By Armok, stop it lads. I don't really see what you are fighting about. One is saying A+B = C, and the other C-B = A, to put it simple. I'm no full-blown physicist, but I think I understand enough of gravity to contribute to this thread. I also am very sure that a "perpetuum mobile" in the truest sense, a machine that gaines net energy, is fucking impossible. It's along the same lines as saying "1-1 is NOT 0". No. That you can't gain energy from nothing is a fact. For every idea that sounded impossible and turned out to be well possible, there are thirty that sounded truly fucking bonkers and still are. The world isn't standing on a turtle, there is no god in the sky above us, Santa doesn't bring us presents, etc.
Anyway, it's been 3 years since my last calculations with gravity and centripetal force, so could this be theoretically feasible:
2 objects of sufficient speed, completly frictionless, orbiting themselves in a stable orbit, which, assuming no outside interference at all, would be eternally stable. (I know not realistic - just a theroretical model). Or would entropy still win and those objects would, given enough time, still crash. If this is possible, then a "perpetuum mobile"-like-device could be constructed, it's just practically impossible instead of theoretically. Even then it would only be "moving without an end", however you still couldn't extract energy from this system.
(Strange Mood over - any comments?)