return to [6.2 Photon kinematics]

Figure 9. Each point A, O, B, and G, in a reference frame for matter, represents a distinct photon at that location at a single point of time. Photons A, O, and G are moving in a positive X axis direction, while photon B is moving in a negative X axis direction. Photons A and O do not exist relative to G and visa versa. The event lines of photons A and O occur here-now relative to each other. Photon B is located here-now relative to photons A and O only when B is on the Y axis with A and O.