Re: absolute velocity, cosmology, special relativity

["John S. Denker" <jsd@MONMOUTH.COM>]

At 10:18 PM 2/20/01 -0600, Jack Uretsky wrote:
> prior to discovery of CBR there was no "preferred" reference frame in the
> universe.  Now there is.

I wouldn't have said that.

It would be better to say the cosmic microwave background radiation gives a
preferred reference frame for the CMBR itself, not for the universe.

To illustrate the distinction:  In space there is a distinctly nonzero
density of matter, averaging about [.1 to 1] atom per cubic meter in
intergalactic space (depending on whom you ask) (with denser clouds) and
about 10^5 per cubic meter within the galaxy (with much denser clouds).
  http://www.britannica.com/bcom/original/article/0,5744,16048+5,00.html
  http://www.physics.ucla.edu/class/00F/GE70A_Morris/notes/ge70ap04.pdf
This stuff is not comoving with the CMBR.  Does this mean there are now
_two_ preferred reference frames, one for the CMBR and one for the matter?

If you wanted to travel through space at relativistic speed, you'd soon be
more concerned with running into the matter than with running into the CMBR.

> Larry asks, what are the consequences of this
> new fact.  This might turn out to be a profound question.

I stand by my assertion that there is a distinction between the physical
LAWS and the physical OBSERVATIONS.  If these interstellar fluids were
somehow unscreenable, they would affect all measurements, and there might,
maybe, be a profound question.  But since we can easily screen out these
fluids and/or account for their effects, it remains appropriate to
formulate frame-independent laws.