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From: michaelm@bcsaic.UUCP (michael b maxwell)
Newsgroups: net.physics
Subject: Re: More on repulsion and attraction
Message-ID: <339@bcsaic.UUCP>
Date: Mon, 21-Oct-85 15:47:05 EDT
Article-I.D.: bcsaic.339
Posted: Mon Oct 21 15:47:05 1985
Date-Received: Wed, 23-Oct-85 05:40:40 EDT
References: <326@bcsaic.UUCP> <608@mtung.UUCP> <10634@ucbvax.ARPA> <613@mtung.UUCP> <1002@oddjob.UUCP>
Reply-To: michaelm@bcsaic.UUCP (michael b maxwell)
Organization: Boeing Computer Services AI Center, Seattle
Lines: 27
Summary: 

In article <1002@oddjob.UUCP> sra@oddjob.UUCP (Scott R. Anderson) writes:
>concept of the field.  It is difficult to think of [virtual particles] in 
>classical particle terms, though, because their primary characteristic is the
>momentum they carry (not to be confused with "the direction they are
>travelling"; this has no meaning).  This momentum can be both pointing
>away from *and* pointing towards the source particle.  What is unusual
>is that like-charged and oppositely-charged particles pick up one or
>the other, exclusively.

Now this is what I was hoping would come up in regards to my original
posting (asking how the exchange of virtual photons "explained"
repulsion between like-charged particles, and repulsion between
unlike-charged particles, if you came in late...).  

I can understand that a virtual particle would not have a direction of
travel, and therefore that the momentum of a virtual particle might not
have anything to do with direction of travel.  I have a more difficult
time understanding how one photon can have a momentum pointing away from
and towards the source particle at the same time--BTW, if they don't have
a direction of travel, how can there be a source particle?  But what I'd
really like to know is, is there some sort of intuitive explanation for
why like- or unlike-charged particles  "pick up" a photon with one or the
other momentum exclusively?
-- 
Mike Maxwell
Boeing Artificial Intelligence Center
	..uw-beaver!{uw-june,ssc-vax}!bcsaic!michaelm