Actually, there are three ways of interpreting red shift: Variations in the actual shape of space as it is observed from a cosmological distance,(static) doppler or red/blue shift resulting from motion toward or away,(dynamic) and red shift caused by gravitation.(static)

On my site, in a Response to Dave Crawford's (U. of Sydney Physics) tired light concept, I describe all three in detail, for they are related, and mathematically play to the same tune.

They play to the same tune of course for reasons related to the nature of reality- and the way we observe it. Dave Butterfield, a mathematician from Colorado Springs has been working on momentum in Gr as related to doppler.

I like the cross-section concept of time, and it is the one I use with my Physics students. Each instant of our life (there are NO true instants, for so far as can be determined, time is a smooth linear kind of dimension, though scaled like space) is a cross section of the whole.

We observe a point on a plane tangent to a sphere (egg) growing and developing circles of increasing size as the sphere moves through our "plane", (growth and development) and then finally circles of decreasing size as we die and depart our place in time.

This is related conceptually to wave/particle duality in the photon and other atomic particles. We see them as particles under some circumstances (a point on a plane tangent to a sphere) and waves in others (concentric circles) as the plane passes through our reality.

It is clear that the universe is dimensionally very complex and we observe it from a rather simple frame.

I assume you have taught vectors? Vector forces and movements resolve to simple geometric figures, squares, rectangles and parallelograms using the Pythagorean Theorem for triangle constructions with angle C of 90 Degrees. We use the Pythagorean Theorem plus a term: c squared= a squared+b squared- 2ab Cos C to describe MOTION and FORCES of any combination of two forces in a Euclidean frame.

This simple example of how motion and forces (with implicit, non-trivial duality) are the reflection of geometric frames of reference was brilliantly extended by Albert Einstein.

Why divergent concepts such as time, space and energy resolve into a geometric universe is difficult for many to understand, but simple variations in energy density creating and determining the other dimensions is probably the explanations. However and whatever, the bottom line is that GR is a verified reality above the Planck realm. Why is DOESN'T work at the Planck realm gives additional clues which can guide us in our search for an extended concept.

I do not believe that from our frame, the universe is steady state. Ultimate reality in GR is found not cosmologically but at each invariant frame.

Yet if we wish to know the truth about our cosmos, I believe we have to understand that the only way to conserve and preserve complexity in the universe is within a rigid geometric construct.

Best Wishes...and Happy Holidays! Sam