Field propulsion systems for space travel

Field propulsion systems were proposed by many researchers to overcome the speed limit of the conventional space propulsion system. Field propulsion system can be propelled without mass expulsion; its propulsion principle can induce a propulsive force (i.e., thrust) that arises from the interaction of the substantial physical structure. This notion is based on the assumption that space as a vacuum possesses a substantial physical structure. This evaluation examines the substantial physical structure regarding the space-time from both General Relativity in the view of a macroscopic structure and Quantum Field Theory in the view of a microscopic structure. Thus, several kinds of field propulsion system can be proposed by making these choices considering the structure of physical space.