Wigner's friend is a thought experiment in theoretical quantum physics, first published by the Hungarian-American physicist Eugene Wigner in 1961, and further developed by David Deutsch in 1985. The scenario involves an indirect observation of a quantum measurement: An observer W {\displaystyle W} observes another observer F {\displaystyle F} who performs a quantum measurement on a physical system.
Wigner's friend is a thought experiment in theoretical quantum physics, first published by the Hungarian-American physicist Eugene Wigner in 1961, and further developed by David Deutsch in 1985. The scenario involves an indirect observation of a quantum measurement: An observer W {\displaystyle W} observes another observer F {\displaystyle F} who performs a quantum measurement on a physical system.
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