Happy Anniversary To The Test That Showed ‘God Does Play Dice’ With The Universe
On September 27, 1972, scientists performed the first test of Bell’s inequality. God does play dice with the Universe, after all.
One of the most puzzling and counterintuitive aspects of quantum physics is the apparent link between determinism and measurement. Make a precise measurement of the quantum state of your particle — of its spin, its position, or which slit it went through — and you determine that property exactly. Choose not to make that measurement, and that property is indeterminate. To measure or not measure, mind-bogglingly, leads to different experimental outcomes.
Could this be right? Could there be a fundamental randomness to the Universe: an indeterminism that is inherent to nature itself? For generations, scientists argued whether the ability to predict only probabilities of outcomes meant quantum mechanics was incomplete. Was there more to nature than all we can see? Here’s the story of how, through cleverly-designed and carefully-executed experiments, we learned the answer.
