Science fiction authors used to say we would use something better when we went into space, but three centuries later we still use rockets. Yes they are more advanced than what propelled our Apollo missions, but the German scientists that pioneered them knew what we still use. We dump fuel into a reaction chamber, make it explode, and use that push to send us flying in the way we want to go. But the Peloran gravtech changed everything. Now we use a gravitic generator to lower our effective mass so it only takes a very small push of the engines to send us flying far faster than we ever could in the old days. It is amazing how much just a single application of alien technologies can change all of our worlds.