John Clauser | |
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 John Clauser in 2024 | |
| Born | John Francis Clauser (1942-12-01)December 1, 1942 (age 82) Pasadena, California, U.S. |
| Education | |
| Known for | Bell test experiments,CHSH inequality |
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| Scientific career | |
| Fields | Quantum mechanics |
| Institutions | |
| Thesis | Measurement of the Cosmic Microwave Background by Optical Observations of Interstellar Molecules (1970) |
| Doctoral advisor | Patrick Thaddeus |
| Website | johnclauser.com |
John Francis Clauser (/ˈklaʊzər/; born December 1, 1942) is an Americantheoretical andexperimentalphysicist known for contributions to the foundations ofquantum mechanics, in particular theClauser–Horne–Shimony–Holt inequality.[1] Clauser was awarded the 2022Nobel Prize in Physics, jointly withAlain Aspect andAnton Zeilinger "for experiments with entangled photons, establishing the violation ofBell inequalities and pioneering quantum information science".[2] In 2023, he declared himself as a climate change denier.
Clauser was born inPasadena,California. His father, Francis H. Clauser, was a professor of aeronautical engineering who founded and chaired the aeronautics department atJohns Hopkins University. He later served as the Clark Blanchard Millikan Professor of Engineering at theCalifornia Institute of Technology (Caltech).[3] His mother, Catharine McMillan, was the humanities librarian at Caltech and sister of 1951Nobel Prize in Chemistry laureateEdwin McMillan.[4]
He received aBachelor of Science in physics from Caltech in 1964, where he was a member ofDabney House.[5] He received aMaster of Arts in physics in 1966 and aDoctor of Philosophy in physics in 1969 fromColumbia University[1] under the direction ofPatrick Thaddeus.[6][7]
From 1969 to 1975, he worked as a postdoctoral researcher at theUniversity of California, Berkeley andLawrence Berkeley National Laboratory. In 1972, working withBerkeley graduate studentStuart Freedman, he carried out the first experimental test of the CHSH-Bell's theorem predictions. This was the first experimental observation of a violation of a Bell inequality.[1][8] In 1974, working withMichael Horne, he first showed that a generalization of Bell's Theorem provides severe constraints for all local realistic theories of nature (a.k.a. objective local theories). That work introduced the Clauser–Horne (CH) inequality as the first fully general experimental requirement set by local realism. It also introduced the "CH no-enhancement assumption", whereupon the CH inequality reduces to the CHSH inequality, and whereupon associated experimental tests also constrain local realism. Also in 1974 he made the first observation ofsub-Poissonian statistics for light (via a violation of theCauchy–Schwarz inequality for classical electromagnetic fields), and thereby, for the first time, demonstrated an unambiguous particle-like character forphotons.[citation needed]
Starting in 1973, Clauser published the newsletterEpistemological Letters, which was created because mainstream academic journals were relunctant to publish articles about thephilosophy of quantum mechanics.[citation needed] Clauser worked as a research physicist mainly atLawrence Livermore andBerkeley from 1975 to 1997. In 1976 he carried out the world's second experimental test of the CHSH-Bell's Theorem predictions.[9]
Clauser was awarded theWolf Prize in Physics in 2010 together withAlain Aspect andAnton Zeilinger. The three were also jointly awarded the 2022Nobel Prize in Physics.[10]
In May 2023, Clauser joined the board of theCO2 Coalition, aclimate change denial organization.[11] Later that year, Clauser called himself a "climate denier" and claimed "there is no climate crisis".[12] Clauser's views on climate change have been described as "pseudoscience".[12] His belief that cloud cover has more of an impact on Earth's temperature thancarbon dioxide emissions is contradicted by the overwhelmingscientific consensus on climate change.[12][13][14][15] Observational evidence shows the overall currentcloud feedback amplifies global warming and does not have a cooling effect.[16]
Clauser is anatheist. He hasemphysema due to smoking cigarettes in his youth.[12]
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