From Bert:
Once you fool with 'c;' you will end up in
a very dark tunnel and no light at the
end.

Bert, what you say is true under the sitting paradigm. The cadre of
'maverik' mainstreamers current messing with c-variability are
Void-Spacers and as such, they are forced to violate some cherished
constants (like the Lorentz invariance and the fine structure constant).
And such a path is dark and fraught with peril.:-)
But the CBB model, because it recognizes the spatial
medium and _density gradients_ therein, does not "mess with" c at all.
Rather it holds c constant in all _density frames_ just as SR holds it
constant in all inertial frames. So c is always constant *locally*
anywhere you go in the universe.
But to visualize 'c-dilation' you have to mentally
transpose to a vantage point 'outside' the universe. Only from this
external frame is lightspeed seen to drop across the expansion of the
universe, concomitant with the drop in pressure/density/'Temp'(PDT) of
the spatial medium. This drop in lightspeed, visualized from 'outside'
and ONLY from outside, is what Wolter called 'c-dilation'.
From our restricted frame here 'inside', we still see
*artifacts* of the expansion in deep-past lookback such as noted by
Davies et al, and in 1a supernovae appearing 'dimmer than they should
be'. Also, 'tiny' PDT gradients are present locally, in the gravity
wells of stars (witness the Pioneer spacecraft anomalous acceleration).
oc