拉斯·昂萨格1903—1976

生平

拉斯·昂萨格1903年出生于挪威奥斯陆。1925年，他取得挪威理工学院化学工程学学位，并于同年前往当时欧洲物理化学研究的中心——瑞士苏黎世联邦理工学院从事电解质溶液的研究。1928年，昂萨格转往美国，开始在霍普金斯大学担任教职。1929年，由于教学成绩欠佳，昂萨格被霍普金斯大学解聘，被迫前往布朗大学。他于1935年在耶鲁大学完成博士论文并与1945年成为耶鲁大学教授。1976年去世于佛罗里达州迈阿密。

Lars Onsager (27 November 1903 – 5 October 1976) was a Norwegian 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. While there, he worked through A Course of Modern Analysis, which was instrumental in his later work.

Career and research

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 (JHU) 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.

Research

Exact solution of the 2D Ising model

To solve the 2D Ising model, Onsager began by diagonalizing increasingly large transfer matrices. He said that this was because he had a lot of time during WWII. He began by computing the 2 × 2 transfer matrix of the 1D Ising model, which had already been solved by Ernst Ising himself. He then computed the transfer matrix of the "Ising ladder", meaning two 1D Ising models side-by-side, connected by links. The transfer matrix is then 4 × 4. He repeated this for up to six 1D Ising models, resulting in transfer matrices of up to 64 × 64. He diagonalized all of them and found that all the eigenvalues were of a special form, so he guessed that the algebra of the problem was an associative algebra (later called the Onsager algebra).

The solution involved generalized quaternion algebra and the theory of elliptic functions, which he learned from A Course of Modern Analysis.

Personal life

He remained in Florida until his death from an aneurysm in Coral Gables, Florida in 1976. Onsager was buried next to John Gamble Kirkwood at New Haven's Grove Street Cemetery. While Kirkwood's tombstone has a long list of awards and positions, including the American Chemical Society Award in Pure Chemistry, the Richards Medal, and the Lewis Award, Onsager's tombstone, in its original form, 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. He was identified as a Protestant.

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 Lars Onsager; Chemistry, Physics and Mathematics. The American Physical Society established Lars Onsager Prize in statistical physics in 1993. In 1997, his sons and daughter donated his scientific works and professional belongings to NTNU (before 1996, NTH) in Trondheim, Norway, his alma mater. These are now organized as The Lars Onsager Archive at the Gunnerus Library in Trondheim.