Back صديق ويغنر Arabic উইগনারের বন্ধু Bengali/Bangla Wigners Freund German Amigo de Wigner Spanish Paradoxe de Wigner French חברו של ויגנר HE Paradosso dell'amico di Wigner Italian ウィグナーの友人 Japanese 위그너의 친구 Korean Przyjaciel Wignera Polish
Wigner's friend is a thought experiment in theoretical quantum physics, first published by the Hungarian-American physicist Eugene Wigner in 1961,[1] and further developed by David Deutsch in 1985.[2] The scenario involves an indirect observation of a quantum measurement: An observer observes another observer who performs a quantum measurement on a physical system. The two observers then formulate a statement about the physical system's state after the measurement according to the laws of quantum theory. In the Copenhagen interpretation, the resulting statements of the two observers contradict each other. This reflects a seeming incompatibility of two laws in the Copenhagen interpretation: the deterministic and continuous time evolution of the state of a closed system and the nondeterministic, discontinuous collapse of the state of a system upon measurement. Wigner's friend is therefore directly linked to the measurement problem in quantum mechanics with its famous Schrödinger's cat paradox.
Generalizations and extensions of Wigner's friend have been proposed. Two such scenarios involving multiple friends have been implemented in a laboratory, using photons to stand in for the friends.[3][4][5][6]
- ^ Wigner, Eugene P. (1961). "Remarks on the Mind-Body Question". In Good, I. J. (ed.). The Scientist Speculates: An Anthology of Partly-Baked Ideas. London: Heinemann. OCLC 476959404. Reprinted in Wigner, Eugene P. (1995). "Remarks on the Mind-Body Question". In Mehra, Jagdish (ed.). Philosophical Reflections and Syntheses. The Collected Works of Eugene Paul Wigner. Vol. B/6. Berlin, Heidelberg: Springer. pp. 247–260. doi:10.1007/978-3-642-78374-6_20. ISBN 978-3-540-63372-3. OCLC 924167486. Retrieved 2022-03-13.
- ^ Cite error: The named reference
deutsch1985was invoked but never defined (see the help page). - ^ Proietti, Massimiliano; Pickston, Alexander; Graffitti, Francesco; Barrow, Peter; Kundys, Dmytro; Branciard, Cyril; Ringbauer, Martin; Fedrizzi, Alessandro (2019-09-20). "Experimental test of local observer independence". Science Advances. 5 (9): eaaw9832. arXiv:1902.05080. Bibcode:2019SciA....5.9832P. doi:10.1126/sciadv.aaw9832. ISSN 2375-2548. PMC 6754223. PMID 31555731.
- ^ Merali, Zeeya (17 August 2020). "This Twist on Schrödinger's Cat Paradox Has Major Implications for Quantum Theory - A laboratory demonstration of the classic "Wigner's friend" thought experiment could overturn cherished assumptions about reality". Scientific American. Retrieved 17 August 2020.
- ^ Musser, George (17 August 2020). "Quantum paradox points to shaky foundations of reality". Science. Retrieved 17 August 2020.
- ^ Bong, Kok-Wei; et al. (17 August 2020). "A strong no-go theorem on the Wigner's friend paradox". Nature Physics. 27 (12): 1199–1205. arXiv:1907.05607. Bibcode:2020NatPh..16.1199B. doi:10.1038/s41567-020-0990-x.