There are much simpler propellant-free ideas for producing relativistic speeds that respect known physics. I particularly like the resonant Photonic Laser Thrus

There are much simpler propellant-free ideas for producing relativistic speeds that respect known physics. I particularly like the resonant Photonic Laser Thruster: https://sci-hub.se/https://doi.org/10.1016/j.phpro.2012.08.026 https://sci-hub.se/https://doi.org/10.1016/j.phpro.2012.08.0... Indeed, the author had already done a bench-top demonstration: https://ykbcorp.com/photonic-laser-thruster/ https://ykbcorp.com/photonic-laser-thruster/