@Bohemianrelativist spin-orbit coupling is fundamentally just that there are relativistic terms in the Hamiltonian that involve both the spin and the ordinary angular momentum
as fqq said, this usually leads one to consider certain entangled states, but it isn't about entanglement directly
really, entanglement is almost never something we consider as a primary thing - it's just a consequence of how quantum mechanics works
@Slereah the drift speed in a metal like copper is typically under a millimetre per second, so I'm not sure where your figure of 3.2 m/s comes from.
@Bohemianrelativist do you mean different atoms in a lattice interacting with each other due to their spin and/or orbital magnetic moments? If so that isn't what we usually mean by spin orbit coupling.
@antimony I was in the Math chat at the time, which is on the same chat network. It was flakey for about 10 minutes or so, then died for a few minutes.
@ArunBhardwaj you have to ping John like @JohnRennie if you want his attention (he says it's okay to do this in his profile, please don't do this for random users)
Why does the flux of a closed surface does not change by the presence of an outside charge Q? There is a field of charge Q that will disturb the field of enclosed charge q. So the net flux should change.
It turns out there are several users with the handle "Buzz". Is there a trick to make them apart (aside from reputation) or ping one rather than the other?
it should be pretty rare that more than one Buzz is pingable in any specific instance - you can only ping people in chat that have been there in the last 2 days, and you can only ping people in comments that have either commented themselves or edited/closed the post
@cOnnectOrTR12 draw the field lines from the outside charge u will see that there are as many field line entering the closed surface as outgoing and the net flux due to the field created by this charge is 0
@cOnnectOrTR12 no fields "get bent" - electrostatics runs on the superposition principle: The total field of two charges is just the superposition of the individual fields of the charges, there are no additional effects
the field lines of the total field don't "look" as if it's just the individual fields superposed, but that's a problem with thinking in terms of field lines, not with the physics
the field lines of the total field don't "look" as if it's just the individual fields superposed, but that's a problem with thinking in terms of field lines, not with the physics
but that's not how electromagnetism works - if you state it in terms of the actual fields, not the field lines, then the total field is just the sum of the two individual fields
the field of the first charge is still fully there, it's just simultaneously there with the field of the second charge - and now if you draw the field lines for the total field, they look "bent"
but for your question about the flux it's a red herring to look at the lines of this total field - since the actual field is the sum of the individual fields, the total flux is also the sum of the individual fluxes
and since the flux of a single charge through any surface it is outside of is zero, it doesn't matter how many other charges you add to this situation
Also in a spring, when I am pulling/pushing it, I am doing positive work all the time (as the direction of the force is the same as displacement) and the spring is doing negative work all the time (before being let go), right? So is my work stored as PE or the work done by Spring?
When I talk about the superposition of two forces then do the two forces vanish and a resultant is left. Like if a force is applied in horizontal direction to a body and a force making theta angle then will the two forces vanish and the only left force will be resultant
Whose direction will be between the directions of the two forces
you can even arbitrarily decompose any vector (field) into two or more different vector (fields) it's the sum of and think about it as the superposition of these components, regardless of whether there's a "physical" meaning to the components or not
The field of the first charge is still fully there, it's just simultaneously there with the field of the second charge - and now if you draw the field lines for the total field, they look "bent"
yes - I'm clumsily trying to express in natural language the fact that $E_\text{tot} = E_1 + E_2$
so when you wonder "what is the total flux through this surface", the answer is "it's the sum of the flux you'd get if you consider the first and second field separately"
@VincentThacker I'm not sure there even are any restrictions - consider that in 2d Minkowski, any two straight non-parallel lines define a coordinate system
you can easily choose two timelike lines for that
@cOnnectOrTR12 to what? You've just repeated the same thing you've already said several times, I have nothing more to say about that
so when you wonder "what is the total flux through this surface", the answer is "it's the sum of the flux you'd get if you consider the first and second field separately"
You are saying if in the presence of an external charge we need to find the net flux we need to take flux from each of the fields of the separate charges separately. Flux from outside charge’s field and then flux from inside changes field
but if my superposition argument is really so difficult for you, here's an alternative way to argue charges outside a closed surface don't affect the flux: only field lines that end inside the surface can contribute to flux because all other lines just enter the surface at one point and leave it at another, contributing a total of zero to the flux
If I think of individual charges at a time then the field of outside charge contribute to zero flux. Field lines enter and leave . As you said. Only field that contributes to flux is inside charge. This is definitely easy.
But how do we estimate net flux if I consider resultant field. Is it possible to imagine that?
Is it possible to think with a bent field. I know the flux is still same. But how do you find this way?
Just imagine a spherical surface around right charge.
The field of lines in the diagram is of resultant field. Now how do you explain field lines from outside charge enter and leave the surface and lines from inside charge only leave the surface.
you'll have to explain why you think it doesn't work that way in this case
it seems very obvious to me from the diagram that the lines from the charge outside either don't cross the surface at all or enter and then leave it again
I was looking at a short video of quanta magazine and in a part the professor mentions a Power law for some hypothetical DM annihilation that looks like P~<σᵥ>ρ²/m, I was wondering if that law maybe has a more known name I can google up or look for in wikipedia, it feels like it could be a law commonly known under some other context.
