Most theories (/ when doing experiments we) assume that the electron, quark, etc are really point particles. What is the evidence for this? I don't think, for example, that experiments at cern convey that they are. They could have an internal structure with a stronger force than the strong force keeping it all intact, for example. Is the point that it does not matter if they have internal structure or not? Or (similarly) that we will never be able to find out if it has internal structure or not due to energy limitations in physical experiments?