[Spaceships] Real Life Non-Super Science Reactionless Engines

[malloyd]

Originally Posted by Agemegos

Agreed. I'm just saying that if you do (abandon the Postulate of Relativity) you can end up with a case in which travel occurs along a space-like interval (FTL in some inertial frames of reference, backward-in-time in others, instantaneous in boundary cases) but it is not possible for any signal from the arrival event to get back within the past-ward light-cone of the departure event.

Can you? If you have a special frame (and hence can define an absolute clock, the one that runs in it) aren't space-like and time-like intervals cleanly separated?