Infinitely small, small and small question. Does an electron have spatial extension?
I am asking you a question: how large is the radius of an electron? Though most of us cannot prove, we are compelled to believe that it has a spin. Here I would like to quote from a book "Quantum man" written by Lawrence M. Krauss.
"...electrons possess a property called spin because they carry with them intrinsic "angular momentum", the property extended objects possess if they are spinning. Classically no such concept exists for a point particle, which cannot behave as if it is spinning because there is no "center" (that is, another point) to spin around. In order to have angular momentum, like a spinning bicycle wheel, for example, classical; objects must have spatial extension." (page 100, lines 6-14)
Does the radius of an electron have finite value still, or is it definitely zero? Which is true?