I have difficulty’s to accept that the electric and magnetic field components of photons as well as of electrons and the other subatomic particles are extended to infinity. For practical use that does not play any role. We observe, that a photon in some distance to the boundaries of a broad enough slit goes through undisturbed while in a narrow slit the photon gets deflected. (Of course from the theoretical point of view with it’s infinite extend of fields, a little deflection happens.)
The claimed extend to infinity has some weaknesses.
How the fields of a photon (electron) are going through the wall around a slit? Even if they go through as phononic excitations, this takes time and some dissipation takes place. The photon (electron) is not the same behind the slit.
Furthermore a quantization of electric and magnetic fields is unthinkable finite extend of these fields. Otherwise the (hypothetical) quanta of these fields would be infinite small.
Is the assumption of infinity of electric and magnetic fields a historical artifact to which no attention is paid or is it a theoretical necessity?