Has anyone ever been able to measure Electron size?

[jeanpinto844]

TL;DR

Determining the size of the electron

Hello!
I was recently listening to StarTalk podcast and (re)learned that the electron is one of the most elusive particles for which there is no known size. Have there ever been any attempts to measure the size of the electron, either directly or indirectly, from either a practical or theory? I know QED just treats the electron and all other particles as waves and does QM and I guess it doesn't matter what the electron size actually is but it would be an interesting fact to know. Thanks!

 

[weirdoguy]

I know QED just treats the electron and all other particles as waves

No it does not, it treats electron and other elementary particles as point-like entities.

 

[renormalize]

TL;DR Summary: Determining the size of the electron

Did you try searching for this topic here on PF? It's been discussed before; here are a couple of links:
Physical size of an electron
The volumn of the electron

 

[malawi_glenn]

Experimentally, there is no sign of electron spatial size. What we have experimentally are upper bounds on its size (one can play the same game as with proton charge form factor when one analyzes the experimental data).

 

[Vanadium 50]

Can you define an electron size? Its field goes to infinity, so it can't be that. What do you want it to mean that an electron has "size x".?

 

[LittleSchwinger]

The "shape" of a particle is often derived from scattering processes by integrating functions called form factors. Such a manipulation of scattering form factors in classical physics would allow you to figure out the shape of a particle, but in quantum theory you have different "shapes" result from each possible scattering process.

Really notions of shape or size don't really apply to quantum particles, I would even refrain from calling them "point-like". For example a photon has no sensible notion of being localised (no position operator) which would be the bare minimum required to start talking about it being point-like.

 

[Vanadium 50]

The OP seems to have gone, Just another drive-by, I'm afraid. A pitym since I think clarification of the question might have got him his answer.

One definition might be "the radius at which the field deviates from that of a point charge". Another might be "the radius at which the field deviates from 1/r² by more than x%." Yet another might be "the size of the smallest box we can put an electron in". These all get different values or in some cases, limits. Ny very large factors - like billions.

You tell me what number you want, and I'll tell you what definition to use.