John thanks for the tutorial. Let me explain why I asked the question I did
and why I still am not sure why the newly found acceleration of the expansion
rate of the Universe doesn't affect the CMB.
First I understand that what is changing is the scale factor. The
parameter is part of the differential term in the Friedmann Equation. What we
may have discovered is that da^2/dt^2>0. However depending on how one
classifies cosmological structure this expansion affects only those
structures weakly gravitationally bound. I believe (and I go from an
unreliable memory here) that structures known as clouds, superclusters, walls
and voids are not gravitationally bound and are therefore expanding. Smaller
structures such as Galaxies, Groups and clusters are in fact sufficiently
gravitationally bound to prevent their expansion. Of course what is
"expanding" is space time itself. The cosmological structures are along for
the ride. The balloon model is illustrative here.
Now as SR tells us, for every observer the speed of light in a vacuum
is a constant.( There may in fact be dispersion effects in the vacuum of
space due to Quantum fluctuations of space time but this effect is only
significant at very high EM energy levels.) Therefore given enough time, a
beam of light will always be able to reach an observer traveling at any
possible velocity. This implies that there no event horizons in a Universe of
constant velocity (assume no black holes exist and ignore our cosmic horizon
due to the big bang). However when an object accelerates, then given enough
initial spatial distance, our original light beam will never catch our
accelerating observer. We have in fact created an event horizon between our
accelerated object and regions of space time. We have created spacelike
separation between regions of our Universe as far as our accelerated observer
is concerned.
Having created a horizon produces inevitable permanent separation of
virtual particle pairs hence we emit radiation (Hawking radiation or Unruh
radiation if you prefer.) at the boundary of the event horizon. These virtual
particles are promoted into existence by some of the energy responsible for
our observer's acceleration.
Given that it seems likely that da^2/dt^2>0 in our Universe, then it seems
unavoidable that this process is also creating more regions our Universe with
space like separation, which in turn should give rise to Hawking radiation.
This would show up as an increased temperature which is a function of
da^2/dt^2. Now something may well be wrong with this train of thought.
However I can't see what it is.