If the emdrive works then conservation of momentum is out the window . At least for purposes of this worldbuilding exercise , I ' m assuming that just as relativity tossed out conservation of mass and replaced it with conservation of energyincludingmass , then physicists will be replacing the current version of c o nservationofmassandenergy with c o n s e r v a t i o n o f m a ssandenergyandinformation . I ' m not good enough at hypothetical physics to describe what that actually means , but if it becomes relevant , I might mention that the various predictions listed at ofmihsc . html tend to be confirmed as they ' re tested over time , lending increasing credence to that theory . But it ' s still early days , and I haven ' t committed to any particular variation of physics yet . If anyone reading this cares to make a more interesting suggestion , I ' ll be happy to read what you have in mind . season 5 episode 25 of Star Trek VoyagerI appreciate the suggestion , but the writing project I ' m trying to turn my attention away from for the week is about various forms of AI , including the occasional sophont one programmed to want to kamikaze .