From my understanding, photons travel at the speed of c in the straightest line possible. Say I take a photon and send it off to the right toward a mirror. It hits the mirror and is deflected in the opposite direction in relation to the angle of incidence. My question is is the photon that is deflected to the left the same photon that I initially sent right? Or did some annihilation/re-creation event happen at the mirrored surface to create a similar but uniquely distinct photon now traveling in the opposite direction? More generally, once a photon is set going, say either to the left or the right in an arbitrarily defined coordinate system, is it's existence confined to a straight line in that direction?