WIGNER, EUGENE PAUL (JENó PáL)

(b. Budapest, Hungary, 17 November 1902;

d. Princeton, New Jersey, 1 January 1995), quantum physics and chemistry, mathematics, nuclear engineering.

Wigner lived a long and productive life. Born in Hungary, Wigner received most of his formal university training in chemistry in Germany, at the same time training himself in physics and mathematics. From this beginning Wigner made numerous important cross-disciplinary contributions, first in Europe and later in the United States, where he spent most of his adult life. Wigner demonstrated the importance of symmetry principles in quantum mechanics, an accomplishment that led to the Nobel Prize in Physics for 1963. Wigner made numerous other contributions to a wide variety of fields. In particular, he was one of the first to apply quantum mechanics to the theory of solids and chemical kinetics, led the World War II effort to design the first high-powered reactors and made numerous other contributions to reactor engineering, and pioneered work in the quantum theory of chaos. Throughout his long career, Wigner trained more than forty doctoral students in theoretical physics as a Princeton University professor and acted as a statesman, lobbying in particular for civil defense. Later in life, even as he continued his scientific and political work, he also turned his talents to the philosophy of science.

The Early Years. Wigner was born on 17 November 1902 to an upper-middle-class, mostly Jewish family in Budapest, Hungary. Eugene was one of three children born to Erzsébet and Antal Wigner; Antal managed a leather tanning factory and Erzsébet was a devoted housewife and mother. Eugene’s tranquil childhood in Budapest was interrupted by World War I, and his managerial-class family was subsequently compelled to flee to Austria for most of 1919, when Hungary fell to communist control.

Although both parents were Jewish, Judaism was not practiced strictly in the home. As an adolescent Wigner received religious education from a local rabbi as well as a priest. Although he prepared for his bar mitzvah at thirteen, later in his teens his family converted to Lutheranism.

Wigner attended a Lutheran high school, where he received solid training in Hungarian literature and language, Latin, history, mathematics, and religion; he received less rigorous training in physics and chemistry. During these years, as his love of mathematics and physics took root, he was known as an excellent but not brilliant student. He also got to know a student in the class one year behind his, Jancsi (Johnny) von Neumann, who would later become a close friend.

Beginning in Europe. When Wigner graduated from high school as a top student in 1920, he was well read in mathematics and physics and wanted a career in the latter field. However, prospects for obtaining a physics professorship in Hungary were poor; Hungary had only three such positions at the time, and Wigner was at a competitive disadvantage in pursuing any sort of academic position due to his Jewish descent. At the same time, Wigner’s father argued that the only practical course was to take chemical engineering as preparation to join the family tanning business. Thus, Wigner began his university career in chemistry, enrolling for one year at the Technical Institute in Budapest and then, in 1921, transferring to Technische Hochschule in Berlin.

Alongside his chemistry course work, Wigner studied physics and mathematics on his own during the next three years. It was an exciting time in physics, and Wigner was in a position to see firsthand the transformation that came with the emerging understanding of quantum mechanics. The University of Berlin attracted many who were making history. Wigner particularly enjoyed a Thursday afternoon colloquium. Regular attendants included Max Planck, Albert Einstein, Max von Laue, and Walther Nernst; Wolfgang Pauli and Werner Heisenberg sometimes joined the discussion. It was at this colloquium that Wigner met other, younger men, including fellow Hungarians Edward Teller and Leo Szilard.

During his third year in Berlin, Wigner began working at the Kaiser Wilhelm Institute in the suburb of Dahlem. It was there that he met Michael Polanyi, a physical chemist who was also a native of Budapest. Polanyi agreed to be Wigner’s thesis advisor for a doctoral dissertation in chemical engineering that contained the first theory of rates of disassociation and association of molecules.

After receiving his doctoral degree in 1925, the twenty-two-year-old Wigner dutifully returned home to Budapest to help his father at the tannery. Not satisfied with the work, however, after a year he happily accepted an assistantship set up by Polanyi with the x-ray crystallographer Karl Weissenberg at the University of Berlin.

Recognizing Wigner’s fine command of mathematics, Weissenberg assigned him a problem that required an exploration of the elementary aspects of group or symmetry theory. Since he was also well-versed in the new physics of the time, Wigner soon realized the vast potential of applying symmetry theory to quantum mechanics. Using the tools of group theory, Wigner was able to derive many rules for atomic spectra following from the existence of rotational symmetry.

After a few months, Weissenberg made arrangements for Wigner to work with Richard Becker, who had recently been given a chair at the university in theoretical physics. In 1927 Becker, in turn, suggested that Wigner work with David Hilbert, a highly distinguished mathematician at the University of Göttingen. Hilbert became ill and retreated from professional work, leaving Wigner without formal responsibilities. Wigner’s time in Göttingen was hardly unproductive, however. He formed friendly ties with James Franck and collaborated with Victor Weisskopf, who was then a student, on a paper on spectral line shape. In addition, at the suggestion of Szilard, Wigner began a book, Group Theory and Its Application to Quantum Mechanics(1931), which became famous. By the time he left Göttingen, Wigner had firmly launched a career in science. Not only had he begun the book that would make his name, but he had started the line of research that would later lead to the Nobel Prize.

The Young American Professor. Wigner returned to Berlin in 1928 to work on his book, which was published in 1931, and continue his research. While there he

received a letter from Princeton University in New Jersey that opened a new chapter in his life. Princeton offered a lectureship in mathematical physics. Although the position was half-time and temporary, the salary was relatively enormous—at seven hundred dollars per month, the pay was more than eight times what Wigner had received in Germany. The unusual offer came because John von Neumann had been offered a full-time tenured faculty position at Princeton but was reluctant to cut his ties in Europe, despite the growing wave of anti-Semitism. To get his foot in the U.S. door while preserving an exit strategy, he asked the Princeton administration to allow himself and Wigner to share an appointment. Princeton agreed, with the proviso that Wigner would not have tenure.

The end result was that in 1930, both von Neumann and Wigner joined the Princeton faculty. For the next three years both young scientists split their time between Europe and Princeton, until the rising tide of Nazism ended their transatlantic crisscrossings. The half-time Princeton arrangement was extended until 1936; von Neumann subsequently joined the faculty of the newly created Institute of Advanced Study at Princeton.

Wigner decided to emigrate permanently and on 8 January 1937 became a U.S. citizen. The previous fall Wigner, disappointed that he had not been given tenure and a promotion, took a leave of absence from Princeton and accepted an acting professorship arranged by Gregory Breit at the University of Wisconsin–Madison.

In his first eight years in America, Wigner conducted research in a wide range of topics in physics and chemistry. During this intensely productive period he made advances in three subfields of physics.

Wigner’s contribution to solid-state physics began at Princeton and continued at Madison. Working with Frederick Seitz, his first graduate student, he found ways to connect aspects of solid-state physics to quantum mechanics. A prime example was the development of a wave function for metallic sodium’s ground state. When the results of this work were combined with calculations made by Wigner on a gas of free electrons, quantum mechanics could be used to derive the binding energy (or energy of sublimation) of the metal from fundamentals. This line of inquiry was expanded upon by Wigner and various students, including John Bardeen.

Wigner also made major contributions to theoretical nuclear physics at its earliest stage. Shortly after the discovery of the neutron in 1932 and the subsequent understanding that atomic nuclei are built from protons and neutrons, he investigated a number of related topics, including early measurements of deuteron properties, neutron-proton scattering, and the internucleon force and its symmetry properties. His work with nuclear forces led to the conclusion that there were four types of such forces, depending on whether they allow for exchange of electric charge and/or spin between neutrons and protons. The force that allows neither exchange came to be known as the Wigner force. Later in the decade Wigner and others, including Eugene Feenberg, developed supermultiplet theory, which employed spatial symmetry to help describe nuclear states. In addition, while at Wisconsin, Wigner worked with Breit to develop a tool still standard in nuclear theory: the Breit-Wigner formula for the reaction cross section in terms of nuclear parameters.

Wigner also made important contributions to the development of relativistic quantum mechanics. In a 1939 paper, “On Unitary Representations of the Inhomogeneous Lorentz Group,” he set his sights on the homogeneous Lorentz group, a group involving time-dependent symmetries (or symmetry groups) that also include time-translation invariance. In his analysis of its irreducible representations, he was able to provide a complete classification of all the elementary particles that were then known.

In Madison, Wigner met and married a young physics student, Amelia Frank. Tragically, she died of cancer less than a year after their December 1936 wedding. Despite the many close relationships he had developed in Wisconsin and his highly productive years there, Wigner in his grief longed for a change of scene. Therefore, he was receptive when Princeton made him an offer. In the autumn of 1938, Wigner arrived at Princeton with the promotion he had previously craved: he was now Thomas D. Jones Professor of Mathematical Physics.

War Takes Center Stage. After returning to Princeton, Wigner became so concerned with the rising power of Adolf Hitler and the growing threat of world war that he brought his parents to the United States. Shortly thereafter came the announcement that fission had been discovered. Like others who knew subatomic physics, Wigner immediately realized that fission opened the possibility of a weapon of unprecedented power.

Although Wigner continued to pursue his multifaceted basic research program, he was increasingly drawn to war-related applied projects. His first worry was that a fission weapon was feasible and the Germans might develop it. He discussed the issue with Szilard and Teller, cohorts from his early Berlin days who had by then also emigrated to the United States. They agreed that Wigner and Szilard should enlist Einstein’s help in warning the U.S. government of the potential threat. The result was the famous letter from Einstein to President Franklin D. Roosevelt delivered by economist Alexander Sachs, who acted as the president’s unofficial advisor.

Wigner and others wondered whether, given subsequent bureaucratic sluggishness, the letter actually speeded the formation of the U.S. atomic bomb project. In any case, the letter did provide six thousand dollars from the U.S. government to Enrico Fermi to further his efforts to create a nuclear chain reaction in a system of natural uranium and pure graphite. Alongside these efforts Wigner and others—including Werner Heisenberg in Germany—made the necessary theoretical calculations, so that by 1942 much of the basic theory for reactor physics had been developed.

In April 1942 Wigner took a formal leave of absence from Princeton and joined the University of Chicago’s Metallurgical Laboratory, where nuclear chain reaction studies were consolidated. He came with his second wife, Mary Wheeler; they had been married a little more than a year. The couple would eventually have two children, Martha and David.

From 1942 to 1945 Wigner supervised twenty theoretical physicists in office space at the University of Chicago. About half a year after his transfer to the Midwest, he was one of fifty people to witness Fermi’s demonstration of the first self-sustaining chain reaction underneath the university’s Stagg Field Stadium.

Wigner and his group studied chain reactions, the effect of neutrons and (γ-rays on matter; they also helped plan and evaluate experimental work. Their main task, however, was a job of enormous proportions: they designed the first full-scale plutonium producing reactors that were later build at Hanford, Washington.

The job drew on Wigner’s knowledge of chemical engineering as well his background in theoretical physics. From the beginning, the general outlines of the Hanford reactors were specified: They would have a lattice made of natural uranium fuel rods that were embedded in a graphite moderator. This left open a number of major decisions, however, including the choice of coolant and how it would be used; the dimensions of the reactor and fuel rods; the design of the fuel rods; and the exact placement of cladding, tube materials, and control rods. All of these decisions required detailed analysis of such issues as heat transfer and pressure drops. Wigner was intimately involved in the smallest design decisions; when DuPont later built the reactors, he personally double-checked every blueprint.

The choice of coolant was particularly key. The original idea was that the reactors would be helium cooled. Thanks to his chemical engineering background, however, Wigner saw a problem, noting that helium-cooled reactors would have to be operated at excessively high temperatures, causing tremendous materials problems. He suggested that, instead, ordinary water be used, a brave suggestion because it had not yet been proven that such a system could sustain a chain reaction. Wigner acknowledged that reactivity would be a bit less if water were used rather than helium, but he insisted that his calculations and Fermi’s experiments showed that a workable water-cooled reactor could be built. As he noted, such a reactor could also be constructed more quickly than a reactor with helium cooling. The head of the Metallurgical Laboratory, Arthur Compton, was convinced by Wigner’s arguments and approved the design of a massive, water-cooled reactor.

Wigner’s group completed a design report for the reactors in January 1943. For the most part, DuPont adopted the design and began construction of the reactors. The start-up of the first reactor in 1944 was marred by crisis: Xenon-135, an unexpected fission product, absorbed so many neutrons that the chain reaction stalled before going to full design power. A team that included Fermi and John Wheeler diagnosed the problem, and DuPont engineers found a way to add extra uranium to the reactor to counteract the xenon poisoning. The Hanford reactors went on successfully to complete their mission: they produced sufficient plutonium for the second atomic weapon, which was dropped on Nagasaki in August 1945.

Further Contributions to Reactors. Wigner returned to Princeton in 1947. As he resumed his research career, he and his group went on to make numerous other contributions to reactor engineering after they turned the Hanford reactors over to DuPont for routine operation. During this period Wigner invented techniques later taught in reactor-design textbooks. In addition, he anticipated what later came to be known as the Wigner disease, that is, the swelling of a reactor’s crystal lattice that occludes the fuel elements, a condition resulting from the intense bombardment of graphite by neutrons. During the war, Wigner’s name was on thirty-seven engineering patents for various types of reactors.

In 1945 Wigner proposed that Clinton Laboratories in Tennessee (which during World War II housed pilot plutonium-producing reactors and enriched uranium for the uranium bomb) should be converted into a postwar reactor facility. In 1948 Clinton became such a facility, known as the Oak Ridge National Laboratory.

In 1947, before the conversion, Wigner served as Clinton’s research director. In this capacity he formed that same year the Oak Ridge School of Reactor Technology, which became an important training facility for the new field of reactor engineering. The most famous graduate of the school was Hyman Rickover, who went on to develop nuclear submarines. As research director, Wigner also laid the groundwork for the Materials Testing Reactor at Oak Ridge, the first enriched-uranium high-powered reactor that was cooled and moderated with water.

After a short time in Tennessee, Wigner decided that he was not well-suited to be a manager in the highly politicized environment of the emerging U.S. reactor program. Therefore, he returned to Princeton at the end of summer in 1947 to do basic research. Wigner continued to be a consultant to Oak Ridge under the management of his successor, Alvin Weinberg. Wigner also served as a consultant to DuPont for the company’s Savannah River heavy-water reactors.

Postwar Academic and Statesman. For the next quarter of a century, Wigner would serve as a Princeton professor, rounding out an academic career that would, in all, span four decades. In addition to pursuing his own research, Wigner supervised a large number of PhD students; most of his more than forty graduate students got their degrees during the postwar period.

Wigner’s scientific interests continued to be broad. He undertook topics in nuclear physics, investigated the foundations of quantum mechanics, and worked in relativistic wave equations. Although his interest in nuclear structure waned, he became increasingly involved in the study of nuclear reactions, a line of inquiry that resulted in more articles than in any other of his subjects of interest.

Wigner also started and fully developed R-matrix theory for nuclear reactions. His work with R-functions and R-matrices extended beyond direct application to resonance reactions. One result of his continuing fascination with mathematics was work on random matrix elements that led to the founding of quantum chaos theory.

Wigner retained a passionate interest in civil defense issues alongside his academic pursuits. Through the 1960s he vociferously argued against the idea of countering the threat of nuclear war by building weapons arsenals capable of mutual assured destruction. In 1963, the year he won the Nobel Prize in Physics for his work on symmetry principles in quantum mechanics, he also directed the Harbor Project, a six-week National Academy of Sciences study of civil defense that included sixty-two scientists, statesmen, and engineers. Wigner’s work as a statesman of science also included participation in international Pug-wash Conferences on Science and World Affairs dedicated to reducing the use of atomic weapons. In addition, he edited and contributed to a 1969 volume on civil defense, again warning about the danger of atomic weaponry.

Retirement. Wigner retired from Princeton University as a physics professor in 1971. This milestone did not, however, mark the end of his career as an intellectual and statesman. In the scientific arena he continued pursuing his lifelong fascination with the mathematical foundations of quantum mechanics, in particular the use of techniques derived from group theory. He also continued teaching, accepting a variety of visiting professorships at, for example, Louisiana State University at Baton Rouge and the Erice summer school in Sicily.

Wigner’s interest in civil defense and statesmanship also persisted. He continued as an adviser to Oak Ridge, particularly focusing on research aimed at finding ways to protect civilians from nuclear war. As part of this effort he devoted considerable attention to work with the Federal Emergency Management Agency. Because the Soviets had loosened political control of his native Hungary by this time of his retirement, Wigner also became active in fostering cultural and scientific ties between Hungarians and the rest of the free world and furthering Hungarian freedom.

At this stage in his life Wigner also turned to philosophical queries. He participated in a broad range of meetings with a philosophical bent, from the annual meetings of Nobel laureates to groups associated with the Unification Church of the Reverend Sun Myung Moon. He also published a series of philosophical essays, Symmetries and Reflections(1967).

Mary, Wigner’s wife of forty years, died of cancer in 1977. In 1979 he married Edith Hamilton. With Edith as his close companion, he continued a vigorous schedule until he was well over eighty. Wigner died on 1 January 1995 in Princeton, New Jersey.

BIBLIOGRAPHY

Wigner’s papers are located at the Manuscript Division, Department of Rare Books and Special Collections, Princeton University Library, Princeton, New Jersey. A complete bibliography of Wigner’s published works is in the Collected Works volumes, listed below.

WORKS BY WIGNER

“On Unitary Representations of the Inhomogeneous Lorentz Group.” Annals of Mathematics 40 (1939): 149–204.

With Leonard Eisenbud. “Higher Angular Momenta and Long Range Interaction in Resonance Reactions.” Physical Review 72 (1947): 29–41.

“On the Distribution of the Roots of Certain Symmetric Matrices.” Annals of Mathematics 67 (1958): 325–328.

With Alvin M. Weinberg. The Physical Theory of Neutron Chain Reactors. Chicago: University of Chicago Press, 1958.

Group Theory and Its Application to the Quantum Mechanics of Atomic Spectra. Translated by J. J. Griffin. New York: Academic Press, 1959. Originally published as Gruppentheorie und Ihre Anwendung auf die Quantenmechanik der Atomspektren (Brunswick, Germany: F. Vieweg und Sohn, 1931).

“Events, Laws of Nature, and Invariance Principles.” Nobel Lecture, 1963. Available from http://nobelprize.org/physics.

Symmetries and Reflections: Scientific Essays by Eugene P. Wigner. Bloomington: Indiana University Press, 1967.

The Collected Works of Eugene Paul Wigner. Edited by Arthur S. Wightman and Jagdish Mehra. Berlin, and New York: Springer-Verlag, 1992–1998.

OTHER SOURCES

Pais, Abraham. “Eugene Wigner.” In The Scientific Genius: A Portrait Gallery of Twentieth-Century Physicists. Oxford: Oxford University Press, 2000.

Seitz, Frederick, Erich Vogt, and Alvin M. Weinberg, “Eugene Paul Wigner.” Available from http://www.nap.edu.

Szanton, Andrew. The Recollections of Eugene P. Wigner as Told to Andrew Szanton. New York: Plenum Press, 1992.

Weinberg, Alvin. “Eugene Wigner, Nuclear Engineer.” Physics Today 55 (October 2002): 42–47. Available from http://www.aip.org/pt/vol-55/iss-10/p42.html.

Catherine Westfall

Wigner, Eugene Paul

(b. 17 November 1902 in Budapest, Hungary, d. 1 January 1995 in Princeton, New Jersey), mathematical physicist who made numerous pioneering contributions to quantum mechanics and fundamental nuclear theory, for which he received the Nobel Prize in physics in 1963.

Eugene Paul (Jenó Pál in the Hungarian) Wigner was born in Budapest, the second of three children, to Anthony Wigner and Elizabeth Einhorn. His father ran a leather-making factory and both parents put a strong emphasis on education for their children. While attending Budapest Lutheran High School, Wigner was especially interested in physics and mathematics; however, after his high school graduation in 1920, practical concerns led him to enroll as a chemical engineering student at the Berlin Technische Hochschule (Institute of Technology) in Germany. He received an undergraduate degree in 1924 and a Ph.D. in chemical engineering in 1925 under the direction of another Hungarian scientist, Michael Polányi.

He returned to Budapest for one year to work in a leather-tanning factory but returned to Berlin in 1926 to take a post as a research assistant at the Technische Hochschule. This association began his first important exposure to the new field of quantum physics. Employing his exceptional mathematical aptitude he began exploring how group theory, a classical study first developed in the nineteenth century by the Norwegian mathematician Sophus Lie, might be applied to quantum mechanics. As the result of this work, Wigner was invited by the great German mathematician David Hilbert to join him at the University of Göttingen. At Göttingen, Wigner conducted his early investigations into the significant connection between rules of mathematical symmetry and corresponding conservation laws of physics—a connection that decisively influenced quantum mechanics and the growing understanding of nuclear structure.

In 1928 Wigner returned to the Technische Hochschule as a lecturer, staying until 1930, when he emigrated to the United States to accept a position as an instructor in physics at Princeton University in New Jersey. Most of Wigner’s career was spent in Princeton. During the period 1936–1938 he joined the University of Wisconsin as professor of physics. He returned to Princeton in 1938 and was named the Thomas D. Jones Professor of Mathematical Physics at the Palmer Physical Laboratories. Along with many other scientists during World War II, Wigner departed from his academic activities to apply himself to military research. Wigner was among the chief theoreticians under the leadership of Enrico Fermi in achieving the first nuclear chain reaction. Fermi, an Italian physicist with an extraordinary combination of abilities in both theoretical and experimental physics, had left his native country in 1938 because of the jeopardy he felt his Jewish wife could encounter under Benito Mussolini’s fascist dictatorship.

The chain reaction was accomplished with a natural uranium-fueled, graphite-moderated assembly (an “atomic pile”) in a squash court under the west stands of Stagg football field at the University of Chicago on 2 December 1942. The scientific team then sent a coded telephone message to the administration in Washington, D.C.: “the Italian navigator has just landed in the new world.” Wigner toasted Fermi with a celebratory bottle of Chianti wine but later recalled in a more serious vein: “For some time we had known that we were about to unlock a giant. Still we could not escape an eerie feeling when we knew we had actually done it. We felt as I presume everyone feels who has done something that he knows will have far-reaching consequences which he cannot foresee.”

This milestone in nuclear science—indeed in the history of mankind—had its origin in an earlier event in which Wigner had played a pivotal role. While in Berlin in the 1920s, Wigner had become friends with fellow scientists from Hungary, Leo Szilard and Edward Teller. At different times they each emigrated along with many other scientists from a Europe that was becoming dominated by Hitler, threatening the livelihood, freedom, and lives of Jews, intellectuals, and political adversaries. Szilard was the first to recognize the potentially serious problem created by the discovery of neutron-induced fission in the element uranium by the German chemists Otto Hahn, Fritz Strassman, and the Austrian-Jewish physicist Lise Meitner.

In 1939 Szilard enlisted Wigner and Teller to discuss the threat of an atomic bomb with Albert Einstein. They felt that only Einstein had sufficient prestige and influence to convey the urgency of the serious problem to President Franklin Delano Roosevelt. Einstein understood the problem at once and immediately signed the letter prepared by the Hungarian immigrants. Though Einstein played no subsequent role in atomic bomb development, his message to Roosevelt is regarded as the catalyst that led to the massive Manhattan Project, which resulted in the successful development of the uranium bomb that devastated Hiroshima on 6 August 1945 and the plutonium weapon that struck Nagasaki three days later, ending World War II.

Although Wigner, Szilard, and Teller had started the program and contributed importantly to technical phases of building the nuclear weapons subsequently used against Japan, they ultimately urged that the bomb not be used. They expressed their objections to the Hiroshima bombing in the form of a petition (written by Szilard) that received the signatures of sixty-seven other Manhattan Project scientists. The administration of Harry S. Truman nonetheless decided to drop the bomb.

From 1946 to 1948, before returning to Princeton, Wigner was director of research and development at the Clinton Laboratories in Oak Ridge, Tennessee (later to become Oak Ridge National Laboratory), a group of four hundred scientists and technical staff engaged in research and development under government contract. At the time, the reactors at the site were the principal source of radioactive isotopes for use in fundamental atomic research and for human applications in medical diagnosis using tracers and therapy in the treatment of cancer.

On 13 December 1963 Wigner shared the Nobel Prize in physics with Maria Goeppert Mayer and J. Hans D. Jensen for their separate discoveries in the theory of the nucleus and fundamental atomic particles. Unlike most Nobel scientific awards, which are generally given for unique single discoveries or inventions, the award to Wigner recognized his contributions to many different areas of nuclear physics over a period beginning in the late 1920s and extending for more than three decades.

Among Wigner’s accomplishments was the recognition that symmetry principles explained patterns found in atomic and molecular spectra. Wigner’s analysis of the application of mathematical group theory enabled physicists to understand relative stability or instability of nuclear isotopes having the same number of protons in the nucleus but different neutron numbers. Nearly a decade after he was awarded the Nobel Prize, Wigner’s early group theory research was described as so farsighted that it was not immediately recognized for its importance as a pioneering advance in mathematical physics.

Interestingly referenced in the Nobel Prize presentation to Wigner was his law of the conservation of parity developed at Göttingen in 1928. The parity law states that particles emitted during a physical process should emanate from the left and right in equal numbers or equivalently that a nuclear process should be indistinguishable from its mirror image. The parity concept was not challenged until 1956 when it was disproved in certain so-called “weak decay” interactions in experiments by Tsung-Dao Lee of Columbia and Chen Ning Yang of Princeton. Lee and Yang were awarded the Nobel Prize in 1957 for their empirical refutation of Wigner’s parity theory in this special case. The theory however remained substantially intact and along with other of Wigner’s discoveries useful as a further guide in nuclear research.

Several aspects of Wigner’s career outside of pure physics caused significant controversy. In the 1960s he pursued methods of protection against nuclear weapons effects which presumed that nuclear war might be survivable if suitable civil defense measures were taken. The advent of hydrogen bombs a thousand times more powerful than the atomic weapons employed against Japan made the defense measures advocated by Wigner questionable. Wigner also found himself among the minority of scientists who defended Edward Teller’s critical testimony in a loyalty hearing that was influential in leading to J. Robert Oppenheimer, the scientific head of the Manhattan Project, losing his government secret security clearance in 1954. Wigner’s public defense of Teller was more a case of personal confidence and trust in his long-time friend, rather than Wigner’s own doubts about Oppenheimer’s loyalty.

In 1936 Wigner married Amelia Z. Frank, who died in 1937. That year Wigner became a naturalized citizen of the United States. In 1941 he married Mary Annette Wheeler, a professor of physics at Vassar College in Poughkeepsie, New York. They had two children. After his second wife’s death in 1977, he married Eileen Hamilton in 1979, and they had a daughter. Wigner retired as professor emeritus from Princeton in 1971. He died of pneumonia at the age of ninety-two at the Medical Center in Princeton.

Along with the Nobel Prize, he was the recipient of honorary doctorate degrees from Princeton and twenty-six other colleges and universities in the United States, Europe, and Israel. In 1958 he received the U.S. Atomic Energy Commission Enrico Fermi Award and in 1972 the Albert Einstein Award. In 1990 he became the first recipient of the American Nuclear Society Award designated thereafter the Eugene P. Wigner Award. That same year, after the fall of the communist government in his native Hungary, he received the Order of the Banner of the Republic with Rubies, followed in 1994 by Hungary’s highest honor, the Order of Merit “as an acknowledgment of his scientific career and of his outstanding achievements in the enrichment of universal human values.” In his 1960 paper “The Unreasonable Effectiveness of Mathematics in the Natural Sciences,” Wigner explained the importance of mathematics:

The miracle of the appropriateness of the language of mathematics for the formulation of the laws of physics is a wonderful gift which we neither understand nor deserve. We should be grateful for it and hope that it will remain valid in future research and that it will extend, for better or for worse, to our pleasure even though perhaps also to our bafflement, to wide branches of learning.

The Eugene Paul Wigner Papers are held at Princeton University’s library. His writings are being compiled in the eight-volume Collected Works of Eugene Paul Wigner (1993), edited by Arthur Wightman. See The Recollections of Eugene P. Wigner as Told to Andrew Szanton (1992) for Wigner’s look back at his life and work. Wigner’s sister Margit was married to the eminent English theoretician Paul Dirac, and in Reminiscences About a Great Physicist: Paul Adrien Maurice Dirac (1987), edited by Wigner together with Behram N. Kursunoglu, the point of view of one great scientist for another reveals much about the character of each of them. Richard P. Hewlett and Oscar E. Anderson, Jr., The New World: A History of the United States Atomic Energy Commission, vol. 1, 1939–1946, and vol. 2, 1947–1952 (1962), is a journalistic account that gives prominent reference to Wigner’s contributions to nuclear weapons and, later, reactor development. Also see G. Emch, “The Philosophy of Eugene P. Wigner,” in Classical and Quantum Systems (1993). Tributes to Wigner in the months after his death appeared in Current Science 69 (1995): 375-385 and Physics Today 48, no. 12 (1995): 40-44. John Gibbon, Q Is for Quantum: An Encyclopedia of Particle Physics (1998), is a useful source for terminology and expositions of concepts in Wigner’s research as well as brief biographical information. An obituary is in the New York Times (4 Jan. 1995).

Leonard R. Solon

WIGNER, Eugene Paul

(b. 17 November 1902 in Budapest, Hungary; d. 1 January 1995 in Princeton, New Jersey), Hungarian-American professor of mathematical physics and recipient of the 1963 Nobel Prize in physics for his pioneering work in quantum mechanics.

Wigner, born JenóPál Wigner, was the second of three children and the only son of Anthony Antal Wigner, a leather-tanning factory director, and Elizabeth Erzsébet Einhorn, a housewife. Doctors incorrectly diagnosed a childhood illness as tuberculosis. While Wigner was recuperating in a sanatorium, he pondered mathematics problems. "I had to lie on a deck chair for days on end, and I worked terribly hard on constructing a triangle if the three altitudes are given," he later said. Wigner attended Lutheran High School, Budapest (1915–1920), and met the Hungarian-born mathematician and mathematical physicist John von Neumann who, he said, "was a much better mathematician than I was and a better scientist. But I knew more physics." He enrolled at Technische Hochschule, Berlin, in chemical engineering, studying physics and mathematics during his spare time. He also attended colloquia at the University of Berlin with the physicists Albert Einstein and Max Planck.

In 1925 Wigner obtained his doctorate under fellow Hungarian Michael Polyani, a physical chemist, economist, and philosopher. Wigner was invited back to Technische Hochschule as an assistant professor in the physics department. He immigrated to the United States in 1930, joined the faculty at Princeton University, and devoted himself to the study of atoms and their applications. He was naturalized as an American citizen in 1937. From 1935 to 1937 he taught at the University of Wisconsin and then returned to Princeton, where he spent the remainder of his career. He was named Thomas B. Jones Professor of Mathematical Physics in 1938 and emeritus professor in 1971. During his years at Princeton, he also spent time at the University of Chicago Metallurgical Laboratory and directed a civil defense project for the National Academy of Sciences (1963) and a similar project for the Oak Ridge National Laboratory (1964–1965).

Wigner's 1933 statement "The problem of modern physics is now: What is the structure of the nucleus?" indicated his serious interest in atomic particles. He helped develop the first nuclear reactors and the first nuclear bomb. For his detailed design of the reactors, Wigner was called "the first nuclear engineer." At a National Academy of Sciences award ceremony in Washington, D.C., on 18 May 1960, Chairman James R. Killian, Jr., said, "The trustees believe the development of the nuclear reactor is one of the great advances in man's capability for using atomic energy for peaceful purposes."

One of Wigner's favorite sayings was "The optimist regards the future as uncertain." At times, however, he was not an optimist. As an early refugee from Nazi Germany, he worried, during the late 1930s, that the United States did not take Hitler seriously enough. Later he worried about Stalin's aims in the Soviet Union. During the 1950s he seemed certain that nuclear war was imminent. In 1939 Wigner advised Einstein to warn President Franklin D. Roosevelt of the threat of the Nazi's nuclear weapons. In 1941 Roosevelt established the University of Chicago Manhattan Project to construct an atomic bomb. Wigner worked on that project (1942–1945) and was Director of Research and Development at Clinton Laboratories (1946–1947).

At Princeton, Wigner developed the ideas that eventually resulted in his receiving the 1963 Nobel Prize in physics. His Nobel lecture on December 12—" Events, Laws of Nature, and Invariance Principles"—was a discussion of the general role of symmetry and invariance in modern and classical physics. Wigner supported his thesis that the laws of nature form the raw material in all natural sciences and said that the success of physics was its explanation of the regularities of nature. Wigner's Nobel Prize was representative of the 1960s' emphasis on quantum mechanics and its focus on the study of the microcosm.

During debates on the Princeton campus over the American incursion into Laos, Wigner argued that scientists should be advisers to the government. Others believed that scientists should rise above the political fray and keep themselves separate from political ends. Wigner, however, believed in a strong civil defense, and many liberals of the 1960s saw his outlook as outdated and bleak. Politically, he was a conservative, and he was accused of being a hardliner on the war in Vietnam. Hostile faculty and students attacked his views in 1969. Generally, however, his priority was physics, and he was largely divorced from social issues. Wigner's name was synonymous with scientific discovery: the Wigner-Eckart theorem in group theory; the Wigner coefficients in the quantum theory of angular momentum; the Wigner effect, the Wigner correlation energy, and the Wigner crystal in solids; the Wigner force and the Breit-Wigner formula in nuclear physics; and the Wigner distribution in quantum chaos. What Wigner called his "precious field" was the application of fundamental principles of symmetry in physics.

He coauthored numerous books on nuclear reactors and nuclear structure, including more than five hundred papers published in eight volumes. Official recognition for his nuclear research included the U.S. Medal for Merit (1946); the Enrico Fermi Prize (1958); and the Atoms for Peace Award for 1959, shared with fellow scientist Leo Szilard. Wigner also received the Franklin Medal (1950), the Max Planck Medal of the German Physical Society (1961), the George Washington Award of the American-Hungarian Studies Foundation (1964), the Semmelweiss Medal of the American-Hungarian Medical Association (1965), and the National Medal of Science (1969), among others. He received honorary degrees from more than twenty colleges and universities in the United States and Europe. Wigner was a member of the General Advisory Committee to the U.S. Atomic Energy Commission from 1952 to 1957, was reappointed in 1959, and served until 1964.

Wigner married Amelia Zipora Franck, also a physicist, on 23 December 1936. She died tragically in 1937, a few months after their marriage. Four years later, on 4 June 1941 he married Mary Annette Wheeler, a professor of physics at Vassar College. They had a son and a daughter. Following Mary's death from cancer in 1977, Wigner married Eileen C. P. Hamilton in 1979 and became stepfather to her child. In an article written by Erich Vogt for Physics Today (December 1995), Wigner was described as "always genuinely solicitous of people's feelings.… It was essentially impossible to follow him through any door."

In 1960 Wigner said, "The enormous usefulness of mathematics in the natural sciences is something bordering on the mysterious." He gave extensive interviews, but he remained as elusive as his subject matter. Dr. Abraham Pais, a fellow physicist, wrote, "He was a very strange man and one of the giants of twentieth-century physics." Wigner helped build the edifice of quantum mechanics. During an interview with the editor Andrew Szanton, he shared his belief in the duty of physics "to provide a living picture of our world, to uncover relations between natural events, and to offer us the full unity, beauty and natural grandeur of the physical world."

Wigner's memoir is The Recollections of Eugene P. Wigner, as told to Andrew Szanton (1992). For a biography, see F. S. Wagner, Eugene P. Wigner: An Architect of the Atomic Age (1981). Tyler Wasson, ed., Nobel Prize Winners (1987), provides chronological details of Wigner's career. See also "Eugene Wigner—A Tribute on His Seventieth Birthday," Physics Today (Oct. 1972); "A Conversation with Eugene Wigner," Science (10 Aug. 1973); "Bargmann and Wigner Honored," Physics Today (Nov. 1978); "Eugene Paul Wigner: A Towering Figure of Modern Physics," Physics Today (Dec. 1995); "Eugene Wigner (1902–1995)," Nature (26 Jan. 1995); and "Symmetry in Physics: Wigner's Legacy," Physics Today (Dec. 1995). An obituary is in the New York Times (4 Jan. 1995).

Sandra Redmond Peters

Eugene Paul Wigner

The Hungarian-born American physicist Eugene Paul Wigner (1902-1995) formulated symmetry principles and, together with group theory, applied them in atomic, nuclear, and elementary particle physics.

On November 17, 1902, Eugene P. Wigner was born in Budapest, the son of Anthony Wigner, a leather manufacturer, and Elisabeth Einhorn Wigner. In 1920 he entered the Technical Institute in Budapest, where, at his father's urging, he concentrated on chemical engineering although his principal interest lay in mathematics. A year later he transferred to the Technische Hochschule in Berlin, still majoring in engineering. However, before long he was a regular visitor at the physics colloquia attended by some of the chief leaders in physics in Germany at that time, including Albert Einstein, Walther Nernst, and Max Planck.

Wigner's doctoral thesis was on the formation and disintegration of molecules. After a year and a half of work as leather chemist, Wigner eagerly accepted the offer of an assistant professorship at the Technische Hochschule in Berlin, where, in the late 1920s and early 1930s, his attention turned toward the exploration of symmetry principles in atomic physics. Related to this was Wigner's recognition that group theory, a branch of mathematics inaugurated almost 100 years earlier, could be used to great advantage in accounting for the quantummechanical interpretation of atomic spectra. His book on this topic, Gruppentheorie and ihre Anwendung auf die Quantenmechanik der Atomspektren (1931; trans. in 1959 as Group Theory), is a classic in the field.

Wigner's stay in Berlin ended in 1933 when the Nazis came to power. His first post in the United States was at Princeton University, the second at the University of Wisconsin (1937-1938). In 1938 he returned to Princeton as Thomas D. Jones professor of mathematical physics. During the 1930s Wigner followed with keen interest research on neutron capture, and he was one of the first to realize its awesome and immediate potentialities.

In 1936 Wigner married Amelia Z. Frank. She died the following year. In 1941 he married Mary Annette Wheeler, and they had two children, David and Martha. After her death Wigner married Eileen Hamilton and had another daughter, Erika.

Among his early efforts to alert the government of the United States was his visit, in the summer of 1939 with Leo Szilard, to Albert Einstein on Long Island. What happened made history. At Wigner's and Szilard's pleading, Einstein consented to address a letter to President Roosevelt about the urgency of producing atomic weapons. In the actual production of the first atomic bomb, Wigner's role was crucial.

Wigner not only took a most active part in achieving the first controlled nuclear reaction in Chicago in December 1942, but it became his task to design the first large-scalenuclear reactor. His secret report of January 9, 1943, outlined the details of the huge reactor, a million times more powerful than the first, to be built near the banks of the Columbia River. The gigantic measure of problems to be solved can be gauged from the fact that Wigner's design called for 200 tons of uranium and 1,200 tons of graphite. He also successfully argued that the cooling should be done by water running throughout the whole graphite structure in pipes whose central part contained the uranium. It is safe to assume that Wigner's feat saved about a year in the production of the bomb and also in the duration of the war. After the war he remained a leader in the investigation of the very essence of reactor theory, the neutron chain reaction, as evidenced by his authoritative work written jointly with A.M. Weinberg, The Physical Theory of Neutron Chain Reactors (1958).

In the 1950s but especially in the 1960s, Wigner's attention increasingly turned to some fundamental questions of physical science and to their major philosophical implications. His articles "Invariance in Physical Theory" (1949), "Conservation Laws in Classical and Quantum Physics" (1954), "The Problem of Measurement" (1963), and "Symmetry and Conservation Laws" (1964) have already proved their lasting value. As to the philosophical ramifications of physics, the same holds for his papers "The Limits of Science" (1950), "The Unreasonable Effectiveness of Mathematics in Natural Sciences" (1960), "Two Kinds of Reality" (1964), and "The Probability of the Existence of a Self-reproducing Unit" (1961).

Wigner's main scientific distinctions are the Nobel Prize in physics for 1963 and the Max Planck Medal of the German Physical Society (1962). His adopted country gave him the Medal for Merit, the Enrico Fermi Prize, the Atoms for Peace Award, and the Albert Einstein Award. In 1990 Wigner received the Order of the Banner of the Republic of Hungary with Rubies from his newly democratized birthplace, Hungary. In 1994, he was presented with Hungary's highest recognition, the Order of Merit.

Most significantly, in 1963, is Wigner's award of the Nobel physics prize for "systematically improving and extending the methods of quantum mechanics and applying them widely." Specifically, he was commended for his contribution to the theory of atomic nuclei elementary particles, especially for his discovery and application of fundamental principles of symmetry. This marked an unusual departure for the Nobel Committee, which normally awards the prize for a single discovery or invention.

Wigner, who retired from Princeton in 1971, was also active on behalf of other scientists. He was one of thirty-three Nobel Prize winners who sent a telegram to President Podgorny of the former Soviet Union asking that Andrei Saktlarov be permitted to receive the Nobel Peace Prize in Stockholm.

His dedication to the defense of America's freedom, and of freedom everywhere, constitutes indeed a major aspect of his life and activities. It was the same unconditional appreciation of freedom, whether threatened by dictatorship from the right or the left, that determined Wigner's position amidst the debates on nuclear armament and civil defense. His philosophy is best evidenced by his insistence on the crucial importance of the role of nonscientists in the modern scientific world: "The struggle for men's minds continues and it is quite possible that the conflict between democracy and dictatorships will be won not by armies, not even by scientists, but by philosophers, psychologists, and missionaries who articulate and communicate our ideals."

Wigner died from pneumonia at the age of 92 on Sunday, January 1, 1995.

Further Reading

Wigner's Symmetries and Reflections: Scientific Essays (1967) contains a selection of his less technical papers on a wide range of subjects. There is no comprehensive account of Wigner's life and work. A profile of him appears in Robert H. Phelps, Men in the News—1958: Personality Sketches from the New York Times (1959). The history of modern physics, of which he was a part, is entertainingly given in George Gamow, Biography of Physics (1961). The extensive use of group theory in physics is fully discussed in Morton Hamermesh, Group Theory and Its Application to Physical Problems (1962). □

WIGNER, EUGENE PAUL

WIGNER, EUGENE PAUL (1902–1995), Nobel laureate in physics. Wigner was born in Budapest and was one of a small number of extraordinarily talented Hungarian-born physicists who contributed to the transformation of Newtonian physics. Wigner obtained his doctorate from the Technische Hochschule (later Universitaet) in Berlin in 1925, where his contacts with physicists of equal standing were established at colloquia of the German Physical Society. He worked at a Kaiser Wilhelm Institute, followed by the University of Goettingen, until his recruitment by Princeton University in 1930, a move precipitated by his early perception of the Nazi menace. In 1936–38 he worked at the University of Wisconsin before returning to Princeton. He moved to the University of Chicago (1942–45) to contribute to the Manhattan Project, before becoming director of research and development at the Clinton Laboratories (later Oak Ridge National Laboratory) (1946–48). However, from preference for teaching and research, he returned to Princeton for the rest of his career. His main interests in theoretical physics concerned quantum mechanics and nuclear reactions but later became more philosophical. He was awarded the Nobel Prize in 1963 (jointly with Maria Goeppert-Mayer and Hans Jensen) for the invariance principle, which concerns the rules governing observable physical events. He was also a practical engineer. His involvement in the Manhattan Project arose from his fear that the Nazis might develop nuclear weapons, and he helped to prepare Einstein's letter to President Roosevelt. He contributed to the design of the first experimental fission reactor in Chicago and the first reactor for plutonium production at Hanford. His honors included the U.S. Medal of Merit (1946), the Fermi Prize (1958), the Atoms for Peace Award (1960), and the U.S. National Medal of Science (1969). In 1970 he was elected a fellow of the Royal Society and other learned societies, including the National Academy of Sciences and the American Academy of Art and Sciences. He was a member of the General Advisory Committee to the U.S. Atomic Energy Commission from 1952 to 1957, was reappointed to the Committee in 1959, and served on it until 1964.

[Michael Denman (2^nd ed.)]