My friend presented a bit of a puzzle to me, and I can't remember enough physics to say whether it would work, and more importantly, why. It goes like this:
Imagine you are an extremely dexterous astronaut equipped with a ball on a string. If the ball is swinging around you and you pull the ball to yourself, tightening the orbit, do you experience a force moving you toward the ball? If so, could you then slowly widen the orbit, and repeat the process to move yourself (and the ball) in a desired direction?
It seems strange to me that a closed system (even one with an internal energy source) would be able to move through space, but I can't think of why it wouldn't work.
Some questions around this:
- What happens to the astronaut force-wise when widening the orbit?
- What happens to the astronaut force-wise when tightening the orbit?
One other note: this is not an attempt to create a perpetual motion machine. Obviously energy is expended changing the orbit of the ball.