# Electron Charge

1. Aug 19, 2015

### i.physics

How electron gets its charge ? For that matter any other particle charge?

2. Aug 19, 2015

### DEvens

Nobody knows. At this time the charge on an electron is a thing that we measure and put into the theory. There is not, at this time, any way to calculate the charge on an electron.

There was some tantalizing work done on the idea of magnetic monopoles, by Dirac.

https://en.wikipedia.org/wiki/Magnetic_monopole

The idea of magnetic monopoles is that the gauge field becomes, eventually, close enough to the actual monopole, something else. That something else is determined by the nature of physics at very high energies, and so very short distances. For example, if string theory is correct then the gauge field eventually shows its string-ness. And that lets you get a monopole.

But there is a mathematical theorem that is known in slang terms as the "hairy ball theorem." It is often quoted as "you can't comb a hedge-hog." It means that a vector field that is tangent to a sphere cannot be everywhere smooth. And that is a problem. In electromagnetism, the A field and the B field are perpendicular. So if the B field from a monopole is radial, then the A field has to be tangent to a sphere. And that is a problem. You get a place where the field is "weird."

Dirac's way around this was charge quantization. If the ratio of the magnetic field on the monopole and the electric charge on the electron was exactly the right amount (or integer multiples) then the "weird" place in the A field would not be observable. It would go away in the phase, which is not observable.

The problem is, so far, nobody has observed any monopoles.

3. Aug 19, 2015

### Mordred

4. Aug 19, 2015

### DEvens

Hmm... I look at that and get seriously confused. It is really unclear to me what they are claiming. It seems like they are claiming they have some kind of magnetic vortex. But why they choose to call it a Dirac magnetic monopole is really not clear to me. The journal article is behind a pay wall and I'm not sufficiently fired up to fork out the cash.

5. Aug 19, 2015

### Staff: Mentor

Those are just quasiparticles. The solution discussed in the post above would need them as elementary particles.

6. Aug 19, 2015

### DEvens

There is a preprint on this. It's not behind a pay wall.

http://arxiv.org/abs/1408.3133

I make no representations as to what is in there. I really do not understand what they are claiming, let alone what it means.

7. Aug 19, 2015

### Mordred

Thanks for the arxiv article. I wasn't sure myself.

8. Aug 20, 2015

### i.physics

How monopole could be related to how electron gets its -ve charge, I mean is it that monopole is possible fundamental property of particles theoretically though ?

9. Aug 20, 2015

### DEvens

Did you read the wiki article?

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