I have read that since photons have no valid reference frame they don’t experience time. They move through space at c so no time value, in essence.
But space and time are the same in relativity and space obviously affects photons ie they experience eachother. Photons redshift over distance and time, as the most obvious example.
So how is it that a photon can’t “experience time” yet it experiences space? Why isn’t redshifting over X ly considered experiencing time already?
I’m just a layman so I’m having a hard time reconciling a photon not experiencing time due to not having a valid reference frame; but that just doesn’t affect its deal with space? It gets a valid reference frame in space then?