Editing Closed system (section)

===In quantum physics===
{{further|Quantum field theory}}This equation, called [[Schrödinger equation|Schrödinger's equation]], describes the behavior of an isolated or closed quantum system, that is, by definition, a system which does not interchange information (i.e. energy and/or matter) with another system. So if an isolated system is in some pure state |ψ(t) ∈ H at time t, where H denotes the Hilbert space of the system, the time evolution of this state (between two consecutive measurements).<ref>{{Cite book |last1=Rivas |first1=Ángel |title=Open Quantum Systems |last2=Huelga |first2=Susana F. |author-link2=Susana F. Huelga |date=October 2011 |publisher=Springer-Verlag |isbn=978-3-642-23354-8 |location=Berlin Heidelberg}}</ref>

<math display="block">i\hbar \frac{\partial}{\partial t} \Psi(\mathbf{r}, t) = \hat{H} \Psi(\mathbf{r}, t) </math>

where {{math|''i''}} is the [[imaginary unit]], {{math|''ħ''}} is the [[Planck constant]] divided by {{math|2π}}, the symbol {{math|{{sfrac|∂|∂''t''}}}} indicates a [[partial derivative]] with respect to [[time]] {{math|''t''}}, {{math|Ψ}} (the Greek letter [[Psi (letter)|psi]]) is the [[wave function]] of the quantum system, and {{math|''Ĥ''}} is the [[Hamiltonian (quantum mechanics)|Hamiltonian]] [[Operator (physics)|operator]] (which characterizes the total energy of any given wave function and takes different forms depending on the situation).