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From: ST401385@BROWNVM.BITNET
Newsgroups: net.space
Subject: antimatter
Message-ID: <8603241716.AA18311@s1-b.arpa>
Date: Mon, 24-Mar-86 11:50:45 EST
Article-I.D.: s1-b.8603241716.AA18311
Posted: Mon Mar 24 11:50:45 1986
Date-Received: Thu, 27-Mar-86 01:17:56 EST
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Organization: The ARPA Internet
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In an article KFL@MC.LCS.MIT.EDU ("Keith F. Lynch") writes:
>
>  One theory says that antimatter is identical to matter only switched
>left to right...
     No theory I'm familiar with says that.  The operation of
changing a particle into its antiparticle is known as charge conjugation
(ie., reversal), refered to as the operator "C".  There is a general
theorem that Charge, Parity (left/right reversal), and Time
conjugation together (CPT) will return a particle to an indistinguishable
state.  (indistinguishable to itself:  That is, if a system is CPT
conjugated, there is no way to discover it within the system.)
   The tough part is going to be reversing time...
>  According to relativity, space is curved.  The curvature can be
>changed by rearranging masses.  So, while I see no way to put a half
>twist into space, it is by no means theoretically impossible or
>unthinkable.
    Unfortunately, a continuous parity transformation would requite
the TOPOLOGY of space to be changed.  Just moving masses around may
change the curvature, but the topology remains the same.  (eg., you
can distort a pancake into a bowl, but not into a coffee cup.  Or a
Moebus strip.)  (however, space which includes singularities
(eg., black holes) already has a distorted topology).

                   --Geoffrey A. Landis, Brown University
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