Re: Old Stars

[jmclean@chem.ucsd.edu (James Mclean)]

Bowman_David/tiger_mpc@tiger.gtc.georgetown.ky.us says:
> ...
> Thus it is these relic photons which date from about 500kyr after the BB which
> are seen today as the cosmic background.  Also these photons did not
> necessarily take "long to get here".  They have been bathing the entire
> universe--going in all different directions since they were formed.  The ones

Given my new understanding of this (Thanks!), a few questions come to mind:

Consider a cosmic background photon which was originally emitted someplace
which I'll call 'there', and is just now getting 'here'.  Say this photon
comes from an event that was 10^10 years ago.  How far apart were 'here'
and 'there' when the photon was emitted?  How far apart are 'here' and
'there' now?  If space has been expanding, it's not clear to me that the
answer to either question is 10^10 lightyears.

-- 
--James McLean
jmclean@chem.ucsd.edu
post doc
UCSD