Uncertainty Prevents Hard Determinism

The Heisenburg Uncertainty Principle provides a universal limit on determinism. The future is no more determined than the quantum uncertainties of position and momentum or of time and energy allow for. The Universe, in effect, plays dice. Those quantum uncertainties are amplified on the macro-scale via the Butterfly Effect whereby the slightest difference in initial conditions results in a completely different outcome after only a few iterations of quantum diffraction and collisions. Thus is, for example, why the weather is predicted based on chance and probability instead of with a sense of absolute certainty.





Sources:

Picture #1: Feynman's Lectures on Physics, Volume 3