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From: rwb@scicom.AlphaCDC.COM (Robert Brumley)
Newsgroups: sci.astro
Subject: Re: StarDate: October 22 Detecting Alien Spacecraft
Message-ID: <707@scicom.AlphaCDC.COM>
Date: Mon, 10-Nov-86 22:28:47 EST
Article-I.D.: scicom.707
Posted: Mon Nov 10 22:28:47 1986
Date-Received: Wed, 12-Nov-86 00:45:29 EST
References: <1353@utastro.UUCP> <1277@abnji.UUCP>
Organization: Alpha SCINET, Denver
Lines: 23
Summary: Gamma rays just a by-product of matter/antimatter propulsion

In article <1277@abnji.UUCP>, anon@abnji.UUCP (anon) writes:
> "Re: detecting alien spacecraft by their gamma ray exhaust"
> But wouldn't that exhaust be focused, like a searchlight, thus being
> impossible to detect unless the spacecraft was travelling derectly away from
> us on earth?


A paper by Dr. Robert Forward which was presented at the American Astronautical
Society meeting last month discussed matter/antimatter propulsion.  Due to
their nature, gamma rays are very difficult to use to propel a spacecraft.
However, when a proton encounters an antiproton, gamma rays are not immediately
produced.  I don't have the paper in front of me, so I can not be sure, but
I believe that on the average 3 charged and 2 neutral pions are produced.
The neutral pions almost immediately convert to gamma rays, thus 2/5 of the
energy is lost.  However, the 3 charged pions last long enough to be used in
a variety of ways.  The point is, the gamma radiation is essentially worthless
and need not be directed.  Therefore, though I am no expert, I would think that
it would be possible that the gamma radiation would just radiate in all
directions.

Robert Brumley

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