Hi All

Abstract from this week's Science...

Swimming in Spacetime: Motion by Cyclic Changes in Body Shape
Jack Wisdom 1*

1 Massachusetts Institute of Technology, Cambridge, MA 02139, USA.

* To whom correspondence should be addressed. E-mail: wisdom@mit.edu.

Cyclic changes in the shape of a quasi-rigid body on a curved manifold can lead to net translation and/or rotation of the body. The amount of translation depends on the intrinsic curvature of the manifold. Presuming space-time is a curved manifold as portrayed by general relativity, translation in space can be accomplished simply by cyclic changes in the shape of a body, without any external forces.

... so maybe spinning systems of masses might make a space-drive.

Adam