Leo P. Kadanoff was a theoretical physicist who contributed widely to research in the properties of matter, to the development of urban areas, and to statistical models of physical systems. His best-known contribution was in the development of the concepts of "scale invariance" and "universality" as they are applied to phase transitions. He was also involved in the understanding of the onset of chaos in simple mechanical and fluid systems.
Leo was born and received his early education in New York City. His academic degrees were received from Harvard University in the period 1957 - 1960. After a postdoctoral period at the Neils Bohr Institute in Copenhagen, he joined the staff of the University of Illinois in 1962 where he became a Professor of Physics in 1965.
During this period he carried out research activities aimed at understanding the properties of matter, especially the phenomenon of superconductivity, and did research and development work aimed at heat protection for ballistic missiles. In 1966 and 1967 he did research upon the organization of matter in "phase transitions" which led to a substantial modification of the way physicists look at these changes in the state of matter. This work led to his receipt of the Buckley Prize of the American Physical Society (1977), the Wolf Foundation Prize in 1980, the 1989 Boltzmann Medal of the International Union of Pure and Applied Physics.
After these successes he turned his research attention to problems of urban growth. In 1969, he moved to Brown University where he became a University Professor. In parallel, he conducted research on mathematical models for urban growth, and upon solid state physics. In addition, he contributed to planning in Rhode Island through his service on the technical committees of the statewide planning program and his presidency of the Urban Observatory (Rhode Island).
In the mid 1970s Leo’s research interests began to focus once again upon physics. After a period in which he worked mostly upon the applications of universality and scale invariance to phase transitions and particle physics, his attention turned to disorder, turbulence and chaos in physical systems. He moved to the University of Chicago in 1978 where he became the John D. and Catherine T. MacArthur Distinguished Service Professor of Physics and Mathematics. At Chicago, he was also particularly interested in complexity, fluid flow, and in the applications of computers to physical calculations.
Leo was a member of the National Academy of Sciences and a Fellow of the American Academy of Arts and Sciences, of the American Philosophical Society, of the American Physical Society and of the American Association for the Advancement of Science. He received the Quantrell Award for excellence in undergraduate teaching from the University of Chicago, the Centennial Medal of Harvard University, the Onsager Prize of the American Physical Society, the Grande Medaille d'Or of the Academy des Sciences de l'Institut de France, and the National Medal of Science (U.S.).