Unlike classical physics, quantum mechanics generally cannot tell us exactly what will happen in an individual event. Instead, it predicts the probabilities of different outcomes. As one of the theory’s early pioneers, Erwin Schrödinger played a key role in debates about what this randomness really means. However, part of his contribution has stayed hidden for more than 80 years.

In a new study posted on the arXiv preprint server, Flavio Del Santo at the University of Geneva has analyzed an unpublished manuscript by Schrödinger, shedding new light on his thinking.