Wilson, Alan Herries
WILSON, ALAN HERRIES
(b. Wallasey, Cheshire, United Kingdom, 2 July 1906;
d. Brent, United Kingdom, 30 September 1995), solid-state physics, semiconductor physics, nuclear fission, chemical engineering, pharmaceuticals, computers, science education, public service.
Wilson had two successful careers, the first from 1926 to 1945 in physics, the second from 1945 in industry. In physics he developed the first quantum-mechanical picture of semiconductors, and in particular his work was seminal in our understanding of semiconductors. He explained the difference between metals, insulators, and semiconductors in terms of a simple band theory of solids accessible to both experimental and theoretical researchers. Partly as a result of his war work, he moved into industry, serving as a director and chairman with the Courtaulds company and later with Glaxo and International Computers and Tabulators. He was active in promoting scientific research in the industrial sector.
Education. Wilson’s forebears were tenant farmers, blacksmiths, and small builders. His father, Herries Wilson (born in 1868), was a marine engineer who left the sea on marriage and then worked as the chief maintenance engineer for the Wallasey Corporation Ferries in the north of England. In 1901 Herries Wilson married Annie Bridges (born in 1865), and in 1904 a daughter, Elizabeth, was born.
Alan Wilson’s education was not unusual for a clever boy. From primary school at the age of nine, he gained a scholarship to attend his local grammar school. For a boy from his background, full-time education would normally end by age sixteen at the latest and be followed by employment in local industries. In preparation for a commercial career, Wilson had followed evening courses in bookkeeping and shorthand. During the end of World War I however, changes had been wrought in secondary education in England and Wales, in particular with the introduction of the Higher School Certificate. As Wilson was successful in the Oxford Senior Local Examinations, at sixteen he was able to remain in school studying for a higher certificate without any clear view of the future. His headmaster introduced him to a scholarship with a value of £150 per annum awarded to any boy from Wallasey who was accepted by Emmanuel College, Cambridge. Taking courses in mathematics, physics, and chemistry, Wilson passed the entrance examination and was awarded the scholarship. His success in the Northern Universities Higher School Certificate was rewarded by a second scholarship.
To avoid having to reread materials that he had already studied, Wilson changed his route from a degree in natural sciences to a degree in mathematics. During the final years of this study, he followed courses in applied mathematics. He encountered Werner Heisenberg’s matrix theory of quantum mechanics (1925), which Wilson found extremely interesting. He graduated in the summer of 1926 with a first-class degree, sharing the Mayhew Prize awarded to the best candidate in applied mathematics.
In 1926, even a first-class degree in mathematics from Cambridge did not necessarily result in a job. Wilson was, however, awarded a research studentship with a grant of £250 per annum offered by the Goldsmiths’ Company. This allowed him to become a research student working with the theoretical physicist Ralph H. Fowler. According to one of Wilson’s students, Ernst Sondheimer,
Fowler was somewhat elusive. Wilson was rather surprised when his supervisor told him “he could now forget all that he had learned in Fowler’s lectures on quantum mechanics” (Sondheimer, 1999, p. 550), because that year Erwin Schrödinger published his wave-mechanical version of quantum mechanics, a new approach that theoretical physicists found far less cumbersome to work with than Heisenberg’s formulation. Fowler suggested that Wilson use Schrödinger’s mechanics to calculate the energy levels of the ionized hydrogen molecule. With his excellent command of mathematics, Wilson managed to tease out this problem, which had been previously intractable to the Bohr-Sommerfeld approach to quantum mechanics. The result was Wilson’s first two papers in 1928, the first of which provided solutions to a generalized spheroidal wave equation, which were then applied to the problem of an ionized hydrogen molecule in the second paper. In order to progress in research in Cambridge, Wilson now had to obtain funding. By obtaining a Smith’s Prize for 1928 and a research fellowship in 1928, he was able to stay at Emmanuel College.
An Academic in Cambridge. At Cambridge Wilson produced a few papers relating to the development of quantum mechanics: two concerned with perturbation theory, and one with tunneling in alpha-particle emission. But, under the influence of Ernest Rutherford, experimental work on the nucleus dominated physics in Cambridge. Mathematical physics was but an adjunct to mathematics; until the end of the 1930s theoretical physics was considered applied mathematics.
Pyotr Leonidovich Kapitza’s recent experimental results on the magnetoresistance in bismuth crystals catalyzed Wilson’s interest in the problems of solids, but he found little success in his efforts to understand this property of bismuth. Wilson had become a member of the Kapitza club, an informal group of mathematicians whose membership was by invitation only. The club brought the European idea of theoretical physics to Cambridge, which Wilson accepted. Nevertheless, he found theoretical physics in Cambridge uninterested in problems of the solid state, which by the end of the 1920s Wilson considered his research interest. Thus Wilson considered himself very fortunate to receive a Rockefeller Traveling Fellowship, which in the first nine months of 1931 allowed him to work in Leipzig with Heisenberg and to visit Niels Bohr and his colleagues in Copenhagen. It was during Wilson’s sojourn in Leipzig that he had the insights that led to his pathbreaking theory of semiconductors and to his two seminal papers on this subject in 1931; these could be taken as a paradigm of a discovery being a fortunate conjunction of the place and the person. In Leipzig Wilson joined a number of theoreticians who were both skilled in quantum mechanics and interested, as he was, in the properties of solids. Among the researchers then working with Heisenberg were Felix Bloch, Edward Teller, and Peter Debye.
According to Wilson (1973), a presentation he gave during a colloquium in Leipzig led to his theory of semiconductors. The research workers at Leipzig were expected to read seminar papers and Heisenberg asked Wilson to present an appreciation of Rudolf Peierls’s recent work on the effects of magnetic fields in metals. Peierls had arrived at puzzling results concerned with the motion of electrons within certain types of solid; they appeared to move in the wrong direction. Wilson was concerned to understand Peierls’s papers fully for, “to give a seminar in German at which I would be cross-examined back and forth would be a bit of an ordeal, and therefore one had to understand someone else’s work more thoroughly than if one was talking about one’s own” (1973, p. 5). This effort, and Heisenberg’s demand that explanations should be made physically intuitive, led Wilson to his band theory of semiconductors. Wilson realized that if bound electrons and the gaps between energy bands were used as the starting point of the explanation, then the anomalous results could be explained in terms of vacancies in the valence bands of crystals and elements. This physical picture led to his insights into holes and electrons in semiconductors. It is interesting to note that positively charged holes in full valence bands could have been considered as negative mass electrons. As Wilson stated, however, “It’s much easier physically to consider a positive charge rather than a negative mass” (1973, p. 5).
Wilson’s first discussion of his theory of semiconductors was followed by other meetings in which he expanded his ideas. One of the meetings was attended by a group of experimentalists from Erlangen headed by Bernhard Gudden. Gudden had been interested in semiconductors from the early 1920s, when he was a colleague of Robert Pohl of Göttingen, whose group in the 1920s were pioneers in the modern study of semiconductors. Gudden had been trying to sort out the confusion that in 1931 surrounded the understanding of metals, semiconductors, and insulators. Wilson’s two papers on semiconductors in 1931 outlined a simple model of semiconductors in which he introduced the concept of donor impurities and calculated many properties of the materials.
In 1932 Wilson decided to submit an enlarged version of his Leipzig work for the Adams Prize, the most prestigious mathematics prize awarded by the University of Cambridge. Founded in the memory of the nineteenth-century astronomer John Couch Adams, this prize was awarded for an essay on a defined topic. For the years 1931–1932 the subject was “the quantum-mechanical theory of aperiodic phenomena.” Though “aperiodic phenomena” does not immediately relate to semiconductors, Wilson’s work won the 1932 Adams Prize.
Between 1932 and 1938 Wilson continued his work on solids. In 1932 two papers considered rectification (the process of converting alternating to direct current), in metal-semiconductor junctions and electrolytic rectifiers. These properties had been used in industrial applications since the end of the nineteenth century but no plausible theoretical pictures had been developed. A paper pointed at the theory of metals proved to be a blind alley. Wilson had expected this work to be a critique of an electron-lattice interactions theory developed by Peierls and others, but it was wrong. In the same year a paper discussing the internal photoelectric effect in crystals presaged Wilson’s interest in the optical properties of metals. And in 1935 his “The Optical Properties of Solids” exhaustively examined the visible and ultraviolet optical properties of metals. In 1936 Wilson detailed the state of the knowledge of metals, semiconductors, and insulators in his important and widely read text, The Theory of Metals, one of a series of important books on the theory of solids that appeared between 1933 and 1936, making the study of the electronic structure of solids into a well-established subfield of modern physics.
It was evident that Wilson’s theory of semiconductors was intuitively attractive, but there remained many areas of disagreement between experimentalists. There was a need for new experiments and for the confirmation or denial of earlier knowledge. Wilson found it almost impossible to persuade any of his Cambridge contemporaries to carry out the necessary work and recognized that it would be difficult, perhaps impossible, to progress in his research on solids without colleagues with whom he could discuss his ideas. Thus from about 1936 he moved his interest to nuclear physics.
Before that occurred, Wilson had been appointed a university lecturer in mathematics and had become a fellow and lecturer of Trinity, a post previously held by Fowler, who in the meantime had become the first Plum-mer Professor of Mathematical Physics in 1932. Since 1929 Wilson had presented a course of advanced lectures on the quantum theory of spectra based on wave mechanics, and joined Fowler teaching thermodynamics. By all accounts he was a good lecturer (Sondheimer, 1999, p. 553). Expecting to remain in academia and become a professor, Wilson worked on two or three papers in the area of nuclear physics but World War II interrupted academic work before he could complete these projects.
The Second World War. World War II changed the course of Wilson’s career. As early as 1938 he had offered his services to the government in case of war, but in the autumn of 1939 he was told his skills were valueless to the war machine. He remained, therefore, in Cambridge continuing lecturing and finishing off some of the research he had begun before the war, as well as carrying out some (part-time) defense research for the government. Since many of his colleagues had been drafted into war work, his workload was enormous.
In early 1941 he was recruited into an organization called the Inter Services Research Bureau (ISRB), which was the public face of the Special Operations Executive (SOE). Wilson found himself attached to a secret establishment known as Station IX near Welwyn, Hertfordshire, U.K. Station IX had been founded in July 1940 on the instigation of Winston Churchill as a mechanism for conducting warfare by means other than direct military engagement; much of this was related to agents in occupied Europe. The work in the station dealt largely with wireless telegraphy and radio and had no resemblance to anything that Wilson ever had done. But after some persuasion he accepted the appointment. Many of the personnel were from the military, but Wilson remained a civilian. After a short time Wilson came to the conclusion that his head of department was not suitable to the demands of the work, a fact he brought delicately to his superiors. He then discovered that this had been the real reason that he was brought to Station IX—the work of the section required “gingering up.” After Wilson’s intervention the section head was moved to less urgent work and within a few weeks Wilson was promoted to be in charge of research and development.
Wilson discovered that he had a talent for running a research and development organization and that he had a special aptitude for managing political situations. Having achieved his purposes at the SOE, Wilson was asked to join Tube Alloys, the British operation related to the atomic bomb, and went to Birmingham where he joined Peierls and Klaus Fuchs, who were then studying the gaseous separation of uranium isotopes. In 1944, when many of the scientists and the bulk of the work of Tube Alloys was transferred to America, Wilson volunteered to remain in Britain. Nineteen forty-four saw his return to Cambridge where he resumed academic work, dividing his time half and half between the atomic bomb and academic research.
Industry. In 1944, responding to the events that had occurred during the war, Wilson left academia to forge a new career in industry. In the course of his war work he impressed some significant men with his organizational talents. One of these, the industrialist Samuel Courtauld of the Courtaulds textile company, realized that after the war scientific research would be vital to industry. Wilson was surprised to be invited in 1944 to join the board of Courtaulds company and serve as its director of research and development.
Wilson was aware that he had no knowledge of the chemistry of artificial fibers with which the Courtaulds’ business dealt, and it seemed at first that joining Courtaulds would be a mistake. But he then came under considerable pressure from those who thought that university men should go into industry. According to Wilson, Sir Edward Appleton, the head of the Department of Scientific and Industrial Research, considered that while there are lots of good scientists in the universities and industry, good organizers who also know anything about science are very rare (Wilson, 1974). In the end Wilson accepted Courtauld’s offer and gave up his hope of succeeding Fowler as the Plummer Professor of Mathematical Physics at Cambridge. He proved very successful in introducing a research stream in the company. By 1961 he became the company’s chairman-designate. Within a year, however, Wilson became unhappy at Courtaulds, because of its involvement with Imperial Chemical Industries in a takeover battle. While this battle was won by Courtaulds, the victory was Pyrrhic and Wilson resigned from the company in 1962.
In January 1963, he joined Glaxo, a leading British pharmaceutical company, and was elected chairman of the board in July 1963. Under Wilson’s leadership Glaxo’s efforts were redirected from the British Commonwealth to European markets and research was restructured with one group dominated by organic chemists, another by biologists. Eventually both groups found major marketable products. When Wilson retired in 1973, the United States was the only noncommunist country in which Glaxo did not have a place. From 1962 Wilson was also a director of International Computer and Tabulators, and for ten years he was active as well in the British computer industry.
From Science and Industry. Wilson received many honors during his life, among them: Fellow of the Royal Society in 1942; a knighthood in 1961; various honorary fellowships, including of Emmanuel College, Cambridge, of St. Catherine’s College, Oxford, and of the University of Manchester Institute of Science and Technology (now part of the University of Manchester); honorary doctorates from Edinburgh and Oxford universities; honorary fellowships of the Institute of Physics, Institution of Chemical Engineers, and the Institute of Mathematics and Its Applications (from which he received a Gold Medal in 1984).
Wilson also played a considerable part in public life, serving as: president of the Institute of Physics and the Physical Society from 1962 to 1964; prime warden of the Goldsmiths’ Company 1969 to 1970; University Grants Committee from 1964 to 1966; the Electricity Council (deputy chairman 1973–1976); Scientific Advisory Committee of the National Gallery from 1955 to 1960; and Board of Governors of the Bethlem Royal and Maudsley Hospitals, chairman, 1973–1980.
According to his former student Sondheimer, Wilson had outstanding intellectual gifts. His understanding of situations was so fast that his conclusions could seem intuitive. His disdain for ruthless maneuverings in business was perhaps a weakness in that domain, for he was a kindly man. Away from work and physics he was interested in art and literature, and mountain walking (see Sondheimer, 1999, p. 561). Wilson married Margaret Monks in 1934, and sons were born in 1939 and 1944. His marriage was very happy, and his wife became a confidante, particularly during his industrial career. Sir Alan remainactive for most of his retirement and died peacefully on 30 September 1995.
Documentary material on Alan Wilson can be found in the Archives of the Royal Society; the London School of Economics; Emmanuel College, Cambridge; the American Institute of Physics; and Cambridge University.
WORKS BY WILSON
“The Theory of Electronic Semi-Conductors.” Proceedings of the Royal Society, Series A, 133 (1931): 458–491.
“The Theory of Electronic Semi-Conductors. II.” Proceedings of the Royal Society, Series A, 134 (1931): 277–287.
“The Optical Properties of Solids.” Proceedings of the Royal Society, Series A 151 (1935): 274–295.
The Theory of Metals: Based on an Essay Awarded the Adams Prize in the University of Cambridge, 1931–1932. Cambridge, U.K.: Cambridge University Press, 1936.
Semi-conductors and Metals: An Introduction to the Electron Theory of Metals. Cambridge, U.K.: Cambridge University Press, 1939.
“Theory and Experiment in Solid State Physics.” Bulletin, Institute of Physics and the Physical Society 14 (1963): 173–180.
“Conversation with A. H. Wilson.” Oral history interview of Sir Alan Herries Wilson by Colin A. Hempstead. Recording and transcript. November 1973. Copies in Niels Bohr Library, American Institute of Physics, College Park, MD, and in London School of Economics and Political Science Archive. This interview demonstrated Wilson’s character, and that his memory of his seminal work was sharp and accurate.
“My Turbulent Years in Industry” (unpublished manuscript). 1974. London School of Economics and Political Science Archives, COLL MISC 1034.
“Solid State Physics 1925–33: Opportunities Missed and Opportunities Seized.” In The Beginnings of Solid State Physics: A Symposium Held 30 April–2 May 1979, edited by Nevill Mott. London: Royal Society, 1980. Symposium first published in Proceedings of the Royal Society of London, Series A, 371 (1980): 1–177.
Hendry, J. Cambridge Physics in the Thirties. Bristol, U.K.: Adam Hilger, 1984. Contains essays written by physicists working in Cambridge in the thirties. These, and the introductions, include comments on Wilson’s work, the relationships between mathematics, theoretical and experimental physics, and the institutional contexts in Cambridge.
Hoddeson, Lillian, Gordon Baym, and Michael Eckert. “The Development of the Quantum Mechanical Electron Theory of Metals.” In Out of the Crystal Maze: Chapters from the History of Solid-State Physics, edited by Lillian Hoddeson, Ernest Braun, Jürgen Teichmann, and Spencer Weart. New York: Oxford University Press, 1991.
Sondheimer, Ernst H. “Sir Alan Herries Wilson.” Biographical Memoirs of Fellows of the Royal Society 45 (1999): 548–562. Includes a fuller account of Wilson’s life and work by a coauthor and research student of Wilson's. The memoir includes a bibliography of Wilson’s published works. I am indebted to Professor Sondheimer for letting me use his memoir as a guide for this entry.