[Bozos of Bones]

I don't know about you, but I think that "let's go back in time" is just for example. No mentioning the current impossibility to travel through time, what tells us that the time flux will be exactly the same? There are off course other points, but let's continue to answer the last thread.
Gravitic drive is a high energy manipulator device. To explain how it would work, think off gravity sling shot effects. The gravitic drive would lock on to a planets gravity, focus it and use it to propell the ship through space. NASA is currently researching the next generation(first was sling-shot launchings to further a craft's range and modify it's course), a kind of ultra-light sail which would be powered by solar beams. The volume of the sail would theoretically be used as a gravity ancor for the craft. Gravity will work maximised on the ship only under a certain angle. If a ship is very close to planet A, and a bit farther is planet B, assuming both planets have same pull force, by merely shifting the angle of the sail the craft would be drawn to planet B by more force.
The generation after that has something to do with quantuum phisics, and I'm currently studying it. More when finished.