To sum up, the classical view, put forward by Laplace, was that the future motion of particles was completely determined, if one knew their positions and speeds at one time. This view had to be modified when Heisenberg put forward his Uncertainty Principle, which said that one could not know both the position and the speed accurately. However, it was still possible to predict one combination of position and speed. But perhaps even this limited predictability might disappear if black holes are taken into account.
