Speed of light exceeded

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From: Sally Seebode (sseebode@earthlink.net)
Date: Thu Oct 12 2000 - 10:55:07 PDT 

Message-ID: <001701c03475$8ef039e0$c720e6c7@Seebode.smuhsd.k12.ca.us>
From: "Sally Seebode" <sseebode@earthlink.net>
Subject: Speed of light exceeded
Date: Thu, 12 Oct 2000 10:55:07 -0700

A student brought in an article from the WAshington Post 7/20/00 that states
that a pulse of light can travel 300 times the speed of light when traveling
through a cesium vapor in a "stable but highly unnatrural state." It goes on
to say that photons have traveled at 1.7 tmes the speed of light when going
through a mirror or opaqe barrier (Raymond Chiao of UC Berkeley). Finally,
it states that even througha pulse can travel faster tahn the speed of light
this does not break Einstein's light speed limit because a) photons don't
have mass and b) no meaningful signal or information can be transferred.

My question is I don't understand how light can not convey information ( I
thought light was information), and I thought that photons had an
infinitesimal mass (or is this just rest mass?)

thanks,
sally

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