In quantum physics, every object, such as an electron, is matched to a mathematical formula called the wave function. The wave function encodes all the details of an object’s quantum state, which means physicists can predict what an object might do in an experiment by combining its wave function with other equations. “The wave function of the universe is like a cosmic secret that physics itself conspires to keep. We can know enormously much about how the universe behaves, yet remain fundamentally uncertain of which quantum state it is in,” says Chen. Strikingly, upon completing the calculations, the team had to conclude that the universal quantum state is essentially unknowable.