Main Question or Discussion Point
Not to get off subject but, when I gaze at the Triangulum Galaxy how “Old” is the light I’m observing?
If you know Relativity no as anything traveling at the speed of light does not experience "time". However you can validly ask "when was a photon of light emitted relative to our reference frame". For somone lacking an understanding of special or general relativity and used to our largely nonreletavistic everyday experiences where Galilean transformations produce close enough approximations to reality that those rules were only valid for speeds much less than the speed of light wouldn't be realized until Michelson and Morley's famous experiment showed the speed of light is a constant of nature and that no "Aether" exists.Does it make sense to ask for the age of light?
True that typical definition of time doesn't apply, hence why I said "time" not time, but it is a useful way to conceptualize a minkowski diagram as it will fall entierly along the spatial axes so it helps get the point across.That is a pop-science nonsense. There is no frame of reference in which light is at rest, so there is no meaningful way to talk about what light "experiences".