Why does light not have an antiparticle?

When an electron and a positron annihilate each other, a flash of light is created, i.e. photons. But what happens when a photon hits its antiphoton?


Antiparticles are partner particles to ‘normal’ elementary particles such as the electron, which must exist due to the merging of special relativity and quantum theory in quantum field theory. An antiparticle has the same mass as the corresponding elementary particle, but the opposite charge. Charges can be the known electrical charge, but also the color charge of the strong interaction or the flavor charge of the weak interaction.

If a particle has no charge whatsoever (all charge numbers = 0), then it is accordingly its own antiparticle. The photon does not carry any form of charge, so it is its own antiparticle. Furthermore, there is no direct force or interaction between photons. For both reasons, they do not destroy each other - rays of light cross each other unhindered without noticing each other.

Alexander Westphal works in the theory group at the DESY research center. In his research he is particularly concerned with so-called inflation and examines the embedding of different inflation models in string theory, a candidate for a completely unified description of the laws of physics.