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From: dub@pur-phy.UUCP (Dwight U. Bartholomew)
Newsgroups: net.physics
Subject: Re: Nature of Photons
Message-ID: <1258@pur-phy.UUCP>
Date: Wed, 28-Mar-84 12:30:55 EST
Article-I.D.: pur-phy.1258
Posted: Wed Mar 28 12:30:55 1984
Date-Received: Fri, 30-Mar-84 00:55:27 EST
References: <2367@allegra.UUCP>
Organization: Purdue University Physics Dept.
Lines: 24


   Your article on the nature of light was very nice.  It was
very understandable (in a general sense.)  Just one tiny point.
I have heard people mention your explanation of how a laser
works, but I have also heard people who swear that the fact
that photons are bosons has nothing to do with it!
   You can think of a laser as a tuned optical cavity.
Such a cavity will only allow light wavelengths exactly fit inside
of the cavity (which consists of two parallel mirrors) (well, one
on the mirrors is only 99% reflecting.  you want SOME light to get out.)
The idea is that an atom gets excited by some external means and
then reradiates some light as it "drops" down into its unexcited
state.  The problem is to get MOST of the atoms excited it any one
time so that not all of the reradiated light is reabsorbed by the
atoms.  One way to do this is to cleverly choose a transition (an
excited state) that stays excited for a long time.  That way you
can "pump" alot of atoms into their excited states before any atoms
reradiate and can thus reabsorb.
   I haven't mentioned anything about bosons.  I am not trying to
knock your arguement down for it sure is an elagent agruement.
So, which is it: Boson or Cavity?

			D. Bartholomew