Re: A Question on cosmic background radiation

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

Robert B Zannelli wrote:
> The recent discovery that our Universe's expansion rate may be accelerating

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;  suggestions are welcome.
....
>     It seems to me that this acceleration, since it is creating spacelike
> separation between regions of space formally connected in timelike metrics,
> should be elevating the temperature of the CMB spectrum in a measurable way.

1) Since it's not really an acceleration, there's no reason
to believe that the exacerbation has any direct effect on
the temperature.

2) The expansion, whether or not it is exacerbating, causes
outward (not inward) accelerations, so we should expect the
temperature to be lowered (not elevated) thereby.  And this
is consistent with observations.  The cosmic background
radiation didn't start out as microwaves;  it started out at
optical frequencies and then cooled due to expansion.

>  may or may not be a worthy question

I thought it was worthy of a thoughtful answer, which is why
it took me a while to answer.  I wasn't ignoring it.


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