Re: Laser as Reactionless Propulsion

Anders Sandberg (
23 Apr 1999 12:32:27 +0200 writes:

> anyway, i think ya probably get my halfassed idea. water is sprayed
> into a tube, where it falls thru a turbine and then thru a wormhole, from
> which it appears directly above the turbine again, and again, and again... if
> the wormhole is stable and is emitted somehow from something in a strong
> gravitional field, might this work?

Depends on the wormhole physics. Given my understanding of it, the device will not work. To keep a wormhole stable you need a "bracing" field of some kind (negative energy is most commonly suggested, although other weird physical processes might work). If you move mass through the wormhole, the mass will interact with the bracing field and this will change it. At least in the negative energy case you would get that the field got weaker as you passed mass through it, and if it ever got to zero, the wormhole will close. My guess is that if you calculate the energy gains and losses in the above scenario you will see that it will not produce perpetual motion, at most an amount of energy equal to the amount of energy put into the wormhole.

Still, general relativity relaxes energy conservation somewhat, energy is not well defined globally and in sufficiently odd spacetimes you can get energy for free. And even in less odd spacetimes you can likely extract energy from the spacetime (as in anisotropic collapsing universes, where you can exploit the shear forces).

Anders Sandberg                                      Towards Ascension!                  
GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y