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From: sra@oddjob.UUCP (Scott R. Anderson)
Newsgroups: net.physics
Subject: Re: Electron radius
Message-ID: <956@oddjob.UUCP>
Date: Thu, 5-Sep-85 02:51:26 EDT
Article-I.D.: oddjob.956
Posted: Thu Sep  5 02:51:26 1985
Date-Received: Thu, 5-Sep-85 10:21:14 EDT
References: <522@sri-arpa.ARPA> <954@oddjob.UUCP> <179@prometheus.UUCP>
Reply-To: sra@oddjob.UUCP (Scott R. Anderson)
Organization: University of Chicago, Department of Physics
Lines: 28

<< Just the facts, Ma'am. >>

>I believe Scott mentioned something of order 10^(-18) meters for the
>electron radius of an electron at rest.   Now where do you think
>Scotty got that number from?

Not an electron at rest, an electron who's position is known exactly.
And this is an upper limit on the electron radius, not necessarily
the radius itself.  I got that number from reading physics textbooks.
Forgive my faulty memory, though (am I getting old already?); the
actual scale is 10^(-17) meters.  This is still a factor of 100 less
than the classical electron radius ~ 10^(-15) meters.

This discrepancy is discussed in many physics books; you might, for
example, look at Jackson, Classical Electrodynamics, p. 790.  One
can also go to the literature for the actual experimental results;
I have done so, and have posted the reference to net.sources.  What's
that?  Wrong type of source?  Oh, in that case, here's one of them:

B.L. Beron, et al., Phys. Rev. Lett. 33, 663 (1974).

This is an e+e- collision experiment, and on the basis of this and
other experimental results, physicists have concluded that electrons
are much smaller than predicted by the classical electromagnetic
arguments recently discussed.

					Scott Anderson
					ihnp4!oddjob!kaos!sra