Photon-photon Annihilation

If photons are their own antiparticles, they should be annihilated if they collide with another photon, right?
- Anonymous (age 10)
Rhode Island

Yes, photon-photon annihilation is possible.  However, the interaction between visible photons is so weak that it has never been seen.  Annihilation of gamma rays (high energy photons) has been detected. The annihilation still leaves the total energy unchanged, so something has to result- e.g. an electron-positron pair.

jjt

(published on 03/02/2018)