According to the third law of motion, you van't have an mass
move in a particular direction unless there is a proportional
opposite mass/acceleration ratio in the opposite direction. No-
one has been able to provide a convincing argument otherwise,
but the best one to date is Shawyer's EM Drive. He claims some
fancy relativistic effects are what allows his engine to work,
but I have read some papers which claim he is a fraud. My
question is, why is it impossible to move a mass in a given
direction without a proportional change in the opposite
direction? I'm not talking about a perpetual motion machine, or
anything. Sure, the device would need to consume at least the
amount of energy proportional to the energy required to
accelerate the mass. Here's a highly hypothetical example: Say
we either can project a gravity well in front of our vehicle,
and/or project a gravity hill behind. In empty space, the
effects of the gravity will be near-negligible by the time they
reach any other object, however close to the ve