Posted: Mar 24, 2017 5:52 pm
by newolder
Obviously, I wasn’t paying much attention when I first read your post - sorry. I’ll try to concentrate…

You seem to be puzzled as to how light is red shifted and how light is different to spacetime.

In reverse order: consider spacetime to be the arena in which events unfold. It’s a 4 dimensional arena that increases can change in size as time passes. The passage of light through arena spacetime is one of the possible events.

Light is red shifted when the arena spacetime grows in size as a light beam passes by. For example: Let blue light enter, stage left when spacetime is, say, 50 metres wide; the arena spacetime grows in extent to, say, 100m wide and the distance between any two points (including consecutive wave crests in a light beam) is doubled; red shifted light, therefore, exits stage left.