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From: sutin@astrovax.UUCP (Brian M. Sutin)
Newsgroups: net.physics
Subject: Re: Do Positrons Have Negative Mass?
Message-ID: <636@astrovax.UUCP>
Date: Sun, 25-Aug-85 13:20:49 EDT
Article-I.D.: astrovax.636
Posted: Sun Aug 25 13:20:49 1985
Date-Received: Tue, 27-Aug-85 06:10:12 EDT
Organization: Department of Astrophysics, Princeton University
Lines: 21

> There's a discussion on net.scifi-lovers relating to negative mass -
> the hope is to produce an FTL drive somehow. This triggered off a
> memory and I'm hoping someone can contribute.
> 
> In about 1966 I attended a seminar by Prof. Fairbanks who researched
> at Stanford U (I think). He was trying to slow down positrons for long
> enough to tell if they fell upwards or downwards.
> 
> Does anyone know how this turned out? If this experiment did not get
> completed, has there been any other work?
--------------------

	There is a theorem of particle physics which states that all
particles with a negative mass travel backwards in time.  This means
that the positrons will fall upward, but they do it backwards, so one
sees a downward fall forwards in time.  Since all the effects of a
negative mass cannot be distinguished from positive mass, all
particles are labeled with a positive mass just to keep things simple.
All this comes from charge, parity, and time symmetry arguements.

Brian Sutin -- Princeton Astrophysical Sciences