Nick wrote:
Space stretching can be represented by a closed
universe where there is no boundary expanding at
the speed of light. Instead the space inbetween
the galaxies is stretching.

To answer my question, the space stretch can be
represented in Riemanian geometry as the expanding
surface of a hypersphere. Curvature would go down
inbetween the galaxies as more distance is created.
Gravity will only get weaker inbetween galaxies.

B. F. Schutz (Schuetz?) book assumes from the beginning, (if I read it
correctly) that the universe is infinite, homogeneous, and galaxies
appear to be moving apart. Also, Einstein suggested a mathematical
problem making the same assumption, which later Friedmann, Lemaitre,
Robertson, Walker all solved independently with the same solution.

Of course it is possible to develop this mathematics to fit this
assumption. The problem is with the assumption. There is no reason to
assume that the universe should be infinite and homogeneous.

The universe may or may not have an infinite amount of matter, but this
matter should be distributed (roughly) by an equipartition of momentum
model, which results in a Lobachevskian geometry (made familiar from
Escher's Circle Limit art). A relativistically expanding sphere that
becomes (possibly) infinitely dense at the edges.

I simply do not agree that space is stretching, nor that we have any
measurements to suggest that it is. You will find a large list of texts
which disagree with me, and you will also find a rare gem which does
agree with me, but which side are you on?