Editing Freeman Dyson (section)

== Biography ==
=== Early life ===
Dyson was born on 15 December 1923, in [[Crowthorne]] in [[Berkshire]], [[England]].<ref name=rsbm/> He was the son of Mildred ({{née|Atkey}}) and the composer [[George Dyson (composer)|George Dyson]], who was later knighted. His mother had a law degree, and after Dyson was born she worked as a social worker.{{sfn|Stocke|2008}} Dyson had one sibling, his older sister, Alice, who remembered him as a boy surrounded by encyclopedias and always calculating on sheets of paper.{{sfn|Finkbeiner|2013}} At the age of four he tried to calculate the number of atoms in the Sun.{{sfn|Dyson|Rītups|2016}} As a child, he showed an interest in large numbers and in the [[Solar System]], and was strongly influenced by the 1937 book ''[[Men of Mathematics]]'' by [[Eric Temple Bell]].{{sfn|Lin|2014}} Politically, Dyson said he was "brought up as a socialist".{{sfn|Ghodsee|2015|p=5}}

From 1936 to 1941 Dyson was a scholar at [[Winchester College]], where his father was Director of Music.<ref name=rsbm/> At the age of 17 he studied pure mathematics with [[Abram Besicovitch]] as his tutor<ref name=MathsatCambs /> at [[Trinity College, Cambridge]], where he won a scholarship at age 15. During this stay, Dyson also practised [[night climbing]] on the university buildings,{{sfn|Schweber|1994|p=486}} and once walked from [[Cambridge]] to [[London]] in a day with his friend Oscar Hahn, nephew of [[Kurt Hahn]], who was a wheelchair user due to [[polio]].{{sfn|Schweber|1994|p=487}}

At the age of 19 he was assigned to war work in the [[Operations research#Second World War|Operational Research Section]] (ORS) of [[RAF Bomber Command]], where he developed analytical methods for calculating the ideal density for bomber formations to help the [[Royal Air Force]] bomb German targets during the [[Second World War]].{{sfn|Dyson|2006a}}{{sfn|Brower|2010}} After the war, Dyson was readmitted to Trinity College, where he obtained a [[Bachelor of Arts|BA]] degree in mathematics.{{sfn|Aharony|Feder|1989|p=66}}<ref name=ias.edu /> From 1946 to 1949 he was a [[fellow]] of his college, occupying rooms just below those of the philosopher [[Ludwig Wittgenstein]], who resigned his professorship in 1947.{{sfn|Dyson|2012}}

In 1947 Dyson published two papers in [[number theory]].{{sfn|Dyson|1947|pp= 225-240}}{{sfn|Dyson|1946|pp=409-420}} Friends and colleagues described him as shy and self-effacing, with a contrarian streak that his friends found refreshing but intellectual opponents found exasperating.<ref name=rsbm/> "I have the sense that when consensus is forming like ice hardening on a lake, Dyson will do his best to chip at the ice", [[Steven Weinberg]] said of him. His friend the neurologist and author [[Oliver Sacks]] said: "A favourite word of Freeman's about doing science and being creative is the word 'subversive'. He feels it's rather important not only to be not orthodox, but to be subversive, and he's done that all his life."{{sfn|Dawidoff|2009}}

=== Career in the United States ===
On [[G. I. Taylor]]'s advice and recommendation, Dyson moved to the United States in 1947 as a [[Harkness Fellowship|Commonwealth Fellow]] for postgraduate study with [[Hans Bethe]] at [[Cornell University]] (1947–1948).{{sfn|Aaserud|1986}}{{sfn|Schweber|1994|pp=392-}} There he made the acquaintance of [[Richard Feynman]]. Dyson recognized the brilliance of Feynman and worked with him. He then moved to the Institute for Advanced Study (1948–1949), before returning to England (1949–51), where he was a research fellow at the [[University of Birmingham]].<ref name=acap /> In 1949, Dyson demonstrated the equivalence of two formulations of [[quantum electrodynamics]] (QED): Richard Feynman's diagrams and the operator method developed by [[Julian Schwinger]] and [[Shin'ichirō Tomonaga]]. He was the first person after their creator to appreciate the power of [[Feynman diagram]]s and his paper written in 1948 and published in 1949 was the first to make use of them. He said in that paper that Feynman diagrams were not just a computational tool but a physical theory and developed rules for the diagrams that completely solved the [[renormalization]] problem. Dyson's paper and his lectures presented Feynman's theories of QED in a form that other physicists could understand, facilitating the physics community's acceptance of Feynman's work. [[J. Robert Oppenheimer]], in particular, was persuaded by Dyson that Feynman's new theory was as valid as Schwinger's and Tomonaga's. Also in 1949, in related work, Dyson invented the [[Dyson series]]. It was this paper that inspired [[John Clive Ward|John Ward]] to derive his celebrated [[Ward–Takahashi identity]].{{sfn|Ward|1950|p=182}}

Dyson joined the faculty at Cornell as a physics professor in 1951, though he still had no doctorate. In December 1952, Oppenheimer, the director of the [[Institute for Advanced Study]] in [[Princeton, New Jersey]], offered Dyson a lifetime appointment at the institute, "for proving me wrong", in Oppenheimer's words.{{sfn|Dyson|1979|p=}} Dyson remained at the Institute until the end of his career.{{sfn|Stone|2020}}{{sfn|Schewe|2014|pp=88–89}} In 1957 he became a [[Citizenship of the United States|US citizen]].{{efn|name=abjure}}<ref name=ias.edu /><ref name=britannica.com /> From 1957 to 1961 Dyson worked on [[Project Orion (nuclear propulsion)|Project Orion]],{{sfn|Klaes|2016}} which proposed the possibility of space-flight using [[nuclear pulse propulsion]]. A prototype was demonstrated using conventional explosives, but the 1963 [[Partial Nuclear Test Ban Treaty|Partial Test Ban Treaty]], in which Dyson was involved and which he supported,{{sfn|Schewe|2014|pp=162-164}} permitted only [[underground nuclear weapons testing]],<ref name=un.org /> and the project was abandoned in 1965.{{sfn|Schewe|2014|pp=147-149}}

In 1958 Dyson was a member of the design team under [[Edward Teller]] for [[TRIGA]], a small, inherently safe [[nuclear reactor]] used throughout the world in hospitals and universities for the production of [[Isotopes in medicine|medical isotopes]].{{sfn|Lo|2014}}

In 1966, independently of [[Elliott H. Lieb]] and [[Walter Thirring]], Dyson and Andrew Lenard published a paper proving that the [[Pauli exclusion principle]] plays the main role in the [[stability of matter]].{{sfn|Lieb|Thirring|1975|pp=687–689}} Hence it is not the electromagnetic repulsion between outer-shell orbital electrons that prevents two stacked wood blocks from coalescing into a single piece, but the exclusion principle applied to electrons and protons that generates the classical macroscopic [[normal force]]. In [[condensed matter physics]], Dyson also analysed the phase transition of the [[Ising model]] in one dimension and [[spin wave]]s.{{sfn|Dyson|1996|pp=287-}}

Dyson also did work in a variety of topics in mathematics, such as topology, analysis, number theory and [[Random matrix|random matrices]].{{sfn|Dyson|1996|pp=443-}} In 1973 the number theorist [[Hugh Lowell Montgomery]] was visiting the Institute for Advanced Study and had just made his [[Montgomery's pair correlation conjecture|pair correlation conjecture]] concerning the distribution of the zeros of the [[Riemann zeta function]]. He showed his formula to the mathematician [[Atle Selberg]], who said that it looked like something in [[mathematical physics]] and that Montgomery should show it to Dyson, which he did. Dyson recognized the formula as the [[pair correlation function]] of the [[Gaussian unitary ensemble]], which physicists have studied extensively. This suggested that there might be an unexpected connection between the [[distribution of primes]] (2, 3, 5, 7, 11,&nbsp;...) and the energy levels in the [[Atomic nucleus|nuclei]] of [[heavy elements]] such as [[uranium]].{{sfn|Derbyshire|2003|p=}}

Around 1979 Dyson worked with the [[Oak Ridge Associated Universities|Institute for Energy Analysis]] on [[Climatology|climate studies]]. This group, under [[Alvin Weinberg]]'s direction, pioneered multidisciplinary climate studies, including a strong biology group. Also during the 1970s, Dyson worked on climate studies conducted by the [[JASON (advisory group)|JASON]] defense advisory group.{{sfn|Dawidoff|2009}}

Dyson retired from the Institute for Advanced Study in 1994.<ref name=nasonline.org /> In 1998 he joined the board of the [[Solar Electric Light Fund]]. In 2003 he was president of the [[Space Studies Institute]], the space research organization founded by [[Gerard K. O'Neill]]; in 2013 he was on its board of trustees.<ref name=ssi.org /> Dyson was a longtime member of the [[JASON (advisory group)|JASON]] group.{{sfn|Schewe|2014|pp=166, 298}}

Dyson won numerous scientific awards, but never a [[Nobel Prize]]. Nobel physics laureate [[Steven Weinberg]] said that the [[Nobel Committee for Physics|Nobel committee]] "fleeced" Dyson, but Dyson remarked in 2009, "I think it's almost true without exception if you want to win a Nobel Prize, you should have a long attention span, get hold of some deep and important problem and stay with it for ten years. That wasn't my style."{{sfn|Dawidoff|2009}} Dyson was a regular contributor to ''[[The New York Review of Books]]'', and published a memoir, ''Maker of Patterns: An Autobiography Through Letters'' in 2018.{{sfn|Schewe|2014|p=299}}

In 2012 Dyson published (with [[William H. Press]]) a fundamental new result about the [[prisoner's dilemma]] in the [[Proceedings of the National Academy of Sciences of the United States of America]].{{sfn|Hawks|2012}} He wrote a foreword to a treatise on psychic phenomena in which he concluded that "ESP is real... but cannot be tested with the clumsy tools of science".{{sfn|Mayer|2008|loc=Foreword}}

=== Personal life and death ===
Dyson married his first wife, the Swiss mathematician [[Verena Huber-Dyson|Verena Huber]], on 11 August 1950. They had two children, [[Esther Dyson|Esther]] and [[George Dyson (science historian)|George]], before divorcing in 1958. In November 1958 he married Imme Jung (born 1936) and they had four more children: Dorothy, Mia, Rebecca, and Emily Dyson.{{sfn|Dawidoff|2009}}

Dyson's eldest daughter, Esther, is a digital technology consultant and investor; she has been called "the most influential woman in all the computer world".{{sfn|McKelvey|2014}} His son George is a [[history of science|historian of science]],{{sfn|Brockman|1996|p=81}} one of whose books is ''Project Orion: The Atomic Spaceship 1957–1965''.{{sfn|Dyson|2002|p=}}

Dyson died on 28 February 2020 at [[Penn Medicine Princeton Medical Center]] in [[Plainsboro Township, New Jersey]], from complications following a fall. He was 96.{{sfn|Stone|2020}}{{sfn|Johnson|2020}}{{sfn|Brumfiel|2020}}{{sfn|Levin|2020}}