Originally Posted by speedfreek

So how would one explain a galaxy with a redshift of z=7, which, using the mainstream "expanding space" model, was 3.5 billion light years away (angular diameter distance) when it emitted the light we are now seeing 12.9 billion years later. That galaxy is now estimated to be nearly 29 billion light years away, due to the expansion of the universe during that 12.9 billion years that the light was travelling for.

The apparent angular diameter of an object shows how large it looked when the light was emitted. If you see a moving object, you see it as it was when the light came from it, not as it is when you receive the light (by which time it might be closer, or further away). In that context, are we assuming here that photons also shrink in size whilst they are travelling through space? Is the speed of light constant too? Would that mean the speed of light was constant relative to the size of a shrinking photon and therefore not constant at all?