Originally posted by sonhouse
So they are not allowed to destroy each other as if one were positive matter and the other anti-matter.
That brings to mind a question: Is there such a thing as an anti-photon? That is, one that if meeting its normal type WILL destroy each other?
This is not related to matter or anti-matter but to quantum statistics.
To answer your question: yes and no. There is an anti-photon, but it is indistinguishable from a photon. There are annihilation reactions involving photons but they require very high energy. For example, if you consider the electron-positron annihilation it can also occur in reverse, with two photons colliding and creating an electron-positron pair.