Path: utzoo!attcan!uunet!lll-winken!ncis.llnl.gov!helios.ee.lbl.gov!pasteur!ames!ncar!mailrus!bbn!rochester!dietz
From: dietz@cs.rochester.edu (Paul Dietz)
Newsgroups: sci.space
Subject: Tachyons
Message-ID: <1989Jan24.121432.3544@cs.rochester.edu>
Date: 24 Jan 89 17:14:31 GMT
References: <8901241509.AA20873@NMSU.Edu>
Reply-To: dietz@cs.rochester.edu (Paul Dietz)
Organization: U of Rochester, CS Dept, Rochester, NY
Lines: 34

In article <8901241509.AA20873@NMSU.Edu> space-request+@ANDREW.CMU.EDU writes:
>Those who find this FTL talk interesting will want to see this month's
>Discover magazine, which has the cover story "Beyond Einstein".  It
>contains some fascinating reference to tachyon theory, etc.  Nothing
>for the hard-core physicist, but easy reading, at least.

The article didn't mention one of the most peculiar attributes of
tachyons.

Consider a tachyon with imaginary rest mass iM and velocity u.
Define beta = |u|/c and gamma = (beta^2 - 1)^(-1/2).  The
tachyon has momentum

	p = M u gamma

and total energy

	E = M c^2 gamma.

The ratio of momentum to energy is

	|p|/E = beta / c.

Since beta can be arbitrarily large, a tachyon beam of fixed power can
carry an arbitrarily large amount of momentum, and therefore provide
any amount of thrust you desire.

It would be amusing indeed if someone discovered tachyons and used
them in a reaction drive.

:-)

	Paul F. Dietz
	dietz@cs.rochester.edu