Photons and determinism, part 2

[bennyboy]

In the relativity equations you will be dividing by zero if you go into the photon's rest frame. Thats what makes it invalid.

Doesn't calculus take care of that for us via limits?

The number of interactions that happen to the photon is independent of the reference frame. The time between two or more interactions would be spaced differently for different reference frames. Moving reference frame would see a smaller time difference between interactions compared to the stationary one. In the photon reference frame, all the interactions occurred at once which would break causality if the photon didn't get destroyed with each interaction.

So a photon gets exactly one interaction-- its absorption into a receiving body. Does this mean, then, that passing through gravity fields (which will have changed as the photon "moves" in our reference frame) does not count as an interaction? It certainly would seem to affect what specific body is going to get to aborb the photon.

Imagine a photon starting on the trajectory toward your eye. Midway between galaxies, a flying black hole and photon have a close encounter. The black hole would change the trajectory of the photon.

Ah yes, but from the photon's reference frame, the distance between it and your eye is 0. In other words, as soon as it is brought into existence, it is already at your eye, meaning that nothing COULD have intervened which would have prevented it from reaching your eye.