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From: ethan@utastro.UUCP (Ethan Vishniac)
Newsgroups: net.sf-lovers
Subject: re: conservation of center of mass of the universe
Message-ID: <512@utastro.UUCP>
Date: Mon, 10-Sep-84 11:34:48 EDT
Article-I.D.: utastro.512
Posted: Mon Sep 10 11:34:48 1984
Date-Received: Fri, 14-Sep-84 09:04:59 EDT
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Organization: UTexas Astronomy Dept., Austin, Texas
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Perhaps this belongs in net.physics ... but converting mass to
energy (or vice-versa) does not in any way invalidate the correct
generalization of the invariance of the center of mass of an isolated
system.  The center of *mass-energy* does just fine thank you.

As to the center of mass of the universe, I'm not sure what that is, or
if that concept can be given any rigorous definition.  However, the
argument still follows if we consider the planets, stellar systems
whatever that include the beginning and endpoints of the matter transmission
as an isolated system.

              Ethan Vishniac