even in a vacuum, perpetual motion is difficult to achieve. but what about the planets, always spinning? perhaps it's not so impossible to achieve by simply replicating a body so massive it gains its own gravitational field, and many more bodies to generate energy. gravity to power. can it be done?
perhaps it is even more frightening to think that one day the earth will stop spinning. days become slower and eventually stop; half the planet is stuck in perpetual day, half in perpetual night. we don't get seasons anymore, no more calendar. it's always november 12th. every day is that same someone's birthday. the weather stays the same; sorry if you don't like winter (or summer, to the southern hemisphere).