So I'm writing a book. It's sci-fi. And the way I want to have these guys in the future produce their electricity is through Gravity. The way it works is there is a Halo-esque giant hollow ring around the planet and inside the ring there are these massive weights that, through the perpetual motion that comes with being in orbit, do the work needed to produce energy by themselves. So theoretically that means infinite energy. But the problem is, any work that the weights do would produce friction which would slow the weights down and eventually therefore stop at some point. So I need a way for the weights to 'work' without causing enough friction to slow them down. I had thought of simply installing some sort of device to 'kick' the weights back up to speed every so often, but you'd still need power to do that and in any case it sounds like a tacked-on idea when I'd rather have a proper solution if there is any.