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From: claus@inuxd.UUCP (David Claus)
Newsgroups: net.physics
Subject: Re:  Light
Message-ID: <778@inuxd.UUCP>
Date: Mon, 8-Jul-85 12:08:34 EDT
Article-I.D.: inuxd.778
Posted: Mon Jul  8 12:08:34 1985
Date-Received: Tue, 9-Jul-85 06:17:39 EDT
References: <345@sri-arpa.ARPA>
Organization: AT&T Consumer Products, Indianapolis
Lines: 19

The speed of light is not always constant.  Einstein assumed that
the speed of light was constant through any round trip.  The
speed of light through one leg of that trip can be greater than
the speed through another leg.

Take for example a light pulse being sent from the earth to the moon
and back.  Light will travel faster on the way back than on the way
there because of gravity effects.  Does general relativity take this
into account somehow?  It is proven that gravity bends light waves
(through sun eclipse experiments) so why shouldn't gravity also increase
the speed of the light wave?  Has there been an experiment that has
measured the speed of light during a one way trip through some
gravitational potential?  Most measurements I've heard of involve
the reflection back and forth of a light wave here on earth.

Can anyone explain this to me.

Dave Claus
AT&T/Indy