Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.2 9/17/84; site bcsaic.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!vax135!cornell!uw-beaver!ssc-vax!bcsaic!michaelm
From: michaelm@bcsaic.UUCP (michael b maxwell)
Newsgroups: net.physics
Subject: Re: Quantum electrodynamics and Feynman diagrams
Message-ID: <334@bcsaic.UUCP>
Date: Wed, 16-Oct-85 12:42:06 EDT
Article-I.D.: bcsaic.334
Posted: Wed Oct 16 12:42:06 1985
Date-Received: Fri, 18-Oct-85 01:13:41 EDT
References: <326@bcsaic.UUCP> <36@utastro.UUCP>
Reply-To: michaelm@bcsaic.UUCP (michael b maxwell)
Organization: Boeing Computer Services AI Center, Seattle
Lines: 20
Summary: 

In article <36@utastro.UUCP> ethan@utastro.UUCP (Ethan Vishniac) writes:
>Virtual particles can have a momentum oriented against their
>direction of motion.  Is this weird? You bet. 

Are you *serious*???  Assuming you are, what determines the direction of
the momentum of the virtual particle?  It seems that in order to explain
attractive and repulsive forces between all four combinations of
electric charges (i.e. {(--), (-+), (+-), (++)}), the direction of the
momentum must be determined by the charge of both the particle emitting
the virtual photon, and the particle receiving the virtual photon.  Is
this right?  Can you explain?  

Similar facts would seem to apply to forces mediated by other particles,
too--e.g. the strong nuclear force.  BTW, is the nuclear force--or rather,
the force between two quarks--ever repulsive?  e.g. when the two quarks
are the same color?
-- 
Mike Maxwell
Boeing Artificial Intelligence Center
	..uw-beaver!{uw-june,ssc-vax}!bcsaic!michaelm