Photon "reference frame" and determinism

[InquiringMind]

I'll give you my understanding of it according to special relativity. An observer always experiences time passing normally in their own reference frame, but observers in different reference frames can disagree on the passage of time. But this is not why a photon is "timeless." At speed c, length contraction becomes infinite, so in the photon's frame of reference, the distance travelled is zero. The photon can still experience time, but it never does, because in the photon's reference frame, the distance to the atom that will absorb it is zero. But in our reference frame these distances are not zero, and a photon lives for a finite about of time, so experiments with light can work (and they do).

And for determinism, look into the idea of light cones. It's been a little while, and I don't remember off the top of my head how to apply that to this situation.