Narrow wave packets that follow the Schrödinger equation approximately follow Newtonian trajectories when external potentials are sufficiently uniform across the packet width.

In a number of models of environmental decoherence, however, it is obvious what the dynamical behaviour should be even at the level of individual components. Specifically, in models where the preferred states are coherent states, comparison of the master equation for the reduced state of the system with the evolution of a classical Liouville distribution suggests that the trajectories of individual components in fact approximate surprisingly well the corresponding Newtonian trajectories. Intuiti