EmDrive (also Relativity Drive) is the name of a spacecraft propulsion system proposed by British aerospace engineer Roger J. Shawyer, who develops prototypes at Satellite Propulsion Research Ltd (SPR), the company he created for that purpose in 2000. New Scientist ran a cover story on EmDrive in its 8 September 2006 issue. The device uses a magnetron producing microwaves directed inside a specially shaped, fully enclosed tapering high Q resonant cavity whose area is greater at one end, upon which radiation pressure would act differently due to a relativistic effect caused by the action of group...