Editing Operator (physics) (section)

{{short description|Function acting on the space of physical states in physics}}
An '''operator''' is a [[Function (mathematics)|function]] over a [[State space (physics)|space]] of physical states [[onto (mathematics)|onto]] another space of states. The simplest example of the utility of operators is the study of [[Symmetry in physics|symmetry]] (which makes the concept of a [[Group (mathematics)|group]] useful in this context). Because of this, they are useful tools in [[classical mechanics]]. Operators are even more important in [[quantum mechanics]], where they form an intrinsic part of the formulation of the theory. They play a central role in describing observables (measurable quantities like energy, momentum, etc.).