Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.1 6/24/83; site utastro.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!harpo!seismo!ut-sally!utastro!ethan
From: ethan@utastro.UUCP (Ethan Vishniac)
Newsgroups: net.physics,net.astro.expert
Subject: quasars and the history of the universe
Message-ID: <291@utastro.UUCP>
Date: Wed, 16-May-84 18:27:46 EDT
Article-I.D.: utastro.291
Posted: Wed May 16 18:27:46 1984
Date-Received: Fri, 18-May-84 00:49:32 EDT
Organization: UTexas Astronomy Dept., Austin, Texas
Lines: 25

To quote from Mr. Gwyn:
>Although I am not convinced that the evidence that quasars are
>remote is conclusive, this question does not seem to be to bear
>directly on the question of which cosmology to choose.

I think I'd better expand on the point I was trying to make.
We see quasars in all directions at very large distances.
The space density of quasars at large distances is very much larger
than the local space density.  In fact we see that in a large shell
around us quasars were common at the point that they emitted the
light that reaches us.  If we just take the light travel time
from them to us we see that quasars were evidently common when
the oldest stars in our galaxy were just forming.  This is a strong
piece of circumstantial evidence that the universe as a whole has
changed a lot since our galaxy was young.  A steady-state cosmology
would not seem to be compatible with this conclusion.


                     "Just another Cosmic Cowboy"
                         
                         Ethan Vishniac
                         {ut-sally,ut-ngp,kpno}!utastro!ethan
                         Department of Astronomy
                         University of Texas
                         Austin, Texas 78712