In 1925 he arrived at a correction to the
Debye-Hückel theory of
electrolytic solutions, to specify
Brownian movement of
ions in solution, and during 1926 published it. He traveled to
Zürich, where
Peter Debye was teaching, and confronted Debye, telling him his theory was wrong. He impressed Debye so much that he was invited to become Debye's assistant at the
Eidgenössische Technische Hochschule (ETH), where he remained until 1928.
Johns Hopkins University In 1928 he went to the United States to take a faculty position at the
Johns Hopkins University in
Baltimore, Maryland. At JHU he had to teach freshman classes in
chemistry, and it quickly became apparent that, while he was a genius at developing theories in physical chemistry, he had little talent for teaching. He was dismissed by JHU after one semester.
Brown University On leaving JHU, he accepted a position (involving the teaching of
statistical mechanics to graduate students in chemistry) at
Brown University in
Providence, Rhode Island, where it became clear that he was no better at teaching advanced students than freshmen, but he made significant contributions to statistical mechanics and
thermodynamics. His graduate student
Raymond Fuoss worked under him and eventually joined him on the Yale chemistry faculty. His statistical mechanics course was nicknamed "Sadistical Mechanics" by the students. His research at Brown was concerned mainly with the effects on
diffusion of
temperature gradients, and produced the
Onsager reciprocal relations in
statistical mechanics, a set of equations published in 1929 and, in an expanded form, in 1931, whose importance went unrecognized for many years. However, their value became apparent during the decades following
World War II, and by 1968 they were considered important enough to gain Onsager that year's
Nobel Prize in Chemistry. In 1933, when the
Great Depression limited Brown's ability to support a faculty member who was only useful as a researcher and not a teacher, he was let go by Brown. He traveled to
Austria to visit
electrochemist Hans Falkenhagen. He met Falkenhagen's sister-in-law, Margrethe Arledter. They were married on September 7, 1933, and had three sons and a daughter.
Yale University After the trip to
Europe, he was hired by
Yale University, where he remained for most of the rest of his life, retiring in 1972. At Yale, he had been hired as a postdoctoral fellow, but it was discovered that he had never received a
Ph.D. It dealt with the solutions of the
Mathieu equation of period 4\pi and certain related functions and was beyond the comprehension of the
chemistry and
physics faculty. Only when some members of the
mathematics department, including the chairman
Einar Hille (who also liked
A Course of Modern Analysis), insisted that the work was good enough that
they would grant the doctorate if the chemistry department would not, was he granted a Ph.D. in chemistry in 1935. Even before the dissertation was finished, he was appointed assistant professor in 1934, His two courses on statistical mechanics were nicknamed "Advanced Norwegian I" and "Advanced Norwegian II" for being incomprehensible. In 1960 he was awarded an
honorary degree, doctor techn. honoris causa, at the
Norwegian Institute of Technology, later part of
Norwegian University of Science and Technology. In 1945, Onsager was
naturalized as an American citizen, and the same year he was awarded the title of
J. Willard Gibbs Professor of Theoretical Chemistry. This was particularly appropriate because Onsager, like
Willard Gibbs, had been involved primarily in the application of
mathematics to problems in
physics and
chemistry and, in a sense, could be considered to be continuing in the same areas Gibbs had pioneered. In 1947, he was elected to the
National Academy of Sciences, the
American Academy of Arts and Sciences in 1949, and in 1950 he joined the ranks of
Alpha Chi Sigma. After
World War II, Onsager researched new topics of interest. He proposed a theoretical explanation of the
superfluid properties of
liquid helium in 1949; two years later the
physicist Richard Feynman independently proposed the same theory. He also worked on the theories of
liquid crystals and the electrical properties of
ice. While on a
Fulbright scholarship to the
University of Cambridge, he worked on the magnetic properties of
metals. He developed important ideas on the quantization of magnetic flux in metals. He was awarded the
Lorentz Medal in 1958,
Willard Gibbs Award in 1962, and the
Nobel Prize in Chemistry in 1968. He was elected a member of the
American Philosophical Society in 1959 and a
Foreign Member of the Royal Society (ForMemRS) in 1975.
After Yale In 1972 Onsager retired from Yale and became emeritus. He then became a member of the
Center for Theoretical Studies, University of Miami, and was appointed Distinguished University Professor of Physics. At the
University of Miami he remained active in guiding and inspiring postdoctoral students as his teaching skills, although not his lecturing skills, had improved during the course of his career. He developed interests in semiconductor physics, biophysics and radiation chemistry. However, his death came before he could produce any breakthroughs comparable to those of his earlier years. == Research ==