against what, releasing strain where.",
"These types of prediction are very complicated. For example, Hollister, CA (east of Monterey Bay, about 100 miles south of San Francisco) hasn't had a l... | [
"Follow up question. ",
"Will 'overdue' quakes be of higher intensity due to more potential being stored?"
] |
[
"How would life look like if Earth was 10% bigger"
] | [
false
] | null | [
"10% higher gravity",
"This is not necessarily true, and depends heavily on how the mass is distributed, how the increase in mass compares to the increase in diameter, and so forth. A bigger planet could theoretically have equal or even less gravity at its surface, as we are further away from the core/bulk of the... | [
"Yes, but the answer is wrong. Surface gravity with respect to earth is expressed as g = m/r",
"A planet 5 times the mass of earth, with a radius 150% of earth's, would have a surface gravity of 2.2 times as strong as Earth's, not 5 times. ",
"g = 5/(1.5",
" = 2.22",
"There are more variables at work than s... | [
"Suggesting the rise of intelligent life as a product of the time/rate of evolution implies a direction or motivation to evolution that doesn't exist. It does not move 'towards intelligence.' "
] |
[
"Why don't trains have better stopping systems?"
] | [
false
] | This thought was promoted watching a video of an emergency stop on a freight train from over in ( ) It takes a scarily long time for a loaded fright train at speed to stop. We've had major improvements in braking in cars (abs, ebd, etc.) Why haven't we seen similar improvements in train braking? Obviously there is much... | [
"I think this is the most important point. But I think you maybe didn't go far enough. If a freight train is going at speed and suddenly grabs the tracks, what good will it do? With that amount of weight, I suspect that the tracks would bend like spaghetti noodles and you'd get a train derailment."
] | [
"It seems like there would be an issue with whatever the train is transporting. If there are 300 people in the train, stopping a fast-moving train within a 50-foot span might be the ",
" thing the conductor could do."
] | [
"Do you have any conception about how much a fully loaded train weighs? An average freight train can weigh up to 10,000 tons. It takes a lot of energy to stop that much weight traveling at high speeds. Indeed, at about 60 mph (around 100 kph) a 10,000 ton freight train's kinetic energy is comparable to the energy o... |
[
"Why would Rüppell's Vulture ever need to fly at the extreme height it has been known to reach?"
] | [
false
] | null | [
"To beat the other vultures.",
"\"Bet you five pieces of carrion I can fly 11,000 meters high!\"",
"\"No way, bro. You're on!\"",
"But seriously, I think this gives us a big clue: ",
"...using their exceptionally keen eyesight to find large animal carcasses, or carnivores which have made a kill. ",
"Thi... | [
"It might be able to spot things that would indicate a carcass, other circling vultures, groups of animals, etc. Also, if you are above another bird, then that bird can't see you, but you can see it. The higher you fly, the safer you are from being attacked by other birds."
] | [
"It might be able to spot things that would indicate a carcass, other circling vultures, groups of animals, etc. Also, if you are above another bird, then that bird can't see you, but you can see it. The higher you fly, the safer you are from being attacked by other birds."
] |
[
"How does studying other scientific fields unrelated to your specialty help you become a better scientist?"
] | [
false
] | Backstory: I go to the University of Buenos Aires, where before starting your undergrad education you must spend a year studying some "general" subjects somehow related with what you want to study (that means that, for example, since I'm pursuing a Computer Science degree I will study the same than all exact sciences. ... | [
"If you are going to be an actual scientist, I would hope you would at least know the basics/intro of every major field, because it lets you understand how different aspects of the world works, gives you a basic introduction in case you ever do need to rely on it, or an appreciation of the history and path science ... | [
"I wish I'd had more of an interdisciplinary science education. I'm from the UK, and the qualifications en route to a degree are:",
"I really wish I had more biology in particular, since a large part of applied physics is actually medical physics and who knows, I might have gone into this with a little more knowl... | [
"Bottom line, it's quite common and (IMO) exciting to work with other fields. Being able to converse across disciplines is useful if you ever find yourself needing to work together in some fashion. In my field, scientific computing, this is absolutely essential. Partly because I participate in a \"mathematical an... |
[
"Why do I sometimes shudder, violently and involuntarily when tasting something very bitter?"
] | [
false
] | null | [
"People have an innate aversion to bitter tastes (which can even be seen in babies). It's thought that the reason behind this is so we can avoid ingesting anything that might be toxic to us. Experiments involving primates and humans found that typical reactions to bitter tastes include gaping and head shaking. I... | [
"Secondary reflex to the sympathetic nervous system."
] | [
"I realize this is unnecessarily pedantic, but the lack of a comma after \"involuntarily\" really bugs me. And I can't edit. Oh well."
] |
[
"Is the universe flat? What does this mean?"
] | [
false
] | I hear some physicists say " the universe is flat." I am trying to wrap my head around this idea. It is obviously 3 dimensional. We see stars in all directions of the night sky. We exist in 3 dimensional space. What does this mean? Not flat like a sheet of a paper. | [
"In this setting, what \"flat\" describes isn't so much the difference between a piece of paper and a piece of cake so much as it is the difference between a piece of paper and the surface of a basketball. It's about a property known mathematically as \"intrinsic curvature\", which measures how parallel lines behav... | [
"https://www.khanacademy.org/science/cosmology-and-astronomy/universe-scale-topic/big-bang-expansion-topic/v/big-bang-introduction"
] | [
"Since the question about what it means for the universe to be flat was already answered, I'll answer your other question:",
"The universe is locally curved, but entirely flat overall. The reason the universe can be locally curved, yet flat overall is because some parts of the universe have positive curvature (l... |
[
"Could you theoretically \"push\" a singularity?"
] | [
false
] | Would it be possible to exact a force on a black hole to move it in another direction? Or is the gravity too strong | [
"Two masses will feel each other's gravitational field and respond to them regardless if they are singularities or not. A black hole singularity will still feel other objects' gravitational fields and orbit them like any other celestial bodies."
] | [
"The blackhole would gain an electric charge. You could then use a ridiculously strong electric field to move the blackhole."
] | [
"Static electric fields don't contain electromagnetic waves/photons, so there's no problem. It's not that the electromagnetic force or field can't escape, it's only particles which cannot.",
"The reason why you can still detect gravity and electric fields can be seen because both forces satisfy a form of ",
"Ga... |
[
"Gauge spinors?"
] | [
false
] | Has anybody looked at the possibility of fields which transform as spinors under some gauge group? If they have (a link to an arxiv paper or two would be nice), what kind of compensating fields can be introduced? What do the interaction terms looks like? etc. | [
"What do you mean by \"spinor\" exactly? I think of projective representations, but the action must be invariant under gauge transformations, so if you had projective reps which are invariant then the gauge symmetry will just be the universal cover anyways (this distinction will not affect the gauge field/connectio... | [
"Thanks, I hadn't really thought about it very hard. I just had the simple line of thought: there are gauge scalars (don't transform), gauge vectors (the fermions) and gauge connections (the gauge bosons), why no spinors."
] | [
"Well this depends on what you mean by \"spinor\" and \"vector.\" Ordinarily I think of having an SO(3) group (more generally SO(p,q)), and defining spinors to be the projective representations. But in the Standard Model, we have SU(3)xSU(2)xU(1), which doesn't have any projective representations. So I would say th... |
[
"What Causes The Stimulation That Opens Na+ Channels?"
] | [
false
] | In my physiology books, it states, "When a cell is stimulated, depolarisation starts to occure due to some of its voltage-gated Na+ channels being open." I think I understand that the channels are opened because an electrical impulse reaches a certain voltage to open the gate (though, wouldn't this change the electrica... | [
"That's not a great sentence.",
"",
"So voltage gated Na+ channels are gated by ",
". So what starts them opening is depolarization. If that initial depolarization is strong enough, then positive feedback happens, as the sodium channels open, which causes Na+ to move into the cell, which depolarizes the cell... | [
"A) Ignore the Na-K ATPase. As far as you could be concerned, it is only there to establish [K+]i >> [K+]o. ",
"B) So we have lots of K+ inside the cell, and lots of Na+ outside the cell, and lots of open K+ channels. So K+ leaves the cell and it makes the cell sit at about -70 mV. The equilibrium potential of K+... | [
"I guess I'm wondering how those initial leaks lead to depolarization. More positive charge is leaving the cell than entering it, mostly through the Na-K ATPase and the K leak channel. I guess I'm not sure what would suddenly change this and start the chain reaction (I'm familiar with the steps once this chain reac... |
[
"How de we prove/know what the Sun is made out of?"
] | [
false
] | null | [
"By optical spectrometry.",
"Simplifying a bit:",
"If you look closely enough at the spectrum of light you get from the sun (by passing daylight through a prism), you'll see that there are gaps (or lines) in it. These gaps are caused by gases in the sun absorbing light of those missing frequencies, meaning that... | [
"In fact, helium was observed in the sun’s spectral lines before it was observed on Earth—that’s how it got its name."
] | [
"The only thing I see as wrong (as a spectroscopist) is that it's not so much that there are \"missing\" frequencies, more so that when you heat/burn hydrogen it'll give off a VERY specific frequency of light. ",
"The sun itself is a blackbody, giving off ALL frequencies of light. (As anything would do at that te... |
[
"How do we know that a black dwarf star exists if it's never been seen before?"
] | [
false
] | [deleted] | [
"It's thought that they don't exist yet, because there hasn't been enough time for white dwarves to cool. Because white dwarves are radiating away all this energy, it is thought that eventually it will cool through this process. If that is wrong, astronomers in a trillion years can find out."
] | [
"I'm referring to proton decay and very long term quantum tunneling effects as matter seeks ever higher levels of entropy."
] | [
"I'm pretty sure it would do neither of those things. White dwarves do not undergo fusion, they're kept alight by heat left over from their past life, and typically consist mostly of Carbon. By the time it's a black dwarf, all that heat energy is gone, and there's even less ability to fuse anything, so it'll still ... |
[
"Why does bread becoming soggy when heated in a microwave and crispy when toasted in an oven?"
] | [
false
] | null | [
"I would think its because bread is relatively moist, and microwaves are particularly efficient at heating water. Toasting it heats the water out of it, microwaving heats the water in it."
] | [
"As said the microwave heats by exciting the water molecules in the item being heated. In bread this destroys the structure of the bread, and instead of it being delicious and fluffy, it is dense and goopy. The structure in the bread that had many many air pockets, which makes it seem soft, are ruptured and collaps... | [
"Precisely. In a toaster, it's a dry heating element. You're basically dehumidifying the toast as well as heating the outer layer of it. In a microwave, you're heating the water inside the toast, causing steam, which has no where to escape and while it does heat your bread, it doesn't dry the moisture."
] |
[
"Is it possible to insert an entire bacterial genome INTO a yeast genome and have the yeast GROW the bacteria within itself?"
] | [
false
] | So I was just wondering if there was any way to insert the entire coding genome of a bacteria into the genome of a yeast in order to grow both yeast and bacteria. Would there be any way to maintain the growth of a yeast cell while it also produces and grows bacteria from within the cell? Sorry if my question is confusi... | [
"No, at least not the way that you word it. If you were to just have a machine, plop one genome into another organism, then tell it to go, you wouldn't get very far. The reason is that the \"shell\" of the yeast would not know what to do with the genome. All of the transcription factors and polymerases (the machine... | [
"Into the yeast genome and grow a bacreria? Nah, that's be impossible. ",
"But you could probably, through thousands of generations force endosymbiosis of a bacteria into the yeast. Preferably, you could start with a bacteria that is pathogenic with yeast. Each generation you kill all the bacteria except those ... | [
"There are a number of reasons. The largest point against your scenario, in my opinion, is the compartmentalization of eukaryotic cells (like yeast). In order for the bacterial genome to be transcribed and replicated, it must be localized in the nucleus of the yeast. This means that it would be physically separa... |
[
"Is there a maximum sound? A loudness at which the medium itself begins to rip apart or react or something?"
] | [
false
] | How many decibels at stp for the local average surroundings would that be? Would it just correspond to whatever pressure the nitrogen/oxygen mix condenses at? How would a system with sound of this intensity traveling through it behave? And related, but can compressional waves still travel through neutron stars and/or b... | [
"The process by which water rips apart under strong enough sound is called cavitation."
] | [
"Aye, but loudness corresponds to the amplitude/energy of the sound wave, which is in turn related to the change in pressures. I guess I should have specified that, rather than the human perception of loudness.",
"Though it seems in ",
"wiki'ing",
" this just now I've found the answer to my first question ",
... | [
"There is a difference between loudness and pressure waves. Consider the following points and evaluate whether your personal definition of \"loudness\" works for what you wanted to find out:",
"Every man-made sound-producing medium has different durability.",
"Every stable system that happens to produce sound h... |
[
"How did Gödel, in his incompleteness theorems, prove a statement that applied to all formal systems, using a formal system?"
] | [
false
] | null | [
"I'm going to assume you mean formal systems that attempt to describe the natural numbers (i.e. can perform arithmetic) here. While the proofs of Godel's actual theorems are incredibly complex and incomprehensible, how he proved that the theorems applied to all formal systems was actually quite simple. Godel's theo... | [
"Great explanation! So essentially, Gödel proved the incompleteness theorems for \"a non specific formal system that can describe the natural numbers\" (my phrasing). In doing so, he proved the theorem for as general a case as possible, thereby applying to all formal systems that describe natural numbers? "
] | [
"Exactly. It's interesting to note that mathematicians in general rarely solve the general case right off the bat; a common technique is to solve special cases and identify common properties or methods used to solve them that could be implemented into a general solution."
] |
[
"Why do hurricanes only hit eastern North America?"
] | [
false
] | null | [
"They are called cyclones and typhoons in other parts of the world. The storms require the warm water and weather conditions of the tropics to form, and generally travel in a western direction until the begin to degenerate and then fall into an easterly flow."
] | [
"Technically they are tropical cyclones, and they are called hurricanes, cyclones or typhoons depending where they occur in the world. This ",
"map",
" explains the names well.",
"Hurricanes",
" happen on both sides of the American continent, but those happening on the West occur south of the US, hitting Me... | [
"The currents run in opposite directions. ",
"North > South on the Pacific coast and South > North on the Atlantic so the water on the pacific coast is much cooler as its coming from Arctic regions instead of equatorial. "
] |
[
"Does water immediately start freeze after reaching 0 degrees?"
] | [
false
] | Also: can water still be liquid below 0 degrees and freeze over 0 degrees? | [
"In general, the answer to all of these is yes, but it depends. Water generally needs a nucleation point to freeze ... a particle of dust, an irregularity in the container, or another crystal of ice. You can supercool water with high purity, where you get the water well below freezing, and it remains a liquid. If y... | [
"Titan, one of the moons of Saturn, is believed to have ice VI as one of its layers, I believe."
] | [
"Sort of, but think of temperature as an average energy in a given medium. You may have some spots that are colder than others, so while the average or a given spot may read 1C you may start to freeze in another spot. Pressure is also a factor here as well. With water, increased pressure will lower the freezing ... |
[
"What is the \"best\" design for a fan?"
] | [
false
] | How and why are all of these different (beyond just aesthetics)? Would someone like to give a basic explanation of the aerodynamics of fan blades, and electric motor efficiency? I'd like to understand why some applications use few blades, and others use many. How does blade width, length, shape, and pitch affect its ... | [
"You're asking for someone to explain 4 years worth of university fluid dynamics to you in a few paragraphs.",
"When I build up the courage I'll give it a shot!",
"For now you should know though that there is no \"best design\". Fans are different shapes because they are serving different purposes, and have dif... | [
"killing power"
] | [
"killing power"
] |
[
"What is physiologically happening when our \"stomach drops\"? ie upon hearing bad news, looking down from a great height, etc"
] | [
false
] | null | [
"Physiology and Anatomy Major (for the time being) here. ",
"So its important to note that there are two sub systems in the nervous system. The first is the sympathetic and second is the parasympathetic nervous system. The sympathetic nervous system innervates most of your skeletal muscles (the ones used for move... | [
"While tesnaku is correct in asserting that the sympathetic system is probably activated, he/she's confusing a few critical points that I want to clear up. I would wager that the reason why you experience this physical sensation of a drop/butterflies is most likely due to ",
"splanchnic vasoconstriction",
" lea... | [
"That question is asking about the feels on the stomach driven by physical effects like going over a hill quickly in a car. This post is asking about psychological effects like realizing you've made a terrible mistake."
] |
[
"Nothing can travel faster than light, but relative to what? Any other object?"
] | [
false
] | [deleted] | [
"There are no frames of reference in which something appears to be going faster than the speed of light."
] | [
"No matter what speed you are travelling at, or if you are accelerating or not, ",
" nothing will appear to be moving faster than light. Not just to you, but to ",
". Nobody will agree on how fast anyone is moving, or how fast time passes, or the lengths of objects. But ",
" will agree what the speed of light... | [
"No matter what speed you are travelling at, or if you are accelerating or not, ",
" nothing will appear to be moving faster than light. Not just to you, but to ",
". Nobody will agree on how fast anyone is moving, or how fast time passes, or the lengths of objects. But ",
" will agree what the speed of light... |
[
"Statistically, when can we expect another active igneous province on earth?"
] | [
false
] | Also, for what percentage of time, over the course of earth's history, have there been active igneous provinces? | [
"I'm going to assume you're asking about \"Large Igneous Provinces\" or LIPs (e.g., ",
"Bryan & Ernst, 2008",
")? While there have been a lot of suggestions that there may be some periodicity to LIP eruptions, it remains an open question. ",
"Ernst et al, 2005",
" provides a summary (and I couldn't find muc... | [
"<different Redditor> ",
"I don't know anything about \"active igneous provinces\".",
"If the question was",
"\"",
" could we reasonably expect to see the next active Large Igneous Province on Earth? ",
"would a likely answer be ",
"\"The East African Rift System / Rift Valley in Africa\" ?"
] | [
"No, as there is already a LIP there (e.g., ",
"Ayalew & Gibson, 2009",
") associated with the Afar plume (e.g., ",
"Chang et al, 2020",
"). The conventional model is that LIPs often reflect the initial eruption of a plume head, so the next LIP would likely form where the next plume forms."
] |
[
"Can bleach expire/'go bad'?"
] | [
false
] | If bleach has an expiration date, what would happen to it if it went past the date? | [
"Bleach is usually NaOCl, which is a relatively stable compound, but it does interact with air a bit, and this volatility is what gives it its strong smell of chlorine. If the lid is kept on and is hermetically sealed, the bleach inside will stay at a steady state indefinitely. The only way it can \"expire\" is thr... | [
"The active ingredient in regular bleach is NaClO - sodium hypochlorite. It really shouldn't lose potency with time in a sealed container.",
"Non-chlorine bleach is usually H2O2 - hydrogen peroxide. It does decompose with time, especially in the presence of sunlight or tiny amounts of a catalyst. This is why it o... | [
"Over time, sodium hypochlorite will degrade to form sodium chlorate and sodium chloride. This degradation is temperature dependent and can be slowed by the addition of sodium hydroxide (lye), which most manufacturers do add. Room temperature storage can usually yield a 2 year expiration (based on concentration of ... |
[
"How long do you need to stay under the sun to absorb the same amount of radiation as one xray scan?"
] | [
false
] | I've just recieved an xray for my foot and wondered, the sun also emits radioactive rays, and of course, chance of cancer increases? But is the amount near a days worth of staying in the sun (negligible) or something that takes you months? | [
"When we talk about “radiation absorbed” we mean “ionizing radiation”, which can take many forms (gamma rays, x-rays, UV) - the point is that ionizing radiation has the ability to degrade molecules in your body. An ionizing radiation dose is measured in a unit called Sieverts (Sv). Most doctors would say that a sin... | [
"It really depends on where you are. The more atmosphere between you and the sun, the more harmful radiation gets deflected or absorbed/transformed before it gets to your skin.",
"Also, the more ozone between you and the sun, the more protected you are.",
"So people at the South Pole and airline pilots are exp... | [
"Two of the biggest factors are probably increased life expectancy plus medical diagnostic ability. Humans over the past 200 years have nearly doubled their life expectancy. Cancer is a disease caused by genetic mutations, which increase in frequency and accumulation as we age. Plus, medical knowledge has vastly in... |
[
"How does zero point energy not correlate with a temperature at absolute zero?"
] | [
false
] | As above, how can kinetic energy exist (in the form of ZPE) at absolute zero without being related to a net positive temperature? Isn't temperature a measurement of the kinetic energy present in a system? | [
"Isn't temperature a measurement of the kinetic energy present in a system?",
"No. The formula <KE> = (3/2)kNT only applies in classical non-relativistic non-magnetic systems. (Here <KE> is average total kinetic energy, k is Boltzmann's constant, and N is the number of particles). The more general definition of t... | [
"The 1.5RT formula is the result of statistical mechanics of a monoatomic ideal gas, using classical physics, as mentioned.",
"Relativity and QM are not included, as the two fields only started to emerge around the same time as Gibbs published the defining work of SM 1902. I wouldn't know if we have a SR and/or Q... | [
"The 1.5RT formula is the result of statistical mechanics of a monoatomic ideal gas, using classical physics, as mentioned.",
"If <KE> is defined as the average total kinetic energy (energy due to translational momentum rather than rotational/vibrational energy or interactions), then the formula holds for ",
" ... |
[
"What are some fun, easy science experiments for elementary-aged kids?"
] | [
false
] | I'm starting a new science outreach program and am looking for some interesting, but relatively simple experiments to do for elementary school kids. Any ideas? | [
"Electricity that works with 3-5 graders. If you have the funds, purchase small light bulbs, c batteries, and wire. You can get a bulb holder too that has clips for the wires, but thats not necessary. Cut and strip wires so that each kid (or small group) has 3 wires. Start off by giving the kids one wire, one b... | [
"Try headrush\n",
"http://headrush.discovery.com/"
] | [
"Try Headrush\n",
"http://headrush.discovery.com/"
] |
[
"Relativistic position uncertainty..."
] | [
false
] | So I was thinking about how length contracts at relativistic speeds and how a particles loose their position information when they have really well defined momentum. Are these two related somehow? Am I making any sense? I'll try with an example: Let me say that I fired an electron in front of me (1 km away) to a really... | [
"No, I'm sorry, they are completely unrelated. Length contraction arises from special relativity, and the Heisenberg uncertainty principle arises from non-relativistic quantum mechanics.",
"The mathematical formulation of each phenomenon makes it apparent that neither requires the other:",
"http://en.wikipedia... | [
"It's not related at all, and it only seems like it could be because your understanding of relativity is flawed.",
"You're correct that relativity says 1000 m is 141 m for an electron moving at .99c. But there's no correspondence between the intervals like you're imagining, where the 141 meters the electron sees ... | [
"oh, ok. I just saw a wild co-relation then I guess. additional ques if you could answer it as well oh kind physicist: where am I exactly going wrong in my thought process? (i can take a guess but better have someone knowledgeable point it flat out than getting lost in thoughts again, right?)",
"edit: didn't catc... |
[
"Best place to launch a space shuttle?"
] | [
false
] | If you had the resources to launch a space shuttle from any point on earth, which point and why? For example if you could launch one from the summit of Mount Chimborazo or the equator which would be better? | [
"The best place to launch something into orbit is typically on the equator.",
"If you're above the equator, you can't launch anything into an orbit with a lower inclination. As an extreme example, if you were on the north pole, you could only launch satellites into a polar orbit. However, on the equator, you ca... | [
"What matters the most is usually the highest velocity, if the pad is moving faster then it's a lower delta-v to orbit (so usually the equator). With that said, depending on your ship, the mountain may very well be better because of the lower air pressure, it would significantly reduce the drag experienced during t... | [
"Launching from the Equator offers the highest initial velocity because the Earth's angular momentum is greatest at it's widest point perpendicular to the direction of rotation. It also offers the best options for orbit trajectory."
] |
[
"Will a photon traveling perfectly away from the center of a black hole, but inside the event horizon, fall back on itself or be able to escape?"
] | [
false
] | I pictured something like this: A follow-up question: Will the photon come to a literal stop for a brief moment while it decelerates and then begins accelerating at the center? | [
"There is no direction \"perfectly away\" from the singularity in a black hole. Every path starting from inside the event horizon leads towards the singularity due to the curvature of space-time.",
"Will the photon come to a literal stop for a brief moment while it decelerates and then begins accelerating at the ... | [
"Once you're inside the black hole, the only way ",
" can ever, possibly go is towards the center. This is because inside the black hole, the radial direction flips roles with the ",
" direction. Outside the horizon, everything has to move forward in time - inside, everything has to move inward in radius!"
] | [
"Based on this line of reasoning, what (if anything) can be implied about a masses movement through time inside the event horizon?"
] |
[
"My boyfriend has these weird marks on his bicep, that he says are from injections where the needle was heated until it was red-hot..."
] | [
false
] | null | [
"I am from russia and while i dont have those marks (i am 23), my mother does, as well as many other people around that age from eastern countries. I assume you mean the marks that look something like this:",
"http://www.ediblegeography.com/wp-content/uploads/2009/10/smallpox-vaccination-scar.jpg",
"\nEdit: Rea... | [
"This is unscientific without photo/s. ",
"Very true. I will hazard a guess anyway ;)",
"The BCG vaccine (to prevent complications from tuberculosis) is usually injected subcutaneously (under the skin, but not in the muscle) on the side of the left shoulder. The vaccine contains cow protein therefore causes the... | [
"amazing! thank you SO much this is exactly it! He's 18, but he's from the middle east, so it makes sense according to a couple other sources i found! he was pretty young when they did it, so maybe he's not remembering the hot part correctly, but it definitely looks like the same as the mark you showed.",
"thanks... |
[
"How did HIV cure cancer in the 7-year old girl?"
] | [
false
] | Here's a link to an article: My question specifically is how did they "alter" the HIV virus strand to target cancer cells? What process method was used? (A link to a scholarly article would be nice) What possible risk are their by using this form of treatment? And finally do you think this can be used for all or many t... | [
"They used a disabled form of HIV (one that cannot give you the AIDS, I'm assuming they removed the viral genes), and modified it by adding a specific gene that produces the \"chimeric antigen receptor\". This receptor gets expressed in the cells infected with the modified HIV, and is displayed on the surface of th... | [
"Legend_Floyd has it right. In a little more detail, the virus is split into 3 separate chunks, so that no single one alone is infectious (and recombination between 3 is unlikely). Also many of the viral proteins are truncated and self inactivating elements are added. The important thing is that the virus functi... | [
"It's an interesting question, but a little outside the bounds of this particular application. The only point of \"HIV\" here is as a delivery system. The \"payload\" is the genes that encode the proteins that reprogram the T-cells to kill all B-cells. If you could come up with a payload that would kill HIV, the... |
[
"Which cognitive functions are affected by depression, and how?"
] | [
false
] | I've learned that depression affects short term memory. What other cognitive functions are affected by depression, and what do we know about the underlying mechanisms? | [
"This ",
"blog post",
" does a good job of answering your question and citing relevant sources. ",
"Here is a list of several impairments in cognitive function that have found to be associated with depression:",
"Patients with depression compared to non-depressed individuals possess several notable differe... | [
"The hippocampus and frontal cortex impairments are what contribute to memory dysfunction, feelings of worthlessness, and suicidal thoughts. Functional imaging studies have shown hippocampal atrophy in depression and reduction of neuronal density and size of populations of neurons in the cerebral cortex as well. ... | [
"Enlarged CSF and ventricles coupled with smaller brain structures can indicate a few things. The first being a neurodegenerative process where cells are dying (this is seen in Alzheimer's and Parkinson's). Also, it could indicate a developmental problem where there is a lack of neurotrophic factors to insure cell ... |
[
"Does the volume of water on earth fluctuate from day to day?"
] | [
false
] | [deleted] | [
"Technically yes, since water vapor has more volume than water. But the vast majority of the mass of H2O on the planet at any given time is water, and for every bit evaporated in one part of the world, a similar amount condenses somewhere else, so any difference would be insignificant."
] | [
"Less technically, there is also a fluctuation because free water is sequestered into the mantle via subduction and released from there via volcanic activity. Also, sequestration into and release from aquifers is not necessarily equal."
] | [
"A bit. Some water is split into oxygen and hydrogen in the atmosphere (hydrogen escapes over time). We get a little bit of new water from ice from asteroids hitting Earth. Living objects convert water to other things, and other things to water. Burning biological material typically releases water (vapor). Some wat... |
[
"How hard is it to see myelin formation on an MRI?"
] | [
false
] | null | [
"That depends a little on what you mean exactly. You can see highly myelinated regions easily on an MRI. You can even figure out which way the axons (on average) must be travelling. So see myelin is easy.",
"But if you wanted to watch myelination and demyelination, that would be very difficult, unless you were ta... | [
"Diffusion tensor imaging is an MRI technique that is often used to measure white matter integrity. One DTI measure is fractional anisotropy, which can range from 0-1 based on the movement of water molecules. If the myelin is intact, then water molecules should only be moving (diffusing) along one line, resulting i... | [
"Thank you very much for this."
] |
[
"What kind of experiments are the astronauts doing on the ISS?"
] | [
false
] | Are they doing astronomy, weather science, or just seeing how things act without gravity? | [
"The short answer is that they do all of those things. With every supply load going up to the ISS they get lots of stuff that people back on earth wants them to do experiments with.",
"A lot of them has to do with how we as a humans will handle living in space for longer periods, which will happen if we are to co... | [
"To add to this: when I was doing undergrad research on magnetic coupling, we wanted to study them in space. So we applied to have our experiment taken to the ISS but were ultimately denied. I imagine nearly every university on Earth has experiments they submit to be taken to the ISS"
] | [
"During his speech in my hometown, Hadfield answered that he convinced his commanders to ",
" to discover the acoustics of an instrument in space, playing his guitar both for pleasure and for work.",
"Then he was given a cease and desist for having played ",
" and posting it on YouTube.",
"That didn't stop ... |
[
"What does \"popping\" joints in your fingers/toes/knees/etc. actually do?"
] | [
false
] | null | [
"No. ",
"Donald Unger",
" won the Ig Nobel Prize for cracking the fingers on his left hand but not his right every day for 60 years, in order to show that there was any connection to arthritis. There was no difference after 60 years."
] | [
"I answered this a year ago. ",
"Read there",
" or reprinted here because electrons are cheap.",
"Physician here, with an undergrad in physics, I have also taken classes in Naval Architecture, where cavitation is a pretty big deal. In preparing this answer, I also discussed it with one of my partners, an oste... | [
"that's why he got the ",
" Nobel prize (it's a parody prize for silly/stupid science)"
] |
[
"Are more turns and smaller wire diameter better than less turns and larger diameter in an electromagnet?"
] | [
false
] | [deleted] | [
"The magnetic field strength of a solenoid (cylindrical coil of wire) is B = μIN/L. ",
"μ is just a constant depending on the magnetic properties of what's inside the coil. Something magnetic like iron would make it higher than air. L is the length, let's say we keep that constant. ",
"So that leaves N, the num... | [
"With N, doubling the number of turns would double the length of wire, which would double the amount of copper. So a proportional relation, twice as much copper, twice as much field strength. ",
"And twice as much heating.",
"If you want to keep things consistent, consider it for both scenarios, not just for on... | [
"doubling wire diameter doubles the strength of the electromagnetic field",
"Nope. The thicker wire just allows more current before overheating. That is because it has a lower resistance. ",
"Which is better? It all depends on your goal. If you just want a stronger magnet, then more current and more turns are n... |
[
"Does the decay energy affect the power output in a betavoltaeic battery?"
] | [
false
] | I mean does a low energy beta emitter produce as much power as a higher power emitter? (in a power cell) (if so - why? why can't we use the higher energy electrons better?) As far as I understood it it isn't the extra electron produced that "becomes" the power but it has something to do with a technology like solar cel... | [
"A higher decay energy will produce more electron/hole pairs per decay. Measured relative to decay power (decay energy * decay rate), there is no large difference.",
"(if we just packed a beta emitter inside a metal casing, would the casing get a higher voltage potential from capturing the electrons?)",
"Yes, b... | [
"Are there even vast differences between beta decay energies of different isotopes to begin with? (I'm having some problems finding tables of beta decay energies and are finding weird (what seems like probability) graphs of energies. Cobalt-60 beta decay energy seems to be comparable(-ish) (in orders of magnitude) ... | [
"The beta particle, neutrino, and daughter nucleus all split the energy given off by the decay. Total energy and momentum are conserved."
] |
[
"Why will your eyes hurt looking at the sun, but not at a lightning strike?"
] | [
false
] | null | [
"Sun damage to the eyes (called solar retinopathy) damages the retina with bright lights. While the sun can cause that, so can other bright lights, such as arc welders or lasers. The more powerful the source, the less time it takes to cause damage. I would guess that the flash of a lightening strike, while fairly b... | [
"Damage from hazards tend to result from the severity of the hazard and the time of exposure. Consider a lighting strike takes 200 milliseconds consisting of 30 millisecond strokes (Wikipedia), whereas your exposure to the sun depends on how long you look. Consider also that much of photo retinopathy is due to ph... | [
"Additionally, sunlight puts out a lot of UV radation, which is significantly more damaging to the eyes. ",
"So does a lightning strike. They are hotter than the surface of the Sun, they emit a larger fraction of the energy as UV. In addition, if you are close you have less protection from the atmosphere.",
"Bu... |
[
"Geologists - Can you explain the plate boundary between Europe and Africa and the location of the Alps to me? (See details)"
] | [
false
] | So I am reading a bit about the alps after a vague mention of plate boundaries in a documentary. The thing that doesn't make sense to me is this: Some maps of the plate boundaries show the boundary basically as a line that goes from the Straight of Gibraltar under the boot of Italy and onward to the east. Another maps ... | [
"The key here is mostly the distinction between major, minor, and micro plates. When most non-geologists (or even non-tectonic geologists) think of 'tectonic plates', they usually think of some set of pretty large plates ",
"like this",
". In reality, we often further subdivide portions of ",
"those plates in... | [
"Thank you so much for the explanation! If you happen to have a bit more time - could you give more information on the history of the Alpine region or link a good explanation on it?"
] | [
"This is a pretty thorough pair of reviews from ",
"Schmid et al, 2004",
" and ",
"Handy et al, 2010",
". The latter has a good series of paleogeographic maps and cross sections tracking the evolution of the Alpine system through time."
] |
[
"Why didn't the universe collapse into a black hole at the Big Bang (when all matter was at the same point in space)?"
] | [
false
] | I don't know if I'm misreading what the Big Bang is, but it seems that all energy in space was located at one point at the start of the universe, and with post, it seems that it would definitely be enough to turn the universe "into" a black hole. edit: I meant in the title, not matter. | [
"Don't think of the Big Bang as an event that's associated with a single point somewhere in space. Think of it as an event that's associated with ",
" points in space."
] | [
"It doesn't make any sense, no. The concept of size is not applicable to space.",
"English is not the language of physics. Maths is the language of physics. So there's only so far we can go with words. The metric equation that describes the large-scale geometry of the universe includes a numerical coefficient cal... | [
"Imagine you have an aquarium completely full with water in space. Let's ignore *how water would behave in the vacuum of space, this is about the absence of gravity. The water fills the aquarium completely, so it's a solid block.",
"That's the very first moment of the universe-reality. The water depicts energy.",... |
[
"Unlike the rest of reddit, /r/AskScience is not about discussion or speculation: it is about authoritative answers from genuine experts."
] | [
false
] | [deleted] | [
"Couldn't disagree more. This subreddit isn't only about being \"correct\". And even if it was, I have seen multiple times where the panelists have been wrong, even about things in their own area of expertise (myself included).",
"What we don't want, is people taking everything somebody says as gospel just beca... | [
"I disagree. Many of the answers I've given in the past were ones I could have given by the time I was in the second year of my bachelor's degree."
] | [
"I have to admit that I have a very different conception of this subreddit and what it should be. And I’ll also admit that I do feel invested: this is the only subreddit that I routinely check and read all the posts. I have learned so much, and it genuinely warms my heart to listen to people who are passionate ab... |
[
"How much power do I have over myself?"
] | [
false
] | [deleted] | [
"Since things like psychotherapy and mindfulness meditation are scientifically proven to improve the lives of depressives, even without medication, I'd say quite a bit.",
"This is a moral and philosophical beehive, however. How about those who are never able to get out of depression -- are they more sick, or simp... | [
"I'd like to add: How much power do we have over ",
" our conditions? When one becomes overly cynical and pessimistic over years or decades, how can one break free?"
] | [
"This is more complex than neurochemistry, which mediates the strength of connections, but also has a lot to do with structure i.e. which neurons connect to which neurons.",
"Both the strength and structure of neural connections is incredibly changeable (plastic) so, by repetitively stimulating desirable populati... |
[
"When the space shuttle piggy backs the 747 like we saw in so many photos recently, does it provide extra lift or just dead weight?"
] | [
false
] | I'm talking about in this scenario: So, extra lift? dead weight? What kind of adjustments must the pilots make to fly around like that? | [
"Yes, but you need to change it's angle of attack continuously ( i.e spin it). This is why a footballer can make a curved kick to bend the trajectory of a spherical football. "
] | [
"I am pretty sure the shuttle is positioned to provide near neutral lift or it would make it very difficult to to fly. The shuttles body itself provides some of the lift. it appears that it is positioned at a slightly positive angle of attack. The result is that the lift from the shuttle is nearly equal to the weig... | [
"From my best understanding of what my Aero Professor said in lecture the other day:",
"The wings on space shuttle arent really designed to provide lift. The shuttle is a Delta Wing design, but the body of the craft is technically a lifting body, meaning the fuselage itself provides some lift. ",
"Also, when mo... |
[
"How do black holes absorb light if they rely on based gravity, which is based on mass, to draw things in?"
] | [
false
] | null | [
"Mass ",
" gravity. Something doesn't need to have a mass to ",
" to gravity. One way of seeing this is the equivalence principle: the motion of an object in a gravitational field is totally independent of its mass. A larger mass doesn't fall faster than a smaller mass. Similarly, something will still fall if i... | [
"Indeed, but the missing piece is Newton's second law tells us how a force affects the motion of an object. So if we are talking about the motion of mass m1, then you need:",
"Gm1m2/r",
" = m1 a",
"and lo! m1 cancels out from both sides, leaving a description of the motion of the object that is independent of... | [
"Correct me if I’m wrong, but if the equation for the force between two objects Gm1m2/r",
" and since the mass of one of the objects is zero, wouldn’t the force be zero?"
] |
[
"Why are oil stained napkins transparent?"
] | [
false
] | If you've ever held an oil stained napkin to a light, you can see through it! This isn't the case with wet, water logged napkins. What causes oil stained napkins to be transparent? Is this property exclusive to lipids? | [
"The short answer is that oil acts as an ",
"index-matching medium",
" for the paper. What that means is that oil has a refractive index similar to that of paper, or at least more similar than the refractive index of air. As a result, the napkin scatters much less light, which in turn allows more light to simpl... | [
"Very well put!",
"I want to add that the phenomenon of impedance matching isn't limited to visible: it is important for sound waves (a megaphone bridges the gap between the acoustic impedance of your respiratory system & that of the open air), lower-energy electromagnetic waves in electronics, and presumably oth... | [
"For anyone who is interested, here is a great video visually showing the phenomenon. You can see how exactly the wave behaves when it encounters a medium change.",
"https://youtu.be/DovunOxlY1k",
"Go to 20:00 (20 minutes). At this moment, the man visually shows how waves get reflected due to impedance mismatch... |
[
"What could have caused a violent reaction between 2 store-bought pool chlorine brands?"
] | [
false
] | A Tale of Two Chlorines Can someone please explain why I had a sturdy plastic bucket literally explode into fragments when I mixed 2 different brands of pool chlorine together? I've never seen something explode like that when exposed to open air. So what I would normally do is mix the chlorine with pool water and the... | [
"According to the MSDS of ",
"HTH",
", the source of chlorine for the disinfectant is calcium hypochlorite. It also contains some calcium hydroxide and calcium carbonate to keep the pH above 7 which prevents the creation and release of poisonous chlorine gas. I couldn't find any information on Clarity as a pool... | [
"It is also possible that the Cal hypo product added with the small amount of water added a lot of the heat too. I worked for a pool company and the first thing they explained was how if you add small amounts of water to Cal hypo products they have a nasty tendency of catching on fire or exploding. Since I'm not th... | [
"Yes, this is what I originally thought was the case for the OP. It sounds like the OP added a whole load of undissolved hypochlorite which while dissolving will produce loads of heat. It's the first error made in any chem lab. People forget - dissolving substances (edit) can be very exothermic."
] |
[
"Does the space shuttle generate lift when riding piggyback on a 747?"
] | [
false
] | Basically how does having the space shuttle riding piggyback affect the dynamics of flight? does the shuttle help create lift or is the drag negate all of that? | [
"Without digging way into the physics, I'd say more drag than lift. Particularly with the aparatus that holds it to the seven four installed.",
"Maybe some lift at higher airspeeds, but the airframe combo is probably speed limited while being hauled.",
"The shuttle is designed to produce lift at high speeds an... | [
"I'm pretty sure they are there for enhanced stability- I'd guess that orbiter does quite the number on airflow around the empenage when it's attached. Probably partially blanks the vertical stab of the 747, necessitating extra vertical stab help. Raises the question of rudder effectiveness while the orbiter is... | [
"What is the purpose of the unusual horizontal fins on the back of the lifter?"
] |
[
"To what extent is determinism true?"
] | [
false
] | I was having a discussion about free will and determinism and there are a couple of points that I need clarification on. Basically, if we knew all of the laws of physics and all of the properties of every particle in the universe could we predict the future? If there is an element of indeterminism is it evident at all ... | [
"The answer is yes and no. There are many tricky issues regarding predictability, some are just a matter of complexity and others are really inherent to physics.",
"First, at small scales, it seems like quantum mechanics only allows us to answer certain questions probabilistically. So, if your question is: \"Wher... | [
"I feel like you haven't made strong statements differentiating between predictability and determinism, which is something that I haven't fully understood about quantum mechanics (and related).",
"I realise that it's impossible for us to know know the states of any particular system enough to predict it accuratel... | [
"Basically, if we knew all of the laws of physics and all of the properties of every particle in the universe could we predict the future?",
"Unfortunately, this question is not yet resolved -- it is an outstanding question. Different interpretations of quantum mechanics either preserve or violate determinism. ... |
[
"Why did this water filter turn black?"
] | [
false
] | [deleted] | [
"The filter contains carbon black as one of the filtering elements.",
"Some of the smaller carbon black particles escaped the inner filter and have become impregnated in the outer filter, turning it black."
] | [
"I may be really wrong here but carbon black would not be used as a filter material... it is a nasty material, maybe \"black colored activated carbon\" is what you meant to say?"
] | [
"That's what the manufacturer calls it. You're right, it's probably activated carbon, though."
] |
[
"Do nervous systems themselves produce heat?"
] | [
false
] | Since the nervous system is carrying electricity for signals (even if it is a minute amount in terms of amperage or voltage), it has to produce some kind of heat unless the tissue that makes up the nervous system conducts without resistance, right? If so then, if we could somehow "overclock" our brains, we could potent... | [
"The brain isn't governed by a clocking type system. Parts all work independantly and dependantly depending on what they're doing and trying to do. Everything in the body has an electrical resistance, including our neurons and synapses, therefore heat has to be given off. There are many ways to overheat the brain, ... | [
"Many neurotoxins cause nerves to fire uncontrollably, or interfere with their ability to stop firing.",
"Nerve action potentials are electrochemical, not strictly electrical. While preparing to fire, sodium ions are pumped out and potassium ions are pumped in, while these gated channels in the cell membrane won'... | [
"Interesting question. The idea of currents in neurons bothered me a lot when I was taking electrophysiology, so I will do my best from what I have been taught by my professors.",
"It isnt the current that carries a signal in a neuron, the neuron couldnt give two hoots about the current, the neuron cares about th... |
[
"Are Black Hole forming Supernovae less energetic than Neutron Star forming Supernovae?"
] | [
false
] | I've been wondering about this for a while but haven't really had anyone to ask. Nothing suggests this is true, but knowing some basics about how supernovae occur, I can't figure out why it wouldn't be. From what I understand, Supernovae occur when Fusion sharply cuts off due to the forming of Iron-56 which can't fuse ... | [
"A large star collapsing to a black hole would not produce a supernova.",
"Well now I'm very confused because I always heard that black holes were ",
" by supernovae. Maybe I or my sources conflated the phrase \"collapse of a star\" with \"supernova\" and that caused the confusion?"
] | [
"A large star collapsing to a black hole would not produce a supernova.",
"Well now I'm very confused because I always heard that black holes were ",
" by supernovae. Maybe I or my sources conflated the phrase \"collapse of a star\" with \"supernova\" and that caused the confusion?"
] | [
"Supernovae that form black holes can actually be more powerful than neutron-star supernovae. Neutrinos and other normal drivers of supernovae indeed tend to drop in energy as the core mass increases, not because the central object is a black hole, but because the central mass is larger and it's harder to escape. "... |
[
"Help finding the IR Identification Chart from a few weeks ago..."
] | [
false
] | Can't...find it using both reddit's search and google. Not remembering the key phrases used in the post either though... help plz! | [
"http://www.reddit.com/r/chemistry/comments/il2ya/ir_an_illustrated_guide/"
] | [
"http://toeholds.files.wordpress.com/2010/09/ir-illustrated.png",
" Is this what you're talking about?"
] | [
":)",
"Sweet. Someone's actually ",
" for it. FWIW, I've finally put pen to tablet for ",
", and when it's done and checked for factual accuracy by NMR-theory folks (that's Rupert here) I'll post it up to ",
"r/chem",
"!"
] |
[
"How do societies/cultures 'lose knowledge'?"
] | [
false
] | The Greek and the Romans (and I'm sure other cultures too) seem to have had an amazing level of knowledge and wisdom in a wide variety of fields. They created things like the Baghdad Battery, the Antikythera Mechanism, special cements which helped create Aquaeducts that are still around millenia later. Also knowledge a... | [
"Usually it’s simply because the average person doesn’t know the exact ins and outs of the most advanced technology of the time. If many people die at one time due to disease or conquest, most of the information about a society dies with them. Think about it, if civilization fell chances are most people wouldn’t be... | [
"Sorry to be a pedant here, but it’s a common misconception that the Great Library of Alexandria was burned intentionally by Caesar. To quote from the wiki ",
"“[Julius Caesar’s] soldiers set fire to his own ships while trying to clear the wharves to block the fleet belonging to Cleopatra's brother Ptolemy XIV. T... | [
"To add to that, even with YouTube, much of how to do things is a practiced skill. Each person who does it has to learn crucial details by doing and personal observation. It’s getting better with CNC and 3d printing but even that has a lot of undocumented and poorly documented knowledge involved. "
] |
[
"Does how hydrated you are effect how strong caffeine effects you?"
] | [
false
] | This is a question that came out of a conversation about how transgender hormone replacement therapy for MtF people can decrease alcohol tolerance because you have less water in your body. This lead to the question of whether or not the amount of water in your system can effect how much caffeine you absorb from coffee.... | [
"Caffeine is absorbed by the gut and dissolves in both the body's water and fat molecules. The \"strong effect\" of caffeine is dependent on your body's tolerance and how quickly it takes for the caffeine to peak in your blood. As far as how long it takes for caffeine to peak in your blood, the biggest factor will ... | [
"You should be wary of the places you came across saying \"coffee dehydrated you\". ",
"Though certain beverages will hydrate you more than others, coffee is still a net-hydrator.",
" What's more, ",
"studies of habitual coffee drinkers find no evidence of dehydration with even 3-6 cups a day",
". The May... | [
"Not your primary question, but the issue with MTF transitions isn’t hormone replacement, it’s the drug Spironolactone, which blocks testosterone (I’ve been on it for the treatment of PCOS) but it’s primary use is as a potassium-sparing diuretic. And it does such a good job at that that I had to keep soy sauce pack... |
[
"How does heat get lost in space?"
] | [
false
] | null | [
"radiative cooling via ",
"thermal radiation"
] | [
"Heat is the result of excited, highly energetic atoms. When heat is given off, these atoms are going from a higher energy state to a lower energy state. So a coal would extinguish in space if it was burning, but that energy would hypothetically be in the carbon atoms of the coal still. Since \"space\" lacks a medi... | [
"Heh. Well at least I understood what you were saying. I checked out that thermal radiation wiki and thought I was going to have to do an askscience \"What the hell is thermal radiation?\" But then I read the wiki again and noticed \"Thermal radiation is electromagnetic radiation...\" so I'm going to assume that he... |
[
"How would random fluctuations in the level of entropy come about? (obvious Layman)"
] | [
false
] | I just don't get how a constantly rising level of entropy would ever fluctuate let alone fluctuate into an extremely low entropic state. All help is appreciated. | [
"So to answer this question, we need to look at what entropy is. It's often described as the amount of disorder in a system, but I don't really like this. Disorder isn't really a well defined physical quantity. What ",
" a well defined physical quantity (and directly related to entropy) is something called mul... | [
"I just don't get how a constantly rising level of entropy would ever fluctuate let alone fluctuate into an extremely low entropic state. All help is appreciated.",
"It is important to emphasize the role of chance in earthly processes. Entropy must increase overall in a closed system, but this doesn't mean there ... | [
"Thank you. I feel I have a much better understanding now."
] |
[
"Using the DNA is a code? or like a code analogy, how does that translate into attributes we can identify with?"
] | [
false
] | For example, if human DNA is like a code. How does a cell translate that code into attributes like blue eye color. Is DNA similar to a "programming code/instruction" or does DNA contain sequences that are associated with attributes that are used during protein synthesis. ...ignore what I said above, basically how woul... | [
"The double-strandedness of DNA is the secret to its replication; you might say the very secret of life:",
"T always pairs with A",
"C always pairs with G",
"So they are two complementary strands.",
"When the two strands separate to replicate, each becomes a template.",
"A new complementary strand forms b... | [
"Your first sentence is a bit misleading, since it implies that all genes are encoded on one strand only. Both strands code, but each individual gene is located either on one strand or the other."
] | [
"DNA sequence is DIRECTLY related to protein sequence. DNA is transcribed into RNA and RNA is coded in clumps of 3 called 'codons' and each codon codes for an amino acid. Many amino acids in a chain make a protein. ",
"So let's take the DNA sequence:",
"TACAGTCTGACGGATCGG",
"The RNA is the complementary seque... |
[
"According to the tests, I'm colorblind, but I've never noticed problems with color vision. Is this normal?"
] | [
false
] | I fail every part of the Ishihara test except for plate #1 - the 'cyan and orange' one. However, when doing the Farnsworth Munsell 100 test online, on a calibrated monitor, I test in the midrange of male color vision capabilities. I have never had a problem with my color vision, do color correction on photos and video ... | [
"Just FYI - did the FM100 test again, and got a 36. Not perfect, but according to the summary after doing the test at ",
"http://www.xrite.com/custom_page.aspx?pageid=77&lang=en",
" it said my color vision was somewhere around the 40th percentile."
] | [
"just to chime in: I just took that test and scored a 12. I also work a lot with color (although I was doing it on an uncalibrated monitor, which is what I blame on getting a 12)."
] | [
"I scored a 7 and I'm pretty happy with that."
] |
[
"Are there any downsides to Fusion energy research? If not with the reactors themselves, then weapons they would enable?"
] | [
false
] | Fusion energy is the holy grail of energy sources and I know it avoids all the nasty byproducts of fission - such as meltdowns, radioactive waste, rare source of fuels. However, fusion as a weapons technology is also much more preferable to fission - in terms of potential yield, commonly occurring fuel with no radioact... | [
"The biggest issue is, that we simply don't know (yet). But I wouldn't be that quick in glorifying fission, at least in the way you do. ",
"Uncontrolled meltdowns are improbable (as it requires power input to output any energy), fuels (typically deuterium and tritium) aren't ",
" more prolific than uranium and ... | [
"But the interesting question is: Why do you consider military technologies a downside to doing research?",
"I think the point about this is that military power isn't the goal that he wants to have achieved by making fusion a viable energy source. In so far it is a downside because it would eventually lead to war... | [
"This is correct. Right now Nuclear proliferation is strictly controlled and easy to monitor. I was wondering if fusion research could make that a futile endeavor."
] |
[
"why is it an artichoke oxidizes very quickly when cut, but cucumbers oxidize very slowly?"
] | [
false
] | null | [
"Cut fruits and vegetables turn brown due to the oxidation of polyphenols by an enzyme polyphenol oxidase, which is released when cells are cut. The rate of browning depends on various factors, such as the phenolic content of the food, the polyphenol oxidase content of the food, the oxygen content of the air, the t... | [
"What's the purpose of polyphenol oxidase? Does an oxidized fruit/vegetable provide less antioxidants for our bodies when we eat them?"
] | [
"Polyphenol oxidase is usually part of a defense mechanism which protects damaged parts of the plant from infection. The compounds it produces can kill bacteria and fungi"
] |
[
"What is the melting point of roads?"
] | [
false
] | null | [
"http://en.wikipedia.org/wiki/Asphalt_concrete",
"Mixing is generally performed with the aggregate at about 300 °F (roughly 150 °C) for virgin asphalt "
] | [
"Thanks"
] | [
"It should be noted that asphalt doesn't have a defined \"melting\" point like e.g. ice. As you increase the temperature, it gradually behaves more and more like a liquid. Over a pretty large temperature range, asphalt is basically a ",
"viscoelastic",
" material. This means that it doesn't flow instantaneously... |
[
"OHow does our large intestine not suffer from the output of stomach acid?"
] | [
false
] | null | [
"As food progress through the intestines, the pH increases because of the chemical released has a tremendously higher pH then the stomach acid."
] | [
"So there is not some hunk of muscle that acts as a doorway from the stomach itself...its just a gradual ph progression that breaks it down?"
] | [
"not much muscle, because the intestines are LONG and they have their pH increased until it reaches near biologically acceptable pH."
] |
[
"Why do rough surfaces encourage nucleation of CO2 in fizzy drinks?"
] | [
false
] | Just went to a cafe, got a bottle of Coke, put a paper straw in it, and it started bubbling up, out of the bottle and straight onto the table and onto me. I know that rough surfaces, such as a paper straw, or mentos do encourage nucleation of CO2, but could somebody explain why this happens to me? Thanks, Noah | [
"The amount of gas that'll dissolve into a liquid depends on the pressure. During packaging, lots of gas is dissolved into the soda using high pressure. When you open the soda, the system isn't at equilibrium anymore, and all of the gas inside the soda ",
" to come out of solution and gasify.",
"The problem is ... | [
"I will consider water as the solvent, as is the case for Coke, and I will consider the surface to be chemically inert, which is mostly true for a paper straw or sand dust, but not sugar.",
"The first point to establish is that the Coke, fresh out of the can or bottle, is ",
" in equilibrium. Carbon dioxide has... | [
"What you're referring to is called a \"nucleation site\". For a proper bubble to form enough CO2 has to gather. But not enough CO2 can gather on smooth surfaces or in the liquid before it will just dissolve away again. A nucleation site can act as a \"save place\" for the CO2 to gather and form bubbles, without di... |
[
"How do they make the first down line on the TV?"
] | [
false
] | If it were just superimposed on top of the TV feed, surely the line would be at the "front" of the image and the players would appear "behind" it? | [
"A simple Google search answers this",
". It's actually very complex."
] | [
"The easiest way to do this would be to have a mounted camera that feeds information about which direction it is pointing and the level of zoom into a computer. From there a projection matrix could be calculated to map the 3d view onto a 2d plane. Each individual pixel color could then be matched to a pre-photogr... | [
"This is what he is talking about",
". Players pass over it so it looks as if it is painted on the field. I am interested as well."
] |
[
"If I were on a space station 2 light years away?"
] | [
false
] | Ok, so basically say I, right now, was instantaneously teleported via some kind of magic to a space station 2 light years away. I have a telescope on this space station that is so powerful I can see people walking around on city streets in minute detail, would the planet I see be Earth in the year 2017? And if so could... | [
"Yes, because the light takes two years to reach you, so you're seeing a two year old image.",
"You would of course need an enormous telescope to see that level of resolution - ",
" bigger than a planet. You also can't actually use this to see into your own past, because you can't travel faster than light - thi... | [
"In principle yes, in practice the amount of light you get back is negligible. You can't even hand-wave that away with a larger telescope as the black hole will set a hard limit.",
"A simple mirror works better.",
"/u/Calricium",
": You'll never see yourself at a time before you set up some elaborate scheme, ... | [
"Actually, everything you see is about 13-100 milliseconds in the past. That's the amount of time it takes for the signal to travel from your eye, down your optic nerve, to the visual processing center of your brain and form the image. Everything you see, everything, happened in the past.",
"There's all kinds of... |
[
"If we are 99.9% empty space, along with everything else - Why can't we see through each other and see through walls?"
] | [
false
] | null | [
"The oft quoted \"empty space\" idea is describing the space in between the electron shells and the nucleus, which is inside the atom.",
"However, if you get light with a short enough wave length then we can see through things. That's how x-rays work!"
] | [
"Electron shells are not discrete orbits around the nucleus like a planetary system. The electron cloud occupies all the space around the nucleus. This \"empty space\" idea mainly comes from the distribution of mass in an atom and a general confusion about what size means on the quantum scale."
] | [
"Because the signal we perceive (visible light) is dominated by the signal which 'bounced' back at us than the signal which 'passed through' the object.",
"The wavelength of visible light is large enough that it doesn't fit through the 'holes' you described.",
"When light is travelling through a substance and '... |
[
"If travelling really fast slows down time, does travelling really slow, speed up time?"
] | [
false
] | null | [
"No. In special relativity, it's never possible to ",
" time, only slow it down."
] | [
"Faster things than Earth experience time more slowly.\nSlower things than Earth must experience time more quickly no? ",
"If you can’t speed up time how can you travel near the speed of light, experience time going so slow your grandchild out ages you but then be able to return to Earth and experience time as no... | [
"Slower things than Earth must experience time more quickly no?",
"What do you mean by \"slower than Earth\"? There is no such thing as an absolute speed, if that's what you're getting at. The speed of any object is relative, and the minimum speed that anything can have is zero. If an object is moving at zero spe... |
[
"On the design of spacecrafts: Why is it better to have a vertical launch rather than a take off like an airplane and a gradual ascent out of the atmosphere?"
] | [
false
] | There are undoubtedly many things that I do not know about aeronautics and flight, but it just intuitively seems to me like it would be easier to launch our spacecrafts like planes and then gradually gain altitude until they are in orbit. Can someone explain why we don't do this, and instead launch straight up with roc... | [
"Long story short, rockets provide enough thrust to make it worthwhile to get some altitude first so you can do your lateral thrust with less air drag.",
"As we develop better technologies it may become more efficient to use horizontal launches with air-breathing engines.",
"http://en.wikipedia.org/wiki/SSTO",
... | [
"I think a lot of the reason that we build large rockets is that we'd need an unrealistically-large lift-producing aircraft to launch the substantial payloads that are frequently required.That, and we spent a ton of money in the 20th century learning about vertical launch rockets, so now they're less expensive than... | [
"I just want to emphasize that the (prospective) advantage of horizontal launch is the use of air-breathing engines for part of the ascent. ",
"Use of air-breathing engines in launch is almost an end unto itself; it reduces propellant requirements dramatically because you don't need to bring your own oxidizer fo... |
[
"At what stage do people typically \"feel\" cancer? How is it possible for someone to just get diagnosed at stage 4, at that point of metastasization shouldn't the person be in massive pain at stage 3 already?"
] | [
false
] | Just heard at Alex Trebek (Jeopardy! Host) was diagnosed with stage 4 pancreatic cancer. From what I know pancreatic cancer takes a long time ( ) and doesn't present a lot of symptoms at first. I understand normal people not having the time or money or even access to get checkups so they ignore that pain in their side ... | [
"There's no answer to this as it is vastly vastly different between any of the 200+ types of cancer, and even within a type it can depend on where exactly the tumor is.",
"For example, the most common subtype of Non-Hodgkin Lymphoma shows up as a very rapidly growing lymph node in the neck or chest (over a few we... | [
"There are a ton of reasons why you might do abdominal scans--if you had severe pain or gastrointestinal issues they might do one to check what's going on. Scans aren't given out super easily, though--for one, CT scans to the abdomen actually expose you to a decent amount of radiation, which isn't something you wan... | [
"Cancer cells don't have a nerve supply, so they can't feel pain directly. You only feel pain when the cancer cells injure the normal tissue around them.",
"Different body parts feel pain through different mechanisms, and many parts of the body do not have pain receptors at all. Most of your gastrointestinal trac... |
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