James,
Presumably any numerical value less than the speed of light in a vacuum.
What is this 'vacuum,' other than blank space?
Now if they say 'space expands,' yet this speed of light remains constant to some other measure than the expanding space, what is the source of that value? If they are going to measure distance, of this 'expanded space,' in terms based on the speed of light, ie. lightyears, then those are the denominator and the expanded space is the numerator, so the 'ruler' in this equation is the stable distance set by C, in the vacuum.
If you come across any arguments for why it is argued this expansion of space is relativistic, I'd like to see them. All I've ever read is that, 'Einstein proved space can either expand, or contract and that is due to the cosmological constant.' As I recall, Einstein's issue, for which he invented the cc, was that gravity caused space to contract and he put it in to keep space stable. As I keep pointing out, expansion and gravitational contraction balance out. So since gravity is mostly manifest as gravitational vortices and the expansion is only of intergalactic space, than logically what is expanding between galaxies, is collapsing into them, proportionally.
Now mass falls gravitationally inward and Einstein considered space to be a measure between spatial points, so this resulted in the contraction of the measure of space. Now radiation is what expands away from galaxies and it is by the redshift of this radiation that we consider intergalactic space to expand and it is only light from those very distant galaxies that manages to travel inbetween all intervening ones, that we can see. In fact, light that slides by galaxies is magnified, as waves that would have spread out, are focused.
So if light is being redshifted by the optics of space, then we are only at the center of our view of the universe, so it makes sense this effect makes us appear at the center. Since these galaxies are not actually moving away, there is no need to invoke an amputated relativity to explain doppler shifting.
As an optical effect, it would compound on itself and create a parabolic increase in the rate of redshift, which is exactly what we see, in that the rate of redshift appears to rapidly decline, then flatten out. Big Bang theory considers the initial decline from the singularity, then invokes dark energy to explain why it then continues at a steadier rate.
The reason why the cosmic background radiation is both very flat, at 2.7k and slightly mottled, won't be because it is the energy of the initial explosion, smeared out by inflation, containing the seeds of galaxies, but because it is light from ever more distant galaxies, that has been redshifted completely off the visible spectrum, down into black body radiation and the variations are simply the faint shadows of those distant sources. The 2.7 temperature would likely be some phase transition level.
I predict that when the James Webb telescope goes up, they will keep finding ever more distant galaxies and galaxy and quasar clusters, that will be increasingly difficult to shoehorn into their model.
Regards,
John M