"Paused" physical system Greetings, physicists and others, who just happen to understand physics. Something is bothering my mind again and I am hoping that some clarity will be given here. So, here is what I am thinking: if I Pause any physical system and, a bit after, sort of press "play" to continue the system - how does the system "know" which way to move? For example, for a simple ball thrown in atmosphere there could be, say, back and front air pressure difference, that can provide the direction information .. but if you start the system with just that information, the ball will actually move the opposite direction, because compressed air in front will tend to push the ball in the opposite direction. There must be more information and actual physical reason for the ball to move in the original way instead some other, random, way. In outer space there could be.. hmm.. blueshift and redshift, which can give you information about the direction and speed of the ball, but what is the reason for the ball to continue moving the way it did? I guess I am trying to understand inertia, because gravitational (and other) body attraction will continue after the system is resumed due to .. gravity (or EM or other). But even then - how would the system "know" the attracting bodies velocity before "paused"? And by "pausing" the system I dont mean doing anything mystical to the universe, but more like .. looking, measuring a moving system at any given point in time. Hope you understand.