and each quark is described by its phase . Use this phase to sort quarks into a pair of sets, and , so that all quarks of the same phase are in the same set. Then and are called phase components of P, and they are out of phase with each other. We write
Now let P be an almost perfectly phase anti-symmetric particle so that for all types of quarks, except perhaps down quarks. Then we define a photon as a particle like P, that also satisfies the conditions
Notice that solitary photons are excluded from particle cores. So under some conditions, we may be able to say that is a free particle.
For EthnoPhysics anti-photons are just like other anti-particles. So is defined from by exchanging ordinary-quarks with anti-quarks of the same type, while leaving the phase and other relationships unchanged. In a photon, for all quarks except down-quarks. So photons and anti-photons have just about the same characteristics as each other
and the two photons have symmetrically opposed wavevectors. So photons and anti-photons are mostly the same as each other, but moving in opposite directions. Next we consider some other types of photons.