John Clive Ward | |
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| Born | (1924-08-01)1 August 1924 London, England |
| Died | 6 May 2000(2000-05-06) (aged 75) Victoria, British Columbia, Canada |
| Alma mater | University of Oxford |
| Known for | Ising model Quantum field theory Ward–Takahashi identity Luttinger–Ward functional Hydrogen bomb |
| Awards | Guthrie Medal (1981) Dirac Medal (UNSW) (1981) Heineman Prize (1982) Hughes Medal (1983) |
| Scientific career | |
| Fields | Particle physics Condensed-matter physics Statistical mechanics |
| Institutions | Institute for Advanced Study Bell Laboratories University of Adelaide University of Maryland University of Miami Carnegie Institute of Technology Johns Hopkins University Victoria University of Wellington Macquarie University |
| Thesis | Some Properties of Elementary Particles (1949) |
| Doctoral advisor | Maurice Pryce |
John Clive Ward,FRS (1 August 1924 – 6 May 2000) was an Anglo-Australianphysicist who made significant contributions to quantum field theory, condensed-matter physics, and statistical mechanics.Andrei Sakharov called Ward one of the titans of quantum electrodynamics.
Ward introduced theWard–Takahashi identity. He was one of the authors of theStandard Model of gauge particle interactions: his contributions were published in a series of papers he co-authored withAbdus Salam. He is also credited with being an early advocate of the use ofFeynman diagrams. It has been said that physicists have made use of his principles and developments "often without knowing it, and generally without quoting him."[1] TheIsing model was another one of his research interests.
In 1955, Ward was recruited to work at theAtomic Weapons Research Establishment atAldermaston. There, he independently derived a version of theTeller–Ulam design, for which he has been called the "father of the British H-bomb".[2]
John Clive Ward was born inEast Ham,London,[3] on 1 August 1924.[1] He was the son of Joseph William Ward, acivil servant who worked inInland Revenue,[3][4] and his wife Winifrednée Palmer, a schoolteacher. He had a sister, Mary Patricia. He attended Chalkwell Elementary School andWestcliff High School for Boys. In 1938 he sat for and won a £100 scholarship toBishop Stortford College. He took theHigher School Certificate Examination in 1942, receiving distinctions in Mathematics, Physics, Chemistry and Latin, and was offered a postmastership (scholarship) toMerton College, Oxford.[3][5]
Although theSecond World War was raging at the time, Ward was not called up by the Army, and was allowed to complete hisBachelor of Arts degree in Engineering Science withfirst class honours, studying mathematics underJ. H. C. Whitehead andE. C. Titchmarsh. He received a bursary from the Harmsworth Trust, and in October 1946, with the war over, secured a position as a graduate assistant toMaurice Pryce, who had recently been appointed a professor of theoretical physics at Oxford.[3]
Ward's total number of published papers was only about 20, a fact that reflects a strong sense of self-criticism. He was also critical of what he called "PhD factories" and expressed scepticism towards the importance attached to having a large number of citations.[6] He never supervised graduate students.[3] He received some significant awards, including theGuthrie Medal andDirac Medal of theUniversity of New South Wales in 1981, theHeineman Prize in 1982, and theHughes Medal in 1983 "for his highly influential and original contributions to quantum field theory, particularly the Ward identity and the Salam–Ward theory of weak interactions".[7] He became afellow of the Royal Society in 1965.[3][8]
Andrei Sakharov said Ward was one of the "titans" of quantum electrodynamics alongsideFreeman Dyson,Richard Feynman,Julian Schwinger,Sin-Itiro Tomonaga andGian Carlo Wick.[9] In this regard, it has been said that physicists have made use of his principles and developments "often without knowing it, and generally without quoting him."[1]
In 1947, Ward and Pryce published a paper inNature, in which they were the first to calculate, and use,probability amplitudes for the polarisation of a pair ofquantum entangledphotons moving in opposite directions.[10][11] For polarisationsx andy, Ward derived this probability amplitude to be:[11]
which can benormalised as:[11][12]
This can be used to derive the correlation of polarisation of the two photons.[10] Their prediction was confirmed experimentally byChien-Shiung Wu and I. Shaknov in 1950.[13] This was the first experimental confirmation of a pair of entangled photons as applicable to theEinstein–Podolsky–Rosen (EPR) paradox.[14] The result was subsequently explained byRichard Dalitz andFrank Duarte.[11][1][15] Apparently followingDirac's doctrine, Ward was never bothered by issues ofinterpretation in quantum mechanics.[12]
With his Harmsworth scholarship expiring, and seeing few prospects at Oxford, Ward responded to a job advertisement from theUniversity of Sydney. He was offered a position, but when he arrived, found that it was for a tutor, and not alecturer. He therefore served out the year, then returned to Oxford to complete hisDoctor of Philosophy (D.Phil.) thesis on "Some Properties of the Elementary Particles". Ward expected that his thesis, an elaboration of his 1947 paper, would be easily approved by the external examiner,Nicholas Kemmer, but at the last minute Kemmer's place was taken byRudolf Peierls, who refused to accept it. Only after a forceful argument by the internal examiner, J. de Witt, was the thesis awarded.[3][16]
Pryce arranged for Ward to receive an award from theDepartment of Scientific and Industrial Research (DSIR) for two years. It was then that he developed theWard–Takahashi identity, originally known as "Ward Identity" (or "Ward's Identities").[1][3][17] This result inquantum electrodynamics was inspired by a conjecture ofFreeman Dyson,[18] and was disclosed in a one-half-page letter typical of Ward's succinct style. In their bookQuantum Electrodynamics,Walter Greiner andJoachim Reinhardt [de] state in their discussion of chargerenormalisation: "the Ward Identity has a much more fundamental significance: it ensures theuniversality of the electromagnetic interaction."[19] In his bookThe Infinity Puzzle,Frank Close wrote: "Ward's Identities are the basic foundations on which the entire edifice of renormalisation rests."[2]
In 1950, Ward's DSIR fellowship was coming to an end. Pryce had become a visiting professor at theInstitute for Advanced Study inPrinceton, New Jersey, and Ward's colleaguesP. T. Matthews andAbdus Salam were visiting members there in the 1950–1951 academic year. Through them, he was able to secure a $3,000 membership for the 1951–1952 academic year. It was at Princeton that he was introduced to theIsing Model, and metMark Kac fromCornell University, with whom he would collaborate on an exact solution of the Ising model using a combinatorial method.[3][20][21] His joint work with Kac on the Ising Model gave rise to what is now being called the Kac-Ward operator.[20][22] When his membership ended he worked for theBell Laboratories in 1952 and 1953.[1] He then accepted an offer of a lectureship at theUniversity of Adelaide fromBert Green, where he worked for a year before taking up another membership at the Institute for Advanced Study.[3]
Ward left the British hydrogen bomb programme and took a job with an electronics company in California. Later in 1956,Elliott Montroll offered him a visiting professorship at theUniversity of Maryland.[3] Noting a recent paper byKeith Brueckner andMurray Gell-Mann on the ground state energy of anelectron gas, Ward gave a lecture in which he proposed a different approach. Montroll recognised that this wasDebye–Hückel theory. Over the next few weeks, Ward later recalled, "We had managed not only to produce a definitive extension of a previously purely classical theory, but also to establish the rules for diagrammatic treatment of problems in quantum statistical mechanics, rules that are now the bread and butter of modern calculations."[3]
Soon after, physicists were rocked by the news that Wu andTsung-Dao Lee had demonstrated in theWu experiment thatparity is not conserved inweak interactions. This inspired Ward to consider particle physics again. Along with many others, he consider howgauge theory could be applied toFermi's theory of beta decay.[3] Ward became one of the authors of theStandard Model of gauge particle interactions; his contributions on electromagnetic and weak interactions were published in a series of papers he co-authored withAbdus Salam.[23][24][25][26] Ward wrote a note to Abdus, informing him thatAlbert Einstein would bespinning in his grave, presumably clockwise.[3]
The contributions of Salam and Ward to the Standard Model were used in the development of the theoretical structure of theHiggs boson.[27] Ward also made contributions toquantum mechanics,[16][28] fermion theory,[29] quantumsolid-state physics,[30] andstatistical mechanics and the Ising model.[31]
In 1955, Ward was recruited byWilliam Cook to work on theBritish hydrogen bomb programme at theAtomic Weapons Research Establishment atAldermaston. The British government had decided that it neededhydrogen bombs, and it was Aldermaston's task to design one.[32] Cook had been put in charge of the project in September 1954. Ward was the only theoretical physicist at Aldermaston; the director,William Penney, although a physicist, was an expert onhydrodynamics and instrumentation. Penney was not happy to have Ward forced on him, and the two did not get along.[33]John Corner recalled that Ward did not fit in at Aldermaston.[32]
British knowledge of thermonuclear designs was limited to the work done by the wartimeManhattan Project:Edward Teller'sClassic Super,[3] and a 1946 design byJohn von Neumann andKlaus Fuchs. All that was known for certain about the American hydrogen bomb design was that it had multiple stages.[32] "I was assigned", Ward later recalled, "the improbable job of uncovering the secret of the Ulam–Teller invention ... an idea of genius far beyond the talents of the personnel at Aldermaston, a fact well-known to both Cook and Penney."[33]
After working through a large number of proposals, Ward hit upon a workable design incorporating staging, compression and radiation implosion.[1][33] At a meeting on 2 December 1955, Ward sketched it on the blackboard. Penny's response was cool, regarding it as too complicated, but Cook recognised it as worthy. Although Ward's design was not the one ultimately adopted for the hydrogen bombs used inOperation Grapple, the concept was influential,[3][32] and the development of a more advanced design than the Americans had would be the key to achieving the overall objective of the project—a resumption of the nuclearSpecial Relationship with the Americans.[33][34] He has been called the "father of the British H-bomb".[2]
After Maryland, Ward looked for a new job. He thought he had found one at theUniversity of Miami inFlorida, but was denied tenure and left in 1959. He then secured a position atCarnegie Mellon University inPittsburgh, Pennsylvania, but was unhappy there. He applied once again for a one-year membership at the Institute for Advanced Study, and was accepted for a third time.Theodore H. Berlin then offered him a position atJohns Hopkins University in 1961. He remained until 1966, when he answered an advertisement for a mathematics professor atVictoria University of Wellington in New Zealand. Australian friends were astounded that anyone would choose New Zealand over Australia. AtMacquarie University inSydney he was welcomed by ProfessorPeter Mason in 1968 with a professorial appointment. He turned down offers from Oxford and Cambridge.[3][1] He eventually became an Australian citizen.[6]
In 1967 he created the physics program at Macquarie University using theFeynman Lectures on Physics as primary textbooks. This program had a strong experimental emphasis and Ward himself (who originally was trained as an engineer) "had great admiration for anything practical".[6] He is credited with being an early pioneer in the use ofFeynman diagrams, and spreading their use in Australia.[35] In the late 1970s Ward participated, with Frank Duarte, in the successfulMacquarie science reform movement,[36] and considered this a "most important accomplishment".[6] The most visible sign was that the university agreed to presentBachelor of Science (BSc) degrees instead of just Bachelor of Arts (BA) degrees, the former being more highly prized by students and workplaces in Australia.[3]
Besides his physics, Ward played the piano and theFrench horn. Ward played the piano at public performances, for example, in August 1968 playing Grieg at Blacktown Town Hall, Sydney. He was a bachelor for most of his life, but he was briefly married while in the US. He had no children.[3] He died onVancouver Island inBritish Columbia, Canada, on 6 May 2000, from a respiratory illness.[1]
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