On the Possibility of a Propulsion Drive Creation Through a Local   Manipulation of Spacetime Geometry
  Since the shape of a free body's worldline is determined by the geometry of spacetime a local change of spacetime geometry will affect a body's worldline, i.e. a body's state of motion. The exploration of this possibility constitutes a radically new approach to the idea of how a body can be propelled: instead of applying a force to the body itself, the geometry of spacetime is subjected to a local manipulation which in turn results in the body's motion. 
Vesselin Petkov