hal@finney.org wrote:
>
> Slashdot has an article at
> http://slashdot.org/articles/00/12/07/0435211.shtml pointing to this
> New Scientist article http://www.newscientist.com/nlf/1209/wing.html
> about a supposed reactionless drive. It seems that when you turn on a
> superconducting magnet, and there is some metal in the magnetic field,
> the magnet shakes with a "jolt".
>
> Goodwin says the metal objects create the judder effect by inducing
> a "brief asymmetry in the magnetic field" as it is set up when the
> magnet is turned on. This initial disturbance of the magnetic field,
> he says, creates a repulsive force on the magnet and pushes it away.
>
> Isn't it obvious that this is just action and reaction? Whatever force
> the magnet fields, the metal which induces the force will feel an equal
> reaction.
>
> Somehow they think this means they can have a reactionless drive.
> It doesn't make any sense to me.
>
> Shades of the Lorrey drive....
Sorry Hal, no, the Lorrey Drive is a matter of a loophole in Mach's
Principle described by Prof John Cramer, and is not a truly reactionless
drive either, even under relativistic conditions. What is decribed above
does seem to be a reaction drive as well, since it involves the key
phrase of 'pushing away'.
A true reactionless drive would pull itself through space without any
kind of traction whatsoever and would be powered by a self contained
power source. Thermodynamics only requires that you either conserve mass
or you conserve energy, it does not mandate you do both at the same
time, as is proven by relativity.
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