wm (08/14/82)
I used to worry about the problem of an absolute frame for rotation until someone explained it to me. I'm really not an expert, but from what I recall it goes something like this. First of all, accelleration is certainly not relative, but motion is. Someone else stated that a object rotating with respect to the (perhaps empty) universe would feel a force on it. I'm not sure if this is true. Consider a dimensionless point in space. If it is rotating in space, would it feel any force? Probably not. Now consider the ant on the edge of the flywheel. At any one moment in time it is traveling in a straight line. In the next moment, it will experience a force which will cause it to diverge from its path and start a new one at a slightly different angle. Even if we are in a reference frame that is traveling at the same velocity as the ant at this moment, we will observe it accellerating in the next moment. Now, if we remove the flywheel from the situation, the ant will continue to move in a straight line (or stay at rest, depending upon our original situation with respect to the ant). From this we can conclude that it is not the universe that is exerting a force upon the rotating ant, but the flywheel. As to what this force is, I don't know, but it is the same force that holds all matter together. Hope this causes more confusion! Wm Leler University of North Carolina, Chapel Hill