2:52 AM
1

Let's consider a single charged elementary particle (electron) in its rest frame. Does it produce a magnetic field because of its spin? Would a neutral elementary particle with non-zero spin at rest produce any magnetic field? If yes, what expression should the magnetic field have? Does it make ...

16 hours later…
6:30 PM
2

There is no position vector in general relativity. I was wondering whether a quantity like $$k_\mu x^\mu$$ where $k_\mu$ are covariant vector components is to be treated like a scalar i.e. invariant under coordinate transformations? A came across that problem, studying gravitational waves. In one...

2 hours later…
8:09 PM
2

I am a bit confused on the way Landau derives the Lagrangian of the free particle in SR (L. Landau, E. Lifshitz - The Classical Theory of Fields) and his conclusions about the equivalence between mass and energy. He claims that there exists an integral that assumes its minimum value on the actual...

2 hours later…
10:12 PM
5

How is it possible that the every particle in the universe agrees on the laws of physics? What enforces those laws. Might the laws change slightly across the universe in the same way the Cosmic Microwave Background Radiation does?

10:37 PM
4

According to the principles of identical particles, the wavefunction of a collection of fermions must be antisymmetric and such a state is entangled. Doesn't this mean that any given electron in the universe (which is a giant system) is entangled with every other electron in the Universe? Why not?