Paul Adrien Maurice Dirac (/dɪˈræk/ dih-RAK; 8 August 1902 – 20 October 1984) was an English theoretical physicist who is considered to be one of the founders of quantum mechanics.

He contributed to the Tube Alloys project, the British programme to research and construct atomic bombs during World War II.

[40][41][42] Paul Adrien Maurice Dirac was born at his parents' home in Bristol, England, on 8 August 1902,[43] and grew up in the Bishopston area of the city.

[49] Paul had a younger sister, Béatrice Isabelle Marguerite, known as Betty, and an older brother, Reginald Charles Félix, known as Felix,[50][51] who died by suicide in March 1925.

[63] Under the influence of Peter Fraser, whom Dirac called the best mathematics teacher, he had the most interest in projective geometry, and began applying it to the geometrical version of relativity Minkowski developed.

[75] Margit, known as Manci, had visited her brother in 1934 in Princeton, New Jersey, from their native Hungary and, while at dinner at the Annex Restaurant, met the "lonely-looking man at the next table".

[80] An anecdote recounted in a review of the 2009 biography tells of Werner Heisenberg and Dirac sailing on an ocean liner to a conference in Japan in August 1929.

Heisenberg was a ladies' man who constantly flirted and danced, while Dirac—'an Edwardian geek', as biographer Graham Farmelo puts it—suffered agonies if forced into any kind of socializing or small talk.

'"[81] Margit Dirac told both George Gamow and Anton Capri in the 1960s that her husband had said to a house visitor, "Allow me to present Wigner's sister, who is now my wife.

What I do see is that this assumption leads to such unproductive questions as to why God allows so much misery and injustice, the exploitation of the poor by the rich, and all the other horrors He might have prevented.

[9][11] He proposed and investigated the concept of a magnetic monopole, an object not yet known empirically, as a means of bringing even greater symmetry to James Clerk Maxwell's equations of electromagnetism.

Ralph Fowler, his research supervisor, had received a proof copy of an exploratory paper by Werner Heisenberg in the framework of the old quantum theory of Bohr and Sommerfeld.

Heisenberg leaned heavily on Bohr's correspondence principle but changed the equations so that they involved directly observable quantities, leading to the matrix formulation of quantum mechanics.

Several weeks later, back in Cambridge, Dirac suddenly recognised that this mathematical form had the same structure as the Poisson brackets that occur in the classical dynamics of particle motion.

[100] At the time, his memory of Poisson brackets was rather vague, but he found E. T. Whittaker's Analytical Dynamics of Particles and Rigid Bodies illuminating.

This formed the basis for Fermi–Dirac statistics that applies to systems consisting of many identical spin 1/2 particles (i.e. that obey the Pauli exclusion principle), e.g. electrons in solids and liquids, and importantly to the field of conduction in semi-conductors.

In fact, in a paper published in a book in his honour, he wrote: "The interpretation of quantum mechanics has been dealt with by many authors, and I do not want to discuss it here.

[131] In 1930, Victor Weisskopf and Eugene Wigner published their famous and now standard calculation of spontaneous radiation emission in atomic and molecular physics.

[137] Dirac was the one to initiate the development of time-dependent perturbation theory in his early work on semi-classical atoms interacting with an electromagnetic field.

Shin'ichirō Tomonaga, Schwinger and Feynman mastered this approach, producing a QED with unprecedented accuracy, resulting formal recognition by an award of the Nobel Prize for physics.

[145] In the 1950s in his search for a better QED, Paul Dirac developed the Hamiltonian theory of constraints[146][147] based[citation needed] on lectures that he delivered at the 1949 International Mathematical Congress in Canada.

The 1963–1964 lectures Dirac gave on quantum field theory at Yeshiva University were published in 1966 as the Belfer Graduate School of Science, Monograph Series Number, 3.

[152] Before his retirement he was offered a visiting position at the University of Miami in Coral Gables, Florida; he accepted, joining its newly formed Center for Theoretical Studies.

[96][154] Contemporary accounts of his time in Tallahassee describe it as happy, except that he apparently found the summer heat oppressive and liked to escape from it to Cambridge.

[81][169] In Lev Landau's logarithmic scale of physicists from 0 to 5 based off productivity and genius, he ranked Dirac a 1, along with other fathers of quantum mechanics, such as Werner Heisenberg and Erwin Schrödinger.

On 13 November 1995 a commemorative marker, made from Burlington green slate and inscribed with the Dirac equation, was unveiled in Westminster Abbey.

[171][173] The Dean of Westminster, Edward Carpenter, had initially refused permission for the memorial, thinking Dirac to be anti-Christian, but was eventually (over a five-year period) persuaded to relent.

[176] The Dirac-Hellman Award at Florida State University was endowed by Bruce P. Hellman in 1997 to reward outstanding work in theoretical physics by FSU researchers.

[177] The Paul A.M. Dirac Science Library at Florida State University, which Manci opened in December 1989,[178] is named in his honour, and his papers are held there.

[180] The street on which the National High Magnetic Field Laboratory in Innovation Park of Tallahassee, Florida, is located is named Paul Dirac Drive.