> > Now Chris Van Den Broeck of the Institute for Theoretical
> > Physics at the Catholic University of Leuven, Belgium, has
> > resurrected Alcubierre's proposal. The trick lies in using a
> > strange form of warped space, involving a "bubble" with a large
> > internal volume but a tiny surface area.
This is available at http://xxx.lanl.gov/abs/gr-qc/9905084. The abstract is:
I show how a minor modification of the Alcubierre geometry can dramatically improve the total energy requirements for a `warp bubble' that can be used to transport macroscopic objects. A spacetime is presented for which the total negative mass needed is only in the order of grams, accompanied by a negligible amount of positive energy. This constitutes a reduction of the absolute value of the energy by 65 orders of magnitude. The new geometry satisfies the quantum inequality concerning WEC violations and exhibits the same advantages as the original Alcubierre spacetime.
Unfortunately the existence of negative matter is still hypothetical. (It's not anti-matter, it is matter with negative mass, which is far more exotic.)