Lars Onsager (November 27, 1903 – October 5, 1976) was a Norwegian-born American physical chemist and  theoretical physicist.  He held the Gibbs Professorship of Theoretical Chemistry at Yale University. He was awarded the Nobel Prize in Chemistry in 1968.

Education and early life 
Lars Onsager was born in Kristiania (now Oslo), Norway. His father was a lawyer. After completing secondary school in Oslo, he attended the Norwegian Institute of Technology (NTH) in Trondheim, graduating as a chemical engineer in 1925.

Career and research 
In 1925 he discovered that the Debye-Hückel theory of electrolytic solutions was wrong. This theory explained Brownian movement of ions in solution. In 1926 he published a correction to the theory. He traveled to Zürich, where Peter Debye was teaching, and told him his theory was wrong. Debye was so impressed by Onsager's work that he asked him to become his assistant. Onsager stayed at the Eidgenössische Technische Hochschule (ETH) until 1928.

Johns Hopkins University 
In 1928 Onsager went to the United States to teach at the Johns Hopkins University in Baltimore, Maryland. He was a genius in developing theories, he was not a very good chemistry teacher, and he was dismissed after one semester.

Brown University 
His next job was teaching statistical mechanics at Brown University in Providence, Rhode Island. Again he was found to be no good at teaching. He did make significant contributions to statistical mechanics and thermodynamics. The only student who could really understand his lectures on electrolyte systems was Raymond Fuoss. Fuoss eventually joined him at Yale University. 
In 1933, during the Great Depression Brown's decided they could not afford to employ someone who could not teach and he was dismissed. .

His research at Brown was on the effects on diffusion of temperature gradients. He came up with a set of equations  in 1929 now called Onsager reciprocal relations. The importance of these equations in statistical mechanics was not realized for many years. However by 1968 they were considered important for Onsager to win the Nobel Prize in Chemistry.  In 1933, after leaving Browns, Onsager 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 
His next job was at Yale University, where he remained for most of the rest of his life, retiring in 1972. At Yale, it was discovered that he had never received a Ph.D. The Norwegian Institute of Technology found that his his work in reciprocal relations was too incomplete to qualify as a doctoral dissertation. Yale said they would accept one of his published papers instead, but Onsager insisted on doing a new research project. His dissertation, called "Solutions of the Mathieu equation of period 4 pi and certain related functions", was too hard for the chemistry and physics faculty to understand. It was only after the mathematics department said they would give him the doctorate instead, that he was granted a Ph.D. in chemistry in 1935. He was appointed assistant professor in 1934, and associate professor in 1940. At Yale he produced brilliant theoretical research, but could not teach or explain ideas to students. He was also unable to direct the research of graduate students, except for the occasional outstanding one.

During the late 1930s, Onsager researched the dipole theory of dielectrics. He again improved on earlier work by Peter Debye. However, when he gave his paper to a journal that Debye edited in 1936, it was rejected. Debye would not accept Onsager's ideas until after World War II. During the 1940s, Onsager studied the statistical-mechanical theory of phase transitions in solids. He came up with a mathematical theory which was enthusiastically received. In a tour de force of mathematical physics, he obtained the exact solution for the two dimensional Ising model in zero field in 1944.

In 1935 he was awarded an honorary degree from the Norwegian Institute of Technology, later part of Norwegian University of Science and Technology.

In 1945, Onsager was naturalized as an American citizen. He  was awarded the title of J. Willard Gibbs Professor of Theoretical Chemistry. Willard Gibbs worked on using mathematics to solve problems in physics and chemistry. Onsager continuing in the same areas Gibbs had pioneered.
In 1947, Onsager was elected to the National Academy of Sciences, and in 1950 he joined the ranks of Alpha Chi Sigma.

After World War II, Onsager researched new topics of interest. He came up with 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 Foreign Member of the Royal Society (ForMemRS) in 1975.

After Yale 

In 1972 Onsager retired from Yale. He 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 guided and inspired postdoctoral students as his teaching skills had improved. 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.

Personal life 
He died from an aneurysm while living in Coral Gables, Florida in 1976. Onsager was buried next to John Gamble Kirkwood at New Haven's Grove Street Cemetery. Onsager's tombstone simply said "Nobel Laureate". When Onsager's wife Gretel died in 1991 and was buried there, his children added an asterisk after "Nobel Laureate," and "*etc." in the lower right corner of the stone.

Legacy 
The Norwegian Institute of Technology established the Lars Onsager Lecture and The Lars Onsager Professorship in 1993 to award outstanding scientists in the scientific fields of  Chemistry, Physics and Mathematics. In 1997 his sons and daughter donated his scientific works and professional belongings to NTNU (before 1996 NTH) in Trondheim, Norway as his Alma Mater.  These are now organized as The Lars Onsager Archive at the Gunnerus Library in Trondheim.

The Lars Onsager Prize is a prize in theoretical statistical physics. It is awarded annually by the American Physical Society. It was established in 1993 by Drs. Russell and Marian Donnelly.

References

Other websites 

 The Lars Onsager Lecture and Professorship (Norwegian  University of Science And Technology)
 The Lars Onsager Archive at Universitetsbiblioteket/Gunnerus Library in Trondheim. (Norwegian  University of Science And Technology)
 The Onsager Committee (Norwegian  University of Science And Technology)
 The Lars Onsager Lecture and The Lars Onsager Professorship (Norwegian  University of Science And Technology).
 The Motion of Ions: Principles and Concepts (Lars Onsager's  Nobel Lecture)

1903 births
1976 deaths
American Nobel Prize winners
American engineers
Nobel Prize in Chemistry winners
Norwegian Nobel Prize winners
Writers from Oslo
American theoretical physicists
Yale University alumni
Norwegian physicists
Naturalized citizens of the United States
Writers from Miami, Florida
Scientists from Miami, Florida