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From: gwyn@BRL.ARPA
Newsgroups: net.physics
Subject: Re:  Light
Message-ID: <393@sri-arpa.ARPA>
Date: Mon, 15-Jul-85 01:32:35 EDT
Article-I.D.: sri-arpa.393
Posted: Mon Jul 15 01:32:35 1985
Date-Received: Wed, 17-Jul-85 05:21:47 EDT
Lines: 13

From:  Doug Gwyn (VLD/VMB) 

Gravity doesn't "bend light waves" according to general relativity;
it warps the structure of spacetime.  Light follows a null
geodesic (think of it as the "shortest path") in all cases,
so that it appears to take a bent path to an observer who does
not take the space-time curvature into account.

It is really meaningless to question whether the "speed of light
is constant" without describing how units of space and time
measurement are to be determined, since speed will be measured in
such units.  The concept of "null geodesic" is invariant with
respect to any choice of units.