[Spaceships] Real Life Non-Super Science Reactionless Engines

[scc]

Originally Posted by Agemegos

Only if you also have faster-than-light transport or communications.

The "no preferred frames I'd reference" stuff, otherwise known as "the Principle of Relativity" goes back to Galileo, and without it the theory of electromagnetism gets very hairy. It has been very firmly established since the Michelson-Morley experiment, and if you dump it you need a new explanation for all the relativistic phenomena that have been observed.

The maxim is "relativity, causality, FTL: choose only two", and nearly everyone agrees that it's FTL that didn't make the cut in this universe.

I'll give you an example based upon my understanding of the problem. You're on a satellite that due to the speed of it's orbit experiences some time-dilation. Now the satellite your on only communicates once per day with Earth, at precisely midnight, Greenwich Mean Time, with asynchronous computer transfers. One day you notice that the daily upload from the ground has started early, you realize that it's because of relativity, but no special frames of reference says that the clocks on Earth are running slow, not yours, and that causality has been broken.