The Wikipedia article on the Dean Drive suggests that there is ongoing research into proving the validity of Dean's proposals - testing to see if there is a 4th law of motion in addition to Newton's 3 existing laws.Back in the 1970's there was an "inventor" named Dean, who was working on the "Dean Drive". It was a Rube Goldberg (or Heath Robinbson) lashup of the level you see in perpetual motion machines. It spun a frame with an included mass and latching solenoid. The thing somehow caught the mass near the axle during part of the rotation, and released it such that it apparantly showed a decrease in weight. It looked impressive, as the machining was excellent. Probably soaked some money out of a few "investors".