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Sunday, May 21, 2017

What would happen if the Earth's oceans were replaced with fresh water?

What would happen if the Earth's oceans were replaced with fresh water?


What would happen if the Earth's oceans were replaced with fresh water?

Posted: 20 May 2017 06:27 PM PDT

What does it feel like walking in areas with high radiation? Does it feel hot or something? Does it smell? Harder to breathe? Or is the only way you will figure it out (w/out a Geiger meter) is when you start to get sick?

Posted: 21 May 2017 05:55 AM PDT

EDIT: Sorry for the wrong flair. Not a science guy so I just kind of associated the elements involved with chemistry

submitted by /u/FangFingersss
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What happens to the gas inside a car's tires when it starts moving, while it's going, and when it stops after already moving? Does it stay stationary, or spin with the tire?

Posted: 20 May 2017 04:04 PM PDT

Does our atmosphere always stay a constant shape around Earth?

Posted: 20 May 2017 02:57 PM PDT

Or would it act like the water around the towel in this experiment done on the ISS by Chris Hadfield

submitted by /u/tehdubbs
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[Physics] If there are no states for an electron to occupy between conduction and valence bands, then what is the Fermi Level if it lies between the conduction and valence bands ?

Posted: 21 May 2017 03:23 AM PDT

[medicine] how come you can't just cut off a wart?

Posted: 20 May 2017 04:30 PM PDT

Which would be the problem of a supercritical helium turbine?

Posted: 21 May 2017 03:18 AM PDT

I was looking about molten salt reactors, the 3 of them sodium, fluoride and chloride salt reactors and, i did seen that in many reactor designs there's the reactor liquid fuel internal circuit, and a second circuit which exchanges heat with the primary salt, and then goes to a water heat exhanger that makes the turbine spin, thinked in deleting the intermediate circuit and send water directly to the reactor vessel with a heat exchanger. But then there's the problem of the reactions the sodium and water at those temperatures can make so i thinked why not changing water to helium at very high pressure? Is an inert gas, isn't flamable, and i think it doesn't react with salts

Which would be the pressures to mantain a supercritical or ultrasupercritical helium state at 500ºC? I would get problems trying to condesing it to delviering it to the reactor again?

submitted by /u/Comunismo_videlista
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Where does the number e come from?

Posted: 20 May 2017 02:27 PM PDT

By whom, how and when was it discovered and proved?

submitted by /u/MeatyOs
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Is there a limit to the density of matter?

Posted: 20 May 2017 04:36 PM PDT

For instance in a super massive black hole the density is greater than the density of the sun.

submitted by /u/Itrusteverything
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Efimov physics: could someone explain the significance?

Posted: 20 May 2017 09:59 PM PDT

I stumble on an article about the Efimov Effect. There were only a couple of posts on reddit about it and most of the comments were deleted.

I'm a lay person (ie. don't have a degree in physics) and was hoping someone might be able to explain why pairing three bosons is such a breakthrough. I've searched everywhere for an answer, but couldn't find anything that explained the potential applicability of this or how this alters the classical view of physics.

Is it just that it suggest things work differently at the quantum level than we think?

Thanks!

submitted by /u/joekerr37
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How can you tell if a solid ball of substance is uniformly dense?

Posted: 20 May 2017 07:47 PM PDT

Supposing that any places of lesser density are exactly centered within it, like a perfectly spherical truffle with perfectly spherical chocolate filling, and assuming you don't know what material it is so you can't just try displacement.

submitted by /u/PistachiNO
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Why is Vaseline, a petroleum derived product, good for your skin? Aren't petroleum and plastics bad for your body?

Posted: 20 May 2017 05:26 PM PDT

what is the strange pendulum effect called?

Posted: 21 May 2017 02:56 AM PDT

https://www.youtube.com/watch?v=dDU2JsgLpm4

what is the term for the effect where the sections start and continue to work independantly of each other?

submitted by /u/MattBlackG
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Can a known file be used to crack encryption?

Posted: 20 May 2017 05:45 PM PDT

With the "locker" viruses spreading around lately, I was wondering if having file with well known content, possibly very large, could be used to determine the code used to encrypt that file. TIA

submitted by /u/bobroberts1954
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[Geology][Physics] If we were to drill a hole that reached the core of Earth, what would happen?

Posted: 20 May 2017 04:15 PM PDT

Akin to electric field, does gravitational field store energy too?

Posted: 20 May 2017 02:30 PM PDT

How do LCD dispays work?

Posted: 20 May 2017 04:40 PM PDT

Is it true that one pound of body fat is equivalent to 3,500 calories?

Posted: 20 May 2017 03:57 PM PDT

How does rust affect a chrome spring?

Posted: 20 May 2017 11:19 AM PDT

I bought a grip strength trainer which uses (chrome) springs for resistance. It was secondhand and the springs are partially rusty inside: Picture

Does this weaken the springs and make them more prone to breaking or do I not have to worry about it as long as I get the rust off? I'm gonna put a lot of stress on them over time so I want to be sure here - if there's some concern, I'm going to send it back.

submitted by /u/Mithridates12
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When looking for test subjects for medicines they often ask for non-smokers. Don't they need to test how the drugs affect smokers?

Posted: 20 May 2017 07:07 AM PDT

Saturday, May 20, 2017

In as simple a way as possible, how are we able to tell the elementary make up of a planet using only a telescope?

In as simple a way as possible, how are we able to tell the elementary make up of a planet using only a telescope?


In as simple a way as possible, how are we able to tell the elementary make up of a planet using only a telescope?

Posted: 20 May 2017 05:19 AM PDT

Just reading a story about how scientists used the Hubble telescope to view HAT-P-26b, s planet 440 light years away. They saw "distinct signatures of water in its atmosphere" and "found fewer heavy elements than they had expected". How can you do this using only a telescope?

submitted by /u/nrthrn_pwrhs
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In T-S or P-V diagrams often there is a number with an s next to it e.g. (5s connected with dashed lines with 4). What is the meaning of that 5s point and what is different from the regular 5?

Posted: 20 May 2017 04:53 AM PDT

Apparently, for Conservation of Energy to be true, time translation symmetry must hold. However, does it really hold in an expanding universe?

Posted: 20 May 2017 12:49 AM PDT

On a relevant note: if we ever find out that the symmetry does not hold, and you can generate infinite energy, would it also invalidate the law that entropy always increases, thus freeing us of the danger of Heat Death, a la The Last Question?

submitted by /u/thetimujin
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They say that a photon takes a million years to make it out of the Sun. But what does it even mean? How do we define that a particular photon now is the "same" photon that was there then?

Posted: 20 May 2017 01:56 AM PDT

When I'm doing photons-in-a-box problem with large enough number of photons, and I add a photon in, and later I let a photon out, there isn't really a sense in which I can say which one of the photons got out, any more that when I add 1+1=2, and then subtract 2-1=1, can I tell which one did I subtract (quite literally, this is how Fourier transform seems to work). They just blend into one wave until I decide to unblend them.

I'm imagining the interior of the Sun to be a giant soup of photons, constantly absorbed, reemitted, bouncing around. Sometimes new photons are created by fusion, and sometimes some photons get out into the interstellar space, but how do we "track" them?

submitted by /u/thetimujin
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When you squint really hard, why do you hear a rushing wind like sound?

Posted: 19 May 2017 03:44 PM PDT

Can you tell a sunrise from a sunset just from looking at a photograph?

Posted: 19 May 2017 06:39 PM PDT

As a star begins to die, what are the effects on orbiting planets before the supernova?

Posted: 19 May 2017 09:52 PM PDT

Say an Earth-like planet (read: Earth) is orbiting a star of 1 solar mass that is nearing it's death. At what point does life on this planet cease to exist (read: no longer habitable)? What exactly happens to scour all possibilities of survival? Or would all be well and good until the supernova begins?

submitted by /u/Sigral
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If I yawn while listening to music, there is a significant noticeable increase in my perception of the speed of the music. Why is this?

Posted: 19 May 2017 04:48 PM PDT

This happens every time, regardless of how tired I am, I use headphones when I listen to music, if I'm moving my head to the beat or something, that keeps in time with the music and I perceive my movement as happening faster too. The increase is between about 20-50%, it varies but it's always a significant difference.

submitted by /u/ScornMuffins
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How do we get high frequency (of few GHz) in electronic circuits ?

Posted: 19 May 2017 06:55 PM PDT

I know about crystal oscillators, that can make frequencies up to 100 MHz and about PLLs, Schmitt-triggered inverters and stuff like that. But I couldn't find a good explanation and put this together to figure out where all does high freqs come from. I guessed it has to do with all the before mentioned concepts, so I would like to clear it out.

submitted by /u/sekirce3
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If you're constantly growing and shedding skin cells, how come your freckles don't disappear/you don't grow new freckles?

Posted: 20 May 2017 04:03 AM PDT

So it's my (possibly inaccurate) understanding that freckles are a result of a certain cluster of cells producing more melanin and appearing darker than the rest of your skin cells. So wouldn't you eventually shed all the dark cells that composed a freckle, or new cells that you produced could mutate to be darker?

As someone who has had the same trademark nose freckle all their life, I know this to be untrue, but why???

submitted by /u/jellybones01
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Why will a RH- mother with a RH+ fetus will have issues, and not a RH- fetus and a RH+ mother?

Posted: 19 May 2017 04:22 PM PDT

Their blood mixes together, so can't the fetus create antibodies for the mother's foreign blood?

submitted by /u/tommyzat
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If I have a description of a time-symmetric continous system (say, a set of random differential equations or a cellular automaton or something), how exactly would I get a formula for the conserved quantity as per Noether's Theorem?

Posted: 19 May 2017 11:12 PM PDT

Why isn't there a 50% chance for 3 flipped coins to all land on the same side?

Posted: 19 May 2017 05:01 PM PDT

I know this might seem like a dumb question, but here's my logic;

'When you flip 3 coins, at least 2 of them are guaranteed to land on the same side, so surely the other coin has a 50% chance of landing on the same side as the other two.'

Now, we can tell from flipping 3 coins several times, that this is probably an incorrect assumption. What I want know is, what is the error in my logic?

submitted by /u/smearglexd
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If it were possible to stably break an atom apart into its fundamental parts, could we hypothetically put the existing particles back together into new atoms?

Posted: 19 May 2017 09:38 AM PDT

For example, take Helium 4 with 2 protons and 2 neutrons. If we broke that apart into its individual components, could we piece it back together into 2 atoms of deuterium?

submitted by /u/Topicu
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If I attempted to hang myself from the ceiling of an elevator using a belt and it began to free-fall ... would there be slack in the belt?

Posted: 19 May 2017 11:39 AM PDT

Can you get better at working with less sleep by training/practicing? i.e. Is there any long term adaptation to chronic sleep restriction?

Posted: 19 May 2017 07:16 AM PDT

Obviously, mental and physical performance will decline during the first few days of sleep restriction. Eventually, presumably after a few weeks, performance will cease to decline and stabilize at a minimum.

The key question is: if you sustain this sleep restriction for a longer period of time (months to years), will performance ever increase above this minimum? and by how much? Is it possible to regain baseline performance if you limit sleep restriction to a small level?

So for example, if you reduced your sleep time from a normal 8 hours to 7 hours for a period of a year, can you regain the same mental performance as before? If you go from 8 to 5 hours, can you perform as if you've only lost an hour of sleep?

Effectively, you would be practicing working in a sleep deprived state, presumably adapting your mind and body in the hope of reducing or eliminating the effects of sleep restriction.

submitted by /u/elsjpq
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[Quantum Mechanics] Don't wave functions that can't be normalized contradict the possibility of an infinite universe?

Posted: 19 May 2017 12:31 PM PDT

The simplest case is a constant potential. We get that the wave function is proportional to exp[ikx] (and exp[-ikx]), so the square of its absolute value is constant, i.e. uniform distribution. But a uniform distribution is impossible in an infinite universe, as it can't be normalized. Doesn't that contradict an infinite universe?

submitted by /u/yarinch
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Is it possible to be shocked by an organisms spinal cord?

Posted: 19 May 2017 11:45 AM PDT

I was talking to my dad earlier and he told me that one time he caught a catfish and gutted it, etc. Eventually, he grabbed its spinal cord and was shocked. I'm assuming this has everything to do with the nervous system of the fish but not exactly sure how it would shock my dad?

submitted by /u/StudentBill
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Could 90-proof (95% ABV) Ethanol dissolve plastic?

Posted: 19 May 2017 10:25 PM PDT

If so how long would it take to dissolve threw a plastic bottle?

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Friday, May 19, 2017

If each day is only 23h56m4s, over the course of 4 years, we accumulate 95.7 hours of unaccounted time when approximating each day to 24 hours. We give ourselves one extra day in February, which accounts for only 24 hours of that extra time, but where does that extra 71.7 hours go?

If each day is only 23h56m4s, over the course of 4 years, we accumulate 95.7 hours of unaccounted time when approximating each day to 24 hours. We give ourselves one extra day in February, which accounts for only 24 hours of that extra time, but where does that extra 71.7 hours go?


If each day is only 23h56m4s, over the course of 4 years, we accumulate 95.7 hours of unaccounted time when approximating each day to 24 hours. We give ourselves one extra day in February, which accounts for only 24 hours of that extra time, but where does that extra 71.7 hours go?

Posted: 19 May 2017 07:01 AM PDT

This also means that our calendar should shift over 3 days every 4 years, changing the "location" of the seasons in our man made calendar

submitted by /u/fornoggg
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Why are the physical electromagnetic fields only the real part of E and B?

Posted: 19 May 2017 02:16 AM PDT

This says that the physical fields are only the real part of E and B, but this is not obvious to me.

Since

eix = cos(x) + i sin(x)

We get an imaginary part of the fields in the picture, but somehow these aren't actually a part of the fields, or how should i interpret i?

submitted by /u/Physix_R_Cool
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Is the earth still cooling from its formation? If so, does that mean eventually all tectonic activity will cease and our liquid mantle will solidify?

Posted: 18 May 2017 08:01 AM PDT

What's the max signal frequency on a DSL wire?

Posted: 19 May 2017 03:44 AM PDT

Edit: OK, I'll try to rephrase, because the DSL apparently has complex techniques for multiplexing & reducing echo & transmission errors..

Let's assume the simplest case, an analogue signal carrying a digital signal in a wire. What's the minimum frequency of the analogue signal that can carry a bandwidth of x Kbps?


Original question: So the telco is saying that my copper wire can provide up to about 35Mbps of DSL connection speed. Does this mean that the carrier signal in the wire is at 35MHz, a little higher, or double of that? Why?

submitted by /u/KRBT
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What is the cause of diffusion and osmosis? How does it work?

Posted: 19 May 2017 05:13 AM PDT

I know the general gist of how diffusion/osmosis works, I just don't know why it works like it works.

submitted by /u/PersonalComputerG
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How do dogs make ATP?

Posted: 19 May 2017 07:10 AM PDT

Every being needs energy. Animals cells make ATP from sugar and oxygen. So where do dogs (and other meat eaters) get sugar from if they eat exceedingly meat.

submitted by /u/LeonardoM011
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Why is silver chloride so insoluble?

Posted: 19 May 2017 04:02 AM PDT

My guess is that the sizes of the silver and chloride ions are just right so the crystal is very stable and thermodynamically favoured over free ions?

submitted by /u/nicktohzyu
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What causes you to remember dreams?

Posted: 18 May 2017 07:20 PM PDT

Having a conversation with the boyfriend just before, we both dont remember alot of our dreams, However almost every night this week both of us have have had weird dreams that we remember the next day, Very unusual for us. Is it something we have eaten? Lack of sleep? Too much sleep? Chemicals in the body that are being produced? Please shed some light on this, this is weird and unusual, im spending half of my day trying to wrap my head around weird ass dreams!

submitted by /u/zoeysheree1993
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Since everything with mass has a gravitational pull, does this mean that Pluto has a pull on me currently?

Posted: 18 May 2017 07:12 PM PDT

To be more specific, I know everything that has mass has a gravitational pull, even atoms. I wanted to know, regardless of how small, if extremely far away planets/stars have an effect on us? It got me thinking that if time is infinite, will everything with mass, every atom, and every quark eventually come together as one big mass in space?

submitted by /u/smallwhales
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How much man-made space debris is there?

Posted: 18 May 2017 03:44 PM PDT

Pictures I see on the internet show space debris covering most of the surface. Obviously, the actual debris isn't that large or we'd be seeing it in the sky everyday. So, how much is actually there? What happens to it? How do we avoid the debris hitting spacecraft?

submitted by /u/Impatient_Nerd
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If electrons are so much smaller than than protons and neutrons, why can't we easily see atom nuclei with an electron microscope?

Posted: 19 May 2017 04:48 AM PDT

What happens with perspective in relation to a reflection in a mirror?

Posted: 19 May 2017 04:29 AM PDT

What I mean by this is the vantage point at the mirror or where you are standing? For example, when you are standing in front of a large hill and there are mountains in the background you can still see the mountains if you are far enough away from the hill, but if you get too close to the hill the mountain will disappear. If you stand just outside range of seeing the mountain and put a mirror (hypothetically tall enough) where you should be able to see the mountain if you were standing, would you see the mountain top or not? [http://imgur.com/a/sqFeR](Pictures of the scenarios I am trying to explain)

submitted by /u/Ilovechinesefood69
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At what point are planets considered to have "cleared the neighbourhood"?

Posted: 19 May 2017 03:22 AM PDT

The Jupiter is a planet, but it still gets hit by comets, which have regular orbits of their own. Saturn's ring is unstable enough that there may even be a new satellite forming out of the mass. Very slowly, but the Moon's orbit is slowly changing and away from the Earth. And then there are the occasional asteroid impacts. So what makes the term "clearing the neighbourhood" important in deciding if a body is a planet?

submitted by /u/seasaltandpepper
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If black dwarfs did exist, wouldn't they blend in with the cosmic background radiation, cooling off to this temperature?

Posted: 18 May 2017 09:16 PM PDT

Is there interpretation of quantum mechanics that violates principle of realism?

Posted: 18 May 2017 02:58 PM PDT

Quantum mechanics violates principle of local realism[1]. So far, we cannot really say whether QM violates only locality or realism or both. My understanding is, that it depends on interpretation of QM - e.g. Bohmian mechanics is nonlocal but doesn't violate principle of realism (if I am mistaken here, please correct me). My question therefore is whether there exists any specific interpretation of QM where we can say that it violates principle of realism (not necessarily only principle of realism)?

Also, it seems to me that various authors treat principle of locality and principle of realism differently, meaning that they are using different definitions of these two concepts. I believe that Bell defined what he meant by principle of locality in [2] - I believe he meant principle of locality in the sense of local causality (though I am not absolutely certain by it, so if anybody can correct me in this I would appreciate it). I also believe that principle of realism are basically hidden variables, am I correct?

[1] - pdf link to Bell's paper: "On the Einstein-Podolsky-Rosen Paradox"

[2] - pdf link to Bell's paper: "The Theory of Local Beables"

submitted by /u/Enfili
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Is the photon really massless?

Posted: 18 May 2017 02:35 PM PDT

When photons enter a medium they couple to phonons and acquire an effective mass. In vaccum however they move at c and are massless. But according to QFT the vacuum is also somewhat like a medium, so can photons in a vacuum really be considered massless or should we think of them having an effective mass as well? I know that there are fundamental principles behind the concept of a maximum speed of information exchange and that electromagnetic waves in a vacuum travel at that speed, but is that actually the end of the story?

submitted by /u/reedmore
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If the only thing keeping an electron in the lowest orbital from crashing into the nucleus is the quantization of energy, how can electron capture occur? Does the electron just go through a series of quantum jumps to the nucleus?

Posted: 18 May 2017 11:21 AM PDT

Is it possible for an element with zero protons and zero electrons to exist/have existed?

Posted: 19 May 2017 12:44 AM PDT

Similar to the element zero on the Mass Effect games. Is it possible for an element like that to exist and if so, how would it interact with other atoms and molecules?

submitted by /u/Davideroni
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Can an isotope have a negative number of neutrons?

Posted: 18 May 2017 08:40 PM PDT

proton = upQuark + upQuark + downQuark

neutron = downQuark + downQuark + upQuark

A nucleus can be described by its number of upQuarks and downQuarks, if their positions are a blur. On the other hand, many videos show protons and neutrons as nonoverlapping balls, which I take to mean vibrations that attract and repel at various distances. Can a neutron and proton in the same nucleus swap positions?

submitted by /u/BenRayfield
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Does pilot wave theory work with experimental results of (delayed choice) quantum erasers?

Posted: 18 May 2017 02:17 PM PDT

I've recently stumbled upon the 'dead but not dead' theory of pilot wave theory in QM. Allthough I did hear that apparently relativity doesn't work well with this theory, I wondered if the theory is consistent with measurement results of (delayed choice) quantum erasers. (I put delayed choice between parentheses because that specific experiment might be considered separately). I'm not too deep into QM, I followed courses on nanoelectronics and I have some experience with Schrodinger equations but in general, my math in QM is not up to speed. I'd like to hear the answer with the least amount of concessions as possible. So if complicated math is needed, feel free to. I'll just dive into it and see what I can learn.

submitted by /u/TunnelFET
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How do animals that camouflage really well find mates?

Posted: 18 May 2017 03:10 PM PDT

The same defense mechanisms which hide them from their predator/prey could also work against them and hide them from potential mates. This could also be very bad for the genetic pool if these animals can only breed with the immediate group they hang out with, right?

submitted by /u/_rb
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How does "polishing out" scratches work on a molecular level?

Posted: 18 May 2017 12:33 PM PDT

Hey today I read an article that said that you can try to polish out small scratches in gold. As gold is quite soft that makes at least some sense however I wondered how that works on a molecular level (u can be precise I am a physicist myself). It also stated that it is somewhat even possible with glas, does anyone know if that is true?

Cheers

submitted by /u/lschozar
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