Lars Onsager Biography

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World of Scientific Discovery on Lars Onsager

Lars Onsager was born in Oslo (then known as Christiania), Norway, in 1903. His parents were Erling Onsager and Ingrid Kirkeby Onsager.

Onsager excelled in chemistry from an early age, and his prodigious talent in the field was exhibited while still a student. One of the topics that caught his attention concerned the chemistry of solutions. In 1884, Svante Arrhenius had proposed a theory of ionic dissociation that explained a number of observations about the conductivity of solutions and, eventually, a number of other solution phenomena. Over the next half century, chemists worked on refining and extending the Arrhenius theory.

The Dutch chemist Peter Debye and the German chemist Erich Hückel, had proposed a revision of the Arrhenius theory that explained some problems not yet resolved--primarily, whether ionic compounds are or are not completely dissociated ("ionized") in solution. After much experimentation, Arrhenius had observed that dissociation was not complete in all instances.

Debye and Hückel realized that ionic compounds, by their very nature, already existed in the ionic state befor they ever enter a solution. They explained the apparent incomplete level of dissociation on the basis of the interactions among ions of opposite charges and water molecules in a solution. The Debye-Hückel mathematical formulation almost perfectly explained all the anomalies that remained in the Arrhenius theory.

Almost perfectly, but not quite, as Onsager soon observed. The value of the molar conductivity predicted by the Debye-Hückel theory was significantly different from that obtained from experiments. By 1925, Onsager had discovered the reason for this discrepancy. Debye and Hückel had assumed that most--but not all--of the ions in a solution move about randomly in "Brownian" movement. Onsager simply extended that principle to all of the ions in the solution. With this correction, he was able to write a new mathematical expression that improved upon the Debye-Hückel formulation. Onsager had the opportunity in 1925 to present his views to Debye in person. Debye was sufficiently impressed with the young Norwegian to offer him a research post in Zurich.

In 1928, Onsager emigrated to the United States where he received appointments at Johns Hopkins, Brown, and Yale universities. In each case, Onsager proved to be a brilliant theoretician but a poor instructor. In his research at Brown University, Onsager attempted to generalize his earlier research on the motion of ions in solution when exposed to an electrical field. In order to do so, he went back to some fundamental laws of thermodynamics, including Hermann Helmholtz's "principle of least dissipation." He was eventually able to derive a very general mathematical expression about the behavior of substances in solution, an expression now known as the Law of Reciprocal Relations.

Onsager first published the law in 1929, but continued to work on it for a number of years. In 1931, he announced a more general form of the law that applied to other non-equilibrium situations in which differences in electrical or magnetic force, temperature, pressure, or some other factor exists. The Onsager formulation was so elegant and so general that some scientists now refer to it as the Fourth Law of Thermodynamics.

The Law of Reciprocal Relations was eventually recognized as an enormous advance in theoretical chemistry, earning Onsager the Nobel Prize in 1968. However, its initial announcement provoked almost no response from his colleagues. It is not that they disputed his findings, Onsager said many years later, but just that they totally ignored them. Indeed, Onsager's research had almost no impact on chemists until after World War II had ended, more than a decade after the research was originally published.

During the late 1930s, Onsager worked on another of Debye's ideas, the dipole theory of dielectrics. That theory had, in general, been very successful, but could not explain the special case of liquids with high dielectric constants. By 1936, Onsager had developed a new model of dipoles that could be used to modify Debye's theory and provide accurate predictions for all cases. Onsager was apparently deeply hurt when Debye rejected his paper explaining this model for publication in the Physikalische Zeitschrift, which Debye edited. It would be more than a decade before the great Dutch chemist, then an American citizen, could accept Onsager's modifications of his ideas.

In the 1940s, Onsager turned his attention to the very complex issue of phase transitions in solids. He wanted to find out if the mathematical techniques of statistical mechanics could be used to derive the thermodynamic properties of such events. Although some initial progress had been made in this area, resulting in a theory known as the Ising model, Onsager produced a spectacular breakthrough on the problem. He introduced a "trick or two" (to use his words) that had not yet occurred to (and were probably unknown to) his colleagues--the use of elegant mathematical techniques of elliptical functions and quaternion algebra. His solution to this problem was widely acclaimed.

Though his status as a non-U.S. citizen enabled him to devote his time and effort to his own research during World War II, Onsager was forbidden from contributing his significant talents to the top-secret Manhattan Project, the United State's research toward creating atomic weapons. Onsager and his wife finally did become citizens as the war drew to a close in 1945.

The postwar years saw no diminution of Onsager's energy. He continued his research on low-temperature physics and devised a theoretical explanation for the superfluidity of helium II (liquid helium). The idea, originally proposed in 1949, was arrived at independently two years later by Princeton University's Richard Feynman. Onsager also worked out original theories for the statistical properties of liquid crystals and for the electrical properties of ice. In 1951 he was given a Fulbright scholarship to work at the Cavendish Laboratory in Cambridge; there, he perfected his theory of diamagnetism in metals.

During his last years at Yale, Onsager continued to receive numerous accolades for his newly appreciated discoveries. In addition to his Nobel Prize, Onsager garnered the American Academy of Arts and Sciences' Rumford Medal in 1953 and the Lorentz Medal in 1958. Upon reaching retirement age in 1972, Onsager was offered the title of emeritus professor, but without an office. Disappointed by this apparent slight, Onsager decided instead to accept an appointment as Distinguished University Professor at the University of Miami's Center for Theoretical Studies. At Miami, Onsager found two new subjects to interest him, biophysics and radiation chemistry. In neither field did he have an opportunity to make any significant contributions, however, as he died in 1976.