The Problem Is How to Calculate the Individual Trajectories of All Molecules

In probability theory, the expectation values are used to describe trajectories of particles. But in quantum mechanics, there is an ensemble of particles that move along trajectory. So some of the mi some of the microscopic properties will really be time averages of something that is happening. And this was another, right, sort of, another controversial idea. It introduces randomnes into these pristine physical, er dynamical systems of mechanics.