# All Questions

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### Upper division physics lab — Project ideas [on hold]

As an experimentalist, I am very excited to be taking my first upper division physics lab next semester! The course covers basic electronics (filters, diodes, transistors, op-amps, analog & ...
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### Frictional loss of matter

How do we account for the loss of matter from an object due to friction ? Is it simply a phenomenon or result of any other process ? Eg :The loss of matter from the rubber tyre
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### How do you work out the energy requirement for a submerged pump?

I was wondering if you were to place a pump in a submerged container and then were to open a hatch allowing water to flood the previously vacant cavity how much energy would be required to discharge ...
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### What is trivial and non-trivial gate in computing?

My question seems like it should be posted in Computer Engineering section, but below is how I found this word. I was reading the textbook: Quantum Computation And Quantum Information - by Michael A. ...
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### Are fundamental forces always attractive/repulsive, i.e. parallel to the separation?

If magnetic monopoles existed it would not be the case - the forces on an electron and a magnetic monopole passing by each other would be at right angles to the vector connecting the two particles! ...
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### Can the strong force be explained by quaternions?

I wonder if the strong force can be explained by quaternions without the use of matrices. I heard that it could, but the source was not reliable.
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### Light in a box with positron walls instead of electrons

I understand that with a hollow cube with the inner walls covered in mirrors given a light source briefly, the light would eventually be absorbed. This is due to electron excitation I believe. So ...
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### Is imaginary time a fifth dimension? [duplicate]

I've read that by introducing the concept of imaginary time, the dimension of time can be treated like a spatial dimension mathematically. Assuming, without imaginary time, one considers the universe ...
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### Time functions in general relativity

In my general relativity notes a function $f$ is called time function, if $\nabla f$ is time-like past-pointing. Say that we are in Schwarzschild spacetime and I want to check if $f=t$ is a time ...
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### Photon walk in stars with convection

I'm having trouble figuring this out. I've read, that when photons are created via nuclear processes inside a star, it can take about 1 million years for photons to actually reach the surface of a ...
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### How to derive the light pressure from maxwell equations? [on hold]

Is there any reference? Was the idea of radiation pressure known to Maxwell himself?
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### Does quantum entanglement arise from quantum theory or is it merely an experimental observation?

I assume that entanglement emerges from quantum mechanics because the idea was around before experimental verification (e.g the EPR paper). How then does entanglement emerge from the theory (please ...
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### Direction, closeness and range of streamlines in a flow domain with solid boundary and free surface?

I have a flow-field with solid boundaries and a free surface, I have plotted the streamlines, however I am not sure whether my graph is correct. In fact, I drew the streamlines by taking a range of ...