ONSAGER, Lars

(b. 27 November 1903 in Oslo, Norway; d. 5 October 1976 in Miami, Florida), physical chemist who received the 1968 Nobel Prize in chemistry for his derivation of a set of equations known as the Law of Reciprocal Relations, which is sometimes described as the Fourth Law of Thermodynamics because it makes possible a study of irreversible processes.

Onsager was the son of Erling Onsager, a barrister of the Supreme Court of Norway, and Ingrid Kirkeby. He had a liberal early education that was a combination of private school and his mother's tutoring, followed by high school in Oslo. The combination gave him an extraordinary background in literature and fine arts. Onsager then entered the Norwegian Institute of Technology as a student in chemical engineering. However, in his first year at the institute he became interested in the theory of electrolyte solutions, an interest that was the beginning of a scientific curiosity and ultimately led to his receiving a Nobel Prize. Onsager soon mastered the new theory, and detected a flaw in it. He studied in a stimulating environment under professors who encouraged his efforts in studying theory.

After graduation in 1925 Onsager went with one of his professors on a trip to Denmark and Germany that included a stay of a couple of months at Zurich University with Peter Debye, coauthor with Erich Hückel of the new theory of electrolyte solutions. Onsager later described his first encounter with Debye, which started with his solemn statement, "Professor Debye, your theory of electrolytes is incorrect." He based his comment on a puzzling discrepancy between the theory and the actual results in experiments. Debye and Hückel had assumed that a central ion in solution would move uniformly in a straight line while all the other ions were randomly undergoing Brownian motion. Within a few years Onsager had developed the theory to include mobilities of all ions in equal proportions.

Onsager immigrated to the United States in 1928, embarking on a dubious career as a college instructor, first at Johns Hopkins University, where he lasted only a year, and next at Brown University. Following that he was at Harvard, where students called his science courses "advanced Norwegian." Onsager was described by a colleague as a contender for the title of world's worst lecturer. At Brown University he did the classic work on irreversible processes that ultimately led to the Nobel Prize, without the advantage of a Ph.D. He presented a thesis for a Ph.D. on this work to Brown, where the highly theoretical work was not doubted but regarded as too incomprehensible.

Yale was kinder. Onsager went to Yale as the Sterling and Gibbs Fellow in 1933, was made an assistant professor of chemistry in 1934, and was granted a Ph.D. in 1935. His dissertation was on the mathematical background for his interpretation of deviations from Ohm's law in weak electrolytes. Interestingly, Brown awarded him an honorary doctor of science in 1962 when he had become widely acclaimed for his research, most of it at Yale. In the early 1960s he was also reworking his "incomprehensible" discovery of "reciprocal relations," which had been ignored at Brown but was recognized with a Nobel Prize in 1968.

At Yale, Onsager's research covered a wide range of subjects that included colloids, superconductivity, turbulence, ice, electrons in metals, and dielectrics. Onsager also found a firm statistical basis for the theory of liquid crystal ordering, which led the way for the research that ultimately produced liquid crystal displays, better known as LCDs. Although he served as visiting professor in many prestigious universities during the years that followed, he officially stayed with Yale until retirement in 1972. In 1968, the year he received the Nobel Prize, he was a visiting professor at the University of Göttingen in Germany. Onsager became a United States citizen in 1945; his Nobel Prize lists him as an American.

In the presentation speech for the Nobel Prize in 1968, Professor S. Claesson of the Royal Swedish Academy of Sciences noted that the award to Onsager was a more than usual application of a special rule of the Nobel Foundation. The rule reads: "Work done in the past may be selected for the award only on the supposition that its significance has until recently not been fully appreciated." Also recognized in the speech was the fact that Onsager's contributions on irreversible thermodynamics have numerous applications not only in physics and chemistry but also in biology and technology.

From 1954 to 1971 Onsager received a total of nine honorary doctorate degrees, plus many prestigious medals and prizes in addition to the 1968 Nobel Prize. In the 1960s two conferences were based on Onsager's work: an international conference at Brown University in 1962, "Irreversible Thermodynamics and the Statistical Mechanics of Phase Transitions," and in 1965 at the National Institute of Standards near Washington, D.C., "Phenomena in the Neighborhood of Critical Points."

Onsager had difficulty communicating with people of lesser intellect throughout his life. Not only did his students find him difficult to understand, but many of his colleagues had the same problem. He had the reputation of being enigmatic and verbally obscure. Onsager simply did not recognize this and would continue lectures and conversations with what biographers describe as the Onsager grin and twinkling Nordic blue eyes, as if he were fully understood by all.

He is also described as having had a mischievous sense of humor. The chair of the department at Brown suggested he do some experiments rather than spend all his time on theoretical work. Onsager replied that he would like to do that, but he must have the equipment he needed: a tube that would stretch from the basement to the third floor of the chemistry building. Also, the tube must be made of platinum. Actually, such an experiment had already been performed—as part of the Manhattan Project for the atomic bomb. The chair never mentioned doing experiments again to Onsager.

Onsager married Margarethe Arledter on 7 September 1933. They had four children. Onsager died, presumably from a heart attack, at age seventy-two. He is buried in Grove Street Cemetery in New Haven, Connecticut.

Bibliographies of Onsager include Nobel archives, Lars Onsager—Biography (1968); H. Christopher Longuet-Higgins and Michael E. Fisher, Lars Onsager November 27, 1903–October 5, 1976 (1991); and Harriet Zuckerman, Scientific Elite: Nobel Laureates in the United States (1995). An obituary is in the New York Times (6 Oct. 1976).

M. C. Nagel