It only works when mixed with red monkey droppings. I heard today that gravity affects time. Apparently, the higher gravity the slower time goes, or was it the other way about? I haven't looked it up yet.. To build a FTL device (engine is so 20th centuary) you need in all liklihood infinate gravity for propulsion (or traction) in a timeframe outside of normal spacetime obviously. This would require moderating and controlling something like a black-hole with n-dimentional physics (that may or may not exist), outside yet inside our timeframe. Good luck with that! The thing would be to bring the device up to full power, whilst preventing anything made of matter being attracted by it, so that for an instant you have infinite gravity causing zero time. Then distance covered by any mass is then irrelevant according to GR. That is, if a to b over t still applies at those energies. Even if you invented anti-gravity, AG would tear the whole thing to shreds. I don't see how it can be done.