Quantum of light is point.
Electron is point/ sphere.
Proton is point / sphere.
In fact none of this is true. A photon is not a point, it has a size, which is described by a probability function. The size varies depending on the frequency.
The electron is worked with as a point, but it has many parameters (spin, charge, etc.) which indicate that it has some kind of complex structure, and a point could not support that structure. But it is small enough that it can be considered as a point in the mathematics used to work with it. At a finer scale its size would have to be considered.
The proton is definitely not a point, since it is made up of 3 quarks and some gluons. None of these is in fact a point. The gluons in particular have length, which is variable. But claiming that they are all points is just totally wrong.
Bill Gill
