# Experimental justification for modelling electron as point instead of charged shell? [duplicate]

Down to what size is there experimental justification for modelling the electron as a point like particle without volume? Asked in another way, at what size scale would it be more correct to model the electron as a charged shell with unknown internal structure instead of a geometric point without volume?

[I am not questioning whether or not the model is correct - only where the cutoff between theory and proof should be drawn when evaluating alternative theories]

EDIT The proposed duplicate question does not contain any answers that would suggest a 'proven maximum size' like I am asking about.

• Where among the answers to that other question is there a numerical value that is related to my question? Mar 6 '19 at 9:52
• @user263399 In what case would anyone find themselves "modeling the electron as a charged shell with unknown internal structure"? How would one test such a model? (All of the electron-compositeness-scale/electron-radius tests I know of, for example in the PDG: pdg.lbl.gov/2015/reviews/…, require some model for how the internal structure works.) Mar 6 '19 at 10:07
• I'm reading cybsoc.org/electron.pdf which toys with electrons being photons confined within a toroidal topology or some such (haven't finished yet) - but in such a case one would expect deviation between the point and shell at some scale. Mar 6 '19 at 10:17
• @AaronStevens - that is correct. All attempts to find a scattering interaction that does not allow for a point-like electron have had a null result. I've lost track of the current experimental bounds on the largest possible size, but its darned small... Mar 6 '19 at 14:06
• Current experimental limit seems to be that the electron is smaller than $10^{-18}m$ in radius. Mar 6 '19 at 14:12