DANGER: Mass-Independent Drive Is Perpetual Motion Machine

> ...the way an MT manuver drive works is counterintuitive (ie only volume is
> important, not mass).  In any drive that depends on mass, this won't work
> well...

Aiigh.  I don't know my Traveller well enough to comment very authoritatively,
but if the above statement is true, a Traveller perpetual motion machine
(i.e. an infinite energy source) exists.  Proof:

Take a body with finite volume V and mass m.  Let the energy required by the
maneuver drive to move the body a distance h against a gravitational field
of constant g be E(V,g,h) .  For a practical drive, there must exist a V,g,h
such that E(V,g,h) is finite.  Choose such a triple.  Note that the energy
gained in moving the body downward from a height h in the field by
conventional means (i.e. dropping the body :-) is mgh .

Thus, one can construct an engine whose energy consumption per cycle is
E(V,g,h) - mgh .  A perpetual motion machine can be constructed if there
exists an m such that E(V,g,h) - mgh < 0, i.e. m > E(V,g,h)/gh .  But for
fixed V,g,h the RHS of this inequality is constant, and we can make m
arbitrarily large -- Q.E.D.

Note that the energy yielded by such a machine increases with increasing m
for any given V.  Thus, one apparently wants an extremely dense object to
act as a piston in this machine...  Note also that such a machine could
apparently fairly easily realize a Doomsday device for the entire Traveller
universe (proof left to the reader), and thus had probably better not exist...

					Bart Massey
					..[email removed]
					..[email removed]