I’m pretty convinced accelerating a counter weight towards the speed of light will allow a craft to propel without ejecting mass. We aren’t there, however the

I’m pretty convinced accelerating a counter weight towards the speed of light will allow a craft to propel without ejecting mass. We aren’t there, however the physics is plausible. The electrostatic method I have heard of in several contexts (Lorentz field propulsion for instance) though holding breath in anticipation of working model.