EmDrive (also Relativity Drive) is the name of a spacecraft propulsion system proposed, and reportedly developed, by Roger Shawyer. New Scientist ran a cover story on EmDrive in its September 8, 2006 issue. The device is a Magnetron with a specially shaped fully enclosed tapering resonator cavity whose area is greater at one end. The inventor claims that the device generates thrust even though no detectable energy leaves the device. The inventor proposes to use it as a spacecraft propulsion system that uses no fuel (other than electricity).
On his homepagehttp://www.emdrive.com the inventor claims that independent peer-review is under way, but so far no publication is available.
The device's operation as described seemingly violates several basic laws of physics, notably conservation of momentum, though the inventor insists to the contrary. John Costella, an expert in relativistic electrodynamics describes the EmDrive as a 'fraud'.
