poltergeist. yeah, or do they? okay. we're gonna talk about that. a fellow by the name of aristotle, who was a giant for the human intellect and the advancing humankind, way back fourth century b.c. classified many things and brought knowledge to a very, very high point. but aristotle made some mistakes-- and not to emphasize his mistakes, but one of the mistakes aristotle made was that if something's moving, again, there gotta be a reason for it. things don't move of themselves, and so we said if something moves, it's because there's a force pushing or pulling. these things started moving, you'd look for a force, wouldn't you? aristotle also. and so he made that one of the dictums, that if something's moving that doesn't ordinarily move, then there's a force acting. and, boom, that was carved in stone in the medieval years. but it bothered some people, because, take for example a cannonball shot from a cannon. here's a cannonball, okay? you put that inside the cannon, what makes the cannonball move? well, you got some gunpowder back here. you ignit