That was a theory I read years ago. The idea is, that there is only one photon which exists more or less outside of time and so is everywhere a Proton would be expected.
The one-electron universe postulate, proposed by theoretical physicist John Wheeler in a telephone call to Richard Feynman in the spring of 1940, is the hypothesis that all electrons and positrons are actually manifestations of a single entity moving backwards and forwards in time.
That was a theory I read years ago. The idea is, that there is only one photon which exists more or less outside of time and so is everywhere a Proton would be expected.
Edit: was actually about electrons
https://en.m.wikipedia.org/wiki/One-electron_universe