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From: debray@sbcs.UUCP (Saumya Debray)
Newsgroups: net.physics
Subject: (Re:)* Faster than Light
Message-ID: <117@sbcs.UUCP>
Date: Thu, 6-Dec-84 10:58:41 EST
Article-I.D.: sbcs.117
Posted: Thu Dec  6 10:58:41 1984
Date-Received: Thu, 13-Dec-84 01:35:00 EST
References: <327@mhuxt.UUCP> <8130@watarts.UUCP> <333@mhuxt.UUCP>, <2460@ihuxf.UUCP> <69@unc.UUCP>
Organization: Computer Science Dept, SUNY@Stony Brook
Lines: 22

I'm not sure if this has been pointed out already, but strictly speaking
it's not the "speed of light" that can't be exceeded, but rather the "speed
of light in vacuo".  It's possible for particles to exceed the speed of light
in other media, and this gives rise to a phenomenon called Cerenkov
Radiation.

If I recall correctly, Einstein's equations say that the speed of light
represents a barrier that cannot be _crossed_, i.e. it isn't possible to
accelerate an object from a velocity below c to one above c (this isn't my
area of expertise, so maybe someone can correct me if I'm mistaken).  It
doesn't rule out the possibility that something might start off travelling
faster than light -- of course, such a "something" would never be able to
decelerate below the speed of light.  These would be detectable by the
Cerenkov radiation they'd emit in a vacuum.  I think they were called
tachyons, and there were some attempts some years back to try to detect
them ... anyone know what happened?
-- 
Saumya Debray
SUNY at Stony Brook

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