negative mass propulsion
Negative mass propulsion is a hypothetical propulsion system based on the juxtaposition of ordinary positive mass and negative mass. In theory, such a system would be able to provide continuous thrust, without violating the principles of conservation of momentum or energy. It would require no input energy and no reaction mass. Workability of the scheme, however, hinges on the existence of negative mass and also on negative mass having negative inertia. The combined interactions of the two types of mass would then result in a sustained acceleration of both masses in the same direction. The concept of negative mass was first considered in depth by Herman Bondi1 in 1957 and revisited in the context of interstellar spaceflight by Winterberg2 and Robert Forward3 in the 1980s.
1. Bondi, H. "Negative Mass in General Relativity," Reviews of Modern
Physics, Vol. 29, No.3, July 1957, pp. 423-428.
2. Winterberg, F. "On Negative Mass Propulsion," International Astronautical Federation, Paper 89-668, 40th Congress of the International Astronautical Federation, Malaga, Spain, Oct., 1989.
3. Forward, R. L. "Negative Matter Propulsion", Journal of Propulsion and Power (AIAA), Vol. 6, No. 1, Jan.-Feb. 1990, pp. 28-37.