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Monday, February 8, 2016

Why does a hair come back if I pull it out by the root? What's causing my body to say, "Oh, I remember there used to be a hair there, better regrow one."

Why does a hair come back if I pull it out by the root? What's causing my body to say, "Oh, I remember there used to be a hair there, better regrow one."

Why does a hair come back if I pull it out by the root? What's causing my body to say, "Oh, I remember there used to be a hair there, better regrow one."

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How can gravity be both a curvature in space time and a boson-carried force?

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The phrase 'dimensions' is used in science fiction all the time as another plane of existence; what does theoretical physics say about dimensions and whether they exist or in what terms the word 'dimension' is used for in science?

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Hopefully apart from length, width, and height.

submitted by /u/saddetective87
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How was avogadro's number initially calculated? How is it calculated now?

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What's happening when people get in a "zone" and suddenly become more productive or successful at repeated tasks? Like when a basketball player starts making a bunch of shots in a row. Is this a skill that can be learned?

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Are eyelid muscles flexing when they are open or when they are closed?

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During the day my eyelids are constantly opened, but at night they're constantly closed. Are the muscles controlling the eye lids constantly flexing all day to stay open or are are they constantly flexing all night to stay closed?

submitted by /u/Jaredlong
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Is it possible to describe knots using mathematical functions?

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[Physics] How is temperature measured or defined in a vacuum?

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Temperature is the average kinetic energy of atoms vibrating and whatnot so what is the temperature in a vacuum where there is no matter? Along this same line, would something cool in a vacuum if there is no matter to "absorb" its thermal energy?

submitted by /u/Mario_Naharis
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If water from a lake continuously flows into a river and then flows into the sea, why doesn't the lake get out of water?

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In a typical substance (lead for instance), how far apart are atoms relative to their size?

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What would a helium-filled balloon do in space?

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I can't wrap my head around what would happen, because in space there is no "up" for a helium balloon to go to, so what would happen?

submitted by /u/imnotquitedeadyet
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Is it possible for sea water to empty into the undersea oil wells that we are draining?

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I was on /r/mapporn and I read this comment talking of how if all the ice melted, and the sea level increased, the seawater could be diverted into the soon-to-be empty oil wells. If it was possible, how much sea level would it be able to lower?

submitted by /u/jesuisunnomade
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Why do antibiotics cause rapid growth in animals?

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I read recently that antibiotics are given to farm animals to make them grow bigger, faster.

Some people didn't believe me, so I looked it up again and confirmed it.

What's happening in these situations?

submitted by /u/SarahC
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What actually are the 'impurities' that allow flux tubes to penetrate superconductors, achieving Flux Pinning?

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I was curious about the process of Flux Pinning, and found that thin flux tubes from a magnetic field actually penetrate the superconductor itself, locking it in place, almost. However, I couldn't find any information on how or what these impurities are or come to be. Are they just small holes?

I'm not sure if this is too mundane a question to answer, but I find the whole subject of Flux Pinning fascinating.

I'm a Physics (British definition of) college student, so I'm essentially a layman, haha.

Thanks a lot.

submitted by /u/SickleSandwich
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Zika virus has been known about for 70 years, why is it only now a big issues? Has it always caused microcephaly, or is this new?

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[Physics]How is there a kinetic energy difference of accelerated objects of different mass?

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Let's say I push a trolley that weighs 1 kg with a force of 10 N for one second. According to F=m*a the trolley will accelerate to a speed of 10 m/s. Let's say I do the exact same but with a trolley that weighs 10 kg, it will accelerate to a speed of 1 m/s.

The kinetic energy of the two trolleys are E = ( 1 / 2 ) * ( 1 ) * ( 102 ) = 50 J and E = ( 1 / 2 ) * ( 10 ) * ( 12 ) = 5J.

If the applied force is the same, where does the 45J difference go? Does it take more energy to apply the same amount of force to a lighter object? That's the only thing I can think of but it doesn't seem right.

EDIT: Formatting.

submitted by /u/Sharproundedges
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Why are the Navier-Stokes equations called "the Navier-Stokes equations" instead of just "conservation equations"?

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I've been taking a CFD course and learning about the Navier-Stokes equations and something that I don't understand is this: why are the NS equations called the NS equations? Because every time the professor or a book or a paper introduces the NS equations, they always make it a point to point out that one equation represents the conservation of momentum, another represents the conservation of mass, and the final one represents the conservation of energy (which for my purposes has always been neglected). If the NS equations are simply the conservation of mass and momentum, then why don't we call them simply the conservation of mass and momentum, or even more simply Newton's laws?

submitted by /u/via_beering
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Wet lab glassware terminology help. What is it?

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Hi. I have found some glassware from a decommissioned laboratory and I'm curious what it is and a possible use for it.

Please tell me at least what it's called so I can google the information. Thank you.

Pictures

submitted by /u/vernimili
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How can this drink have 8 grams of carbs, but also 0 calories?

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http://imgur.com/WPnAmoi

What kind of carbohydrate can't be turned into energy?

submitted by /u/seanpadraic
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Sunday, February 7, 2016

Why are antennas a half wavelength?

Why are antennas a half wavelength?

Why are antennas a half wavelength?

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What would happen if it was a wavelength instead of half?

submitted by /u/HornySkeleton
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In the early 20th century, when ads for cigarettes were claiming their products were "supported by doctors," was there actual scientific evidence (biased or unbiased) that doctors used to make these claims at that time?

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I know it was fairly popular for even the doctor to smoke. I wonder if any of them that did actually based their choices on evidence of the time thinking they were making a sound decision.

submitted by /u/Whitytighty1
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Which 6 of the 16 Einstein field equations are duplicates, and why?

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This video around 12 minutes in explains that the Einstein field equation contains two indices, each of which can take one of four values (0,1,2,3 for t,x,y,z), which means one equation is really 16. Six of these equations are purportedly "duplicates." Which are they, and why?

submitted by /u/ktool
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Why do acetylation and methylation have their respective effects on DNA?

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Is there a simple concept behind this. I have trouble remembering which does which, and so knowing why it happens will help.

Thanks

submitted by /u/gorightthroughformsu
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How is soil perchlorate concentration affected with depth on Mars?

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In other words, can one dig a bit deeper beneath the martian top soil and find soil with a lower perchlorate concentration (for human use)?

If not, what would be the most efficient way of neutralizing these perchlorates while conserving water?

submitted by /u/6ixer
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Common sense tells me nuclear fusion and nuclear fission are mutually exclusive as a means of creating energy. Yet I know that stars make energy by fusing elements, and that our nuclear reactors exploit nuclear fission. How is it possible that both create energy?

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What is the smallest object that we have been able to observe the gravity of?

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What effect, if any, did the huge losses of life in WWII have upon the genetic health of the war torn populations?

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If a sphere's infinite amount of points were expanded from the center of the sphere(like a balloon) would there be gaps in between the points?

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Like if you marked every point on a sphere and each mark grew a straight "hair" away from the center would the sphere become hairy?

submitted by /u/oreNoWasuremono
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How fast would two Earth size planets have to be moving to orbit each other 100 miles apart?

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Does the gravity of the spinning earth drag satellites with it?

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Today I heard a space podcast talking about different orbital routes and saying that the "polar route", a circle which crosses north and southpole, is good because you can scan the whole earth while it is spinning under the satellite.

I heard that the earth drags the spacetime into some sort of spiral because it's rotating, so my question is: How big is the effect of this "space time wraping" on satellites?

submitted by /u/Simyala
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What is the difference between hydrogen and anti hydrogen?

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How do they vary chemically? Can I drink anti water without it affecting me?

submitted by /u/DementedDeutron
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Are there any (hypothetical) puzzles that can only be solved when moving parts of the puzzle at relativistic speeds?

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Does it make sense to speak of "liquid diamond?"

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I came across a topic here that mentioned liquid diamond for the sake of argument, and it struck me as odd. Doesn't the rigid structure of the carbon atoms determine the diamond allotrope of carbon? But indeed I quickly found reputable sources that mention it. How is this possible? What would it's properties be?

submitted by /u/sagan_drinks_cosmos
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Are there instances when an infection with one pathogen 'miraculously' cures another pathology or condition within the same patient?

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I feel as though I've heard anecdotal evidence that patient X had, for example, a pathology (acquired or intrinsic) and after becoming infected with another illness found their other malady disappeared. Any validity to this or evidenced-based studies you are aware of?

submitted by /u/Smad3
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Does quantum mechanics describe electricity?

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In quantum theory electrons move through two slits in a wave like fashion so does it makes sense that electricity jumps around to static points, not a wave. Like lighting. Further more, am I right in understanding that quantum theory explains the colours we see? ROYGBIV./

submitted by /u/xMordethx
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How will we service the James Webb telescope if needed?

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Is there any relationship between an organism's number of chromosomes and it's complexity or features?

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I was reading the Wikipedia article on humans and learned that all the other apes have 24 rather than 23 chromosomes. This made me interested in how many chromosomes other species have, and the list I found seems to be all over the place. Daisies have 2, rice has 24, hegehogs have a few hundred, a lot of mammals seem to have around 40, what exactly is going on here? I don't see any kind of pattern aside from the difference between hominids with 24 and 23 chromosomes. Plants, mammals, birds, and insects all seem to have all sorts of chromosome counts, so what's the deal here?

Why is there such a massive diversity of chromosomal numbers? Why do things with such different numbers of chromosomes look so similar? Why does it take 24 chromosomes to make rice but only 2 to make daisies? Is rice incredibly compliated? Inefficiently structured? Is a lot of it just redundant junk?

I have to say I'm absolutely mystified. This is something I'd never given the slightest thought to in the past but it seems significant.

submitted by /u/aidrocsid
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Is the density of the water at the bottom of the ocean lower than the water at the surface?

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If the rumor of gravitational waves is confirmed, would it be evidence of gravitons?

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I know it's not complete evidence, but it seems like now we can start to identify some properties of gravitons

submitted by /u/darkconfidantislife
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Saturday, February 6, 2016

Are neutrinos and antineutrinos identical?

Are neutrinos and antineutrinos identical?

Are neutrinos and antineutrinos identical?

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If neutrinos carry no charge, and an antiparticle is simply the opposite charge, are neutrinos identical to antineutrinos? Do they behave and interact differently in any ways?

submitted by /u/RobMu
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When a diverging lens is placed in a material with a higher index of refraction than the lens's material, does it behave like a converging lens?

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Say a glass diverging lens is placed in liquid diamond and an observer inside the medium looks through the lens. Is it like looking through a converging lens now?

submitted by /u/arthitmitc
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If I were to drink something that is usually injected (morphine, heroin etc.) would the effects be the same as if I were to inject them? If not, why?

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Is it true that a shooter absorbs an equal amount of force into his body as is being projected in the bullet?

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When did people realize that stars don't last forever?

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I've tried to google the answer, but I couldn't find anything. I know that people understood that the sun works by nuclear fusion in 1929 or so. Before then about 100 years earlier, they had an idea that our sun is made out hydrogen and helium, but I guess they didn't understand how it worked.

I am asking this because I found a poem published in 1881 that talks about the Big Bang, the extinction of all stars, and ultimately the heath death of the universe. All those things were discovered 50-100 years later.

submitted by /u/covor
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What will happen to a photon travelling through space and never hitting anything?

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Does a photon ever decay if it doesnt get absorbed?

submitted by /u/christroflobal
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When in a dark environment, why does objects which you are looking at directly appear darker and harder to see, but objects which you see at the corner of your eye or in the peripheral vision appear brighter?

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Do Animals Have A Sense of Rhythm?

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Do animals perceive a beat or a rhythm the same way humans do? Can they react to it or move to it perhaps?

submitted by /u/karmaniak
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Bought a helium balloon today, went outside in the cold, what happened?

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got a helium balloon for my 3yo son. it was warm inside the store, outside it's pretty damned cold, freezing or below.

inside the balloon was firm, like it was fully inflated. in the less than 30 seconds walking to the car, it had lots of slack in the balloon itself like it had lost around 30% or so of it's helium volume. once inside the car, the balloon firmed back up like it had been fully inflated. what occurred?

submitted by /u/KorranHalcyon
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Does air temperature and humidity affect the propagation of sound waves?

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I am not only referring to its speed, but also to its dispersion and attenuation, e.g. I feel that sounds seem more 'crisp' and travel further during the cold and dry winter months.

submitted by /u/giantsqueed
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When integrating real functions, we're basically getting an area under the function. Is there a similar analogy for complex integration?

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I'm a student, currently 2nd year of physics. We're doing complex integration and I just can't grasp visually what we're actually doing. Is there a comparison with surfaces under real functions, or is it something completely different where I should just deal with the fact that I need to look for residues and integrate over closed surfaces?

submitted by /u/Elemelond
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I have a ball. What is the least amount of information I need to give you about the ball in order to determine the mass of the sun?

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Using current technology and materials, what is the tallest entirely habitable structure we could build?

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Is the Peach-Koehler-Force the same for a edge dislocations and a screw dislocation?

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My Burgers vector is b=(b,0,0), the edge dislocation is ds=(0,ds,0) and the screw dislocation is ds=(ds,0,0).

When I try to work it out with dK=[σb x ds] (where σ is the symmetric stress tensor) I get

dK=(σ_zx * b * ds, 0 , -σ_xx * b * ds) for the edge dislocation and

dK=(0 , σ_zx * b * ds, -σ_yx * b * ds) for the screw dislocation.

My textbook says that those two are equal but offers no explanation and I can´t see why those two should be equal.

submitted by /u/Uniacc1234
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Does having a small head make you less intelligent?

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Do people with a small head (like myself) have a lower amount of intelligence?

submitted by /u/Saikawa_Sohei
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How do we know what sounds hieroglyphs make?

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Might not be directly ''sciency'' but didnt know where else to ask.

How do we know for example that the word Nefer, wich is egiptian for Good sounds like nefer?

Dont know if im expressing myself correctly, but imagining that in 1000 years, someone found our alphabet, they would have no way of knowing what sound the letter A does right? Assuming no one who knows the language is left

submitted by /u/Guillz
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