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From: don@allegra.UUCP (D. Mitchell)
Newsgroups: net.physics
Subject: Photons must be Bosons
Message-ID: <2369@allegra.UUCP>
Date: Wed, 28-Mar-84 21:36:59 EST
Article-I.D.: allegra.2369
Posted: Wed Mar 28 21:36:59 1984
Date-Received: Fri, 30-Mar-84 01:13:29 EST
Organization: AT&T Bell Laboratories, Murray Hill
Lines: 12

Stimulated emission can ONLY happen with bosons.  In fact, physicists
say photons obey "Bose-Einstein" statistics because Einstein first
explained stimulated and spontaneous emission (the famous "A" and "B"
coefficients).

Only with Bosons do you get the situation that the probability of
stimulated emission (of a photon is a certain state) will be
proportional to the number of photons (all in that certain state)
comming by the excited atom.  Also, when the atom emits, the photon it
gives off will be in the SAME STATE as the big herd of photons coming
by; that is, it will be the same frequency and direction and will be in
phase with them.  That is why laser light is coherent.