The Principle of Indeterminacy, which saw the light in the summer of 1927, says in effect that you cannot know both a particle’s velocity and position. You can guess statistically what any batch of electrons might do, but you cannot predict the career of any one particle. They seem to be as free as dragonflies. You can perfect your instruments and your methods till the cows come home, and you will never ever be able to measure this one basic thing.
