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From: knutsen@sri-unix.ARPA
Newsgroups: net.physics
Subject: Re:  Light
Message-ID: <345@sri-arpa.ARPA>
Date: Mon, 1-Jul-85 18:14:01 EDT
Article-I.D.: sri-arpa.345
Posted: Mon Jul  1 18:14:01 1985
Date-Received: Thu, 4-Jul-85 04:08:07 EDT
Lines: 15

From:  knutsen (Andrew Knutsen)

	The Michelson Morley experiment showed that the speed of light
is independent of direction. If the influence was being transmitted thru
a medium, this would only happen if the source were at rest with respect
to the medium. Since the earth cannot at all times be at rest with respect
to such a medium (due to its rotations and orbits), MM called the aether
into question and was one of the stepping-stones leading to special
relativity.

	The speed of light is slowed in glass because it is absorbed
and re-emitted by the glass atoms. No such thing seems to happen in
a vacuum.

Andrew