The existence of [equations of motion](Equations%20of%20motion%20in%20quantum%20mechanics.md) for [closed quantum systems](Closed%20quantum%20systems.md) is implied by the following postulate:  ^fcda57 This postulate describes the [dynamics of closed quantum systems,](Equations%20of%20motion%20for%20closed%20quantum%20systems.md) however it may be extended to [open quantum systems.](equations%20of%20motion%20for%20open%20quantum%20systems) #QuantumMechanics/QuantumDynamics #QuantumMechanics/FoundationsOfQuantumMechanics