title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"How does a virus, such as chickenpox or HSV, physically damage the skin to cause blisters?"
] | [
false
] | [deleted] | [
"Usually a virus does not cause direct damage that you can see on a macroscopic level. The sores caused by some herpesviruses such as HSV1 are caused by self-directed immune responses which cause damage to your own body. "
] | [
"Why at the skin though, does the virus concentrate in skin cells somehow?"
] | [
"It has been a long time since I have learned about these. From what I remember HSV1 likes to reside latently in the trigeminal ganglia. If i remember correctly it migrates to the area around your lips, which is where cold sores occur due to the immune response against the virus. "
] |
[
"How is a male anglerfish not rejected by the female's immune system?"
] | [
false
] | So I know the has a rather unique reproductive strategy, where the male latches onto a female and atrophies until basically he is just his reproductive organs receiving nutrients from the female. As I understand it, at the attachment site their circulatory systems essentially connect. Looking now at humans, if I were ... | [
"Hagfish and Lampreys (aka jawless vertebrates) have the most basic type of adaptive immune systems, however they do not have B cells or T cells. Instead, they use VLR (Variable Lymphocyte receptors) cassettes to recognize pathogens. However, plants and invertebrates have \"innate\" immunity that recognizes certain... | [
"Alternate question. What's the most primitive form of animal with an immune system?"
] | [
"While I am not an authority on vertebrate immunology, I am somewhat familiar with the subject and literature. The adaptive immune systems of all vertebrates have many similarities at the cellular and molecular level, although the organs differ considerably. Fish have T-cell receptors, MHC molecules, cytokines, and... |
[
"Antarctic Life, how did it get there?"
] | [
false
] | As far as I've read, there are only two flowering plants on Antarctica, and a bunch of various lichens and mosses and a handful of vertebrates. What's the theory on how all of this more evolved life (if that's the right term) got there? Like, did Antarctica split off from the other continents, or did animals/plants tra... | [
"Antarctica is thought to have once been connected to both South America and Australia. It was probably populated my marsupials which originated in South America and ended up dominating Australia. As the continent drifted south and ocean currents changed, the climate became much colder and most life died off.",
"... | [
"Antartica used to be part of Gondwanaland along with South America and Australia. ",
"It also wasn't always frozen, in fact in the grand scheme of life on earth, it's only done so twice, first at the end of the Ordovician and again in the current ice age.",
"That isn't to say it hasn't always been cold, more ... | [
"Also to add to this they recently found fossilised remains of rainforest plants under the ice in some places so it almost certainly was not always a frozen desert like we see it today. \nIt would have been much warmer in the past."
] |
[
"Is it possible to determine our birthdate from our bodies through some biological/chemical/physical means?"
] | [
false
] | null | [
"The approximate age of a person can be determined a number of ways (prortion of naive T cells, growth plate presence in bone, etc.), but these approximations are all based on average values across many humans, so there isn't a way to get exact birthdate - usually you'd be looking at a 2-5 year window of age."
] | [
"This is true, however the invasive surgery into the semi-circular canals should be avoided in any living patient."
] | [
"Otoliths (acceleration-sensitive structures) are located way in the inner ear. In order to get to them, you'd have to do a lot of cutting. That's okay if you're doing an autopsy, but not okay if the subject is still alive."
] |
[
"Why are cats so much more focused on cleanliness than dogs? Is there an evolutionary advantage for cats to remain clean and no such advantage for dogs?"
] | [
false
] | I was watching the cat at my work clean herself today, and I realized that dogs only tend to lick themselves when they're wounded. They don't clean themselves the way cats do. If they're both predators I don't understand why it would be more beneficial for cats to remain clean and not for dogs to stay clean. | [
"Cats and dogs are predators, but they have very different hunting strategies.",
"Dogs are chasers. When they find prey, they run them down and kill them. Cats are pouncers. They lie in wait and strike when prey is in range.",
"The difference means that it's not very important to a dog if the prey knows ther... | [
"Related?",
"Cats do not like to eat near their water. Cats consider water that is near food to be contaminated. This goes back to the fact that cats are hunters. When they catch prey, things can get messy, leaving nearby water contaminated. While our indoor cats are not usually catching prey, the instinct of the... | [
"Could this be why many cats drink out of toilets and sinks rather then the water dish that is provided to them that is usually next to their food?"
] |
[
"What's the difference between photoelectric effect and photovoltaic effect?"
] | [
false
] | null | [
"The photoelectric effect refers to emission of electrons from one material into another, typically into a vacuum, although air photoemission (into a gas) or internal photoemission (from one solid through a barrier into another solid) also exist. The defining characteristic of photoemission is that the electrons ar... | [
"For materials that can act as a photovoltaic, it depends on how energetic the photon that hits it is. For silicon, the band gap (the minimum energy to excite an electron for photovoltaics), is about 1 electron-Volt, which corresponds to the energy of a near infrared photon.",
"In contrast the work function of si... | [
"THANK YOU! All of the other answers were great, but your answer was EXACTLY what I was looking for!"
] |
[
"How do scientists know that the red shift means the universe is expansing and it doesnt mean that other stars are moving away from us through empty space?"
] | [
false
] | How is the red shift of stars any diffferent than the red shift i would get if I launched a rocket away from earth wirh a bright light. Both indicate they are moving away from us? | [
"Those are both the same thing.",
"Imagine a round inflated party balloon with a bunch of ants crawling on it. If the ants move randomly, every ant tends to see about half the other ants moving away from it and half moving towards it, at various angles. In order for an ant to see ",
" the other ants moving away... | [
"The measured redshift increases with distance, which indicates not just that galaxies are moving away from us, but that that further galaxies are moving away ",
". What would cause galaxies to be moving away faster the further away from us they are? The expansion of the universe. "
] | [
"To elaborate, the observed redshift could, ",
", just be observed because all of the distant galaxies conspired to be moving away from us at a velocity proportional to their distance from us. However, that would mean that there is a special point in the universe---us, right at the center. (At least, the center w... |
[
"Why didn't reindeer herding catch on with the natives of Canada, like it did with the Sámi in Scandinavia?"
] | [
false
] | null | [
"The transition from hunter-gatherer to agricultural society is one of the most significant shifts a civilization can undergo. Historically, it seems to happen in warmer climates first, with more temperate climates transitioning later. (Why it happens this way is another question...) There are very few examples of ... | [
"The Saami were originally hunters, and traces of this such as trap ditches can still be seen. The transition to a cash economy was forced by the northwards expansion of Swedish control in the 18C. As a result of this, they moved towards herding. ",
"The lack of a similar change in North America may be as simple ... | [
"No, I was only talking about herding reindeer and accompanying them on their migration, treating them more as property than prey. I'm afraid I haven't read anything on when they came to be used as beasts of burden."
] |
[
"Why are mountains so tall in other planets?"
] | [
false
] | null | [
"Mars has lower gravity than earth so mountains can grow higher before the pull of gravity causes issues such as with Mauna Loa which due to its weight pushes down into the planets crust an additional 20K feet below the surface of the ocean."
] | [
"Another important point about Mars is that it doesn't have plate tectonics. Olympus Mons has been able to grow to the heights it has because it hasn't moved relative to the hotspot underneath it."
] | [
"Speaking specifically about Mars and other planets without an ocean: they don't have an ocean, and mountains on our planet are generally measured relative to sea level. While Mauna Kea measured from sea floor to peak is still much smaller than Olympus Mons, it is not hard to imagine tectonic or volcanic forces sim... |
[
"If we never would've existed, would every lake in the world have different species of fish?"
] | [
false
] | null | [
"No, fish eggs can be transported around by ducks or other water fowl.",
"This happens all the time. Go ask a farmer. They will dig a hole, which turns into a pond after the groundwater fills it. A few years later it will be full of fish.",
"Over longer timescales you will have floods that allow different la... | [
"Are you trying to understand how humans affect the biodiversity of lakes?"
] | [
"Would Every single lake in the world ever have different species? The odds of this are astronomically low, however, nonzero..."
] |
[
"Is dark matter affected by the gravity of black holes?"
] | [
false
] | Astrophysicists always talk on the abundance of dark matter in the Universe, so I started wondering what effect black holes would have on said dark matter. I understand that black holes also fall into the category of dark matter, but I'm talking about the abunant dark matter that allegedly surrounds everything, includi... | [
"Yes. The one thing we know about dark matter is that it interacts gravitationally; that is how we detect it."
] | [
"Dark matter has never been observed directly. It is a way to explain why measurements don't line up with theory. ",
"In theory, you can measure the light coming from different parts of a galaxy and determine how much stuff is there. Our sun is at least 99.8% of the mass of the solar system, so measuring the numb... | [
"that is how we detect it.",
"Should read: this is how some believe observations should be interpreted."
] |
[
"How can the observable universe be larger than the age of the universe?"
] | [
false
] | I was reading the Wikipedia article on the universe and it states two things that seem contradictory to me. The radius of the observable universe is 47 billion light years. The age of the universe is 13.7 billion years. How do we observe things that occurred more than 13.7 billion years ago? Here's the page: | [
"The universe is expanding."
] | [
"The most distant thing we can see is the Cosmic Microwave Background. The light from it traveled 13.7 billion light years to get to us. However, the matter that emitted that light is now 45 billion light years from us. This is because the metric expansion of space can result in the distance between two objects inc... | [
"As the others have said, it's because of the expansion of space itself - a concept that's really hard to grasp if you've never taken a general relativity class (I've taken a class that did GR for the last 3 weeks or so and I don't really understand it)",
"Link that might explain it for you: ",
"http://en.wikip... |
[
"Does \"slow light\" age?"
] | [
false
] | null | [
"The popular picture that photons in a material are constantly absorbed and emitted cannot account for a lot of what happens when light interacts with solids/liquids. If you think about it, how could this essentially random process generate a consistent speed of light in a material, which can be expressed as the re... | [
"The popular picture that photons in a material are constantly absorbed and emitted cannot account for a lot of what happens when light interacts with solids/liquids. If you think about it, how could this essentially random process generate a consistent speed of light in a material, which can be expressed as the re... | [
"Indeed, which is exactly what I said above, that the photons are absorbed and emitted by atoms and vibrational modes. It's true that the latter plays a larger role, but I was simply trying to answer OPs question and the interaction of electromagnetic fields with solids is extremely complicated"
] |
[
"What are the possible consequences to a baby's immune system who was born into quarantine?"
] | [
false
] | Let's say that the baby was born at the hospital, went home the same day and has had contact only with their parents since then. Is it possible (or probable) that this baby will have a compromised immune system compared to babies who go out and see other people if they stay in quarantine for, say, 6 months? One year? | [
"Not necessarily, but it will depend on 3 things: If the baby was naturally born, if the mother breastfeeds, and if they vaccinate.",
"Last I checked, it was still being researched, but natural birth introduces some bacteria to the baby that is beneficial (I’d have to do some research, though; Ob-Gyn isn’t my foc... | [
"FYI, most pediatricians want you to wait a few weeks/months before taking your baby out in public anyway. They are not vaccinated at birth so they are highly susceptible. So in that respect it's not that different. The baby will already be exposed to the rest of the family members, they are not in isolation so ... | [
"There's also plenty of bacteria in the home; it's not like a house or apartment is perfectly sterile and we only encounter microbes on the street."
] |
[
"When two light beams distructively interfere, where does their energy go?"
] | [
false
] | null | [
"when two beams of light destructively interfere, they only do so in ",
" location. There will always be other locations in the optical system where there is constructive interference which contain the seemingly missing energy. The entire system still contains the same amount of energy when you take all interfe... | [
"If you have two sources of waves, there is only ",
" way that they could destructively interfere - if the sources occupy the same spot. In that case, the system is indistinguishable from not having any waves at all.",
"If you have two spatially separate sources, you will never get destructive interference thro... | [
"not ",
", no. It would be more correct to say that some parts in the optical system experience constructive interference, while corresponding parts experience destructive interference."
] |
[
"Does gut bacteria affect our taste?"
] | [
false
] | [deleted] | [
"I'm a grad student in the microbiome field and I have never heard of anything like that. Peanut allergies are not (directly, at least) caused by gut bacteria or digestion - they are the result of an immune system reaction to something in the peanuts.",
"I would guess you hate peanuts because you associate them w... | [
"I can't speak to the nature of bacteria enhancing flavor detection, but I believe flavor would be more affected by oral microbiomepopulations more than gut. I just read an NPR article about dog olfaction and it mentioned human sense of smell as mostly connected to flavor/taste via a process of retro-olfaction, I t... | [
"Oh right! I believe the protein is what causes an immune response (I can have peanut oil, just not actual peanuts). Thanks for the insight!"
] |
[
"Shouldnt everyone get checked on toxoplasmosis and treated?"
] | [
false
] | null | [
"Whether something should or shouldn't be done is a matter of policy and should be addressed to a different sub. Perhaps there is a medical or health policy sub."
] | [
"This is not a policy question but a risk assesment depending on if my viewpoint is right.",
"I can reformulate it, if you want."
] | [
"In general, we also do not allow posts asking for medical advice so questions of the form \"should I be screened for X?\" would not pass muster either. Perhaps something along the lines of \"what is the incidence of X\" or \"are cases of X increasing?\" would work"
] |
[
"How do bubbles seem to magically appear in fizzy alcoholic drinks? Why are they generally sourced near the bottom and sides of the glass?"
] | [
false
] | My best guess that is the magic bubble appearance is based somewhat on saturation of the internal liquid, but it's worth wondering why the same bubble stream doesn't happen with soft drinks. Assuming it is the saturation, why does it happen at the bottom and sides of the glass, and not all throughout? | [
"What you observe is a describe case of a more general effect where bubbles preferentially form at interfaces or rough patches of a given vessel. First of all, consider why bubbles form in the first place. In the beginning carbonated drinks are ",
"supersaturated",
" in CO2, meaning that they have a higher conc... | [
"The ",
"etched logos",
" you see at the bottom of some branded pint glasses provide nucleation points, ensuring that their product looks appropriately bubbly and appealing. "
] | [
"Cool, so my beer would stay carbonated longer in a supersmooth glass? "
] |
[
"What happens to the human body when a person comes in contact with nuclear materials/extreme radiation?"
] | [
false
] | [deleted] | [
"Wikipedia on radiation poisoning.",
"Wikipedia on NBC suit"
] | [
"There are a variety of radiation sources, and each acts differently.",
"Gamma radiation and Beta Radiation act similarly to light: They can be fairly easily blocked (Gamma by several feet of concrete, beta by clothing or a thin wall). Both can cause immediate burns as well as cancers by damaging DNA.",
"Alpha ... | [
"Well I can answer your first question. Radiation is just one a list of \"effects\" and compounds that are termed mutagenic. The main idea is that these things generate mutations in your DNA. How it exactly works is probably beyond my scope (I guess it has to do with inducing kinks in the backbone?). But the effect... |
[
"Wouldn't plants be more efficient at gathering light if their leaves were black?"
] | [
false
] | From what I understand the colours we see are the non-absorbed wavelengths of visible light, meaning the green we see is light energy the chloroplasts are not utilising. If plants leaves were black wouldn't they gaining more usable energy? | [
"It would be more useful to take advantage of the full spectrum, but apparently evolution seems to have trapped plants in a different solution. ",
"Bacteriorhodopsin",
" is a simpler light harvesting complex found in archaea, and it absorbs in a single broad peak centered in the green region. Archaea that use i... | [
"No, because not all frequencies are useful for photosynthesis. This would just heat the leaves up and hurt the plant. For example, light in the near infrared is pointless to photosynthesis and therefore plants are very reflective in that range."
] | [
"Chlorophyll only absorbs energy from blue and red light, not green.",
"Right, but more broadly, the question is \"why didn't plants evolve new kinds of molecules sensitive to other wavelengths\"? After all, there are at least half a dozen different kinds of chlorophyll, each with somewhat different absorption sp... |
[
"Is there a reason North is associated with 'up' and South with 'down'?"
] | [
false
] | null | [
"pure convention; it used to be that in Europe, maps had east at the top - from which we get the verb 'to orient'; which was literally to turn a map so that the east (the orient) was at the top. ",
"http://en.wikipedia.org/wiki/Map#Orientation_of_maps"
] | [
"It's totally arbitrary but an interesting little sound byte is that the true north pole is actually the magnetic south, as proof I submit to you that like poles repel, correct? Then why would the north needle on the compass point to the north. Mind = Blown"
] | [
"I was simply stating a that was vaguely relevant to the question that people might have found interesting. Yes, in terms of naming the poles then you are entirely correct. North or south, a name is just a name. But in magnetic terms the core of the earth (as I'm guessing you already know) is a giant ball of molten... |
[
"Is it possible to build an electrostatic dust collector? Would it be effective?"
] | [
false
] | Every week or two my screens and my furniture are full of dust so I want to know whether it is possible to build an electrostatic dust collector. E.g. an electrostatically charged metallic ball that you can place somewhere in the room which attracts most of the dust so it doesn't get onto your furniture. Would it be ef... | [
"\"Air Ionizer\" style devices are essentially what you're proposing. ",
"The problem is that they process very little air, in general. So you need to, generally, put some fan to move air through them to actually pass dust through it. They also produce some amount of Ozone (O3) which is toxic to some degree. So a... | [
"Yes, it's possible and it has been done commercially for years. I have a large (size of a 1950s TV set) 25+ years old air purifier that has a large \"cassette\" style electrostatic filter. Essentially it's just a stack of evenly spaced out plates, electrostatically charged to attract dust, and a couple of fans to ... | [
"Is it effective? Or why did they stop selling it?"
] |
[
"Why do you throw up after swallowing too much of your own blood?"
] | [
false
] | Why can't it go through the digestive system? | [
"Blood is in essence warm, salty water. Our bodies have safeguards to prevent drinking too much contaminated water such that it would throw off our ability to regulate fluids within our cells. If you were for example to drink more than a pint of similarly salty water I suspect you would experience similar effects."... | [
"Ah thank you, that makes sense. Sorry if this is a dumb question, but why are we able to drink a big bowl of warm, salty broth without our bodies reacting the same way?"
] | [
"Because it isn't as salty as our blood. About 85% of the sodium in the body is present in the blood and lymphatic fluid; it is almost as salty as the ocean! While you can drink a big bowl of broth, I don't expect your tummy would react particularly well to drinking a big bowl of seawater."
] |
[
"How does etching a chunk of silicon with different crystal planes exposed get eaten away with time?"
] | [
false
] | I'm aware of how potassium hydroxide etches silicon anisotropically. The 100 planes get eaten the fastest while the 111 planes get eaten the slowest. This is commonly used to form trenches in 100 planes bounded by 111 surfaces. What would happen if you dunked something in KOH? It's hard for me to visualize. There are 1... | [
"Assuming that chunk of silicon was single crystal, then each set of faces would be a different plane. That means that each face (pair of faces I believe) would etch at a different rate, with the rate being constant throughout the face and the etching direction perpendicular to the face. As the chunk is etched, som... | [
"Chemist here, ",
"If you were to dunk the bottow right shape into KOH for \"science,\" imagine if you were to just \"push in\" the <100> planes inwards, maybe 4 atomic planes in, then you \"push in\" the <110> planes in 2 atomic planes in. These \"pushed in\" surfaces would represent what was etched away, while... | [
"imagine it would only etch the 100 planes. then you would first get the shape above it and eventually end up with a cube (if you take away layers of the 100 faces, those get broader while the other faces shrink untill they are gone). now if the other ones etch aswell, but not as fast that whole process will of cou... |
[
"Why are laws of physics absolute?"
] | [
false
] | I'm only asking this question from a ignorant stand point of view. I usually hear a normal discussion on tv, radio or even in life, and it goes something like this: Person A: "Dude, that new spaceship can travel faster then the speed of light." (Sorry can't think of a great example right now) Person B: "Dude, that goe... | [
"We just call it a law because so far, all the evidence we have support them. So, we are not certain that they apply to the whole universe but you can't just make a random claim that is not supported by any evidence or is impossible to test. ",
"As for evolution, a lot of the naming is political, but it does inde... | [
"That really isn't how \"law\" works in the scientific community. Specifically, laws are relationships and trends in specific sets of data. Most laws enumerated as such are really just relics of an older age and the word doesn't seem to be used as much anymore. This is probably mostly because we know that laws are ... | [
"There is no strict definition as to what constitutes a Law or a Theory (or a Conjecture or a Principle or a Rule). There is no Grand Council of Science that holds a vote to see if a Theory is ready to be promoted into a Law. There are Theories than are nigh absolute and Laws that are dead wrong.",
"There are s... |
[
"Any chemists on reddit know about a legal liquid/solid..."
] | [
false
] | ...with a melting point 10-20 degree Celsius above or below room temperature? I need something that can be flexible for a short amount of time then solidify to hold his shape. Any ideas? | [
"Gallium."
] | [
"You could try Polymer Clay, like Fimo or Sculpey. It is stiff at room temperature, and when heated up, it becomes pliable.",
"http://en.wikipedia.org/wiki/Polymer_clay"
] | [
"You want flexible, or a liquid that you could cast into a shape then freeze? ",
"H20 is quite legal so you can pour it into a mold then freeze it. It freezes roughly 20 degrees below room temperature.",
"However if you want something you can mold then keep it in such shape, why not try making bread or cookies... |
[
"Most cities do not allow wells to be drilled on city lots. Why is this? Doesn’t ground water partially come from rain water? We have been artificially moving water from rivers, etc and converting it to ground water via sprinklers that we could reuse to water our lawns?"
] | [
false
] | null | [
"There are a lot of considerations here and my post will surely miss many of them. To start however, it's important to have a clear understanding of groundwater, i.e., ",
"aquifers",
". What you're mostly describing or envisioning, would be an unconfined aquifer which can be recharged through infiltration from ... | [
"Also, urban living and thousands of wells is how you get dysentery and cholera outbreaks. Of course our waste water system is different but doesn't really eliminate it."
] | [
"Many towns and cities still have a ",
"combined sewer and stormwater system",
", which means that in periods of high rainfall the combined capacity is exceeded and sewage is discharged directly into local rivers, streams, lakes, etc."
] |
[
"If we were to see a black hole up close, would we be able to see everything that fell into it on the event horizon?"
] | [
false
] | I remember being told that if you were to watch someone fall into a black hole, at a certain point they would seem frozen in place forever (as light can't escape beyond this point). If a lot of stuff has fallen into a black hole, would we see a jumble of clutter at the event horizon of everything that has ever fallen i... | [
"Yes, but the images of the objects also become increasingly redshifted exponentially fast to the point that they become completely invisible to any kind of detector in a very short time. "
] | [
"The image would fade away very fast. As for the shape it can stretch or thin or deform depending on the trajectory of the object; moreover in general there are multiple images."
] | [
"Not just redshifted. There's also fewer photons leaving. The object would only emit finitely many before hitting the event horizon, so only finitely many escape."
] |
[
"How do sprays like Febreze actually work?"
] | [
false
] | null | [
"To eliminate odors, a product needs to remove the volatile compounds causing the odor. Hydroxypropyl beta-cyclodextrin works by binding the volatile compounds in its ring. When bound, the compounds causing the odor are no longer volatile, which means they become vapor/gas less readily. Since the compounds aren't v... | [
"Wikipedia",
" lists the active ingredient as hydroxypropyl beta-cyclodextrin which is a cylic structure that can trap compounds inside it."
] | [
"Febreeze is a solution of beta-cyclodextrin, a compound consisting of seven sugar rings grouped as a larger cyclic structure.",
"These sugars twist within the overall ring to orient themselves so that their hydroxyl groups (OH) are pointing outwards and their other functional groups are facing inwards, to the ri... |
[
"Why do phone/laptop/etc batteries hold less and less charge over time?"
] | [
false
] | null | [
"The causes of batteries degradation vary by battery type. Modern electronic devices typically use one of several varieties of Lithium-ion battery, which are generally degraded by three things: high temperatures, frequent deep cycling, and high state-of-charge ",
"[1]",
" ",
"[2]",
". (This last one means... | [
"A problem common to all batteries, re-chargeable or not, is that undesired side-reactions occur. These can lead to the formation of insoluble deposits that cannot participate in the charging cycle. This lowers the capacity of the battery.",
"Basically, irreversible chemical reactions degrade battery life.",
... | [
"I can explain one of the types that reduce battery capacity.",
"When you charge and discharge a li-ion battery, you'be basically moving lithium ions to and from the cathode and anode. Metallic Li deposits can begin to form on the anode that inhibit ion transport. These deposits can end up \"filling\" the carbon ... |
[
"Happy Pi Day everyone!"
] | [
false
] | Today is 3/14/16, a bit of a rounded-up Pi Day! Grab a slice of your favorite Pi Day dessert and come celebrate with us. Our experts are here to answer your questions all about pi. Last year, we had an pi day . Check out the comments below for more and to ask follow-up questions! From all of us at , have a very happy P... | [
"You could determine the value of pi experimentally. Take a small stick (or set of identical sticks) and draw parallel lines on a piece paper with a spacing equal to the length of the stick.",
"Then repeatedly drop the stick from a decent height onto the paper and count the total number of drops and the number of... | [
"There are plenty of algorithms that are suited for computers related to pi, but which are tractable with pen and paper? Can finding the n'th digit be done on paper reasonably?"
] | [
"I like how we have a computer simulation of a method to find pi using nothing but a pen (which could be the stick) and paper."
] |
[
"How does quantum annealing work?"
] | [
false
] | [deleted] | [
"To understand quantum annealing, it's first going to be necessary to understand classical annealing (disclaimer: my knowledge of classical annealing comes from discussions on quantum annealing, so if I mess something up, hopefully someone who knows more can correct me).",
"Here is how classical annealing works. ... | [
"If you don't mind me adding something, there's a simple but essentially-accurate analogy to be made here for classical annealing: Take a bunch of different-sized objects (rocks perhaps) and throw them randomly into a box. Things 'want' to be in their lowest energy state, which in this case means having the rocks a... | [
"Thank you, detailed and easy to read."
] |
[
"Change in weight when going below the earth's surface?"
] | [
false
] | Intrigued by something I read today, and hope someone can enlighten me! When descending into the earth, your weight will steadily decrease, as there is less mass to provide gravitational force. I'm assuming that at some point the decrease will slow and eventually stop. But at what point might that occur? To clarify m... | [
"The blue curve in this graph",
" shows the interior gravity of the Earth, as best as we can tell from measurements of the density at different layers, which is determined from measuring the speed of different earthquakes. There was a more recent measurement using neutrinos, which is really cool but also not very... | [
"And inside such a homogenous sphere, measured weight would also decrease in linear fashion, correct?"
] | [
"And inside such a homogenous sphere, measured weight would also decrease in linear fashion, correct?"
] |
[
"Question about the physics involved in \"tube transport\", video inside."
] | [
false
] | null | [
"I'm not singularly familiar with the concept, however thinking logically the carriages would almost certainly have pressure sensors on or be hooked into a monitoring system on the network, so if a breach occurred it would be notified and would slow down. If a breach appeared in front of it before it could be warne... | [
"Thanks for responding!",
"I wonder how long it would take to slow down from 6500 km/h though. Wouldn't going from zero air resistance to instantly hitting air at that speed cause the capsule to be crushed? Especially if the capsules aren't even aerodynamic, like in the video. "
] | [
"It's a difficult one. You'd assume the capsule would be fairly sturdy (Although as you noted it's a little blunt), but you can only decelerate so fast before you liquify the people inside.",
"I get the impression that's an extremely optimistic peak speed for one that traveled round the world, as that's 1800 metr... |
[
"If I hit a baseball with a bat, can the ball go faster than the speed that I'm swinging the bat?"
] | [
false
] | I'm thinking of a ball that is stationary, like on a tee. I guess that maybe the question would work better for a golf ball now that I'm thinking about it. If it is a pitched ball, can the ball ever go faster than the combined speed of the bat and the ball? Does it matter what the ball is made of, or how strong the per... | [
"Yes, the ball can. Assuming an elastic collision, both kinetic energy and momentum of the system must be conserved. Focusing on the small period of time surrounding the hit of the ball, obeying these two conservation laws means that the ball can shoot off with a much higher velocity than the bat, because the bat... | [
"the ball isn't being accelerated to 2v. it's velocity ",
" by 2v. ( from v to -v). ",
" for a perfectly elastic collision between the ball and bat.",
"maximum separation speed is only v+u. in reality flyout velocity is much lower as the bat continues motion in the same direction as the hit ball (this subtrac... | [
"Note that this is different than throwing a ball. When throwing a ball, the maximum ball speed is the speed that your hand is moving through air."
] |
[
"How does the mold on my bathroom ceiling obtain nutrients?"
] | [
false
] | null | [
"Found this:",
"Link"
] | [
"Fungi are master degraders and can use many diverse sources of nutrients. They can breakdown the wood, the paint, etc. for growth. In addition their growth pattern is by a network of hyphae so the mold you see may not be eating anything it could be a search party looking for richer nutrients with a base in the w... | [
"No, kill them, it's okay! If your paint is safe to bleach, spraying them with a pure bleach solution works best in my experience. Don't feel bad about killing the fungi, they wouldn't mind slowly destroying your house. :) Let them do their work in the forest.",
"Here is a very cool article about what happened... |
[
"If an object is moving through interstellar space at a significant fraction of c, does it have a sort of \"wind resistance\" from the interstellar medium?"
] | [
false
] | null | [
"Yes, it does. What is more, ",
"lethal radiation",
" would arise from the \"wind resistance\".",
"Using Einstein's special theory of relativity, Edestein—an expert in radiology—concluded that astronauts will die instantly from radiation overload, thanks to the kinetic energy of the atoms surrounding the ship... | [
"Does that mean that all is not relative and there is a way to stay still compared to space?"
] | [
"No, it simply means that any given matter has some velocity with respect to some other lump of matter. If one accelerates a spaceship up to a velocity close to c ",
" the starting velocity of the ship, then one will find that most of the matter in space that one encounters will have a much lower velocity (closer... |
[
"Run the United States Economy off of Solar Power? Sustainability Student help."
] | [
false
] | null | [
"the inefficiency is the most common response i have received so far. Even though solar has come a long way, it just hasn't come far enough. Most people i asked say that once harvesting solar power is more effective it COULD produce enough to run the economy. You are the first one to bring up the point of scarce... | [
"I'll add to this answer in regards to the sheer amount of area of solar panels required to power everything. We're talking about covering an area roughly the size of the Sahara desert to power everything. ",
"If you want further reading, I'd suggest this ",
"online book",
" by a very noteable scientist invol... | [
"The biggest inhibitor to changing how all renewable sources interact in our economy is energy storage. If you can solve the storage problem economically, and in a way that can scale then you have a chance."
] |
[
"Has there been a line of related species (documented by fossil evidence) that lost a certain trait, and then gained the same trait after years of evolution?"
] | [
false
] | null | [
"Fish have fins. Mammals eventually descended from fish, and the first mammals did not have fins. Eventually, dolphins descended from the first mammals, and dolphins have fins. So fins were lost and re-acquired, so to speak."
] | [
"Yes, I believe what you're looking for are ",
"atavisms",
", which are the re-appearance of traits that were present earlier in the evolutionary history of an organism but had been lost. They occur because the genes for a trait don't necessarily disappear if the trait. Those genes just aren't expressed, for an... | [
"This is highly improbable. Loss of a trait is due to a long sequence of highly improbable mutations with each step selected for. Given the same environmental/selection factors there is no reason to believe the same end point would arise a second time. ",
"Reversal of a lost trait would require randomly tracing b... |
[
"Why are there static and kinetic coefficients of friction? Why isn't there just a single coefficient of friction?"
] | [
false
] | null | [
"What I believe is that there are two main cause of friction- Interlocking and inter surface adhesion. Now when the body is at rest, both of these causes are in action, but when the body stars moving, the inter surface adhesion diminishes because it needs some time to form bonds between particles on both the surfac... | [
"The reason you have two coefficients is due to the fact that the kind of interactions you have when two bodies are resting together or sliding one on another are indeed very different.",
"But let's start from the beginning with the usual example of the mass on a slope. Let's also assume that we can change the in... | [
"Imagine a box on a rough floor. It takes more force to start moving the box, this is the static coefficient. Once the box is already moving you don't need the same amount of force to overcome the sliding or kinetic friction."
] |
[
"In your opinion, is this a scam or a honest request from a very bad doctor?"
] | [
false
] | I got at my work. As a scientist, I sometimes get collaboration offers, so it could make sense. But I also get emails from Nigerian widows. This letter has a lot of scientific words, but they're in sentences that don't make any sense to me, almost as if a randomizer has been used to write it. At least, let's say tha... | [
"Crackpots often come up with theories at home and then try to shop them around to professors at universities, whose names they find via google. Most Math departments have a collection of such letters and they pull them out from time to time when they need a giggle. ",
"Most of these people are a little crazy an... | [
"Well, the second guy had a point. Think about all the chicks gravitating around race cars."
] | [
"I was also going for the crazy person theory. Good to know it's not unusual. I'm starting my collection today!"
] |
[
"In what order did the kingdoms become multicellular? And, are symbionts ubiquitous?"
] | [
false
] | I'm writing an essay and I've come up with some questions I'm having a hard time answering. Maybe it's because I don't know how to Google very well, or because whoever asked this question first didn't put it up on the web for the Google to find, but I can't seem to find concrete answers to these questions. From my und... | [
"Multicellularity has evolved several times, independently in plants and animals for sure, and perhaps more than once within the fungi. A key point is that all true multicellular organisms are made fron eukaryotic cells (as opposed to prokaryotes), and eukaryotes evolved only once (i.e. all eukaryotes can be traced... | [
"Some of this is simply unknown. Precise phylogeny of these groups of organisms is ",
" difficult. In the first place, fossil remains of soft-bodied organisms are rare, making radiometric dating difficult at best. In the second, there has been such a long time of divergent evolution that in most common sequences,... | [
"So, after plants, both fungi and animals evolved at the same time - there was one common ancestor and its lineage essentially split into two, so both groups were born simultaneously and are equally distant, evolutionarily, from plants.",
"Was this common ancestor unicellular or multicellular?\nAm I right in unde... |
[
"How exactly does a shock wave from an explosion kills you (assuming that you don't die due to heat and objects flying around)?"
] | [
false
] | null | [
"A shock wave is a region where the pressure changes instantaneously on one side to the other. The region where the jump in pressure occurs is called the shock front.",
"",
"A shock wave that's large enough to kill you has to be quite powerful, with a significant pressure change across the shock front. The mom... | [
"During grenade training, they told us to never, under any circumstance block your nose if you sneeze while in the grenade hut. Holding your breath while a grenade goes off nearby could result in a ruptured blood vessel or pop a lung."
] | [
"The same way that sound can pass through walls. The pressure at the boundary has to be equal on either side of the boundary, so the pressure in the air and the pressure in your body when it reaches you are equal (some energy might get lost through absorption or reflection, but for a shock wave big enough to kill y... |
[
"Is it impossible to reach Absolute Zero?"
] | [
false
] | This idea starts with m=E/c which most of us know states that mass is primarily a function of a body's energy. That being said, Absolute Zero (0 K) as I understand is the total absence of energy (assuming the body in question has no potential energy) in non-organic compounds. So if a body was to reach Absolute Zero, ... | [
"Absolute Zero (0",
" K) as I understand is the total absence of energy ",
"It's not, and it's never been defined that way either. I don't know where your understanding comes from, but it's incorrect. (Also, temperature is not defined any differently for organic and non-organic compounds. The definition has not... | [
"This is correct, but I think by 0",
" K OP meant \"zero degrees Kelvin,\" which is incorrect terminology (you don't say \"degrees,\" you simply say \"zero Kelvin\"), but it's a common mistake."
] | [
"An important point is that temperature is a measure of average kinetic energy not the total energy. Zero Kelvin means all particle motion has stopped but the mass energy still exists along with the zero point energy of the system and hence we dont lose mass as we cool atoms down. ",
"Edit: to actually answer you... |
[
"How does a frisbee fly?"
] | [
false
] | So since frisbees only fly well when they are spinning, I imagine it has something to do with that. Does the rotation induce some sort of lift as it flies through the air? | [
"The rotation doesn't cause lift, but it keeps the disc stable as it flies. When a frisbee is flying straight without wobbling or flipping, it acts like a wing, but if it isn't spinning, it will go out of control almost immediately."
] | [
"So, the aforementioned \"wing\" comment is correct, although I'd like to tangentially add that throwing a disc \"flat\" will not actually end up allowing you to throw it further. You actually want to try throwing it \"hyzer\" or \"inside-out\" (that being with the leading edge tilted opposite to the direction of s... | [
"this is correct. look at the profiles of a couple disc golf disks:",
"https://michaelfonta858.files.wordpress.com/2013/04/photo.gif",
"They look a lot like wings! But as we know, wings only work at relatively small angle from their direction of travel, else they stall. So we have to get the frisbee to stay fla... |
[
"Why is it when tap water is cold, it appears to be clear but as it gets warmer it appears to become tinted and cloudy?"
] | [
false
] | I noticed this after I filled a water bottle back up with tap water. I have a well if that makes any difference. | [
"It's difficult to say as you are asking about your own individual situation which we don't have definitive information on (and there could be health ramifications).",
"In general the cloudiness is tiny gas bubbles. They are dissolved in the water (when under pressure in the pipe) and come out of solution when e... | [
"I am on city water and have a tankless water heater. If I turn a faucet on 'hot', I can hear and see a difference in the water once the water switches from cold to hot. "
] | [
"I know what OP is talking about, and it's just water vapor trapped in tiny bubbles so small it looks cloudy, they will float to the top and the water will clear up in about a minute for a standard sink."
] |
[
"How different is sublingual absorption of drugs compared to gastric?"
] | [
false
] | [deleted] | [
"I notice that people have written at length about why we use sublingual rather than oral administration at times, going into details of the hepato-portal circulation and metabolism in the liver.",
"However, nobody has answered your specific question about how the rate of absorption differs between the two routes... | [
"The main reason for sublingual administration of drugs is because some drugs such as nitro glycerin are degraded in the small intestine. To get the effects of the drug it has to enter the circulatory system in a different route "
] | [
"To expand on this for broader understanding (as this answer is completely correct), the stomach and most of the intestines drain into a venous system that leads to the liver instead of the systemic circulation. This means that blood and anything absorbed into it via the intestinal and gastric mucosa goes through t... |
[
"Why is a Planck time defined the way it is?"
] | [
false
] | defines the Planck time as t(p)=sqrt((hG)/c )). Since a planck time is the time it takes light to travel a Planck length, why is it not simply defined as t(p)=h/c? Since G is involved, I assume it has something to do with general relativity? The c really threw me for a loop though... Any help would be appreciated. | [
"The way it is defined is the unique way (up to a constant factor) to combine h,G and c to get something with the units of time. It ",
" also equivalent to the time it takes light to travel a planck length. h is not the Planck length, it's the Planck constant (and it has units of angular momentum) - very differen... | [
"It's a pretty simple proof. The basic units are Mass (M), Length (L), and Time (T). G has units of L",
" M",
" T",
" . c has units of L T",
" . h has units of M L",
" T",
" So if you write [T] = G",
" c",
" h",
" then this becomes a 3x3 matrix problem for x,y, and z. You can use standard techniqu... | [
"No; it's a popular misconception that the Planck length (say) is the minimum possible length, or things like that, but we don't know enough about quantum gravity to know if any of that is true. It's just a way of combining constants to figure out where we know we need quantum gravity by."
] |
[
"What, exactly, makes an orbit stable or unstable?"
] | [
false
] | [deleted] | [
"from pure mechanical point of view, you can get unstable orbit only in relativistic mechanics and only very close to the center of gravity (close to the event horizon).",
"in newtonian gravity, you always get some kind of orbit. the sum of potential and kinetic energy is constant. if you have more potential ener... | [
"In reality, there are always external forces that act on orbiting bodies.",
"For the second question, in the ideal mathematical case, the moon's orbit should be stable and constant. In reality, it's not, as we know it's orbit is expanding. I understand this is caused due to the moon's effect of slowing down th... | [
"I'm familiar with the basic, super simple model of orbit with Kepler's laws and Newtonian gravity. In that context, everything either orbits, crashes, or flies away.",
"This is only true in the context of a two body system. When more than 2 bodies are present, the system becomes chaotic and eventually unstable.... |
[
"Could a bullet made of frozen blood really be more effective than a bullet made of water?"
] | [
false
] | null | [
"First of all, blood is ~80% water, so the same general problems with ice bullets still apply. In addition to that, blood has a whole bunch of stuff dissolved in it that disrupts the formation of ice crystals and mechanically weakens the frozen phase. So, a bullet made from frozen blood would actually be worse th... | [
"I don't know if it constitutes an authority as per the side bar, but Mythbusters had an episode dealing with frozen water / meat / gelatin bullets, ",
"'Magic Bullet'",
". ",
"But blood bullets could potentially have higher lethality than ice bullets. The trick would be to keep from infecting yourself with... | [
"Thanks!"
] |
[
"Are there any “holes” in the periodic table that could be filled with undiscovered elements?"
] | [
false
] | null | [
"Nope, just any elements with Z > 118."
] | [
"Would discovering new ones create holes?"
] | [
"It could. For example, if 120 were to be discovered before 119."
] |
[
"What is the largest (and/or most massive) known solid/liquid body?"
] | [
false
] | As far as I understand, and and are designated including their atmosphere, which accounts for most of their mass and volume. If we ignore the atmosphere, what would be the largest solid and/or liquid body known to us in the universe? In particular, I'm interested in bodies that are kept solid not by extreme pressure, b... | [
"Check out the ",
"Sloan Great Wall",
". It's 1.37 billion light years in size, or about 1/60 of the size of the Universe. ",
"Though that may not quantify as the largest 'body', it is indeed the largest known system."
] | [
"I should have said ",
" not ",
". Sorry about that. VY Canis Majoris has only a mass between 30 and 40 solar masses."
] | [
"How is 'structure' being defined there, exactly? It's an impressive record."
] |
[
"Not trolling, just seemed like the right place to ask. Will I get cancer if I stick my testicles in the microwave?"
] | [
false
] | null | [
"No, but you will eventually boil the water in the exposed cells. It won't be fun."
] | [
"How are you going to close the door on those bad boys? "
] | [
"I realize this is old, but ",
"/r/shittyaskscience"
] |
[
"why aren't semis shaped like a bullet train?"
] | [
false
] | [deleted] | [
"Most semis are designed they way they are because they require a large amount of air flow to help the radiator to cool the engine more efficiently.\nA flat front end, decreases aerodynamics but increases the air flow to the radiator.\n",
"How radiators work"
] | [
"There have been attempts to improve aerodynamics of semis: if you see a semi that has plastic vanes hanging underneath the trailer, those are placed to improve airflow.",
"Many of the newer semis also have better aerodynamics in their body shape, however semis last ",
" longer than your average car does - so t... | [
"A vehicles drag coefficient is affected by the frontal area, therefore a semi truck is always at a disadvantage. Bullet trains' aerodynamic nose shape is actually very long, adapting it to a semi truck front would increase its length so much I assume road maneuverability would be terrible.",
"However, the semi ... |
[
"If I fired a conductive chain from the ground up into the clouds during a thunderstorm, would lightning 'follow' along the chain?"
] | [
false
] | When I was a kid, I wanted to create a lightning machine, and this was the best idea I had at the time. Since air is not very conductive but it still ionizes to allow energy to travel along it during a thunderstorm, would helping it along cause a predictable lightning strike? | [
"Yes, this would work. In fact, ",
"it is already done on a regular basis",
" by lightning researchers, launching rockets into thunderstorms which trail a thin copper wire behind them attached to the ground. These ",
"lightning rockets",
" are apparently effective at inducing lightning when the right condit... | [
"hypothetically, could this be done with something on the order of a model rocket?",
"hypothetically"
] | [
"Yes, but probably not very reliably. The higher your rocket gets, the more likely lightning will hit it though. Also your surroundings will also play a role. ",
"Storm clouds",
" can be much higher than most model rockets 10,000-20,000 ft vs 1,500 ft so I would guess that this would not induce lightning but in... |
[
"Are there alternatives to randomized double blind trials when such trials would be unethical?"
] | [
false
] | Hello all, so this has come from an interesting debate, but I need to explain it first with an analogy. First, imagine a person who wanted to test the theory that removing a malignant tumor would be helpful to a cancer patient. Following a double blind trial, they then ask a surgeon to remove only half of the tumors fr... | [
"There are two parts to your question.",
"Part 1: when placebo is unethical, what do you do in your control group?",
"The answer to this is that you never define your study in terms of \"control group gets placebo\". Instead, you always define your study in terms of \"control group gets best currently available... | [
"This basically covers it. I would just add that in some extreme cases, I believe clinical trials may be halted if the new treatment performs drastically better or worse than the \"best currently available\" control. This would be done when it is considered unethical to continue with treating patients in the two gr... | [
"If I recall, an example of when halting was done was with the study on low dose aspirin for reducing the risk of heart attack. "
] |
[
"When they announce discovery of a new breed of bird or fish or whatever, are they always meaning \"Never before discovered\" or does it sometimes mean a new crossbread from previous breeds/types?"
] | [
false
] | null | [
"It depends on the type of animal (wild v. domestic) but the majority of the time they mean never before discovered. But discovered can mean different things, maybe it a species that we've never seen before or maybe it's an animal that we misclassified. An example of this is the platypus, after genetic testing it i... | [
"Yes, but the emphasis is on \"different\", not on \"producing offspring.\" In case of subspecies, unless they found a lone individual specimen, it would be trivial to note the population can produce ",
" (offspring are not sterile) offspring.",
"So what makes them sufficiently different? In many cases (especia... | [
"So does that mean two different animals successfully produced offspring?"
] |
[
"I understand the need for a standardized order of operations, but is there a reason behind the specific order? Or is it arbitrary like the order of the alphabet?"
] | [
false
] | null | [
"It’s just a shared language so that people can understand one another’s equations.",
"For what it’s worth, when people to whom math is important write equations out, they write them in a way that is pretty clear even if you’re not familiar with the standard order of operations. The “lol 6 x 7 ÷ (4-1)” Facebook r... | [
"It's more like grammar rules. Standardized grammar rules is an attempt to capture how people speak and write, in order to teach them to students. Standardized order of operations is an attempt to capture how mathematicians usually write and interpret their algebraic expressions (which had been gradually developed ... | [
"Order of operations is only relevant to how we ",
" equations. Using PEMDAS we would say 1 + 3 * 5 = 16, but if we all agreed to instead use PEASMD (just made that up) we could say 1 + 3 * 5 = 20. There's nothing objectively incorrect about using the second system, it's just not convention and you'll confuse eve... |
[
"Why don't we use capacitor as normal battery? Would it charge faster?"
] | [
false
] | well, all is in the title | [
"While you can make capacitors behave like a battery by using a ",
"sepic",
" converter, capacitors are far behind batteries in energy density. From ",
"wikipedia",
", \"Conventional capacitors provide less than 360 joules per kilogram of energy density, whereas a conventional alkaline battery has a density... | [
"And in fact, ultracapacitors ",
" used instead of normal batteries where it makes sense. For example, some Solid State Drives (SSDs) use an ultracapacitor so that if the power is interrupted, the SSD can still work for a very short time. This allows the SSD to write data that was in temporary storage to the fl... | [
"That's not the reason we don't use capacitors. They ",
" dump all of their energy very quickly if you short circuit them, but any reasonably-designed circuit will work just fine. The problem with capacitors, as aleenaelyn said, is that they simply don't hold very much energy compared to batteries."
] |
[
"Many bacteria seem to have developed a highly symbiotic relationship with humans to the extent without either side, the death of both organisms would result. Does this situation ever occur with viruses?"
] | [
false
] | null | [
"I don't have a link at hand, but I remember listening to a lecture on the subject. It seems our DNA in fact contains several pieces of used-to-be vira that has been integrated into our DNA. Not exactly the same, but still fascinating. "
] | [
"I've heard this before too. I wonder if viruses aren't responsible in part for genetic mutations that allow for evolution of the species."
] | [
"No. The reason for this is that bacteria are metabolically active, with numerous organelles performing various functions. They break down substances and bio transform others -they're quite the little workhorses. These same functions are often beneficial to other organisms. Viruses, however, are simply packets of p... |
[
"Coconut oil health uses."
] | [
false
] | I hope this goes here- just used coconut oil on my son's diaper rash because of the anti fungal, antibacterial, antiviral and yeast killing properties. What other health benefits are there for the little known super food? | [
"Was it applied in their diapers?"
] | [
"Not that I'm aware of, usually mice prefer to eat it. You did only ask about coconut oil and health, not just diapers. ",
"Coconut oil's beneficial properties in regards to diaper rashes more stem form it's ability to create an impermeable membrane and promotes the restoration of the intrinsic immune system of t... | [
"Thank you- I appreciate the info and dealing with my late(for mommy) night mommy humor. I've read about the ups and downs of the oil before but have never seen anything definitive. "
] |
[
"How do the lungs heal after a smoker quits?"
] | [
false
] | I'm a biochemistry major who just quit smoking and I'm curious about the processes (e.g. chemical reactions, replacement of cells, removal of debris) that are taking place within my lungs. When I go on the internet, I get a very broad sense of what is going on, but I'm more interested in the details and science. Could ... | [
"A little bit to get people started. ",
"\"The British doctors study showed that those who stopped smoking before they reached 30 years of age lived almost as long as those who never smoked.\" ",
"Wikipedia",
"/",
"Cancer.org",
" ",
"Histopathological Changes from the ",
"Surgeon General",
" (PD... | [
"Great references in the second half. I despise the first half (which we often see in a timeline format) since it groups together all smokers - those who some maybe a cigarette a day with those who go through 2 packs a day. Is there any research that defines averages of consumption?"
] | [
"I expect he means to say that the total damage vs number of cigarettes curve looks logarithmic. That doesn't seem entirely counter intuitive to me."
] |
[
"Motionless Water Doesn't Freeze?"
] | [
false
] | null | [
"You just happened to make supercooled water! This happens if you cool water gently enough without disturbing it. Its temperature is below freezing, but yet, is still a liquid. It will turn to a solid at the slightest provocation.",
"A nucleation site is needed for the ice to form -- basically a rough spot or tur... | [
"The process is called ",
"supercooling",
"."
] | [
"I think this is the same (but obviously opposite) reaction type as super heating water in the microwave. If you heat water in a very very smooth container and there is no break in surface tension the water will actually super heat without boiling. Then when you break the tension by moving the glass the water actua... |
[
"Why is it that whenever I stir orange sherbert quickly with a spoon to make it soft the outside of my cup freezes over?"
] | [
false
] | null | [
"It could be caused by increased heat transfer due to convection caused by stirring. Normally, with no stirring, the outside of the sherbert will be warmer than the center after it is taken out of the freezer and some time passes (because the room temperature warms the glass which warms the outside layer of the she... | [
"The cup of sherbert is going to rob its surroundings of heat, BUT it's very viscous so no convection currents will form to distribute the heat that it is absorbing. So it absorbs some heat, and melts a thin layer of sherbert that then acts as an insulator to the rest of the cup, slowing the process of absorbing ev... | [
"The cup of sherbert is going to rob its surroundings of heat, BUT it's very viscous so no convection currents will form to distribute the heat that it is absorbing. So it absorbs some heat, and melts a thin layer of sherbert that then acts as an insulator to the rest of the cup, slowing the process of absorbing ev... |
[
"Why don't all clouds form at the same elevation?"
] | [
false
] | [deleted] | [
"Most clouds form at the same height, at least the cloud base does. This is due to the temperature of the air at that point reaching the dew point (the temperature at which a certain amount of water vapor is 100% saturated) and the clouds will start to condense around Cloud Condensation Nuclei. ",
"This elevation... | [
"The below comment is specifically for cumulus clouds:",
"Cumulus clouds usually form at what is referred to as the lifted condensation level (LCL). However, the LCL isn't exactly where the temperature is equal to the dewpoint, it is were the temperature of a surface parcel, if lifted, would cool to the surface ... | [
"If you are referring to why clouds form at different altitudes (i.e., stratocumulus vs altocumulus vs cirrus) each cloud type actually has a different formation mechanism. The formation mechanism for cumulus is explained in my other comment. Cirrus (the thin wispy clouds) actually form in a variety of ways. The... |
[
"How do ants survive long drops?"
] | [
false
] | [deleted] | [
"Because surface area is squared, and volume is cubed.",
"Therefore when something gets bigger, its volume starts to increase more and more away from it's area.",
"So relatively speaking, ant has huge surface area relative to its volume.",
"Mouse has large surface area relative to its volume.",
"Human has l... | [
"Correct me if I'm wrong, but it would stand to reason that the less mass something has, the less force is exerted when it falls. At a very low mass, that force would be very small."
] | [
"The force of gravity on a lower mass object is indeed smaller, but the acceleration due to gravity is the same on all objects because it scales with force/mass. In a vacuum all objects fall at the same speed. A feather and brick and an elephant will all fall exactly the same speed and hit the ground at the same v... |
[
"Will global cooling over the next two years from this Tonga volcanic explosion be bad enough to interfere with crop production? What should we really expect?"
] | [
false
] | null | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"thread",
"If you disagree with this decision, please send a ",
"message to the moderators."
] | [
"I want to know what the current answer is if the volcano had stopped after that particular explosion."
] | [
"Again, this is not known yet. We do not have numbers of the amount of material added to the atmosphere, only estimations from preliminary satellite data (and the event is clearly ongoing as there have been subsequent smaller eruptions since the large blast yesterday). The question remains unanswerable."
] |
[
"Do women have digestive systems that are significantly different from that of a man?"
] | [
false
] | I always hear that women have more sensitive stomachs. There seems to be a lot of products on the market that are aimed towards improving the digestive systems for women. Is that all just marketing, or is there some truth behind it? | [
"It's just marketing. Individual variation is more than the variation between the sexes.",
"That being said, my girlfriend assures me that the only waste products produced by females are rose petals accompanied by the sound of childrens laughter."
] | [
"No, they don't. Bacterial gut flora vary between people based on region, diet, day to day changes, medicines, hormones... There is a lot that alters the microflora that makes up a GI tract, but not gender. There is a lot of marketing schemes that people use, and this is one of them. Nothing about being a woman or ... | [
"I thought there had been a few human microbiota studies that did indeed show differences between men and women? I know this exists, obviously, for the uro-genital tract. My recollection of the larger studies though with multiple collection sites on the body is a bit hazy. Am I misremembering?"
] |
[
"Do any animals have Fresnel eye lenses instead of biconvex ones?"
] | [
false
] | Eye lenses seems to have evolved independently numerous times but did the evolutionary process ever give rise to a crystalline lens shaped like a ? | [
"You are correct that reduced image quality is a drawback of Fresnel lenses. But it is conceivable that the compactness advantage of a Fresnel lens could outweigh the image quality loss in an animal's eye, just as as it does in some human-designed imaging applications.",
"Edit: I should also mention that Fresnel ... | [
"You are correct that reduced image quality is a drawback of Fresnel lenses. But it is conceivable that the compactness advantage of a Fresnel lens could outweigh the image quality loss in an animal's eye, just as as it does in some human-designed imaging applications.",
"Edit: I should also mention that Fresnel ... | [
"No, this has never happened.",
"However, one of Richard Dawkins' favorite examples of cool/multiple eye evolution is the brownsnout spookfish, ",
"http://en.wikipedia.org/wiki/Brownsnout_spookfish",
".",
"This fish has evolved a 'typical' biconvex eye and a separate eye that uses a reflector made of guanin... |
[
"Would a wooden chair, a paper book or a computer survive in a sealed untouched room for billions of years?"
] | [
false
] | null | [
"Iron preserved in vacuum, therefore not in contact with electrolytes, should as far as I am aware survive. At least it will not deteriorate due to oxidation. Minerals, (in the form of a stone table?) could survive.",
"Glass actually behaves sort of like a ",
"liquid",
" over time. It might only exist as 'mel... | [
"The notion that glass behaves as a liquid over time is a ",
"common misconception",
"."
] | [
"Hard drives need to be spun up every few months to keep them from going bad, so a computer with a mechanical hard disk most likely would not survive. Assuming that the room that these things are in is shielded from radiation, I see no reason why a chair or a book wouldn't survive, as long as the room is properly p... |
[
"Does the atomspheric pressure increase when more co2 is produced?"
] | [
false
] | null | [
"Very slightly, yes.",
"Although scientists generally prefer the metric system, it can be very useful to think of pressure in terms of imperial units. When we say the pressure at sea level is \"14.7 pounds per square inch\", that literally means for every square inch of the surface, there's an extremely tall skin... | [
"Scientists typically speaking about pressure in bar or atmospheres. Those are hard to conceptualize. Pounds per square inch is easy. You can conceptualize a 20 lb dumbbell or rock sitting on top of your head to resemble the air pressure. ",
"It was just to help people understand what atmospheric pressure ",
".... | [
"Co2 is measured in ppm. By the time the co2 level raised to the point increased atmospheric pressure was an issue, the chemical effects of raised co2 would have changed the atmosphere in ways that were much less favourable than increased pressure."
] |
[
"What are the benefits from discovering only a few atoms of elements like 118 (Oganesson) and others that were created in an accelerator?"
] | [
false
] | Certain man-made elements like Tennessine (117) or Oganesson (118) have been created in a particle accelerator but only a few atoms detected at a time. If we cant physically do anything with these new elements, what are the other benefits from creating/discovering them? And whats the importance of synthesizing others l... | [
"It allows us to test and constrain theories in nuclear physics. They don't have any practical use, but they are very useful and important to people who study nuclear physics and nuclear chemistry."
] | [
"Testing nuclear models with isotopes we can produce also helps to predict the properties of isotopes we cannot produce, like very neutron-rich isotopes that play an important role in the production of all heavier elements. You see where a model fails if you test it for the most extreme cases you can make."
] | [
"I figured since scientists theorize new elements they would have to synthesize them to prove if theyre calculations and everything were right, i just wasnt sure of what comes next. Like Ok so we were right....we synthesized what we theorized, now what? It makes sense they could just use the answers and info they g... |
[
"Is there a reason why bacteriophages are not widely used?"
] | [
false
] | [deleted] | [
"I'm not a biologist, but I was a science journalist and wrote an article about this about 12 years back. I talked to the most active Western researchers in the area; they were hopeful about progress what with the research from Tbilisi finally making its way into English but nothing much seems to have happened.",
... | [
"You got it spot on. My colleague (who did a bunch of projects on it) also mentioned that the immune responses are the main problems: essentially meaning you can give this treatment exactly just once."
] | [
"I haven't really been keeping up but ",
"this",
" 2005 article says that they're still using phage therapy in Georgia. ",
"As for my article, I wrote it while I was still in journalism school. That means a) it's not so good and b) it was never published. I dug around, but I don't think I've still got a copy.... |
[
"Let's say you have a very long rope, about as long as the circumference of the Earth."
] | [
false
] | So here's the thought: Let's say the rope is 1m long: You and your friend are facing each other, each holding on to a different end of the rope. When you are 1m away from eachother, the rope is taut, and no part of it touches the ground. Let's say that the rope is 40m long: Your friend stays where they are, but you wa... | [
"The rope would create a tangent to the curve of the earth at a certain point (an intersecting point with the ground) between you two after a certain length depending on the height of the two people.",
"So, no, it touches the ground in the middle at some probably easy to determine length value based on height."
] | [
"Here, I illustrated it for you OP (not to scale): ",
"http://i.imgur.com/WNsdG.jpg"
] | [
"I think the actual question you had in mind was hamstrung by your hypothetical. Allow me to posit another hypothetical that may more accurately represent your question:",
"Say you built a single large support and from it you and a friend began constructing a bridge in opposite directions which paralleled the cur... |
[
"When animals yawn, is it contagious to members of their own species like it is in humans?"
] | [
false
] | null | [
"It has been reported in a couple of species, like ",
"gelada baboons",
", and has also been demonstrated to work in response to video images of a conspecific yawning in ",
"macaques",
". I think both articles discuss previous research as well, mostly in ",
"chimps",
".",
"I'm not aware of any evidenc... | [
"Definitely not in all animals; there was actually an Ig Nobel given out for ",
"this",
" where the authors found that red-footed tortoises show no evidence of contagious yawning."
] | [
"I went to a seminar where the lecturer discussed empathy in other animals, citing yawning a a basic example (possibly) of empathy between animals. I don't remember the more lower-level-intelligence animals that yawned after another to show empathy, but I can tell you that chimps have been shown definitively to do ... |
[
"Do older people vaccinated for Covid have a “good” immune response from it?"
] | [
false
] | My otherwise very healthy and independent 94yo grandmother received her first Covid vaccine 5 days ago. I asked her if her arm was as sore as mine and she said it doesn’t hurt at all. I was wondering if the immune response in the older population has been studied much. I’m just curious if her complete lack of side effe... | [
"Just as everyone has a different reaction to COVID infection, ranging from being asymptomatic to dying in full organ failure, everyone seems to have a different reaction to the vaccine. The strength of the reaction doesn’t correlate to the strength of the immune response. My partner hardly noticed his, but one of ... | [
"The studies for moderna showed 86% immunity after 1 dose for those over 65 I believe, so it actually proved very efficacious for elderly patients. Pfizer was closer to 50%.",
"As far as side effects it’s different for anyone. The lack of side effects will not tell you one way or another on its efficacy, everyo... | [
"Something to note that hasn’t been mentioned is that even if a vaccine is safe, pain levels can vary widely depending on how high/low it gets injected, and how whether whoever is doing it went a little too deep, not deep enough, etc. ",
"There are many reasons besides the ingredients, these things can happen."
] |
[
"Why does the c in e = mc^2 equal the speed of light?"
] | [
false
] | I’ve been thinking about it for a while and I can’t seem to figure it out. Why does the speed of light have anything to do with this equation. Ofc it’s not a coincidence and I just don’t understand how mass and energy have anything todo with the speed of light. | [
"When we have an object in special relativity, we assign it 4 numbers for its location in time, x, y, and z. Think of this like an address. The President of the United States lives at 1600 Pennsylvania Avenue, Washington D.C and our object lives at,",
"Great! The only problem though is that time doesn't have the ... | [
"essentially it's stating that to create energy, you would have to accelerate a mass (of any magnitude) to the speed of light squared.",
"No, that's not what the equation says, not even remotely. You can't accelerate anything to the speed of light, let alone its square.",
"Of course the speed of light is the s... | [
"essentially it's stating that to create energy, you would have to accelerate a mass (of any magnitude) to the speed of light squared.",
"No, that's not what the equation says, not even remotely. You can't accelerate anything to the speed of light, let alone its square.",
"Of course the speed of light is the s... |
[
"1 in 100 persons are immun to HIV. Would evolution do it's thing if we would not use condoms?"
] | [
false
] | Found this in TIL So let's say we were not as smart to use rubbers, would over time all those non-imune people die and hiv be cured by survival of the fittest? Is it our scientific knowledge that hinders evolution to take care of hiv? | [
"Layman here.",
"Aside from the obvious ethical problems, yes, but in a fairly slow way. So would things like glasses, vaccines and boiled water, btw, so don't jump into conclusions.",
"Even if we assume we're 'primitive' people with no ways to treat the sick, the actual effect on survival would not be very big... | [
"True, but then you would likely have children infected with HIV, in which case they probably wouldn't survive to reproductive age without any intervention. Anti-retroviral therapy significantly reduces rate of transmission of HIV from mother to child...but to follow the hypothetical notion of the question, we'd ha... | [
"Given the low incidence, you would have had some healthy children already before getting infected by HIV. True, your next children will have a higher risk of infection, but your genes would have already been passed on in other individuals."
] |
[
"(Physics)Can a wave produce a wave without acting on anything?"
] | [
false
] | null | [
"There is more than one way to think about waves, but you may be describing something along the lines of the ",
"Huygens-Fresnel principle",
", which essentially says that one way of describing the overall shape of a wave as it propagates, is to assume that every point along a wave is constantly producing new w... | [
"So.. Say you have a wave, and then you look at one point on that wave. That point is also producing a wave. Are points on that wave also producing waves and so on?"
] | [
"Yes"
] |
[
"December 21st was the shortest day of the year. Does each day get longer by an equal amount?"
] | [
false
] | I know that there is the least amount of sunlight on the 21st and the most sometime in June, but does it increase an equal amount each day? 10 seconds more today, 10 seconds more tomorrow etc., If not, is it on some kind of scale that can be measured or is it relatively random? | [
"No. If each day got longer by an equal amount, then the day before would be even shorter. When you deal with smooth functions, then the difference from the minimum or maximum is usually proportional to the square of the distance as long as you're close by. That applies here. So if the next day is x units longer, t... | [
"Would it be appropriate to think of the year in sunlight as the same as about a wave of light? Thinking of the traditional picture. Something akin to this \n",
"http://www.lehighsla.com/images_level3/Student_YourProg/JB_1213/Gr4Light/BlueRedSm.jpg",
" \nWith the lowest Valley and highest peak being roughly the... | [
"Like I said, it's approximately a sine wave. That's what those pictures are. Waves of light are not restricted to being sine waves. They're just generally decomposed into sine waves because it makes the math easier."
] |
[
"Why doesn't the water produced from combustion extinguish the flame/ combustion?"
] | [
false
] | [deleted] | [
"When wood burns, due to ",
"pyrolisis",
" it releases flammable gases. Those are responsible for the visible flame when they burn.",
"As soon as you pour water on the coals they cool down, not only because water itself is cold but also because it absorbs heat when it evaporates (you hear the \"psssshhhh\" as... | [
"In general, there are two ways to stop combustion. One is by reducing the amount of energy available to propagate the combustion reaction. This happens when cold water absorbs heat, thereby reducing the available energy. Less energy means slower kinetics and if enough energy is taken away, the reaction will stop."... | [
"What combustion are you talking about? The space shuttle engines would be my guess and the answer is simple, the water produced from the reaction is already at or near the temperature of the combustion itself. It has to be, considering it WAS the combustion milliseconds ago. Also because of the heat, this water is... |
[
"How far from a black hole are particles typically close enough to transmit sound waves?"
] | [
false
] | Please correct me if I'm wrong, but sound does typically not travel through space due to the lack of molecules to transmit the sound. As atoms get caught in the event horizon, is there some distance that they become close enough, as they race toward the singularity, such that sound can be transmitted? | [
"sound propagates in any environment that is dense enough. even in very sparse interstellar clouds there is concept of propagation of \"something like sound wave\".",
"in general, accretion discs around black holes are dense enough environment for sounds to propagate... e.g. so called ",
"quasi-periodic oscilla... | [
"Can you articulate your question a little better? It's a bit confusing particularly the sound wave part."
] | [
"What do you mean by that?"
] |
[
"Ask Anything Wednesday - Economics, Political Science, Linguistics, Anthropology"
] | [
false
] | Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical post? No question is too big or small for AAW. In this thread you can ask any science-related question! ... | [
"Why isn't graphene getting more love? Indeed I get a lot of skepticism and nay saying about graphene?",
"Furtherance of my understanding of this will be greatly appreciated!"
] | [
"Linguistics question, is there a word, phrase, or logical fallacy that describes this situation:",
"Person Y and Person Z are debating online. Y holds a position on a topic that Z disagrees with. Z searches online and actively looks for someone saying something incredibly stupid/insensitive/deplorable who suppor... | [
"I thought straw man needed to be a made up character, not an actual person that exists?"
] |
[
"Do hurricanes affect aquatic life?"
] | [
false
] | Their damage to land and its lifeforms is uh.... well very obvious to say the least. But does a category 5 hurricane have dramatic effects on the aquatic life underneath it? In regards to shallow coast lines as well as while it is out in the open ocean? Thanks! | [
"Not dramatic effects, but there is an effect. First, it will tend to aid in mixing from deeper regions and surface regions, which is beneficial in terms of spreading the nutrient love around. For another, fish will tend to swim a bit deeper to avoid any turbulence.",
"It is pretty dramatic for us humans, but for... | [
"Wow, I mean, I expected as much but it’s still crazy to think about haha"
] | [
"There actually is a significant effect, although it's mostly confined to shallow water.",
"Sessile species (ones that are attached to the ocean floor and don't move, like corals) can be buried by dirt and mud churned up by the storm. We see this all the time when studying marine fossils. It can also bury specie... |
[
"What is the safest way to jump from an airplane without a parachute and survive?"
] | [
false
] | null | [
"Spread out, controlled dive, with very slight forward velocity, relax, roll on impact.",
"...and land on something that will break your fall. And hope whatever it is doesn't spear you to death."
] | [
"First, look for something soft to land on. If you fall out of a commercial aircraft at cruising altitude, you will be about five miles up, but keep checking below you for a place to aim.",
"Spread out. You want to make as much surface area as you can and decrease your terminal velocity. ",
"If you see smoke or... | [
"It'd be great if they could roll out one of those inflatable slides while they're at it."
] |
[
"Nuclear reactor meltdown"
] | [
false
] | I've read and I am familiar with Chernobyl, but I am unclear as to what, exactly, a nuclear reactor meltdown means. So, a nuclear bomb is based on the idea of a fissile material having an uncontrolled reaction. That is, as I understand it, at any given instant, each nuclei could be struck by a neutron. This could, then... | [
"xoites here isn't correct; Three Mile Island (TMI) ",
" have a meltdown (and it says so right under the picture of TMI in the link), but only a ",
" meltdown.",
"But to back up. The nuclear fission reaction in power plants gives off neutrons. Those neutrons cause further nuclear decays, and you have a chain ... | [
"His source is clearly vodka and orange juice!"
] | [
"To add to you discussion of chernobyl, the rods not only failed to insert, but their design created additional positive reactivity in the core, I.e., the tips of the rods had the opposite effect that a control rod should."
] |
[
"Pain is obviously the way of the body telling us something is wrong, but why can it get so severe that it cripples us?"
] | [
false
] | [deleted] | [
"Does your question basically boil down to 'why does the body not work perfectly'? There are plenty of examples of healthy physiologic processes that can become harmful when taken to an extreme. For example, the ability of your blood to clot is a great help to keep from bleeding out, but when clots form in bad lo... | [
"I'll reiterate my last paragraph:",
"I'll also add a note of caution against many explanations that are basically '",
"just-so stories",
"' that inevitably pop up in these sorts of posts. If there's any evidence suggesting that (for example) pain leads to resting which is good for healing, great. But don't... | [
"Under normal circumstances, such as a cut or small wound, the body tells us that there is indeed an injury. Or doing something anatomically inappropriate, sticking your finger in boiling water, or touching something sharp for example is a defensive mechanism from your body that tells your brain \"Don't do that aga... |
[
"How much does our skull change how we actually hear our voice?"
] | [
false
] | According to : But when we hear our voice when we're actually speaking, we hear it in two different ways - externally and internally. First, you hear the sound that comes out of your mouth ( the one that other people hear), and at the same time you hear that which is coming from vibrations produced by our vocal cho... | [
"Your skull does not change the pitch, only the frequency spectrum. (equalization) ",
"You can do your own experiments easily:",
"Record a friend, and play it back. Does this sound like the original voice? If so, your recording and playback system is sufficient. You can go over the top with high end microphones... | [
"The idea was to create one myself. A software where one could adjust the settings of the voice and finally let other people hear how the voice in our head sounds. But to make this I need to know how I need to change the voice.\nI will start trying with frequencies and see if I get to any results"
] | [
"Could you recommend an app or software for this?"
] |
[
"How direct is the correlation between psychological and physiological changes in the brain?"
] | [
false
] | For example, If I were to change the way I feel about a certain idea, lets say abortion (for lack of a better example right now), what would the corresponding physiological change be? Would certain neurons/parts of the brain undergo change? and if so what would these changes be? | [
"The mind is the product of the brain. Everything in our mind is contained in the brain. Any change in the mind is going to be reflected in some way in the brain. This could be changes in the biology (new synapses, change in firing, change in neurotransmitters, etc).",
"We don't know what the specific changes are... | [
"The entire enterprise of psychology and neuroscience is based on the premise that psychological experience is based ",
" brain activity (which is, of course, influenced by the environment, genes yadda yadda yadda). I don't mean this in any way to be insulting to anyone, but this premise is in ",
" contradictio... | [
"What you are thinking of is called an \"engram\". It's a theoretical pathway of linked neurons which is where a particular memory is stored. No one has found one yet, but it is a great theory. You know when you have those 'lightbulb' moments? That is the instant your neurons have made a new connection. You now hav... |
[
"If current tests to date have shown that matter and anti-matter interact with light the same way (i.e. anti-hydrogen photon emission spectrum is the same as hydrogen), how can we assume that the universe is made up of an abundance of regular matter, and not isolated clusters of each type of matter?"
] | [
false
] | null | [
"It's because there'd have to be some region of space where the anti-matter and matter parts are in contact, and that spot would look VERY unusual. ",
"Galaxies can be very isolated, it's true, but not so isolated that it wouldn't be observable."
] | [
"There would still be a region where that antimatter comes into contact with a matter area"
] | [
"In the distant past everything was closer together. Far enough back, at the time the CMBR was formed, everything was a continuous plasma cloud filling the universe. If it consisted of regions of matter and antimatter, the borders between regions would be violent places and it would have left a major imprint on t... |
[
"What is happening when I push my stomach out to make myself appear fatter/bigger. What is happening when I suck my stomach in. (where does all the size go?)"
] | [
false
] | null | [
"My surgeon friend told me that organs move around a lot. Once doctors get inside it's not like the diagrams. They usually identify the target organ by the relation to other organs, not where it sits in the body cavity.",
"gross."
] | [
"You're pushing your diaphragm (the muscle below your lungs/above the abdominal cavity) down and relaxing your abdominal wall. Since your organs don't have anywhere else to go they \"push out\" giving the appearance of a beer belly. The reverse is also true. You're just sucking the stomach and liver up into the spa... | [
"While it might make more sense initially to securely anchor abdominal organs, if they were anchored they couldn't move to conform to spaces when the shape of the abdominal cavity changes- i.e. during pregnancy, when you bend over, as you grow, gain weight, etc."
] |
[
"Does holding a glass to the wall/floor really help you hear what is going on in the next room?"
] | [
false
] | [deleted] | [
"Yes it does. ",
"When sound from the inside of the room hits the wall it causes the atoms in the wall to begin to vibrate in accordance with the frequency of the sound wave. When you press the glass against the wall on the other side, the glass begins to vibrate in this manner as well. Although sound travels fas... | [
"I think this is a good answer! Carrying out experiments is half the fun of science and should be encouraged! Especially for quick easy things like this. OP will then know the answer to their question and can think about asking ",
"this happens."
] | [
"How about you conduct a ten second experiment and find out yourself."
] |
[
"Why does Nuclear Power Need Cooling? Could they not convert the hot water back to steam?"
] | [
false
] | [deleted] | [
"This isn't specific to nuclear power. This occurs in all power sources where you convert heat to electrical energy.",
"Turbine output needs cooling because the turbine can't remove 100% of the energy from the water. If you had a closed cycle between the reactor and the turbine, and the turbine didn't remove al... | [
"Thanks for clarifying that. My point was two-fold, although I didn't explain it well. The first issue is that it would be difficult to bring hot water from a NPP to homes, just because of the distances involved. The second issue is that, even though they are completely separate systems as you pointed out, most ... | [
"Repost: I completely misundestood your question earlier, here is the amended answer, sorry!",
"The water needs to be cooled down before pumping it back over the fuel due to the ",
"second law of thermodynamics",
" which states that that any closed-loop cycle can only convert a fraction of the heat produced d... |
[
"Does a baby's crying wake a person more readily that other noises?"
] | [
false
] | I'm interested to know if there has ever been any sort of scientific study to learn whether or not humans are more predisposed (through evolution or any other process) to wake up when they hear a baby crying as opposed to other noises such as an alarm clock for example. | [
"It sounds like you are talking about ",
"signal detection theory",
"means to quantify the ability to discern between information-bearing energy patterns (called stimulus in humans, signal in machines) and random energy patterns that distract from the information (called noise, consisting of background stimuli ... | [
"If I'm a close relative or a friend who has spent a relatively large ammount of time with the baby then? I'm guessing our brains doesn't discriminate there, or atleast our sense of helping a crying baby/child"
] | [
"yes, but ",
" is the question."
] |
[
"Why don't electric vehicles come with 5, 6, or 7 speed transmissions?"
] | [
false
] | I know the first generation Tesla Roadster had a 2-speed, but why is it that most electric vehicles out there don't have standard transmissions? I know it has something to do with the way that electric motors produce torque/power, but what is the actual explanation? | [
"Electric motors have a far wider range of speeds at which they can produce useful work than do gasoline engines. ",
"A gasoline engine works by pumping air through a cylinder. It has a fairly low maximum torque it can provide. Too slow, and it won't even provide that. Too fast, and drag forces start to eat ... | [
"Fountain pens are more fun than ballpoints because you can fill them with ink, wipe them down when you're done, complain about your inkstained hands, and argue about which nib is better. ",
"For that matter, slide rules are more fun than calculators because you can keep track of exponents in your head and get a... | [
"One reason is that transmissions connected to electric motors have to be extremely strong. Tesla tried to make a 2 speed transmission for the Roadster but it kept shredding itself. Don't know the specifics but an electric motor produces full torque at anything considered turning (>0RPM).\nThe main reason is that t... |
[
"Do cancers have their own 'fingerprints'? How can you tell a cancer is metastatic instead of a new local occurrence?"
] | [
false
] | null | [
"Yes they do - as a cancer grows it acquired hundreds to thousands of genetic mutations. Some of these mutations are common among all cancers such as the Ras or Raf genes. A lot of these mutations happen just by chance. By genotyping the tumors you can tell if it has the same chance mutations as the original tumor ... | [
"Hi there! This is what I do ",
"! I'm a pathology resident and mod over at ",
"/r/pathology",
". Not only do cancers have fingerprints, we can often tell where they're from even if we never saw the primary. While cancers almost by definition carry mutations, rearrangements, or some sort of dysorganization of... | [
"Sure: karyotyping is done by capturing images of cells in the metaphase stage of mitosis where you can see the individual chromosomes. They are stained so some bands are light and some bands are dark. You can then identify which are chromosome 1 (the longest) which are 2 (next longest) which are 3 etc. Then you ca... |
[
"When scientists \"map\" the human genome, what are they actually doing?"
] | [
false
] | I know they're writing out the code that makes us human, but how exactly are they doing it? And along those lines, how do they map the genome of an entire species? Shouldn't genetic variability across our species make the job essentially impossible? | [
"Genetic mapping is different from DNA sequencing.",
"DNA sequencing is the process of determining the exact sequence of nucleotides in an organism's DNA. We have had the technology for about 40 years, but it was such a painfully slow process that we've only done whole genomes in the last 15 years. ",
"The Sang... | [
"For many of the genes, we have had a good explanation of how they affect let's say hair color. For example, a gene may encode for melanin protein that specifically localizes to the hair, making it darker. ",
"Each gene has a promoter associated with it, which can be regulated by other proteins (which are deemed ... | [
"I heard an amazing lecture on the radio last night about synthetic life:",
"http://www.cbc.ca/ideas/episodes/2012/01/04/synthetic-life-1/",
"Essentially, they have been looking at what individual pieces do inside bacteria genomes. So, for example, they know this is the gene for creating blue pigments, and thi... |
[
"Why is the stomach affected when you get nervous?"
] | [
false
] | It's seems to vary from cramps, to the feeling of needing to go to the toilet, to feeling sick. Scientifically, why is the stomach that takes so much abuse from nervousness? Surely, increased heart rate, sweaty palms and stuff, is more than enough. | [
"When you get nervous or scared, your body reacts with a ",
"fight-or-flight response",
". This involves, among other things, diverting blood away from your digestive system to your muscles and brain, in the anticipation that you'll either have to fight something or run like mad. This is why under stress, peopl... | [
"I was away working 7 days a week for a couple months under high stress and I found that my stomach/bowels, bladder, respiratory system were all effected by the nervousness and stress. I am also curious why."
] | [
"If you smell like shit and piss threats are less likely to eat you / beat you up"
] |
[
"Why can we walk perfectly fine on the edge of a sidewalk but not the edge of a cliff?"
] | [
false
] | null | [
"Hi Benstrosity thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of the fol... | [
"Human Body"
] | [
"Neuroscience"
] |
[
"If you can determine what elements are in a star by the black lines on its spectrum. Can you find even more elements in the invisible spectrum?"
] | [
false
] | null | [
"[I'm reading \"invisible spectrum\" as \"the part of the EM spectrum outside of the range visible to the human eye\" (after all, we have instruments that can see them just fine :D).]",
"The energy levels of electrons in the elements/molecules are what determines the wavelength of the light that's absorbed (or em... | [
"Thank you!"
] | [
"Hi AndyKansas thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of the foll... |
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