title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"What is the primary driver in muscle fatigue?"
] | [
false
] | I realize that there are many factors contributing to the successful function of muscular contraction, such as sufficient ATP, muscular glycogen stores, oxygen, lactate clearance, calcium, etc. Are any single one of these (or perhaps an unconsidered factor) the main influence in muscular failure? | [
"Fatigue is a complex (means from multiple systems, not complicated) integration of signals. First and foremost, failure to sustain muscle contraction arises almost entirely from a decrease in neural drive. This is not to say muscle fatigue is \"mental\" or \"psychological\", it is like a centrally-driven protectio... | [
"During exercise lowered pH is the main influence leading to muscle fatigue. pH decrease is caused by lactic acid build up.",
"\nThis occurs when not enough oxygen is available, therefore disallowing oxidative phosphorylation (massive ATP production) and the Krebs cycle to occur. ",
"Your cells respond by conve... | [
"As an aside to this, pain in the lungs or from poor respiration in general can usually be attributed to a build up of Carbonic acid in the blood. Carbonic acid is how CO2 is naturally stored in the blood and is converted during respiration. When doing strenuous exercise, especially cardio, if you are not adequatel... |
[
"Since the universe is expanding and it takes distant light longer to reach us - are there any astronomical objects that we lost track of because of this?"
] | [
false
] | null | [
"We live in a very special time, the only time when we can observationally verify that we live in a very special time.",
"-Lawrence Krausse"
] | [
"This is not correct.",
"No object will ever ",
" from our view. What will happen is that there will be a point in any object's life past which we won't be able to observe it. As time goes on, we will always (in principle) be able to see that object reach, but never quite attain, some maximal age. (Along with t... | [
"The most distant object we've found is a ",
"protogalaxy",
" which we are seeing as it was 13.42 billion years ago. It is now about 32.7 billion lightyears away, and receding superluminally.",
"This will be the first object to disappear. I am not awake enough to try the math, but if you could use the Hubble ... |
[
"What is the predicted life expectancy of someone who is now 20 years old?"
] | [
false
] | null | [
"That isn't really right. That's an aggregate life expectancy for someone dying now (i.e., typically born around 1930). For instance, as a Canadian Male, the life expectancy today is ~77 ",
"I choose that because I am one",
". But the life expectancy is increasing with time, increasing roughly one year every... | [
"That isn't really right. That's an aggregate life expectancy for someone dying now (i.e., typically born around 1930). For instance, as a Canadian Male, the life expectancy today is ~77 ",
"I choose that because I am one",
". But the life expectancy is increasing with time, increasing roughly one year every... | [
"On that note, is there a site with life expectancy tables for different ages, at different points through history, in different places?"
] |
[
"How come you need to focus your eyes differently to see a screen vs the glare on the screen?"
] | [
false
] | null | [
"The rule for a plane mirror (or a glossy surface which acts like one) is that it creates a ",
"virtual image",
" of whatever is in front of it at the same distance \"into\" the mirror. So, the light coming from the glare is coming at you as if it were coming from the same distance and location as the source it... | [
"Ah right. Virtual images and real images were covered in my high school physics class. But I forgot to think of the distance in terms of real and virtual images and was thinking the image was coming from the same source, the screen, instead of the screen being a mirror for a virtual image. Thanks!"
] | [
"Are you referring to where you can see the reflection of someone or yourself in a laptop screen?",
"I believe it is because the surface acts like a mirror and you are focussing either 100% of the distance to the pixels on the screen, or ~200% of the distance to the image of the reflection on the screen.",
"As ... |
[
"Did primitive human groups have 'leaders'? And if so how were the 'leaders' decided?"
] | [
false
] | Edit: By primitive I mean pre-civilization, like Neanderthal time. | [
"What we do know is that current hunter-gatherers who haven't been influenced much by outsiders tend to live in highly egalitarian societies, mostly regardless of geographic location and ancestry. Resources are shared, work is playful and collaborative, and any attempt to increase authority or status is immediately... | [
"Primitive humans, or the genus ",
", first appear in the fossil record approximately 2-2.2 million years ago. Their brain size was still small, though, similar to relative apes. What distinguished these early humans is the evolution of the first metatarsal, the first metacarpal, the gluteus maximus muscle, obliq... | [
"But that's only a particular segment of societies, which haven't progressed from being hunter-gatherers. Perhaps there's something about one's society being overly egalitarian that slows or prevents change and development."
] |
[
"What happens on an atomic/subatomic level when two objects collide?"
] | [
false
] | Is the interaction just between the colliding atoms' electrons or does it make more sense to think about it on the atomic level? How close do the nuclei get? Do their valence shell orbitals overlap? Is the collision "hard" and instantaneous, or is it more akin to bringing two magnets together? | [
"It's the interaction between the electrons, certainly. But there's no simple answer here, because their interaction isn't simple. It's quantum-mechanical rather than classical, it's a many-body problem (every electron affecting every other one), and it has to obey the Pauli principle. So any description you give i... | [
"I've heard two explanations. One is that the electron clouds repel each other by exchanging photons (electromagnetic repulsion). The other is related to the Pauli principle that two identical fermions (electrons are fermions) can't occupy the same state, so it's a Pauli pressure. The former seems to be the more co... | [
"Well, both views are oversimplified really. Chemical bonding (or lack thereof) can't be physically modeled in purely electrostatic terms. It's in fact been proven mathematically by Teller (and more rigorously later by someone else, IIRC). It'd make my life a lot easier if it could, since the Poisson equation is a ... |
[
"Why can't we see the EM force?"
] | [
false
] | The electromagnetic force is caused by the exchange of photons between charges. If I put my head (or some other detector) between two charged particles, why can't I see the photons flying back and forth between the charges? If I were to "see" these photons, would I disrupt the EM force between the two charges somehow? | [
"Charged objects don't actually shoot photons back and forth. These \n\"virtual photons\" don't exist and it's not a good way to think about it. If you're calculating, for example, the angle that one electron will scatter off another it can be useful to treat the scattering as if photons are being changed, but it d... | [
"Virtual photons are a mathematical trick that we invented to simplify (and unify) our understanding of charged particle interactions. They are a mathematical trick on paper, like the negative apples that you learn about in the fifth grade."
] | [
"Quantum fields interact, that's what is physically happening. Now how you describe the interaction is up to you, in a lot of cases it is convenient to treat the interaction as particles in others situations it's more suitable to use wave equations. Virtual particles is just a mathematical tool to express some dist... |
[
"What is the difference between a continent and an island?"
] | [
false
] | As far as I know, continents are basically just huge islands, so how is the difference between an island and a continent decided? | [
"'Continent' is a word without a set distinction. There are 7 continents by convention, but they are not a scientific thing.",
"An Island is a piece of land surrounded by water. Again, by convention it is small but there is no upper limit.",
"CGP Grey made a useful video on continents."
] | [
"Well, technically they are a scientific thing - a continent is a landmass above a continental tectonic plate. However, the scientific definition doesn't really match up with the normal 7 continents"
] | [
"If you can avoid the locks on the Panama Canal; sure. In theory that is. And academic at best.",
"Generally speaking continents are not islands though."
] |
[
"When We \"Think\", Does It Consume Energy? If So, How Much?"
] | [
false
] | I always use the metaphor of our brains as a computer (even though I have no idea how our brains work). A computer uses energy to process commands...does our brain work in a similar fashion? When I was thinking about this to myself five minutes ago, did I consume energy to do it? If so, how much energy is used? (Not of... | [
"Questions very similar to this have been asked before. There are a lot of interesting responses here:",
"http://www.reddit.com/r/askscience/comments/zuzs9/if_the_brain_uses_20_of_the_bodys_energy_would/",
"http://www.reddit.com/r/askscience/comments/klgci/the_human_brain_uses_on_average_20_of_the_bodys/",
"h... | [
"You might also be interested to know that fMRI, a neuroimaging technique that allows us to detect activation in brain regions as a function of some cognitive/behavioral activity, relies on detecting changes in BOLD (blood oxygenation-level dependent) signal, which is in turn a proxy for the amount of energy that n... | [
"As a persons thinks, the cells in the brain (neurons) are firing. When neurons fire, they increase their metabolic activity, i.e. glucose consumption. Positron emission tomography using [F-18]flurodexoyglucose (FDG-PET) of the brain exploits the brains metabolic consumption of glucose to allow us to image brain a... |
[
"What happens to dead bacteria in the human body?"
] | [
false
] | [deleted] | [
"About a third of your poop (dry weight) is dead intestinal bacteria, the vast majority of bacteria present in your body."
] | [
"Allow me to introduce you to a fun concept that is actually really important to anatomy and microbiology: ",
"The donut model of the human body",
". There is a tube that runs ",
"from your mouth to your anus",
". Everything inside that tube is technically \"outside your body.\" Your stomach acid and other ... | [
"Basically none of that bacteria is \"inside\" your body. Your blood and organs and stuff are sterile. The bacteria are either on your skin and fall off or they are in your digestive system (surrounded by your body, but separate) and get pooped out."
] |
[
"Why do I occasionally see flashes of white in my peripheral vision?"
] | [
false
] | null | [
"Those flashes of light are most likely caused by mechanical stress in your retina. Everyone gets them from time to time, so they themselves should not be a source of worry. If they're happening frequently it could mean you have a problem and should have an eye exam right away. Everyone should be checked regular... | [
"I was having occasional \"flashes of light\" in my peripheral vision and it was caused by a small tear in my retina. Get your eyes checked and be sure to bring this up with them. Good luck, hope everything turns out ok."
] | [
"That sounds like something different and perhaps serious. I would recommend an appointment with an ophthalmologist (",
" an optometrist) perhaps with a retina specialty. Answering this with anything else would go beyond the medical advice rules."
] |
[
"How do I calculate the electrical conductivity of different solutions?"
] | [
false
] | null | [
"It would be important to know the concentrations of the solutions. If they are the same molarity, and the solutions are treated as ideally diluted, you can use the conductivity of strong electrolytes (googling theses keywords will lead you to the right answer). "
] | [
"See sidebar: Try /homeworkhelp or /chemhelp. "
] | [
"pH only measures the relative concentrations of H+ and OH-, but other ions in solution will also contribute to conductivity."
] |
[
"what's the lowest altitude a satellite can orbit stably?"
] | [
true
] | [deleted] | [
"Stability is relative, measured in anything from weeks to gigayears, and depends whether you're asking \"how long will my sat stay in orbit at all\" or \"how long will my sat stay within X kilometers or X degrees of its ",
" orbit.\" Factors can include atmospheric drag (doesn't take much to deorbit from LEO, th... | [
"The \"satellite\" would have to produce constant thrust to overcome air resistance. This is what we call ",
".",
"Also note that orbital speed is over 7 km/s at low orbits; this is more than 20 times the speed of sound. Good luck getting any vehicle to sustain that speed in atmosphere and not fall apart."
] | [
"See I told you it was stupid."
] |
[
"tell me about density wave theory"
] | [
false
] | And explain in great detail. Please. I get the general gist of it, and how it's apparently responsible for spiral arms rotation in our galaxy, but what I'm confused about is the of these compression waves... that's completely eluding me. Interference from other galaxies? Or what? | [
"Just like to note that spiral density waves also occur in the rings of Saturn."
] | [
"explain further, please! :)"
] | [
"I've just read through the ",
"Wikipedia article",
". Sadly, I know nothing more than is presented there. I'm interested in this topic and hope some expert will weight in."
] |
[
"Would surface area impacts gravitational pull ?"
] | [
false
] | [deleted] | [
"Gravity is a dependent on mass, not shape, so it doesn't matter how much of the surface is exposed. We're pulled to the center of the Earth, not the surface. The surface just keeps us from falling to the center of mass."
] | [
"keoAsk is correct, there is no dependence on surface area within any mathematics that govern gravitational forces."
] | [
"No. the reason you can manipulate magnetic fields with conductors is because the electric field and magnetic fields are related. That's why we call it the electro-magnetic field. currents of electric charges ( and subsequently, changes in electric fields) will create magnetic fields.As of now, we do not know of an... |
[
"How Do we take Photos of Atoms Without affecting them?"
] | [
false
] | null | [
"You can't. Any interactions that would change the probe to create an image would cause a change in the atom. That's how forces work. If you're talking about making it not move around, you can try to use a probe that will only excite the electrons, which just changes the orbit the electron is in instead of changing... | [
"You can't. Experiment as a general abstract concept is always about perturbing a system and measuring its response.",
"You generally image individual atoms using either Scanning Tunnelling Microscopy (STM) or Atomic Force Microscopy (AFM). STM basically measure the quantum states allowed for an electron at a g... | [
"Like others have said, you can't prove a system without perturbing it in some way. However, transmission electron microscopy (TEM) and scanning transmission election microscopy (STEM) allow us to collect structural and compositional information down to the atomic scale without damaging the sample too much. The ele... |
[
"Is it possible to predict if a reaction is exothermic/endothermic based on the relative stability/energy of the reactant and product?"
] | [
false
] | i.e If an alcohol is halogenated into a alkyl halide, would it be exothermic or endothermic? (Assuming there's no supporting data) Since the C-Cl bond is weaker than the C-OH bond, I imagine it would be exothermic but I'm not sure if this is the correct reason why or not. But since -Cl is a better leaving group than -O... | [
"So you're getting at the difference between reaction kinetics and reaction thermodynamics here. Just because something is thermodynamically favorable doesn't mean that it will ever happen.",
"If you knew the energy of the bonds broken and the energy of the bonds formed, you should be able to predict the thermody... | [
"You're on the right track homie,",
"Think basic carbon combustion:",
"x CH4 + y O2 --> x CO2 + z H2O",
"The C=O and H-O bonds in the product are extremely stable relative to the O=O and C-H bonds in reactants which makes this reaction super exothermic.",
"The example you gave is difficult to qualitativily ... | [
"In general, reactions that are spontaneous (will happen) at room temperature/pressure tend to be exothermic, the exceptions are non-combustion reactions that release gas e.g. acid reacting with carbonates, as the entropy increase from generating a gas allows for a endothermic reaction to still be spontaneous. ",
... |
[
"Say two galaxies are combining, what would happen if two stars collided?"
] | [
false
] | Obviously the chances of this happening are remote due to the vast distances between stars. But somewhere out there, in one of the 100+ BILLION galaxies, this has to have happened, right? What would happen? | [
"http://en.wikipedia.org/wiki/Stellar_collision",
"There's a violent, bright phase associated with the collision, and obviously depending on the masses, the result can be a supernova or black hole formation. Other than that, it's a merging of two bodies into one, just like when non-stellar masses collide."
] | [
"The kinetic energy of a Sun-sized star moving at 220 km/s toward another Sun-sized star (orbital speed of the solar system around the galaxy) would be about 5 x 10",
" J. The gravitational binding energy of the Sun is about an order of magnitude larger, at 6.9 x 10",
" J.",
"So in this case, we wouldn't exp... | [
"You get 1 black hole - nothing can escape the event horizon, including another black hole. Unless they were on a perfect collision course they'd orbit around each other (I think that is the correct term) getting closer and closer until they merge and the 2 points become 1 point. Also interestingly, no matter would... |
[
"Different LDH Enzymes in Yaks?"
] | [
false
] | [deleted] | [
"I think you have misunderstood something. The functional LDH enzyme is actually a tetramer (made up of 4 components). The 4 components are usually a mixture of individual proteins produced from two separate genes LDHA and LDHB. Different tissue types tend to have different LDH components coming together to form th... | [
"Oh wow, that's awesome! Can I ask you what the difference in functionality is between them? Do they both play a role in anaerobic respiration? This is my main issue with this because I don't understand why organisms would produce two different enzymes that perform the same function."
] | [
"You need both genes (A and B) to combine to have one functional enzyme. They are not separate enzymes and they do not have separate functionality (that I know of). Think of LDHA as being an engine and LDHB being the body of a car. Neither one works alone, but when you combine them you have a working car."
] |
[
"Why does plastic become so brittle when you melt it and then cool it down?"
] | [
false
] | null | [
"It very much depends on the plastic... 'plastic' is an extremely broad term. Plastics (polymers) that are solid under normal conditions exhibit a glass transition temperature (similar to a melting point, but not quite); the strength and other material properties of a polymer can be highly dependent on the way the ... | [
"It depends on what the manufacturer wanted in the first place... amorphous material is more transparent than crystalline material (depending on the ",
"size of the crystalline regions",
"), but amorphous material can be weaker. ",
"PET",
" (polyethylene terephthalate has an interesting twist, in that it ab... | [
"Can you expand on that? How does heat change its molecular structure when it was forged by heat to begin with?"
] |
[
"When travelling at relativistic speeds, time flows faster, but for which object?"
] | [
false
] | [deleted] | [
"The difference is that the person in the spaceship doesn't have ",
" inertial frame of reference they have ",
". Specifically, they have one frame of reference when they're flying away from the earth, then they move to a different frame of reference when they turn around to head back. In their first frame of r... | [
"No, because acceleration is not relative. While the person on the spaceship sees Earth apparently accelerating away, an accelerometer on board the ship would indicate that ",
" is the one accelerating, not Earth. Earth stays in an inertial frame the whole time, while the person in the relativistic spacecraft wil... | [
"It's only velocity that is relative. I know a lot of SR is counterintuitive but this part actually makes sense. If you woke up one day in a windowless box, you couldn't tell the difference between moving or standing still, right? But you can literally feel it when you accelerate. If you can feel something, it alre... |
[
"Does the weight of an atmosphere pushing down on you contributes to gravity you feel standing on the ground?"
] | [
false
] | null | [
"If you were standing on a spring scale on Earth and reading your weight, and then the Earth lost all of its atmosphere somehow, the scale would start reading higher.\nWithout air pressure we would lose the small buoyancy force we have that is equivalent to the weight of the air we are displacing."
] | [
"The atmosphere is pushing on us from above just as much as it is below, so no it doesn't push us down. It's like how if you take a water balloon and submerse it in the ocean 10 feet down; it isn't pushed down by the water above it because the pressure is also pushing on it equally from underneath."
] | [
"Unless I'm misunderstanding something about the physics, the water pressure doesn't affect whether the balloon sinks or floats. That's determined by the weight of the water the balloon displaces compared to the weight of the balloon."
] |
[
"Can the Casimir effect take place near a black hole?"
] | [
false
] | [deleted] | [
"The Casimir effect is force between conducting plates in the vacuum, not the conversion of virtual into real particles. The description of the Casimir effect in terms of particles popping into and out of existence, while often given, is actually misleading; that is actually a description of the what the calculati... | [
"This is a good question, but to answer it, I need to set the record straight about what is, unfortunately, so often said.",
"Particles can pop into existence and disappear again by colliding with their simultaneously formed anti-particle. ",
"Even this is actually not quite right. The particle/antiparticle pa... | [
"This is a good question, but to answer it, I need to set the record straight about what is, unfortunately, so often said.",
"Particles can pop into existence and disappear again by colliding with their simultaneously formed anti-particle. ",
"Even this is actually not quite right. The particle/antiparticle pa... |
[
"What makes something transparent?"
] | [
false
] | I don't know if this is a dumb question, but can anyone explain what makes a substance transparent at an atomic level? | [
"in geology, there are a few minerals that are 'transparent' just because of the alignment of the lattice ",
"ulexite"
] | [
"All light has a characteristic wavelength and frequency. The frequency corresponds to energy levels. If a photon encounters an electron, the electron can absorb the photon and move to a different energy level. This is quantized, so only specific frequencies can be absorbed. In transparent objects, there are no... | [
"When light hits a material, it is either absorbed, transmitted, or reflected/refracted. Obviously, when talking about a material being transparent, the dominant mechanism at play is the transmission of light through the material. Reflection is (generally) determined by the difference in ",
"refractive indeces",
... |
[
"Ask Anything Wednesday - Engineering, Mathematics, Computer Science"
] | [
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! ... | [
"Hey my Prof once said, that if the computer progress keeps going so fast, we will have a computer with the intelligence of a human being by 2050. What do you think about this?"
] | [
"I'm more pessimistic about the development of AI, and think we haven't come very far in terms of simulating intelligence. There are no promising approaches I'm aware of other than simulating the brain directly. Although processing power for this may be getting closer, it's still a long way off, and there's also j... | [
"Of course, by the time we have a space fleet who knows what tech will look like, but there will be one thing that stays true: bombs just don't do much in space. ",
"The reason bombs cause so much damage on Earth is because they create concussion waves in the air, and those waves rip things apart. In space, there... |
[
"Why is Arachnophobia so common?"
] | [
false
] | null | [
"Wait, ",
" arachnophobia common? I know that most people don't like spiders or are startled by them, but actual diagnosed cases of arachnophobia are common?"
] | [
"Like many things, the argument boils down to nature vs nurture vs a mix of both. ",
"One school of thought is that due to the presence of deadly venomous spiders, we evolved an innate fear to the very sight/shape of them. The extra caution, and instinctive fight or flight response, thus gave arachnophobes a slig... | [
"this, and the common knowledge that some are deadly and can kill you without you even knowing you were bit"
] |
[
"How scientifically significant is James Cameron's journey to the bottom of the Mariana Trench?"
] | [
false
] | I've been enthralled by the story of James Cameron going to the bottom of the Mariana Trench (relevant info , and all over reddit) and I've gotten the impression that it's a fairly big event in science and human history. Is this actually significant though? does it open up any possibility for ground-breaking research o... | [
"I don't see any huge breakthroughs, but there's potential for good science anyway.",
"If he finds no animals, or maybe just a few of the same kind of amphipods that we've seen in other trenches (though not as deep), it's new knowledge but not very unexpected.",
"If he finds shelled organisms, that's a lot more... | [
"This kind of thing sparks interest in lots of people, including little kids. ",
"This alone makes it worth it."
] | [
"It's true though - I showed my sixth graders this story yesterday and even the kids who rarely speak in class got all excited and started sharing and asking questions. In some ways it mirrors what Neil deGrasse Tyson has been recently discussing with respect to space exploration and inspiring a whole new generatio... |
[
"If the International Space Station passed right in front of you at 17,500mph, could you see it?"
] | [
false
] | I was wondering about this one during my morning commute. The ISS travels ~17,500mph in orbit. Under great conditions you can actually see it without a scope as it passes overhead. But this question isn't about seeing it in orbit. I'm curious if human vision would register the ISS if it passed at ~17,500mph right in ... | [
"The ISS is about 109 m long in its longest dimension (which is pretty big), so travelling at its orbital speed, it would take about 0.014 seconds to travel past a given point. That's almost 10 times longer than a 3 inch baseball at 100 mph, which transits a point in 0.0017 seconds."
] | [
"I like that. Thinking of the ISS slowing down to a baseball-level speed is easier to picture. Thanks!"
] | [
"Like you, I'm not sure if that has anything to do with visibility, but if it does, then it should be hard to miss."
] |
[
"Is depression more frequent amongst people in developed countries?"
] | [
false
] | I live in a highly privileged country (Norway), and yet my impression is that a lot of people here are depressed. In a peaceful society you don't have to tackle a lot of serious day to day-problems of the kind you might see in underdeveloped countries, or even in America. Things like fighting for your life, your rights... | [
"A ",
"2011 study",
" reported:",
"On average, the estimated lifetime prevalence [of depression] was ",
" (t = 5.7, P < 0.001). Indeed, the four lowest lifetime prevalence estimates (< 10%) were in low- to middle-income countries (India, Mexico, China, South Africa). Conversely, with the exception of Brazi... | [
"Psych grad here. Maslow's hierarchy has been pretty well debunked as not scientificallly valid beyond MAYBE very general statements at best. Asnd your statement that s\"Before someone can worry about something like depression, they have to worry about more fundamental issues\" is also untrue. Depression is REPORTE... | [
"Maslow's Hierarchy of needs",
".\nEssentially, Before someone can worry about something like depression, they have to worry about more fundamental issues, for example food, water, shelter, a steady income. In higher income countries, more of the population has their basic physiological needs met, so they can wor... |
[
"Is cancer perfectly preventable? WHO says 30%-50%"
] | [
false
] | As per the title, WHO says " ". I wonder what this means? Does it mean if I live a perfectly healthy lifestyle, I still have a chance to get cancer? Can anyone answer my question I fear that I may get cancer one day? | [
"Population statistics are not easily applied to an individual. If all people were to eliminate all modifiable risk factors for cancer, the incidence of cancers would decline 30-50% in that population. Some risk factors, such as age and genetics, are not modifiable, so cancers would still occur. A similar strategy ... | [
"It means 30-50% of cancer cases could have been prevented. It also implies that for 50-70% of cases it is not reasonable to expect that they could have been prevented.",
"This doesn’t factor in the many cases where statistically people ",
" have gotten cancer but for some reason don’t. (All those old chimney s... | [
"Yes if nothing else kills your first you will die of cancer. It is the reality of cellular replication and rolling increasingly busted dice over and over.",
"It is true that if you live a healthier lifestyle you improve your dice rolls, in some cases dramatically.",
"No smoking, no drinking, no drugs, no exces... |
[
"How do we know how far away distant objects in space are?"
] | [
false
] | null | [
"For closer objects such as those in our galaxy we use parallax.",
"Even then, parallax doesn't even cover our whole galaxy - turns out the angles involved are ",
" small and hard to measure.",
"Cepheid stars are a class of stars used as standard candles (perhaps the most useful type).",
"Cepheids are reall... | [
"For closer objects such as those in our galaxy we use parallax.",
"Even then, parallax doesn't even cover our whole galaxy - turns out the angles involved are ",
" small and hard to measure.",
"Cepheid stars are a class of stars used as standard candles (perhaps the most useful type).",
"Cepheids are reall... | [
"Massive co-incidence to see this question being asked as this is the unit i am currently studying in physics.\nThere are several ways:\nthe first being radar. we send out a radio wave or use a laser as bounce it off a planet. knowing the speed of light in a vacuum we can use the simple equation of d=vt and work ou... |
[
"What's the catch with TV explanation of Relativity?"
] | [
false
] | There was a program on TV (either on Discovery or National Geographic) that explained why time depends on velocity like this: Person A stands on the side of the road where person B drives a car at a speed close to c. B's car has a light based clock that measures the time based on the number of times a beam of light tra... | [
"The catch is that when you move the clock, you also have to move ",
" from the observer by the road to the observer in the car.",
"It's easier to just imagine two clocks from the start. The driver has one and the pedestrian has one. The pedestrian sees himself standing still, while the driver rockets past him.... | [
"I think you mean parallel to the direction of motion. Only lengths along the axis of motion are contracted. Like I said, the problem can still be made to ",
" if you turn the light-clock by a quarter turn, but it's considerably more complicated. It becomes a three-dimensional problem instead of a two-dimensional... | [
"Huh. That's more complicated than I would have expected a popular depiction to get. Good for them!"
] |
[
"I've heard that the most current physics models state that all basic particles are simply excitations of a series of quantum fields. If this is true, then would it be reasonable to imagine the universe as a series of peaks on a massive intensity field?"
] | [
false
] | I'm imagining some sort of otherworldly/heavenly analytical device that sums all energy across the universe into a series of intensity peaks, like an XRD or XPS or any number of analytical devices we use on earth. That would make deep space the background noise. Is there any conceivable way to estimate the total energy... | [
"I accidentally wrote a book :/ ",
"So, quantum mechanics describes the universe in terms of a ",
". The state specifies which particles are around and when. So state X might be \"there are six electrons over there at such and such places at 6:00 pm\" and state Y might be \"there are four neutrons over there, a... | [
"Excitations are not peaks."
] | [
"Can you elaborate? "
] |
[
"How does the circulatory system adjust to the greater volume of bodymass in obese people?"
] | [
false
] | [deleted] | [
"The heart has to beat harder, and the left ventricle, which pumps blood out to the body through the aorta, becomes thickened.",
"https://www.medscape.com/viewarticle/495041_6",
"In some people, there's a decrease in vascular resistance, so they don't get high blood pressure, but most obese people get hypertens... | [
"Will the distended left ventricle correct itself when the person loses weight? Or do you have to do exercises / take medication for it? Or will it stay distended forever?"
] | [
"In addition to this, people with greater body mass have a greater volume of blood as well. ",
"That is, a 100kg man will have more blood, regardless of body composition, than a 75kg man. "
] |
[
"When you cut a pill in half, are you really cutting the dosage in half?"
] | [
false
] | [deleted] | [
"Yes. This works. But it only works with tablet pills that are not sustained release or extended release. it doesn't work for gel capsules or anything else that can't easily be cut in half. Extended release pills can have their \"extended release\" feature messed up if they are cut."
] | [
"If the contents of the pill are homogeneous then cutting the pill in half would effectively half the dosage."
] | [
"All the answers here are very correct. Another reason as to why we have patients cut a tablet is for cost savings measures. However, that would be dependent on if the patient understands that (s)he needs to cut the tablet, if (s)he can see the tablet, if (s)he has the dexterity/strength to do so, and if (s)he ca... |
[
"How long does the nuclear chain reaction last in a nuclear/atomic explosion?"
] | [
false
] | When a Nuclear/Atomic bomb is detonated, how long does the nuclear chain reaction actually last? Watching videos of nuclear blasts shows about 3-5 seconds of growing light intensity in the core before the bright light at the center dies out and then all that remains is a burning fireball. | [
"A nuclear chain reaction lasts around 70-100 shakes. So that comes out to 700 nanoseconds to 1 microsecond. The light you are seeing is part of a more complex process due to plasma trapping of the light. This trapping causes a double flash to occur for nuclear weapons. "
] | [
"A shake is ten nanoseconds and is roughly the time between generations. "
] | [
"A shake is ten nanoseconds and is roughly the time between generations. "
] |
[
"Why is the background smooth in IBM in atoms?"
] | [
false
] | In it says the background consists of "a substrate of chilled crystal of nickel" but why isn't this background also a bunch of individual atoms? Why is it smooth? | [
"There are a lot of incorrect and inaccurate responses in this thread but hopefully this post will clear things up. It's pretty detailed but I'm always happy to answer additional questions about all things STM related. ",
"\nIt says in the paper that this figure came from that the atomic structure of the nickel s... | [
"Thank you for actually reading the paper and giving a proper response. My blood was beginning to boil at all the incorrect things I was reading here, but I didn't feel confident enough in my own knowledge to properly answer the question myself."
] | [
"For everyone else who isn't in the know, STM stands for Scanning Tunneling Microscope (as opposed to the Scanning Electron Microscope that I'm familiar with). OP, can you give some insight as to how the two are different? "
] |
[
"If water is so rare in the solar system, why are comets comprised mostly of it?"
] | [
false
] | Most of the material I've read suggests that comets are made primarily from ice and/or frozen CO2. Water? It seems like water is extremely rare in our solar system, so why is it present in such abundance in comets? | [
"Water in and of itself doesn't appear to be rare in the solar system. Its on the Moon, its on Mars, its on Europa, and probably many other places we haven't looked yet. What IS rare is liquid water, which requires the right temperatures and pressures to exist."
] | [
"Water is not rare in the Solar System. It's only rare in the inner Solar System, inside the radius of the asteroid belt. When the Solar System was forming, the inner part was hot enough to vaporize the water, and the solar wind blew it outward to the point that it could recondense into ice. The materials that stay... | [
"http://lmgtfy.com/?q=water+on+the+moon",
":)"
] |
[
"Do we pee out the oils we ingest?"
] | [
false
] | [deleted] | [
"Oil is fat. It's digested, and either stored or transformed into energy.",
"Note that nothing goes directly from your digestive tract to your bladder. "
] | [
"Think of it this way: your body is one giant tube from mouth to anus, with a lot of other stuff to assist in its purpose: arms to get food in there, legs to chase your prey, a brain and eyes to figure out what to put in... But pee comes from one of these secondary systems; it's not part of your g.i. tract. Stuff g... | [
"Pretty much- in the comments he says he was \"leaking\" for 9+ hours. The intestines are pretty efficient at absorbing fats (",
"This",
" states ~95%), so there most likely wouldn't be much left over ~6 hours after recovery."
] |
[
"Will Voyager 1 eventually crash into a star or a planet, or will it continue on forever?"
] | [
false
] | I'm just interested in ball park probabilities here: if not found, is it more probable that it will eventually crash into something, or is it more probable that it will travel on forever (well, until it dissolves)? | [
"This is going to depend on what you mean by \"eventually.\" All satellites are gravitationally bound to our galaxy, so it is necessarily going to fall into something at some point. Because assuming it doesn't hit anything before, it will have to pass through the core. There the gravity will be intense enough that ... | [
"\"Lol, these people used LENSES!\"",
"-Future alien"
] | [
"That being said, it will most likely sail for thousands of years before it even has a chance of hitting anything else. Its last big hurdle is the Oort cloud (which might not even exist!) but even that is so sparse the chance of it causing a problem is basically zero ",
"Assuming it doesn't hit anything in the Oo... |
[
"Whenever Marine One flies over my house, my TV flickers out. Why?"
] | [
false
] | null | [
"Multi-band airborne jamming has been around for a while ",
"e.g. EC-130",
", so such a device mounted on Marine One is certainly possible."
] | [
"Any type of radar guided object could operate at any frequency, so Marine One would obviously block out all frequencies except it's own exclusive networks. ",
"It would be no sense for a high personnel designated air craft to only jam a specific, highly common signal, and if it did so, would greatly jeopardize a... | [
"This is pure speculation here so take it as you will. But I'm not so sure about jamming necessarily being the cause. I don't doubt that Marine One has some electronic countermeasures on board but I doubt that it's flying with those on all the time. Electronic counter measures is like you being in a dark room and p... |
[
"How does radiation effect precious metals?"
] | [
false
] | This is a multi part question and I'm not really sure how to ask it. Please forgive me if I ask a question in a stupid way How do metals like gold, silver and copper become radioactive (irradiated (if somebody could clear up the semantic, that'd be nice)) and what happens to these metals when that happens? Does simple ... | [
"I think you are confusing neutron radiation with the normal types of ionizing radiation emitted by radioactive objects (alpha, beta, gamma). The type of radiation that makes elements, including gold, radioactive is neutron radiation. If the nucleus of an atom happens to pick up a neutron from a neutron radiation s... | [
"Just to clear up a few points:",
"Irradiated = Exposed to radiation (not necessarily changing anything about the target)",
"Radioactive = Emitting radiation (generally because something is unstable and decaying, but can be induced)",
"Then we have the types of radiation, because you can spend the rest of you... | [
"There are radioactive isotopes that emit neutrons. Californium 252 is a prime example. It also is not the only one.",
"https://en.wikipedia.org/wiki/Isotopes_of_californium#Californium-252",
"Edit: I forgot to add that uranium also emits neutrons as well as heavy ions. Many of the heavier isotopes have a deca... |
[
"Orbital mechanics question: can you burn for a direct capture of mars orbit as you leave earth orbit?"
] | [
false
] | A friend and I got into a discussion about this. He says its impossible to do without a significant retro burn. I say it’s just requires a lot of precision and is impractical but possible. What say you? | [
"The only way to be captured into the orbit of a massive body when you are starting from outside the sphere of influence is either:",
"\nA: you do a retroburn after getting there to stabilize the orbit. ",
"B: you slow down with an aerocapture, and the do a prograde burn at apoapsis to circularize (otherwise y... | [
"Mars has two moons actually, Phobos and Deimos. But neither have nearly enough mass for a significant gravity assist so your point's still valid."
] | [
"Without any of the listed methods (or lithobraking) whatever speed (relative to the body) you have when you approach a large body will be conserved when you move away from the body, regardless of size. "
] |
[
"How is a jet engine different from a propeller?"
] | [
false
] | null | [
"They're two totally different things. A jet engine is a device that adds energy to a stream of air flowing through it. This is used in different ways. In a traditional jet engine (turbojet) the jet engine adds almost all of its energy to the airstream through the engine, and the result is a hot, fast exhaust that ... | [
"It's important to note that Turbofan jets (used in most civilian jet liners) use the power from the turbojet engine to spin a fan like a propeller. Most airliners get around 80% of their thrust from the fan and not the jet itself."
] | [
"On what level? They both generate thrust by accelerating air backwards. A turbojet gains more thrust from the exhaust gases, a turbofan is more focussed on just accelerating bypass air. A turboprop does the same thing as a piston engine prop, just more efficiently in thinner air, due to being driven by a turbine."... |
[
"Are people with aphantasia less effected by PTSD?"
] | [
false
] | From my limited understanding, aphantasia sufferers are incapable of picturing images in their head, be it a memory or a fantasy, they just can't do it. So if PTSD sufferers suffer from "flashbacks" to their traumatic event, would somebody with aphantasia just not experience that? | [
"Flashbacks often involve people, places, and events. Part of the flashback is the association of the people, place, or event with the trauma. For example, a car backfiring can remind a military veteran of gunfire. A mental image is not required."
] | [
"First I'm going to parse out \"flashback\" to make sure I'm understanding your use of the term. Officially, a flashback is a dissociative experience in which one loses touch with present reality and dissociates back to the time of the trauma. A flashback is a lot more than just cued re-experiencing.",
"Couldn't ... | [
"Thanks for the sources and further explanation of a flashback. I learned something today!"
] |
[
"Old electrical thingies?? What are these and exactly how were they used?"
] | [
false
] | Link to picture and slightly more info . I hope I'm asking in the right subreddit. If not and you have a more appropriate suggestion, please let me know. Thanks! | [
"insulators. for antenna wire, I believe.",
"http://www.theodoregray.com/periodictable/Elements/027/index.s7.html#sample23",
"yup.",
"damn, I'm fucking old."
] | [
"Yeah, they are antenna insulators. Often used by radio hams, of which I am one.\nThey're probably worth no more than $10, if glass."
] | [
"Wow! Mine aren't blue, but do you mean to tell me that I just found about $60 in the woods here? Cool!"
] |
[
"Is Liquid Fluoride Thorium Reactor technology a plausible solution to the energy crisis?"
] | [
false
] | [deleted] | [
"Yes. LFTRs would be able to supply our current energy needs for thousands of years, and do so cheaper than coal power plants.\nThere are minor engineering problems to be solved, but I have not found any serious showstopper during my research. So I remain optimistic."
] | [
"I have limited knowledge of Thorium salt reactors, but from what I have read, it would be an excellent energy solution. The technology is just very new and needs to be developed. "
] | [
"In fact, the technology is old - it has been prototyped in the ORNL lab in the 70s. Unfortunately, politicians killed the program in favor of LMFBR uranium reactors."
] |
[
"What is the *largest* factor to why being submerged in water feels colder that air of the same temperature?"
] | [
false
] | I read previous answers to similar questions but they all sort of co-mingle the different factors. I know that the mass of water around you is larger as is the specific heat, but the thermal conductivity is also higher. Is either of the two factors- thermal mass vs conductivity significantly more responsible for the se... | [
"NAUI-certified SCUBA diver here -- I remember learning this in our certification class.",
"The main reason why being submerged in water feels so much colder than being in air of the same temperature is because of the thermal conductivity. The colder water \"sucks\" the heat out of your body much more rapidly th... | [
"Id like to add a follow up question: what if the fluids are at a higher temperature than your body? Water would feel warmer because of its ability to move heat to you, correct?"
] | [
"No, that's pretty much completely wrong. What happens is that a small layer of fluid around your body gets heated/chilled to match your body temperature. If it's air, the low thermal conductivity means that only the air right next to your body will be affected, which doesn't take a lot of work. The air next to you... |
[
"They say there are galaxies that today are some 14 billion light years away, that the light we see from them is 14 billion years old and has taken that long to reach us. 14 billion years ago wasn't the universe WAY smaller and that galaxy way closer?"
] | [
false
] | So does this mean that so much space was created between us and that galaxy during that time that it was new space the light had to travel through? And what does a photon do when, while traveling along in old space it suddenly bumps into a bit of new space? How do light waves handle the transition from old space into n... | [
"Space isn't really a \"thing\". When we say \"space is expanding\" what we mean is \"things are getter further apart from each other\". So \"new space\" and \"old space\" aren't really ideas that make sense.",
"For very distant galaxies, the distance we usually give is the distance the galaxy is ",
". But ther... | [
"So does this mean that so much space was created between us and that galaxy during that time that it was new space the light had to travel through? And what does a photon do when, while traveling along in old space it suddenly bumps into a bit of new space? How do light waves handle the transition from old space i... | [
"And what does a photon do when, while traveling along in old space it suddenly bumps into a bit of new space?",
"Space isn't expanding like that. It's more like a large (maybe infinite) rubber sheet that stretching uniformly. Every spot is getting larger at the same rate. There is no \"new space\" or \"old s... |
[
"New to micropipettes, what tips should I get?"
] | [
false
] | [deleted] | [
"I just order crummy tips in big bags from VWR: \n",
"https://www.vwrcanlab.com/catalog/product/index.cgi?product_id=4693330",
"Do you have any special requirements like filtered tips or something?"
] | [
"These would prolly fit: ",
"http://www.fishersci.com/ecomm/servlet/fsproductdetail?storeId=10652&productId=1688814&catalogId=29104&matchedCatNo=212363||2123635&endecaSearchQuery=%23store%3DScientific%23N%3D0%23rpp%3D15&fromSearch=1&searchKey=21||3||236&highlightProductsItemsFlag=Y"
] | [
"Talk to the various company reps that cover your institution and get some samples from them. Find what you like that fits what you have. Honestly, if I had to start fresh, this is how I'd do it (plus you end up with some free tips out of it!)."
] |
[
"Have all of our space probes been launched in the same direction ?"
] | [
false
] | null | [
"Relative to Earth, not at all, though most tend to be launched roughly forward or backwards relative to our orbital direction because that's the easiest way to get to other planets.",
"Relative to a sun, only 5 probes so far have achieved escape velocity and they're moving in fairly different directions, though ... | [
"Neither. Around the galactic center, so orthogonal to that direction."
] | [
"What directions the sun moving in? Toward or away from the galaxy’s centre?"
] |
[
"Question about power generators and superconductors."
] | [
false
] | I haven't cracked my physics books in a while - but I recall an idealised generator being decribed as a coil of conductive wire spinning on an axis in a magnetic casing. Would replacing the wire with superconductive wiring change or perhaps even improve the performance of the generator? Would it still even work? | [
"In general the conductive wire in a ideal generator is assumed to have zero resistance, or be superconductive. Changing the type of wiring shouldn't change the underlying physics that the generator operates on; it should still function. You wouldn't suffer energy loss to resistive heating, because there is no re... | [
"so we'd get a slightly more efficient generator. Thanks!"
] | [
"You might actually be able to get a considerably more efficient generator. Superconductors (if I recall correctly) display the Meissner effect, which is the expulsion of all magnetic flux. In a magnetic casing, you'd end up with a much better rotator. You'd have to worry about the frictional heating from the compo... |
[
"What limits the size of trees?"
] | [
false
] | That is, if they have plenty of water, good soil, light, and no weather-related obstacles, then what prevents them from growing hundreds of feet into the air? Edit: So they have reached around 400ft, but is it possible to go even higher? | [
"This was covered in my Biology class. I don't remember the exact height (although I ",
" it was somewhere in the 300s), but there was a number of feet after which the capillary action was no longer strong enough to draw up the liquid required."
] | [
"As I recall from a trip to the Sequoia National Forest, this can be overcome somewhat by drawing moisture directly out of the atmosphere. Redwoods are able to grow taller than they would be able to if they were in a very dry climate, as they're able to get moisture from fog that condenses as moist air moves up th... | [
"I took a botany class from ",
"Professor Sillett",
" at HSU. He was featured in an article in National Geographic climbing Redwoods (",
" ",
") where he had located the tallest Redwood. He explained to the class that due to gravity the water columns can only go so long before snapping like a rubber band. O... |
[
"Did bird feathers evolve from reptile scales?"
] | [
false
] | Did bird feathers evolve from reptile scales or did they come about through some other way? | [
"Feathers and scales develop in similar ways, and it's possible feathers did evolve from scales. For a long time each of these structures were thought to have different proteins unique to each. However, the type of keratin thought to be unique to feathers ",
"also exists in embryonic alligator scales",
". Allig... | [
"Thank you for such a through response. It's so great to have knowledgeable people willing to share and explain what they know to people who aren't overly familiar with the subject. I really think this forum and people such as yourself help advance scientific literacy among the public. Thank you."
] | [
"Whoa, wait. I get that you're trying to communicate something about how evolution is not linear, but what you're saying is really misleading, and you're incorrect in what you say about the common ancestor of living birds.",
"The common ancestor of birds was a dinosaur, as all birds are dinosaurs, and that common... |
[
"How old is the snow on top of Mt Everest?"
] | [
false
] | Saw an post earlier that talked about the snow on top of Mt Everest. This got me thinking about the lifespan of snow. Living where I do, the Pacific North West, I think of snow as a fleeting thing, tied to a season. Lasting a few days at most. I think of how delicate snowflakes seem and imagine they can't last too lo... | [
"Snow can stay in one place indefinitely, but the individual flakes will be pressed together into porous ice. Ice cores are used to measure the composition of the atmosphere thousands of years back from the trapped air. The age is determined because like a tree's rings the snow deposition has seasonal variations, s... | [
"Not an expert, but the types of ice are mostly based on pressure. If enough snow has fallen to compress the bottom into porous ice, given enough time it will do so. As you move up through the layer, less weight means less pressure, and eventually it is not enough to compact the snow.",
"Assuming no more snow fal... | [
"Thanks so much for your speedy reply.",
"What sort of time frame does it take for the snow to be pressed together? I understand it probably has a lot to do with conditions.",
"If it just magically stopped snowing, but the temperature remained low, would the snow still turn into porous ice?"
] |
[
"How long can satellites in Earth's orbit stay in orbit?"
] | [
false
] | I'm a huge fan a VSauce and one of Michael's videos he posted last week said that satellites in geo-stationary orbit can stay there for over a years. How is this possible? Is this actually realistic? Humans can't even perceive time periods that long, how could we make something that would last that long? | [
"The satellites have no hope of remaining functional for that long.",
"The large number is not because we can build them to last, but because an object in geostationary orbit (even a piece of rock) has virtually nothing slowing it down and essentially nothing to perturb its orbit so it can stay there for so long.... | [
"Satellites ",
" correct their orbit, but almost entirely because of decay due to atmospheric drag or corrections to avoid space debris. The ISS is in LEO at about 410 kilometers, and atmospheric drag causes the orbit of the ISS to decay about 2 kilometers per month. Geostationary orbit occurs at about 36,000 kil... | [
"Like ",
"/u/serious-zap",
" said, there's nothing to bring you* down when you're ",
"that high.",
" The main thing to watch out for in lower orbits is drag. According to ",
"Wikipedia,",
" the density of air at sea level is about 1.225 kg/m",
" . The ISS orbits at an altitude of about 400 km. Accordi... |
[
"Can an artificial structure, as in a city, ever become so large that it the structure actually effects the interior weather patterns?"
] | [
false
] | I just watched a bunch of Samurai Jack. There's plenty of other sci-fi movies out there that have a similar thing though - a massive, sprawling city that stretches far up into the air, has bridges between the buildings, and makes it possible for a person to go quite some time without ever needing to touch the ground. I... | [
"Yes, ",
"this happens regularly",
" in large cities. All of the concrete, brick, and asphalt of modern cities tends to retain heat absorbed during the day, which keeps the nights abnormally warm and can affect the local weather."
] | [
"I don't know about cities, but the vehicle assembly building at the Kennedy space center has to have massive HVAC units running to maintain the inferior at a very specific point, other wise it is possible for clouds to start forming inside the building. \nWhich, btw, is FUCKING AWESOME!!",
"There's also a wind f... | [
"The Boeing factory near Seattle is so massive, it once began generating its own weather systems.",
"Watched a neat documentary on it a few months back, ",
"EDIT: ",
"link",
" for the NatGeo documentary."
] |
[
"Is there any nutritional benefit from eating sweetcorn?"
] | [
false
] | Ok, so, fun story time. Yesterday I ate sweetcorn. Today I discovered perfectly preserved sweetcorn in my poop. Like, you could wash it and sneak it into someone's meal, and they wouldn't notice. This got me wondering... So, it obviously wasn't digested, or it'd've blended in with all the other shit. So... is there any... | [
"The pericarp of maize is almost entirely undigestible by the human metabolism, including our gut flora. We rely on chewing to disrupt that pericarp and give access to the digestible starches inside. If you swallow corn whole, the pericarp remains unbroken and very little digestion is able to occur. Even when you "... | [
"Well that was simple enough. Thanks! The sweetcorn was in pasta so it wasn't really a chewing-heavy meal."
] | [
"tl;dr The corn kernels in your poop are filled with poop not corn :)"
] |
[
"Why is 5 the minimum number of points required to trace a conic curve?"
] | [
false
] | On the program Geogebra I have, to trace a conic section you need to create 5 points on the plane by which can be traced hyperbolas, ellipses, etc. Any arrangement of the points takes me to a different conic... it's weird | [
"A conic is described by an equation Ax",
" +Bxy+Cy",
" +Dx+Ey+F=0. Given 5 points, we are given 5 equations in 6 unknowns. Therefore this equation is solved by a one dimensional space of coefficients, all giving the same conic since multiplying the above equation by any real number gives the same conic.",
"I... | [
"The conic sections are the nondegenerate second-order polynomials in the Cartesian coordinates (x, y). That is, every conic section can be written in the form Ax",
" + Bxy + Cy",
" + Dx + Ey + F, where at least one of A, B, and C is not zero. Do note that \"nondegenerate\" refers ",
" to the polynomial; some... | [
"Ok yeah, you're right. You know I haven't done this in too long if I forget you can divide polynomials by a constant D:"
] |
[
"How does chewing tobacco cause cancer?"
] | [
false
] | What is the mechanism that causes tumors to form after the gums/cheeks are in contact with tobacco? | [
"Tobacco contains a carcinogen called N-Nitrosonornicotine. Specifically in the case of chewing tobacco, it's been shown that (S)-N-Nitrosonornicotine causes oral cavity cancer (ref: ",
"http://www.ncbi.nlm.nih.gov/pubmed/23671129",
").",
"Now, when I was kid there was this myth of fiberglass being in tobacc... | [
"Carcinogens (like (S)-NNN) are chemicals that can enter cells and reak havok on an organism's DNA. Luckily, your cells have ways to stop cell growth when it detects damage in the DNA. However, the errors can slip through and cause the cell to undergo uncontrolled cell growth. The now non-functioning cell will cont... | [
"Thanks, that's very helpful! ",
"So how is it that the (s)-N-Nitrosornornicotine causes tumors to form?"
] |
[
"How is biometric authentication not practically the same as using the same password for everything?"
] | [
false
] | Sure it is a good password so it can't practically be guessed, but in the event of a database leak with all our fingerprints they are no longer secure and can no longer be used, ever really. | [
"Biometrics, although intended as an authentication method, are significantly different than passwords.",
"In a general context, you are thus correct: since a biometric represents something you have, and you can't alter it very easily (although that's the very thing cosmetic surgery is fighting against), it would... | [
"So the recent trend towards using the fingerprint scanner on your phone for just about everything?",
"Not that secure since it is not an honest system?"
] | [
"Depends on the implementation. For instance, on the iPhone, your fingerprint is used by Touch ID to unlock the Secure Enclave; in this context, it's a local context and it's not attempting to guard against the possibilities that somebody has your fingerprint or your phone. That doesn't make it less secure. It's s... |
[
"Why are there no heat shimmer effects in the Soviet Venera probe pictures?"
] | [
false
] | null | [
"The \"heat shimmer\" effect isn't caused by the air you're looking through being hot. It's caused by the air you're looking through being different temperatures.",
"Different temperatures of air bend light differently. When you have two different temperatures of air mixing, the way the light bends to reach you... | [
"The winds are pretty weak near the surface of Venus, reaching at most about 10 km/hr.",
"This part is true, but...",
"In part, this is due to the fact that Venus rotates slowly compared to the other planets (only once every 243 days). ",
"...that's not why. In fact, up in the middle atmosphere the winds of V... | [
"It does turn out to be true that the surface of Venus does not have large temperature gradients (i.e. the temperature is fairly constant). The winds are pretty weak near the surface of Venus, reaching at most about 10 km/hr. ",
"In part, this is due to the fact that Venus rotates slowly compared to the other pla... |
[
"When one shines say a lazed of light which is in the red wavelength and a laser of identical optics emitting a blue wavelength, does the combined light appear yellow due to a wave interference of frequency, or a compilation of the varying wavelength's energy?"
] | [
false
] | null | [
"Red and blue laser light do not combine to form other frequencies.",
"Instead, visible colors are created by brain processing (",
"Land theory",
") and by the frequency-sensitive cone cells in your retina.",
"If red and blue light should strike your retina, the red light triggers the red-sensitive cones an... | [
"Wow I must have been tired, I meant red and green lasers, whoops"
] | [
"But blue lasers are ",
"much cooler!",
"But don't need a laser. Shine red and green LEDs at a piece of paper. Adjust them until you see yellow or orange light. But there are no yellow or orange frequencies there. It's entirely an illusion inside your brain.",
"Perhaps there are aliens which have hundreds... |
[
"is there a finite amount of photons for objects?"
] | [
false
] | null | [
"Many stars are so faint that they require long exposures to image. If you reduced the shutter speed to some arbitrary value, one could find a period of time where no photons arrive. You could do this with the Sun, also, if you could get the shutter speed high enough."
] | [
"layman here",
"I believe you have stumbled upon wave/particle duality. From what I understand, objects (emitters) do indeed emit a finite number of photons. You can use a device such as a photomultiplier to actually count these photons.",
"However, these photons also exist everywhere in the electromagnetic fie... | [
"Due to the expansion of the universe, there are (probably) regions so hugely far away that photons have not had time to reach Earth, and as such are invisible (i.e., beyond the infinite redshift surface if you like sci-fi-like technical terms).\nHowever, as one looks back in time by observing more and more distant... |
[
"Why are Electric and Magnetic Fields Interdependent?"
] | [
false
] | Correct me if I am wrong but to my understanding electric and magnetic fields are interdependent. In that they result from each other. However why are they related and why are they so interdependent? | [
"Well, they're two aspects of a more general thing, the electromagnetic field. One can become the other depending on your reference frame."
] | [
"To expand on this, the electric and magnetic fields are two sides of the same four-dimensional coin. In special relativity there's an object called the ",
" depending on our frame of reference, I.E., where we are and how fast we're going, we see different parts of this tensor as electric and magnetic fields."
] | [
"Without going into the why, when i was doing Physics E&M in college my professor told us to think about it the magnetic field as momentum to the electric fields acceleration. (Or vice versa).",
"Just as momentum resists acceleration, the magnetic field resists changes in the electric field. So when you change ... |
[
"Does pupil constriction only happen when your eye is exposed to light in the visible spectrum?"
] | [
false
] | null | [
"Yes, it only reacts to light, if it is visible, which can be dangerous to your eyes, if you are exposed to strong UV or infrared light sources.\nE.g. people who blow hot glass without protection often get eye problems later in life, due to the infrared exposure. Their pupils don't contract, because in the visible ... | [
"Yes, it only react to visible light, which can be dangerous to your eyes of you are exposed to strong UV or infrared light sources.",
"The most common danger being sunglasses that reduce visible light (so your pupils contract less), but don't have a good UV filter (so you still get almost full UV exposure)."
] | [
"Also why it is very important to use proper solar glasses/film when viewing the sun. Using something that just darkens the sun may not block the intense uv light."
] |
[
"Is there a marked difference in the gut fauna of people who have different lifestyles?"
] | [
false
] | I'm thinking of athletes versus sedentary people, vegans versus meat eaters or vegetarians, people with wildly 'unhealthy' diets or who are alcoholics to give some example. | [
"Yes! There are significant differences. One study shows that obese people have a far less diverse gut ecosystem within them than non-obese people.",
"A common core microbiota between obese individuals and their lean relatives? Evaluation of the predisposition to obesity on the basis of the fecal microflora prof... | [
"The whole field has come a long way since 2009.",
"I believe your conclusion is not wrong, but i think the predominant theory right now is that the lower diversity is not causative. A qPCR study is also not a very good way of making conclusions on diversity. There is tons of sequencing (amplicons and metagenomes... | [
"Actually a study came out in April pointing to the fact that vegans/vegetarians have somewhat different gut flora and that red meat isn't directly contributing to cardiovascular disease, rather it's a bacteria present in the gut of omnivores, which produces a molecule when meatbolizing meat that is. So even when v... |
[
"Why does tiredness bring out the addict in me? It makes me wonder if sleep therapy could be used to treat addiction"
] | [
false
] | null | [
"This sounds related to the study about how self control is a limited resource. Here's a good ",
"synopsis",
", and a more ",
"academic paper",
" about it. I don't think the paper is the same one mentioned in the synopsis, but one of the researchers is the same and the subject they're studying is very simil... | [
"How?"
] | [
"It's the HALT syndrome: Hungry, Angry, Lonely or Tired. These feelings make one vulnerable to addictive behaviors."
] |
[
"Could our solar system ever have been home to a hot Jupiter?"
] | [
false
] | I've heard that hot Jupiters are very common in other solar systems, and some rocky planets may even be the remnant cores of former hot Jupiters. Is there any evidence that our solar system ever had one that was destroyed or whose core is now one of the inner planets? | [
"None of the rocky planets are big enough to be have once been gas giant cores, and there's no evidence of the sort you describe. When we say that hot Jupiters are common, we mean that A, they're not as vanishingly rare as we once predicted; and B, that they're common in observed exoplanet systems, but this is due ... | [
"Thanks for the response! Thanks for pointing out the observation bias. "
] | [
"There's really only one way to get rid of a Jupiter-sized object: eject it from the solar system, or have it fall into the Sun. The gases are too tightly bound to a large planet to be stripped off leaving a core behind.",
"There is some evidence that ",
"the planets have migrated",
" from their initial posi... |
[
"When fission of uranium 235 occurs, what causes so much release of energy? Is it the binding energy being broken or the strong repulsive force of the protons? Or both?"
] | [
false
] | null | [
"The energy released by ",
" nuclear reaction, called the Q-value (which can be positive or negative), depends only on the binding energies of the nuclei in the initial and final states.",
"Coulomb repulsion between protons is one of the contributions to the binding energies of nuclei. It’s a negative contribut... | [
"So we make the atom unstable by creating an imbalance between the two energies when we add the neutron. This makes the atom split into two. The products have less binding energy than the reactants. High state to low state releases energy. ",
"I assume the binding energy in the products is less since the atom is ... | [
"The products have less binding energy than the reactants.",
"For an exothermic reaction, the sum of the binding energies of the products is ",
" than the sum of the binding energies of the reactants. So there's extra energy available in the final state to be carried away as kinetic energy."
] |
[
"Any evil scientists out there? I'm wondering what it would take to stop the earth from orbiting the sun, or stop it from rotating on axis."
] | [
false
] | Say I only had resources to pull off one of them, which would be more devastating to life? Hypothetically speaking, of course. | [
"The earth can't \"stand still\" around the sun. Currently, it's in a stable orbit. If it lost that speed it would fall into the sun. If it gained speed it would escape from the solar system eventually. The kinetic energy of the earth in its orbit around the sun is around 3*10",
" Joule. This is at least 10",
"... | [
"I'm sorry, i still fail to understand why the time or number of loops comes into play.",
"I just re-read your post again, and i still don't understand it. Either i am missing something fundamentally tricky at play, or you somehow fail to understand the concept of actio and reactio, i.e. how opposing impulses of ... | [
"Actually I may have missed something...let me write it out.",
"Inertia of train (i) x angular velocity of train (w)=Inertia of earth (I) x induced angular velocity of earth (W)",
"Yes actually you might be right. I think I calculated how long it would take to miss a day, rather than to stop the day."
] |
[
"If we start mining asteroids...."
] | [
false
] | ... Wouldn't that increase the mass of our planet? Then, wouldn't that eventually increase the gravity of earth and do all kinds of strange things? | [
"I think you underestimate how massive the Earth is. We already are accumulating over 14000 tons of space dust every year on Earth, and have been doing so at least that fast for as long as the Earth has existed. The impact is, practically, nothing.",
"I doubt humans will ever mine enough to make an impact, but th... | [
"The present total mass of the asteroid belt is estimated to be of order 5x10",
" Earth masses.",
"Source",
"So that's about 0.05% of Earth's mass, assuming we brought all of the asteroids to Earth. For the amount of mass that we would actually bring back, that's a fairly negligible amount. "
] | [
"The asteroid belt",
" has a mass of 10",
" kg.",
"Assuming all of this mass was redistributed on to Earth with no waste, the ",
"force of gravity on Earth",
" would not noticeably change."
] |
[
"Let's hear it from the psychologists: Why DO people insist on posting a question in forums and chats instead of reading manuals, FAQs, or wikis, or using a search engine? Even for the most blindingly obvious things?"
] | [
false
] | [deleted] | [
"These people are doing exactly what you have in your posted question. They're trying to get a human response. Just like how a student will learn more from a teacher than a text book, or how single player games vary from multiplayer.",
"The internet is a very lonely place, and reading old forums where someone has... | [
"Everyone here has addressed this point regarding human answers, interaction, etc. I'll look at it from another perspective.",
"r/askscience",
"As someone born with innate curiosity, I think ",
" what other people asked is a beautiful thing. Getting a mundane explanation from someone helps the person who aske... | [
"Isn't this just an example of confirmation bias? For all you know 99.9% of people are happy to get info from existing sources but you don't notice them because they don't leave a trace. The only people you see are the ones that have decided to make a post, no matter how small a fraction of the total they represent... |
[
"Are Cooper pairs in superconductors an example of perpetual motion?"
] | [
false
] | The question says it all, I'm simply wondering why the unimpeded motion of electrons in superconductors wouldn't be an example of perpetual motion, because I imagine that would be... rather silly. All I can find through google are phrases such as "This is the closest known thing to perpetual motion" and so on, which gi... | [
"To add to what you said, it takes energy to keep the system at low temperature. Once you turn off the heat pumping technology, the 'perpetual' motion stops. So you always lose to the second law. "
] | [
"To put it simply ... perpetual motion exists, for it is a law of nature. More specifically, it is Newton's first law of motion: Objects in motion stay in motion (as long as nothing else interacts with that object).",
"Accordingly, it should come as no surprise that it may be possible to have a superconducting ... | [
"Haha, good quote ... I'm gonna have to remember that one. :)"
] |
[
"why do we feel sick to our stomachs when we get nervous/see something disturbing/get scared/upset?"
] | [
false
] | Browsing WTF got to me like never before and I've had a shitty feeling in the pit of my stomach for the last 20 minutes. WHY? | [
"It activates your autonomic nervous system - specifically the sympathetic branch, and activates your \"fight or flight\" response. Voiding and puking are potential outcomes. "
] | [
"I am sad to see these answers are not really thorough (is this ELI5?!), so I'll do my best. It's a very complicated process but this is me trying to break it down to the simplest of actions, so please follow this like a story.",
"There are control centers in the medulla oblongata (the lowest part of our brain) ... | [
"I am not sure Giacomo Rizzolatti would agree with you. Mirror neurons were documented in the ventral premotor cortex (frontal lobe) 20 years ago. There is some indication in recent research that \"mirror neuron\" areas specialized for empathy could be involved in something like this. But ultimately, that nasty fee... |
[
"Why does the Lorentz force act in the direction of the cross product?"
] | [
false
] | In school we have learned that the Lorentz force acts on a moving charge that propagates through a magnetic field. We have also done the calculations with the cross product and gone through its various applications. I do understand the mathematical part of it but when I asked my teacher why exactly this is true, she ne... | [
"Just to start of, the Lorentz force generally refers to the electric ",
" magnetic force. The magnetic force is given by q(v x B), but the electric force is not given in terms of a cross product. ",
"So considering the magnetic force, you could just say that it is an empirical observation, that the force is al... | [
"Electrons are ",
" excitations in the electric field. They are excitations in the electron field. Photons (light) are excitations in the electromagnetic field. As ",
"/u/destiny_functional",
" said the electric and magnetic fields are not really distinct, but part of one electromagnetic field. "
] | [
"the magnetic field is just the part of the electromagnetic field that does this. take a look at the unified notation ( ",
"https://en.m.wikipedia.org/wiki/Lorentz_force",
" ) using the electromagnetic field tensor Fmn. it's antisymmetric, formed from the 4 potential Am via Fmn = dnAm - dmAn, then the space-spa... |
[
"Why does radiation at infrared and microwave wavelengths have such strong heating effects?"
] | [
false
] | [deleted] | [
"A lot of other people here are pointing out things that are tangential to your question. When EM radiation is absorbed by a material, it deposits heat, regardless of whether it is radio, microwave, infrared, visible, x-rays, or gamma rays. The amount that an object heats up depends on the power of the source. I... | [
"Well, there are a few reasons, for microwave radiation, it heats strongly because an awful lot of things contain water. And microwave radiation happens to work very well on water, this is because:",
"What does this mean? Well, as microwave radiation passes through the water it has its own electromagnetic field. ... | [
"I can answer the part about infrared.",
"In a substance above absolute zero, all of the molecules are moving around and vibrating. However, within the molecules, the atoms are also vibrating. The frequency with with two bonded atoms vibrate is related to both of their masses and the strength of the bond. It help... |
[
"Are there seasons in other planets?"
] | [
false
] | I just binge watched Evangelion. The ed (Fly Me to the Moon by Frank Sinatra) had the lyrics “let me see what spring is like on a, Jupiter and Mars” Just a really stupid question from a 17 year old | [
"Some planets have noticeable seasons, others don't. Seasons as we know them are caused by variations in how strong the sunlight is over a large region of the planet. Three ways to create regular variations are axial tilt (angle of the planet's poles towards or away from the star), orbital eccentricity (variation i... | [
"Seasons on earth are dictated by the tilt on the axis and duration of sunlight... (laymen terms)",
"Any planet that has a variation of its positioning on its axis, or tilting away or towards the sun like earth does during summer (depending where in the world you are) technically it will have seasons.",
"Planet... | [
"It is also tidally locked to the Sun, meaning it will always face the same side towards the Sun as it orbits, so it does not even have a day/night cycle.",
"Mercury does not always have one side facing the sun. It is tidally locked, but in a 3:2 ratio of days to years, not 1:1. See ",
"https://en.wikipedia.org... |
[
"Is there a maximum number of antibiotics a microorganism can be resistant to?"
] | [
false
] | I'm aware of some bacteria being resistant to both the first and second line of antibiotic treatment, but is there a limit to how much resistance a bacteria can have? | [
"Probably not. ",
"Bacteria can carry mobile genetic elements (such as plasmids), which are essentially bits of DNA that they can exchange with each other via a process called horizontal gene transfer. These elements can include a wide variety of genes encoding resistance to potentially every class of antibiotics... | [
"You'd fundamentally be limited by the maximum number of plasmids a cell can carry. High-copy vectors like pUC19 can have 1-200 copies in a cell, so that's an upper limit. However, multiple transformations are increasingly unstable, and getting past 5-10 separate plasmids would be a nightmare. The plasmids will st... | [
"Also many cells will only tolerate a single type of plasmid with a specific origin of replication. To have multiple types of plasmids in the cell they will need different origins of replication which will also put a limit on the number of plasmid encoded resistance. You could then just have plasmids integrating in... |
[
"Why do diseases and viruses exist?"
] | [
false
] | [deleted] | [
"Firstly, I just need to clarify the potential ambiguity with the question - bacteria and viruses are two different things.",
"Secondly, there are several reasons why bacteria can cause disease in human. One of the biggest reason being some bacteria are parasites and utilise our body in order to survive. Sometim... | [
"To sum it up, just because there is no evolutionary benefit to other organism, does not mean they are not extremely well suited to survive themselves. This coupled with their extremely fast reproduction rate make for great evolutionary organisms."
] | [
"We are, all of us, genetic mutations.",
"Some organisms cause disease, some don't. Both have found a nice which allowed their ancestors to reproduce. They exist because they can."
] |
[
"What really happens when in a dream we feel touch sensation?"
] | [
false
] | Last night I had a dream where I was touching something metal, and it did feel like I was touching the thing in real life. The texture, the coldness, the "push" felt very real. Now as far as I know, a touch sensation was sent from our fingers and interpreted by our brain. However while dreaming, my fingers didn't reall... | [
"You hear sounds, see colors in dreams, all of which seem just as real. Taste and touch are no different. Your brain actually unhooks itself from commanding your conscious body for a while to go and dream. So it is by itself generating all of the sensations, visions, smells, and tastes that you experience in a dre... | [
"Thanks for the answer. Is there any way for us to tell whether that something we experience is real, or just sensations generated by our brain?"
] | [
"Well you felt it, didn't you?"
] |
[
"How addictive are cigarettes?"
] | [
false
] | I know that sounds like a stupid question, but a few days ago I smoked - for the first time- a few joints with a few friends, which were mostly tobacco. I immediately felt lightheaded (due to the nicotine, I guess), and later I felt some rather pleasant relaxed state of mind (which I attribute to the other ingredient)... | [
"Yeah,they are really addictive. ",
"http://www.drugabuse.gov/publications/research-reports/tobacco-addiction/nicotine-addictive"
] | [
"Indeed, nicotine is more addictive than most addictive substances, even more than heroin, based on percent of people addicted after use. ",
"http://www.nytimes.com/1994/08/02/science/is-nicotine-addictive-it-depends-on-whose-criteria-you-use.html",
"\n",
"http://www.nytimes.com/1987/03/29/magazine/nicotine-h... | [
"There are two components to cigarette addiction. (1) physical addiction to the content of the smoke (mostly nicotine). (2) psychological addiction to the habit of smoking. Smoking gives you something to do with your hands, it is a tool while expressing yourself, it has social context. Also, we are programed b... |
[
"If I eat a 3500 calorie surplus today, how long until 1 pound of fat is produced on my body?"
] | [
false
] | If I go to, say, a buffet and eat my exact daily caloric expenditure plus 3500 kcal (the number, as I understand, of calories equal to 1lb of pure fat), how long until it manifests itself in the form of body fat? Thanks so much for the help! Edit: For some reason people are making conditional statements regarding init... | [
"Hypothetically, the fat would mostly be stored within 4-48 hours of ingestion. The fat gets broken down in the stomach and small intestine, absorbed into the lymphatic system and broken down into free fatty acids, then most are transported around the blood in the form of triglycerides (because lipids aren't water ... | [
"No, that's actually pretty much instantaneous (well, continuous, for as long as you're exercising). Assuming that you're already at maintenance levels (ie you've burnt and consumed the same amount of calories in the past 24 hours), when you start exercising you'll start burning your energy stores. First will be gl... | [
"Does the same 4-48 hour window apply to when I hop on the treadmill and burn the same excess??"
] |
[
"Is there a speed a cell phone can go to not receive wifi or cell signal anymore?"
] | [
false
] | If I am moving at near the speed of will I still get lte? | [
"The frequency bands for both Wi-Fi and LTE are both reasonably narrow, so you will hit a point where the waves for the node you are trying to connect to are red or blue shifted to the point where your device will not be able to communicate on them",
"A long time before you get to that point, you will not be in r... | [
"Looks like high frequency wifi is in 2400-2483.5 MHz band so if you have a large enough red/blue shift to take you outside of this band it seems you should lose signal.",
"So to shift from one end to the other you need a speed of around 0.03c."
] | [
"so about 20.1 million miles per hour. i understand what 0.03c is as a concept but to really wrap my mind around that kind of velocity using terms i'm more familiar with helps."
] |
[
"Why is a lump of coal black, but a diamond is clear?"
] | [
false
] | null | [
"Coal is a sedimentary rock composed of many minerals. Diamond is a mineral composed of a carbon-based crystal structure. If impurities are present in that structure, the clarity of diamond (or any mineral) can be altered. That is why we see varying colors of diamonds.",
"A better question would ask why graphite ... | [
"You're probably thinking \". . .if they're both made of carbon?\" But they're still very different substances. Coal is a mixture of who-knows-how-many different compounds, most of them of very high molecular weight. There are a lot of aromatic rings in there, but it's not an easy mixture to analyze. The key thing ... | [
"To build on the other answers here, visible light is absorbed by electronic transitions in molecules, i.e. by exciting electrons to a higher energy state (vibrational and rotational transitions are too low in energy for visible light, absorbing in the infrared and microwave range respectively). However, the transi... |
[
"Will more stars be visible in the night sky as time goes on?"
] | [
false
] | Basically I'm wondering if eventually the night sky will look like the Hubble deep field picture. (This is assuming the earth will still be here which I know it won't but let's say from a space station or something) | [
"Both. Poster 1 is correct, but looking at the very very distant future. Poster 2 is looking at the (relatively) short term future. Poster 2 is basically saying we still have areas of the universe from which light of stars has not reached us due to distance. However, at a point in the future we will hit a limit as ... | [
"Actually the answer is yes. There are still distant galaxies who's light has yet to reach us on Earth. It's estimated that the number of visible galaxies will increase by a factor of 2.36 before we reach the limit of galaxies that will be in the future observable universe."
] | [
"To the naked eye, the sky should basically stay just as bright until Andromeda and the Milky Way collide and combine into one. New galaxies coming into view as time goes on shouldn't really effect much (at least not for a really long time) since you can't see individual distant galaxies anyways without a really go... |
[
"Do people with autism have an easier or harder time communicating in sign languages, compared to spoken languages?"
] | [
false
] | Many people with autism struggle (more than their neurotypical peers) to interpret facial expressions and body language. Facial expressions/body language is important for communication, but are especially critical for sign language. Do people with autism have more trouble or less trouble with communicating in sign lang... | [
"So, just here to give my two cents. ",
"I am autistic.\nI am not deaf.\nI know minimal sign language (the alphabet and a few other signs)",
"In my opinion, I think sign language would be harder to communicate. It still uses a lot of facial expressions to convey points and because there is no inflections in the... | [
"Similarly interested. Only found ",
"this one article.",
"In preparing for this research, we were alarmed as to the paucity of available literature pertaining to best practices for deaf children with autism in the areas of intervention, education, diagnosis, language acquisition, and general quality of life co... | [
"I'm commenting on this because that is a very interesting question and I'd like to watch the responses.",
"My completely unqualified, in no way educated in the subject matter at hand, totally off the top of my head best guess would be that the autistic individual would have the same difficulties with sign langua... |
[
"Why does the distance from the sun not affect the earth’s seasons but it’s small tilt does?"
] | [
false
] | [deleted] | [
"The tilt of the earth affects how the energy of the sun is absorbed by the ground and water (shallow angles of sun means less watts per given area), as well as the length of the day. During the summer, the sun gets higher in the sky for a longer period of time, imparting much more energy into the ground and water,... | [
"The tilt is 23 deg, so hardly insignificant.",
"The difference due to tilt means the difference between 24hrs of no sun and 24hrs daylight either at the top or bottom of the world and significant temperature variations. At the equator the temperature variation is low. ",
"The range in Earth orbits is from 14... | [
"The tilt and length of daylight accounts for about a 48% difference in energy from the sun, per ground area (depends on latitude). The difference in distance accounts for about 7%. Plus, there is a large buffering effect from the oceans."
] |
[
"Does the sun (and solar system) revolve around a bigger star?"
] | [
false
] | I just finished reading the actual reason for the ban on Copernicus' "De Revolutionibus…" by Catholic authorities in early 1600's and it got me wondering. Also I don't really know if this is a dumb question but I assume all science questions seem dumb to you. | [
"No, the sun [",
"1",
"] revolves around the galactic center [",
"2",
"] of our galaxy, the Milky Way. It takes about 250 million years to get all the way around [",
"3",
"]."
] | [
"The center of our galaxy could also contain a supermassive black hole, so it could also be said that we are revolving around a black hole. "
] | [
"This is not related to the question, but please do not assume such a thing. Science questions are never dumb, unless they are built to specifically push some kind of non-science agenda. If you are genuinely curious about something, your question will never be considered dumb by a true scientist. Anyone who does co... |
[
"Is it safe to simultaneously run dozens of Wi-Fi and Bluetooth devices?"
] | [
false
] | [deleted] | [
"Why does it cause cell damage? The wave is around 10cm, way to big to interact with any cell, right?"
] | [
"Why does it cause cell damage? The wave is around 10cm, way to big to interact with any cell, right?"
] | [
"Water and fats actually vibrate pretty strongly at around 2.4GHz. This causes them to heat up. Microwave ovens emit that frequency of radiation to cook food with, but they are far more powerful (~500W) than what a cell phone emits."
] |
[
"If I'm using a black background for my desktop and browser, am I saving energy?"
] | [
false
] | [deleted] | [
"No. Your LCD monitor has a back-light which illuminates the entire screen and is always on. When you perceive the color black, it is a shutter configured to block the light.",
"This video explains how LCDs work and does it in a very clear way.\n",
"http://www.youtube.com/watch?v=jiejNAUwcQ8",
"However, if t... | [
"For old-style CRT monitor, a black screen saves more energy.",
"For LCD monitors, it depends on what type it is. To display black, some require an applied electric field to disrupt the liquid crystal conformation so it no longer acts as a waveguide. Others have rest state as black. So, ",
"it depends",
".",
... | [
"I don't think we're advanced enough to have a single white led per pixel, and if so, I don't know if that would use less energy vs a light bar.",
"No, but at least some tv's have an array of LED's at the back (as opposed to a line of LEDs on top and bottom) and will dim these individually based on colour content... |
[
"Why do computers take so long to shut down?"
] | [
false
] | After all the programs have finished closing why do operating systems sit on a "shutting down" screen for so long before finally powering down? What's left to do? | [
"Edit: I think there was some mention of trying to redirect these sorts of questions to ",
"/r/AskEngineers",
", as your question doesn't have much to do with science (not even computer science). I don't mind answering, so my answer's below, though.",
"Every process (roughly speaking, every application) is gi... | [
"I think there was some mention of trying to redirect these sorts of questions to ",
"/r/AskEngineers",
", as your question doesn't have much to do with science (not even computer science).",
"The question is about computing, which is one of our fields, and is entirely welcome. Many of our panelists are engin... | [
"Add to this, if you're in an office, that there is probably some kind of file synchronization going on between what you have on your computer, and what's on the network. when you shut down, the system makes sure that all the files are fully synchronized.",
"This might not just be your files, but may also be pr... |
[
"What happens to males and females after they experience an orgasm? (Chemically, in their brains)"
] | [
false
] | I did some light research, and i came up with a few things, but i wanted to ask you guys too, being a direct source - and hey, the more information, the merrier. From what i found, Mens levels of testosterone drops and "both genders experience similar chemical changes" - i was hoping someone here had some more specific... | [
"The \"similar chemical changes\" aren't far from what you might predict. But it's really during orgasm that the brain chemistry really goes off the rails and post-orgasm is mostly recovering from that. Mostly those changes involve a lot of relaxing sorts of things like serotonin and prolactin. Also there are hormo... | [
"I found a Ted talk on this subject. \n",
"https://www.ted.com/talks/mary_roach_10_things_you_didn_t_know_about_orgasm?language=en"
] | [
"Thanks for that post, incredibly interesting and amusing."
] |
[
"If humans evolved to be (relatively) hairless, why do we still grow hair on our heads?"
] | [
false
] | [deleted] | [
"Our ancestors lost their body hair to more effectively cool down through sweating. Since our species walks upright though, the part of the body most exposed to the sun is the top of our heads. It's hypothesized that such thick hair on head was needed as protection from the sun.",
"More on hair loss: Body tempera... | [
"Your hypotheses are doubtful. ",
"Ruxton and Wilkinson make a good case that hair loss is best explained as a ",
"thermoregulatory mechanism",
", and would make early humans better hunters. As mentioned below hair under the arms and around the groin is thought to help retain pheromones and attract mates. ... | [
"Hair also does a good job at protecting the head from the sun."
] |
[
"What causes the tiny jerk when a car comes to a complete halt?"
] | [
false
] | Whenever cars come to a complete halt, it is always noticed that the passenger will feel a force forwards for about 95% of the deceleration time, even when the vehicle is at crawling speed. Suddenly the vehicle will jerk backwards to a halt. I understand the basic ideas of fictitious force in the decelerating frame of ... | [
"TL;DR: The jerk is the release of energy from the compression of the car's suspension. See the video below.",
"The car 'leans' forward as you brake because the wheels are forcing the car to slow down, while the rest of the car still has momentum forward. That lean builds up potential energy in certain parts of t... | [
"Something similar happens in spacecraft. If you watch the launch sequence in Apollo 13, which is quite accurate, you'll notice that just after the main engines cut out the astronauts seem to be jerked toward the front of their seats just before being pushed back into their seats by the 2nd stage lighting. This is ... | [
"Most modern cars have ABS (anti-lock brakes) so that situation (kinetic locking to static) is specifically designed against. Also, it makes sense that you wouldn't want a large difference between the kinetic and static friction coefficients, though I wasn't able to dig up a source ",
"past this mention on wikipe... |
[
"Does the heat of a concentrated spot of sun increase exponentially with the size of the magnifying glass used to focus it? Does magnifying power make a difference?"
] | [
false
] | null | [
"It increases exactly with the area of the lens. As long as everything else is equal, a circular lens with twice the horizontal (perpendicular to the direction of the light) area with have double the power of the original, because it gathers double the amount of light. "
] | [
"Thanks! I'm looking for a good fresnel lens and wasn't sure how to estimate the power I could get from one versus another, but that's very helpful. Do you know anything about how to actually calculate it?"
] | [
"That is exactly correct. Think about it this way, you have the same amount of sunlight hitting everything and all of the light that hits the lens gets focused to a single point. Therefore the amount of energy (proportional to the amount of light) is directly proportional to the area of the lens. The caveat to this... |
[
"What is the difference between Hox Genes, Regulatory Genes and Gene Switches?"
] | [
false
] | I am having difficulty differentiating the three. Are Hox Genes and Gene Switches both Regulatory Genes or are they something different? My sources don't specify clearly enough. | [
"Hox is short for homeobox genes, which are a set of genes involved in limb formation and creating the embryonic body plan of many animals. Many hox genes are regulatory genes, which just means that they are genes whose products (mRNA and proteins) increase or decrease the expression level of other genes. Gene swit... | [
"The terminology is unfortunately confusing and one needs to be careful. Although Hox genes contain and are originally named because of the homeobox sequence, not all homeobox-containing genes are Hox genes (other examples include the POU genes and CDX genes). The homeobox encodes for a protein sequence called the ... | [
"I want to point out that, as far as I can remember, the phrase \"gene switch\" isn't used in technical literature. I suspect it may have been used when transcriptional regulation in the lac operon was first discovered, and may hold over in textbooks, but has otherwise been replaced with more precise terms like pro... |
[
"Could we land a probe in the polar region of Venus?"
] | [
false
] | The Venus express showed that surface temps near the poles are actually quite cold. If we built a probe to handle the pressure and acid rain, could we land it in a relatively hospitable location temperature-wise and have it last? | [
"I think you might be confusing the Venus Express science results here.",
"What the spacecraft recently found was that ",
"the ",
" above the pole",
" was colder than expected. If you look at a ",
"map of ",
" temperatures",
" near the pole also collected by Venus Express, you'll find that it's still ... | [
"No, it's actually quite cold in the upper atmosphere of Venus. We expected it to be somewhere around -90C (-130F), but instead measured it as -157C (-250F)."
] | [
"The most cited model upper atmosphere would probably be VIRA, the Venus International Reference Atmosphere (",
"Keating, et al, 1985",
"). It's based on Pioneer Venus and various Venera spacecraft measurements as a starting point for the thermal component, and includes observations of night-glow emission for t... |
[
"When you're eating or drinking and it \"goes down the wrong pipe\", does it end up in your lungs?"
] | [
false
] | null | [
"Hi, I'm an anesthesiologist and I answered this question ",
"here",
" about a month ago. Check it out if you like.",
"It kind of blew up and lots of people asked follow-up questions. My proudest moment as a Redditor!"
] | [
"It depends on the size of the bite. If it's big, it will stay lodged in the throat - in the trachea, for example. This is where the Heimlich maneuver might help. If it's smaller, it will travel further down, to one on the bronchi (usually the right one), or even further down, if it's still smaller. This can lead t... | [
"People with repeated aspiration pneumonitis/pneumonias can end up with chronic scarring in the lungs. It is a risk factor for bronchiectasis and can mimic some kinds of pulmonary fibrosis. I've pinned several cases of severe lung disease to chronic aspiration. ",
"That said, in nonsmokers and those with otherwis... |
[
"Is it a coincidence that two of the monoliths in Monument Valley have the same superficial 'mitten' structure', or does this reveal a systematic geological process leading to formation of such structures?"
] | [
false
] | null | [
"Cool question. No, I think it's not a coincidence, in that similar geology and weathering patterns made it possible for the \"mitten\" structure to occur more than once in Monument Valley.",
"One important thing to know to understand the mittens is that they are actually long and skinny, even though you might th... | [
"The monoliths I think he is referring to are pictured here:",
"Clicky - \n",
"Monument Valley Mittens",
" ",
"Pastey -\n",
"https://pixabay.com/en/monument-valley-arizona-monoliths-798063/"
] | [
"This is correct.",
"We humans love to create patterns for things in nature. We see \"mittens\" formed from normal geologic weathering. ",
"When you actualy visit these places and hike around a bit you'll notice that these landmarks don't really resemble mittens (or whatever else they may be named after) from ... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.