When a complex system is left alone, it will return to its initial state with almost perfect precision. Gas particles in a container, for example, will return almost exactly to their starting positions after some time. For decades, scientists have investigated how this ‘Poincaré Recurrence Theorem’ can be applied to the world of quantum physics. Now, researchers have successfully demonstrated a kind of ‘Poincaré recurrence’ in a multi-particle quantum system.