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From: ethan@utastro.UUCP (Ethan Vishniac)
Newsgroups: net.physics,net.astro.expert
Subject: paradox????
Message-ID: <287@utastro.UUCP>
Date: Wed, 16-May-84 10:49:26 EDT
Article-I.D.: utastro.287
Posted: Wed May 16 10:49:26 1984
Date-Received: Thu, 17-May-84 04:59:07 EDT
Organization: UTexas Astronomy Dept., Austin, Texas
Lines: 43

[In the beginning was the word, and the word was tenure]

D. Gwyn writes:
>Here is my favorite cosmology:
>	(1) Space isotropic (same, on a large scale, in all directions).
>	(2) Distant light red-shifted `a la Hubble.
>	(3) Therefore, light is "infinitely" red-shifted in the limit
>	    that it originates from a certain large distance (call it
>	    the "radius of the universe" for definiteness).
>	(4) The local average density of matter etc. is static (does
>	    not change in time).
>	(5) The above all apply to every point in the universe, at
>	    every time.

I have mentioned elsewhere why the essential elements of this cosmology
fail to explain our observations of  the universe.  In this note I
just want to note an apparent paradox in this model that Mr. Gwyn has
not addressed. Perhaps he has something in mind.

   Stars can be considered as machines for manufacturing entropy.  To
put it more exactly, they take a lot of hydrogen and make it into heavier
elements.  The photons produced from this are casually strewn across the
cosmos.  If the universe is not expanding, and is steady state, then it
would appear that the material in the universe will gradually be made into
heavy atoms (ultimately  isotopes near Fe56).  This is certainly not
a universe which is constant in time.  Gwyn's universe seems to require
some form of magic to undo the increase in entropy caused by the stars.
An example of such an engine would be to say that the tooth fairy goes
around breaking apart the heavier elements down into hydrogen.
In our own galaxy we see this process (the increase in entropy, not the
appearance of the tooth fairy) in that the oldest stars are almost
pure hydrogen and helium.  Younger stars, formed from an increasingly
contaminated interstellar medium, can have as much as 4% heavier atoms.
Our own sun has about 2%.


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