> causal actions having some finite propagation time.
I think I know what you're getting at, but somehow the phrasing bothers me, as if there is meta-time or as if cause and effect have time between them... for the photon at light speed, time isn't passing, it's emitted and then zero "time" later it hits something very far away.
It's more like we somehow need to think of cause and effect chains that have orderings without time.
I wonder if future generations will ever look back and casually quip something about "well they believed X existed, that was their problem, it all makes intuitive sense if you just..."
Yes, the basic idea is that photons do not 'experience' time. They 'experience' creation, all points along their path, and absorption 'simultaneously'.
However, you have to be careful with terminology. There is no inertial frame co-moving with the photon. All we can say is: as a massive particle gets faster relative to an observer's frame, the time it experiences relative to the observer's frame becomes shorter, and in the limit, as it approaches the speed of light (but never reaches c), the experienced relative time approaches zero (but never reaches 0).
This is well explained by Don Lincoln on the Fermilab YT channel:
I think I know what you're getting at, but somehow the phrasing bothers me, as if there is meta-time or as if cause and effect have time between them... for the photon at light speed, time isn't passing, it's emitted and then zero "time" later it hits something very far away.
It's more like we somehow need to think of cause and effect chains that have orderings without time.
I wonder if future generations will ever look back and casually quip something about "well they believed X existed, that was their problem, it all makes intuitive sense if you just..."