The total energy of any physical system is given by its [Hamiltonian.](Hamiltonians.md) In quantum mechanics this energy expression comes about from the application of an [observable](Observable.md) called the _Hamiltonian operator._ ^658f3f # Quantizing a classical Hamiltonian # Time independent Hamiltonian operators [[Hamiltonian operator (time independent)]] ## Time independent perturbation Hamiltonians # Time dependent Hamiltonian operators .md#^11f289) ([... see more](Hamiltonian%20operator%20(time%20dependent).md)) #QuantumMechanics/QuantumMeasurement/QuantumObservables