# Point entity?

1. Jun 19, 2008

### sudabe

why we take electrons as point particles? just because of its magnetic moment?
maybe there is something wrong with the idea of the magnetic moment of a point charge.
i appreciate if you help.

2. Jun 19, 2008

### Staff: Mentor

So far, we have no experimental evidence (from high-energy scattering experiments, for example) that electrons have structure or a finite size. All we can do so far is find upper limits on the size of an electron.

For example, see http://arxiv.org/abs/hep-ph/0002172 which uses an experiment at LEP to set an upper limit of about $10^{-19}$ m for the electron radius. (That doesn't mean that they actually found such a size, it just means that if the electron has a size, it must be smaller than that or else they would have "seen" it.)

Last edited: Jun 19, 2008