Apparently, an electron has mass not greatly smaller than a proton (roughly 1/20, I read, the rest being just binding energy) its volume should, therefore, not be a lot smaller, and its radius between 1/3 and 1/2 the radius of a proton.
Can you explain why it is considered a point-particle (unlike the proton), that is: having no spatial extention? Doesn't mass have to occupy space anymore? In a recent answer user AnnaV showed that it has even been filmed, why do they think it must be definitively smaller than 1/10^-16 cm? How can such a lot of mass be squeezed into a vanishing point?
A proton is made up from point particles. It has a measurable radius because (speaking very loosely) that is the outermost radius of the point particles within it. For comparison consider an atom.
The answer by John Rennie could be a good explanation if it didn't rise a doubt. A proton is made up by 3 or 6 or more quarks, but even if we considered thousands or millions of point particles which are attracted by a very strong force, they would occupy a tiny portion of space. There is nothing I read that implies that the volume can be blown to huge proportions,like in an atom, an electron orbiting a nucleus.
Can someone explain that?