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Tuesday, February 28, 2017

Quantum Mechanics and Classical Physics: What lies in the middle?

Quantum Mechanics and Classical Physics: What lies in the middle?


Quantum Mechanics and Classical Physics: What lies in the middle?

Posted: 27 Feb 2017 06:34 PM PST

If quantum mechanics helps physicist to describe nature at the atomic level (eg. subatomic particles) and classical physics helps physicist describe nature at a macro level (eg. celestial bodies) is there a point at which one can use both to describe or calculate for something? What is the smallest thing we can describe using classical physics and what is the largest thing we can describe using quantum mechanics? Does something like that even exist? Or does the opposite exist, where one can't describe something using quantum mechanics or classical physics?

submitted by /u/cunalatamarco
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Why can our eyes precisely lock onto objects, but can't smoothly scroll across a landscape?

Posted: 28 Feb 2017 04:54 AM PST

Is the sun perfectly round?

Posted: 28 Feb 2017 04:13 AM PST

I was watching sunrise this morning through very dense fog, and the sun appeared as a perfectly round circle. Is the sun actually a perfect sphere or is it somewhat oval, etc

submitted by /u/RainbowSixSWAT
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[Astronomy] Excluding polar regions, can planet have a night and day that are not equal in length?

Posted: 28 Feb 2017 06:43 AM PST

Nighttime and daytime are not exactly equal but it's very close at the equator. Is it possible for the planet to slow down somewhat while rotating to give each cycle significant differences.

submitted by /u/CarmakazieCthulhu
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Do people bleed slower in space?

Posted: 27 Feb 2017 11:08 PM PST

My limited understanding would lead me to guess that the blood vessels are still applying pressure that would force the blood out, even in a zero gravity environment. But does the lack of pressure from gravity cause the pressure to be substantially less? I remember reading that blood pressure in general is lower in space.

submitted by /u/PopoSama
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In the post red giant stage of a star, why do the outer layers drift into space and not collapse onto the white dwarf?

Posted: 27 Feb 2017 03:37 PM PST

How do centipedes sense moisture?

Posted: 28 Feb 2017 06:18 AM PST

I assume they do because I've found them in crazy places they would never otherwise be - I never saw any in my house until I ran a humidifier in my daughter's room for a day or two, then we found two in her room. Once I had a cup of water next to my bed and the next morning there was a centipede in it (different house). And of course I think it's well known that they lurk in showers and damp basements and garages. I'm terrified of those guys and if there's a way to keep them away from me without bug-bombing my living space I'd love to hear it.

submitted by /u/mandyvigilante
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How do spacecraft get rid of excess heat?

Posted: 28 Feb 2017 12:13 AM PST

I've read the wiki article as a start but finding visuals would also be nice.

Are there also hypothetical methods of venting heat in space that we currently don't have the technology for?

submitted by /u/AndyLC
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Is there a sonic boom equivalent in water?

Posted: 27 Feb 2017 02:21 PM PST

Why is vision grainy at night or in dark areas?

Posted: 27 Feb 2017 03:12 PM PST

At night time why does human vision appear grainy?

submitted by /u/polonium2000
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Why is Jupiter too small to become a star but Trappist-1 is a star despite being the same size?

Posted: 27 Feb 2017 03:28 PM PST

Over the years I've read about how Jupiter is like a mini star that never grew large enough to form and make our system a binary. However, my understanding is that Trappist-1 is a brown dwarf that's the same size as Jupiter so how did it form?

If it was originally a larger star that shrunk then why didn't it swallow the other planets near it when it was bigger?

submitted by /u/Ellers12
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Do GPS Satellite s need to know their exact distance from the surface of the earth?

Posted: 28 Feb 2017 05:14 AM PST

How is the speed of a space probe measured?

Posted: 27 Feb 2017 01:01 PM PST

We often hear that "probe A" is leaving the solar system at a speed of XXX km/h with a very specific speed. But if I remember my science courses correctly speed is always relative to something. And that something moves in space (e.g. the Earth moves around the Sun, the Sun moves in the Galaxy etc.). Shouldn't this influence the speed given for a probe (or even a space rocket)?

Thank you for your answers !

submitted by /u/ModoZ
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How is it possible that the behavior of light can be explain by both waves and particles?

Posted: 27 Feb 2017 05:58 PM PST

Since waves and particles have different properties, how is it that light can be identified as both?

submitted by /u/JustKeepDoing
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What would happen to a flame if the ambient temperature was the same as the flame?

Posted: 27 Feb 2017 02:27 PM PST

So in a normal combustion the flame points upward because hot air rises, what would happen if the ambient temperature was the same as the flame with no external factors. What would the flame do?

submitted by /u/Matrixhammer
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Is there a limit to possible telescope resolutions?

Posted: 27 Feb 2017 01:31 PM PST

Telescopes in space are becoming better and better. I wonder if there is any limit to the detail an image of a distant object can have? Leaving problems caused by an exoplanet's atmosphere and too much light from a nearby star beside - would it theoretically be possible to get a detailed image from an object (like an exoplanet) lightyears away? Or does anything about light limit the available detail on a far distance?

submitted by /u/SmireGA
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Did cosmic background radiation light up the whole universe?

Posted: 28 Feb 2017 03:13 AM PST

If cosmic background radiation started off as short wavelength radiation, and is now radio/microwave radiation, was there a time when it was visible light and the whole universe had a background glow?

submitted by /u/patch47000
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How to derive the Relativistic Doppler shift in Energy?

Posted: 27 Feb 2017 02:21 PM PST

In his paper "On the Electrodynamics of Moving Bodies" Einstein presents a derivation of the doppler effect on light energy by first deriving the change in amplitude. After that imagines a plane wave of light, moving in the universe at an angle from the x-axis. He then imagines an imaginary sphere moving with the light in one frame of reference, such that the sphere always encloses the same 'bit' of light. He applies the Lorentz Transformation to the sphere, obtaining an equation for an ellipsoid in the other frame of reference. By multiplying the ratio between volumes by the ratio between amplitudes he gets the ratio between the energy of the light in both frames of reference. The problem is I have no idea how to take the volume of the ellipsoid. Anyone know how to do it or another easier way of finding the energy ratio (without Planck's constant)?

submitted by /u/isnar000
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Do electrons move at Absolute zero?

Posted: 28 Feb 2017 02:28 AM PST

Is there a top speed to the expansion of the Universe?

Posted: 27 Feb 2017 01:31 PM PST

It is evident that the universe is expanding and this process is accelerating. My questions are thus; 1) What is causing the acceleration of the expansion of space-time, and 2) Is there a point when the expansion speed will exceed the speed of light, perhaps causing stars and other sources of light to vanish from the sky?

submitted by /u/Obversus
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Monday, February 27, 2017

How can a Black Hole have rotation if the singularity is a 0-dimentional point and doesn't have an axis to rotate around?

How can a Black Hole have rotation if the singularity is a 0-dimentional point and doesn't have an axis to rotate around?


How can a Black Hole have rotation if the singularity is a 0-dimentional point and doesn't have an axis to rotate around?

Posted: 27 Feb 2017 04:53 AM PST

How could I experimentally derive the speed of light with nothing more than a convenient store trip, basic household supplies, and a car?

Posted: 26 Feb 2017 09:05 PM PST

Obviously not rock hard limits on supplies, but the general idea is basic, cheap, materials that anyone could get.

submitted by /u/TimAnEnchanter
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How deep would I have to dig into the earth to stop finding life?

Posted: 26 Feb 2017 02:05 PM PST

I assume dirt, soil, earth is home to lots of different bacteria and organisms. So how deep would I have to dig to stop finding them?

submitted by /u/Tbrahn
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Are there significant nutritional differences between kale and other leafy Brassica oleracea cultivars (collards, brussel sprouts, etc.)?

Posted: 26 Feb 2017 08:50 PM PST

Does using my gas oven in winter "waste" energy?

Posted: 26 Feb 2017 07:56 PM PST

My wife and I had a science disagreement and I'm hoping some people here can lend me their opinion.

My wife claims that using an oven frequently is inefficient and my argument is that in winter its irrelevant. Any energy you spend heating up the oven EVENTUALLY equalizes to the interior of the house which EVENTUALLY has a negative offset in the amount of time you have to run the central heating. While no one should use an oven to heat up their house for a variety of reasons (for example it doesn't circulate around the house very well) its technically very efficient.

Our oven is gas and does not vent to the outside, so my understanding is that it has roughly a 100% efficiency rating at converting natural gas to thermal energy. Our central heating is a gas furnace. I'm not sure what the efficiency rating is but it's newer which seems to be around the 90% to 98% efficiency mark.

Are there factors I'm not considering here?

submitted by /u/djslivva
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Do quantum effects affect DNA?

Posted: 26 Feb 2017 09:22 AM PST

On wikipedia, the "Quantum Realm" is defined to be on the scale of 100nm, and DNA is described to be about 2nm in width.

With these numbers, how is DNA able to maintain its structure? Shouldn't its constituent particles be able to occasionally tunnel out of the potential wells holding them in place? If so, why is this not a problem? If not, why not?

submitted by /u/prettycoolpictures
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Why is the Moon now considered a planet based on Alan Stern's findings?

Posted: 27 Feb 2017 07:12 AM PST

What exactly does his new definition change that would count the Moon as a planet? And is it possible that in the near future this new definition become the more recognized definition?

submitted by /u/KarkatTheVantas
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Calculating the volume of a pool of water on a flat surface?

Posted: 27 Feb 2017 05:15 AM PST

Hi, this real life question recently popped up for me and I'm not sure how to tackle it.

Assume there's a pool of water on a flat, non-porous surface (in this case, a tile floor). The pool of water is 16 square feet in surface area. How much water is actually in the pool? I'm not exactly sure how to calculate it because, to my mind, there's no definable depth to the pool because it's on a flat surface.

So I guess my question is, when left to its natural state, how much water does it take to spread over a 16 square feet area on a flat surface?

submitted by /u/Vogeltanz
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Why does the top quark never hadronize?

Posted: 26 Feb 2017 05:32 PM PST

If the top quark has a half-life about one-twentieth of the time required for hadronization by the strong interaction, wouldn't one in a million top quarks hadronize?

submitted by /u/Tranquilsunrise
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Does the material inside a neutron star move much relative to itself?

Posted: 27 Feb 2017 12:44 AM PST

Neutron stars will have a rotation rate around an axis, but is it understood if the material/neutronium itself will move relative to other parts of the star? Or is the material more or less static, not withstanding some other new matter coming in (like if it eats another nearby planet/star/etc.)

submitted by /u/BigRedTek
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Can we detect exoplanets that do not transit their star?

Posted: 26 Feb 2017 03:47 PM PST

It seems most of the exoplanets we discover are discovered when they transit across their star, but do we have any way of discovering planets in which the orbital plane does not transit the star?

submitted by /u/TheRealFalconFlurry
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What is the difference between the dynamical Casimir effect and hawking radiation? You are creating real particles from virtual ones in both cases, right?

Posted: 27 Feb 2017 05:37 AM PST

What factors into a flame's size (like a candle's flame). And did anyone come up with a way to calculate something like that?

Posted: 27 Feb 2017 03:32 AM PST

Why are there only 2 fissionable isotopes?

Posted: 26 Feb 2017 11:59 AM PST

Theoretically, every isotope of every element can go through fusion. Why is this not true for fission? Why is it that only Uranium-235 and plutonium-239 are fissionable?

Chemistry

submitted by /u/KryptonRogue
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How does superglue or any other strong adhesive work on a molecular level? How and why does it make the two objects stick together without any chemical process?

Posted: 26 Feb 2017 05:11 PM PST

Why are Black holes black in spite of time dilation?

Posted: 26 Feb 2017 05:50 PM PST

Anything that falls into a black hole seems to slow down to a crawl to an outside observer because of time dilation effects. So shouldn't we be able to see all the stars that have fallen into the black hole frozen in time because of this instead of just blankness?

submitted by /u/sriharivignesh
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Can we ever know if a mountain was taller than Everest in Esrth's history?

Posted: 26 Feb 2017 09:35 PM PST

Is it possible for us to figure out if we've ever had a taller mountain? Or is everest the tallest mountain ever on earth?

submitted by /u/Question_Help_Please
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Will a magnetic compass react faster the closer it gets to the magnetic north pole?

Posted: 26 Feb 2017 12:04 PM PST

My daughter and I built a water compass from a cork and needle earlier today and while we were playing around with it she asked me a question for which I was unable to find a definitive answer.

Imagine three people were standing on the surface of the Earth, one just a few feet from the magnetic north pole, one just a few feet from the magnetic south pole, and one on the equator. Each of them has an identical water compass with them (it's not freezing or windy at the poles, so just go with that) and they're holding the needles south. They release the needles at exactly the same time. Would all three compasses point north at the same rate, or would they react faster as they approached magnetic north?

My instinct is to say "yes, they would react faster" since they react to a handheld magnet much faster depending on how closely the magnet is held to the compass but I don't know if that theory scales up to planetary poles.

submitted by /u/bubonis
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How do Physicists actually come up with scientific formulas?

Posted: 26 Feb 2017 11:25 AM PST

For eg, how did Newton actually come up with the gravitational force equation- Gm1m2/r2. How did he come up with the inverse square law? How did he calculate the value of G? What precise measurements he took?

submitted by /u/aman92
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Is something that smells losing mass?

Posted: 26 Feb 2017 02:36 PM PST

Take the smell of cookies baking in the oven. The wonderful smell fills my home. Are particles in the cookies going airborne? Something must be leaving the cookies for me to smell them in another room. So are the cookies losing mass? What becomes of whatever I'm smelling? Do I have cookie dust around the house?

submitted by /u/Human_Flag
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How close could a neutron star be formed without afecting the Solar System?

Posted: 26 Feb 2017 01:14 PM PST

I'm curious about the magnitude of this phenomenon and how could it affect us. I'm also interested in knowing how much time might pass until the supernova becomes a stable neutron star.

submitted by /u/macaguamarillo
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How does oversampling affect Fast Fourier Transformation?

Posted: 26 Feb 2017 11:31 AM PST

Sunday, February 26, 2017

Would the universe eventually return to a low entropy state after heat death due to quantum tunneling?

Would the universe eventually return to a low entropy state after heat death due to quantum tunneling?


Would the universe eventually return to a low entropy state after heat death due to quantum tunneling?

Posted: 25 Feb 2017 10:47 PM PST

If the universe reached heat death (assuming something like the big rip didn't happen first), would quantum tunneling still occur? If so, would the universe be expected to eventually randomly reach a sufficiently low energy state that stars, galaxies, and planets could reform? I assume the odds of this happening are incredibly low, but if the universe is going to sit around in heat death forever wouldn't the probability approach 1?

submitted by /u/butWhoWasBee
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Can the equations of fluid dynamics be used to describe/model the flow of electrons?

Posted: 26 Feb 2017 07:05 AM PST

Does electron capture have a bearing on the particulate nature of the electron, versus its wave description?

Posted: 25 Feb 2017 08:11 PM PST

Does electron capture have a bearing on the particulate nature of the electron, versus its wave description?

Quantum Field Theory demands that we commit to an ontology of the electron as a local ripple in the electromagnetic field, above and beyond that field's vacuum state.

Beryllium is known to decay via a process of electron capture . (see http://hyperphysics.phy-astr.gsu.edu/hbase/Nuclear/radact2.html#c3 )

The Compton Wavelength of the electron has a size that is roughly on the order of the distance between the nucleus of the beryllium atom and its first inner electron orbital. This distance is between 0.90x10-10 m and 1.05 x 10-10 m . The radius of the nucleus, however is on the order of 10-15 meters.

Imagine that we have committed to an ontology of the electron as synonymous with its Schroedinger Wave. Then we dispense with having to discuss the electron's "actual location" (as if it were also a localized particle or perhaps a point particle). We may even go on to say something clever like : "the actual location has no physical meaning". In this situation, we expect that the wave-like nature of the electron denies it's ability to interact with features of the universe smaller than the deBroglie wavelength.

But from peak-to-peak of that wave, the nucleus of beryllium is approximately a factor of 0.0000159 times smaller. If electron capture physically happens (and it does happen) , and the nucleons are transformed into other particles as a result of this absorption, can we justifiably deny any meaning to the electron having a more "localized" character beyond its Schroedinger Wave and a purely QFT framework?

Your thoughts .. ?

submitted by /u/moschles
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Has SETI changed their search parameters to account for recently-announced discoveries of exoplanets in habitable zones?

Posted: 25 Feb 2017 08:43 AM PST

If SETI can now locate potentially-habitable exoplanets and calculate the round-trip time of electromagnetic emissions/broadcasts, are they focusing efforts on those locations?

submitted by /u/Avalanche2500
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On average, how far back do we need to trace an individual's family tree in order to find their most recent common ancestor with any other random person from the population?

Posted: 25 Feb 2017 07:40 AM PST

How do mirrors and the concept of left and right generalize to 4 and higher dimensional spaces?

Posted: 25 Feb 2017 10:16 AM PST

For example, does 4D space have another left/right type of symmetry that is independent of left/right? And how do mirrors work in 4D and higher spaces?

I'm reading Martin Gardner's book entitled The Ambidextrous Universe, and this thought occurred to me.

submitted by /u/MapsAreCool
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What does phase coherence mean experimentally when considering individual molecules?

Posted: 25 Feb 2017 04:19 PM PST

For example, in superfluids and quantum optics the concept of phase coherence implies that the phase of each molecule's wave function is a constant difference away from its neighbouring molecules. I also realize that phase differences can result in interference effects.

But what exact "observable" or tuneable property does phase correspond to here? Can an experimentalist (with perhaps advanced technology) independently modify the phase of a single molecule in some desired way? If so, how?

submitted by /u/CallMeDoc24
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What are some unsolved problems in Computer Science?

Posted: 25 Feb 2017 10:42 AM PST

Why is escape velocity a thing? Isn't it escape force?

Posted: 25 Feb 2017 10:42 AM PST

If I had a tiny rocket with an infinite energy supply but it could never move faster than 1 km/hr, wouldn't it eventually escape earth's atmosphere, albeit at a very slow speed?

Alternatively, if escape velocity refers to a speed where no more thrust is required to escape, doesn't that make phrases like "earth's escape velocity" really imprecise? Doesn't it depend on starting elevation and the rate of acceleration to that escape velocity?

submitted by /u/West_Wing_Did_It
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Is it possible for planets to collide in orbit?

Posted: 25 Feb 2017 08:40 AM PST

If you get metal plates or if you have prosthetics, are you unable to enter into MRI's due to magnets?

Posted: 25 Feb 2017 08:27 AM PST

Or as a broader question, if you have metal anywhere in your body due to medical issues, do you have issues being around magnets?

submitted by /u/wpphilosopher
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How does NASA detect planets near star with perpendicular disc to us as observer?

Posted: 25 Feb 2017 06:13 AM PST

Is there a physical limit to how much "space" can be put on a USB disk?

Posted: 25 Feb 2017 08:07 AM PST

Does knowing (or presuming) that a problem is solvable increase the likelihood of solving it?

Posted: 25 Feb 2017 11:54 AM PST

Regarding the story of George Dantzig solving 2 unsolved math problems because he didn't know that they were unsolved, I was wondering if there's evidence/studies showing that a presumption of solvability increases the probability of solving a problem.

submitted by /u/DrBerminverter
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Is there any/could there be any two elements that could undergo both synthesis and decomposition in the same environment?

Posted: 25 Feb 2017 03:20 PM PST

I'm asking if you could have elements X and Y you could have both

X + Y --> XY

and

XY --> X + Y

but not have to change the surroundings, and would therefore spontaneously switch between XY and X + Y

submitted by /u/fluffy465
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How did we domesticate cats?

Posted: 25 Feb 2017 03:11 AM PST

They're not pack-animals (apart from lions I guess) and most wild cats are ferocious killers (as far as I know).

So how did we manage to breed the small docile housecats?

submitted by /u/taracus
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Why are all deep trenches on Earth underwater?

Posted: 25 Feb 2017 04:12 AM PST

I know that approximately 70% of the Earth's surface is underwater therefore it would make sense for most of the deep trenches on earth to be underwater, but why aren't there any massively deep trenches/canyons/ravines on land?

While asking this question I realized that most of the deep places on earth would naturally be filled with water because it would drain in, but even the deepest lakes and seas are nowhere near as deep as a somewhat deep area of the pacific ocean, let alone a trench such as the Mariana Trench.

Why is this?

submitted by /u/TRPAlternative
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Does there exist an infinite series for all numbers?

Posted: 25 Feb 2017 12:11 PM PST

We know from basic taylor series that we can sum the reciprocals of all the factorials up to infinity and get e. We also have similar series for calculating pi and ln(2).

Excluding the case of Riemann paradox, can we generate an infinite sum for all real numbers?

And I suppose this naturally leads to another question, what about the complex numbers?

submitted by /u/Dazkins
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How are captured asteroids possible?

Posted: 25 Feb 2017 05:12 AM PST

How is it possible for a planets gravity to pull an asteroids into a stable orbit?

submitted by /u/kkingsbe
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Is a plane of single atoms visible?

Posted: 25 Feb 2017 01:51 AM PST

Let's say someone produced a sheet with infinite area that is one atom thick of some element. Could you see this sheet and if not at what thickness of atoms do you start seeing it?

submitted by /u/WHATShisNAME96
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