Swimming in spacetime: motion by cyclic changes in body shape.
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 spacetime 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.
Wisdom
Jack
J
Massachusetts Institute of Technology, Cambridge, MA 02139, USA. E-mail: wisdom@mit.edu