# Wigner, Eugene

# WIGNER, EUGENE

Eugene Wigner was one of the dominant theoretical physicists of the twentieth century. His life and work spanned much of that century, in particular, the exciting era when quantum mechanics burst onto the physics scene. He was born in Budapest, Hungary, on November 17, 1902, and died in Princeton, New Jersey, on January 1, 1995. His association with Princeton University exceeded fifty years.

His early education was in Budapest, and he received much stimulation from an excellent secondary school and from a classmate, the great mathematician, John von Neumann. He was also strongly influenced all of his life by a group of Hungarian physicists and chemists who were roughly his contemporaries: Michael Polanyi, Leo Szilard, and Edward Teller. To satisfy his father's wishes he obtained his doctorate in chemical engineering—at the Technical University of Berlin, in 1925—but dramatic events in science soon turned his interests to his beloved physics.

Much of twentieth-century physics—indeed the heart of modern physics—is connected to the invention and application of quantum mechanics, which governs all science at small distance scales. The need for the new framework arose from puzzles pertaining to the light spectra of atoms. The ideas that brought the breakthrough for quantum mechanics came in the middle of the 1920s. Wigner's work began just a year or two later, and he was a central member of that brilliant group of physicists who appreciated what could be done with the new framework of quantum mechanics. It opened the door for the description of almost all of science, first the structure of atoms, then of atomic nuclei, and eventually of particle physics, and it led to the creation of entirely new fields of science, such as microelectronics and microbiology.

Wigner led. He seems to have grasped intuitively, right from the beginning, how important symmetry principles would be for the description of quantum

systems and therefore also the importance of the field of mathematics, group theory, which lent itself naturally to the articulation of symmetry ideas. His early book *Group Theory and its Application to the Quantum Mechanics of Atomic Spectra* was epoch making. When nuclear physics was born in 1932 with the discovery of the neutron, Wigner at once became one of the leaders in the early development of this important new field out of which particle physics eventually grew. Also, with the first three of his more than forty Princeton Ph.D. students—Frederick Seitz, John Bardeen, and Conyers Herring—he built the foundations of modern solid state physics.

World War II and the Manhattan Project brought Wigner his greatest challenge and with it the greatest flourishing of his scientific genius. He was head of theoretical physics in Enrico Fermi's team at Chicago that built the first nuclear reactor. But even before the Stagg Field reactor went critical, Wigner's small team had, within the span of a few weeks, fully designed the whole set of Hanford reactors for the production of plutonium, which was so critically important for the success of the Manhattan Project. His expertise in chemical engineering was a great help in the detailed design of the Hanford facility. He spent the rest of the war at Chicago literally creating the field of reactor physics and thus laying the foundations for the entire world effort in nuclear power.

Wigner's contributions to particle physics pertain to the foundations of the subject but also to many quantum mechanical concepts—for example, line breadth, resonance analysis, etc.—which he originally devised for atomic or nuclear physics but which later became essential for articulating particle physics. In applying symmetry principles to quantum systems he made a remarkable progression of ideas from the use of compact groups (the permutation group, the rotation group, etc.) for the classification of the symmetries of atomic states to the noncompact crystallographic groups for solid-state physics and finally to the noncompact Poincaré group for the invariance principles of particle physics. The work on the Poincaré group also led to important contributions to the understanding of relativistic wave equations by The odor Newton and Eugene Wigner and to the concept of localization of the position of elementary systems. Although his contribution to symmetries and quantum mechanics was immense, he focused on global symmetries and had no fondness for the local symmetries of the electro-magnetic theory of Maxwell in which the physics remains invariant to adjustment of a gauge at any point in space. Such local symmetries underlie almost all of the important developments in particle physics of the last few decades of the twentieth century. Nonetheless, Wigner's contribution to symmetry and quantum mechanics was immense and earned him the Nobel Prize in Physics in 1963.

Looking at Wigner's long career, what is most impressive is the depth and great breadth of his contributions to science. There is scarcely any area of physics which was not deeply affected by his work and in which some important phenomenon is not named after him. His work continues to have an impact on entirely new fields such as quantum chaos. In particle physics his influence affects the whole field.

The breakup of the Austro-Hungarian empire after the Great War and the chaotic socialist dictatorship of Bela Kun that briefly followed had a profound effect on Wigner, as did the advent of Hitler in Germany. Like most of his great Hungarian scientific contemporaries, Wigner's roots were Jewish. He tended to be profoundly pessimistic about the development of international affairs, and his magnificent contributions during World War II were carried out under great personal stress. He greatly valued stability in governance and became a very proud American. As a person he was very kind and considerate of his colleagues although somewhat formal, consistent with his European (Hungarian) roots. In fact, his formality was almost legendary. But his many students and colleagues revered him as a person with an unparalleled combination of strengths in science which he imparted freely and joyously to those with whom he interacted.

*See also:*Conservation Laws; Symmetry Principles

## Bibliography

Wigner, E. P. *Group Theory and Its Application to the Quantum Mechanics of Atomic Spectra,* translated by J. J. Griffin (Academic Press, New York, 1959).

Wigner, E. P. *Symmetries and Reflections* (Ox Bow Press, Woodbridge, CT, 1979).

Wigner, E. P. *The Collected Works of Eugene Paul Wigner Part A: The Scientific Papers,* edited by A. S. Wightman (Springer-Verlag, New York, 1993).

Wigner, E. P. *The Collected Works of Eugene Paul Wigner Part B: Historical and Biographical Reflections and Syntheses Volume 7,* edited by A. Wightman and J. Mehra (Springer-Verlag, New York, 2001).

*Erich Vogt*

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