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Re: A Question on cosmic background radiation



Spinoza321@aol.com wrote (off list):
...
why doesn't the apparent d^2a/dt^2>0 have an impact on the CMB.... it
is believed that an accelerated object experiences radiation, similar in
nature to Hawking radiation. This is known as the Unruh effect.

I thought I already answered this.

At 07:28 03/15/2002 I wrote

I don't think "accelerating" is the right word.
If a velocity changes, we say there is an acceleration.
But since the Hubble parameter has units of 1/time, not
distance/time, a change therein shouldn't be called an
acceleration. Maybe we should call it an "exacerbation"
or something....

Applying Unruh's temperature-versus-acceleration formula to
something that is not really an acceleration is not physics.
It's just "a specious and fantastical arrangement of words, by
which a man can prove a horse-chestnut to be a chestnut horse."
http://www.bartleby.com/251/pages/page358.html

Now my question remains. Assuming that in
fact d^2a/dt^2>0, then similar boundaries must be created in our universe.

The parameter "a" has to do with the local geometry of the universe.
It tells us nothing about the topology, and certainly nothing
about the boundary conditions. See e.g. section "D" of box
27.2 on page 725 of Misner, Thorne, Wheeler for an explicit
warning and illustrative example.

Now I suspect
there is a flaw is this chain of reasoning but I can't see
what it is. .... My post to the list
which laid this thought process out in detail was ignored.

No, it wasn't.

If you want to see a third flaw in the reasoning, try this:
Just what is it that is accelerating?
-- The background-radiation photons are on lightlike trajectories,
and always have been, so you're going to have a hard time accelerating
or decelerating them.
-- Unruh's argument, as I understand it, involves acceleration
of a black-body source. Now the source of the cosmic background
radiation ceased to exist many billions of years ago, so I fail
to see how any expansion or exacerbation at the present time could
have any relevance thereto.