# All Questions

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### Protoplanetary disks, angular momentum and prograde orbits

So you've got a protoplanetary disk and you're going to gravitate yourself some planets together. The disk is made up of the usual planetary system stuff, dust and gas and whatnot, orbiting a common ...
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### How come a greater normal force doesn't make us feel lighter?

If I were to push an object rightward with my hand from rest, the object would receive a net force in the right direction and accelerate. If we created a free-body diagram for this situation, it would ...
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### EM: Conducting media

I have a question concerning the following exercise: The physical electric field associated with a plane wave in a material has the form: $\vec{E_{phys}}= E_0e^{-a_1z}\cos(a_2z-a_3t)\vec{y}$ ...
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### Does a photon follow a straight trajectory in a thin transparent film?

Does a photon follow a straight trajectory in a thin transparent film if the source has emitted a photon inside the film with impulse parallel to the film surface. (lambda greater than thickness)? ...
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### Formation of nucleus

Is it even remotely possible for a nucleus to be formed in the following way? Consider two nucleons approaching each other at extreme speeds. Could the relativistic increase in mass be so high to ...
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### Is gravity the current limitation to laser cooling?

This is something I've been wondering for a while. I've read about the experiment with NASA to reach unprecedented cold temperatures in space because of the microgravity environment not being such a ...
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### How fast should 6 liters flow out of the sink through a 6cm pipe?

I had 6 liters in the sink when I pulled the plug. It took the water about 30 seconds to get through a pipe which has about 5cm in diameter. I think the pipe might be blocked a bit, causing it to have ...
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### What is quantum foam?

Can someone please explain me what quantum foam is? Is it the space-time fabric or just any other field? Also please explain this image
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### Exact definition of momentarily comoving reference frame (MCRF)

Consider a particle $P$ in the framework of special relativity with position $r(t)=(ct,x(t),y(t),z(t))$ respect to an inertial reference frame $\Sigma=(ct,x,y,z;O)$. I need to know if the following ...
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### Decompression sickness

In decompression sickness why does nitrogen gas come out as bubbles? Is it because under high pressure the nitrogen gas was converted into liquid nitrogen and during the process of coming to the ...
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### Can anyone explain that “the human body is made of energy (photons)”? and how many photons it contains?

The modern research has shown that our body is basically made of energy not matter in a sense that atom itself is basically consists of energy waves, so it is nothing but energy. How we can explain ...
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### Deep Inelastic Scattering - electromagnetic current

When one tries to compute the deep inelastic scattering for the process: where $l$ is a lepton with incoming momentum $k$ and outgoing $k'$, $h$ is an hadron with momentum $P$, $q$ denotes some ...
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### Entanglement in Quantum field theory [duplicate]

How is entanglement represented in a field theory? For instance how can I represent a maximally entangled state such as a Bell state? Would such an approach also apply in a Conformal field theory ...
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### Have I found all of the zero order laue zone points for an FCC crystal being imaged along the [111] zone axis?

Since the equation for laue zones is hu+kv+lw=0 and the electron beam is incident in [uvw]=[111] can I say that the first order laue zone points are [hkl]=[-110],[1-10],[-101],[10-1],[0-11], and ...
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### Where can I learn about band theory?

I'm studying quantum mechanics and I want to understand perfectly where the bands of the electronic sturcture come from. I've read that it is related with the periodic potential, Bloch waves and ...