We are extremely sad for the passing of Professor Donald G. Aronson on April 17, 2019. Beloved for his collegiality and his sense of humor, Don was deeply respected for his research contributions in partial differential equations and dynamical systems. He was a font of departmental history, especially about its early years. Don read and traveled widely; his knowledge of history, the arts, and literature was remarkable. He was a music lover who went to hear live performances whenever he could. He was also an extraordinary gourmand, a food adventurer who thoroughly enjoyed dining.
Don was born on October 2, 1929, in Jersey City, NJ. He often described Jersey City as a rough and tumble suburb of New York, and delighted in perpetuating the reputation that it was run by thugs. In spite of his humble beginning, or perhaps because of it, he went on to attend the Massachusetts Institute of Technology upon high school graduation. He received all his degrees — BS, MS, and PhD — from MIT, earning the last one in 1956. His wrote his thesis under the famous Norman Levinson, entitled “Boundary Layer Problem for a Linear Parabolic Differential Equation”. In 1954, while still a graduate student, he got a summer job as Scientific Officer at the National Research Development Council (NRDC) in London, England. There he programmed the Alan Turing designed Ferranti Mark I computer, the world’s first supercomputer. He also worked with Christopher Strachey to simulate the proposed Ferranti Pegasus, which was eventually built in 1956.
Perhaps not surprisingly, his first job was with the Digital Computer Lab at the University of Illinois in Urbana Champaign (UIUC). The institution was famous for being the birthplace of an early US supercomputer, the Illiac. He was appointed as a Research Associate, a position he held only for one year. In 1956, he moved to the University of Minnesota to join the Department of Mathematics at the then Institute of Technology (now College of Science and Engineering). It should be noted that at that time there were two mathematics departments at the U, the other being in the College of Liberal Arts. (They were later merged in the mid 1960’s.) Don was first appointed as Instructor for a year. He was Assistant Professor from 1958 to 1962, becoming Full Professor in 1965, a mere seven years since his initial tenure-track appointment.
Don has 91 publications listed in MathSciNet. His two most highly cited works are with Hans Weinberger:
- Multidimensional nonlinear diffusion arising in population genetics. Advances in Mathematics 30, 1978.
- Nonlinear diffusion in population genetics, combustion, and nerve pulse propagation, in Partial differential equations and related topics, Lecture Notes in Math., Vol. 446, Springer, Berlin, 1975.
To give a sense of the importance of the 1978 work, MathSciNet reports that the paper was cited over 50 times in 2018, a full four decades after its appearance. A way to interpret the continued citation is to say that the work was definitive and has not been surpassed. Don wrote a very influential monograph “The Porous Medium Equation”, published by Springer in 1986 in their Lecture Notes in Mathematics series. In 1976, he was the principal lecturer in the CBMS Conference at the University of Houston. The topic of his lectures was nonlinear diffusion.
Don worked in several areas of partial differential equations and nonlinear dynamics. Perusal of his list of publications indicates that he wrote papers in nonlinear diffusion, analytical and computational study of bifurcations, pattern formation, mathematical ecology, and mathematical biology. Don had over 40 co-authors, consistent with his idea that mathematics research as a “team sport”. Indeed, life-long friendships resulted from many of these collaborations. Many collaborators were colleagues, postdocs and students in the department, but a good number of them were not. Some are based abroad, mostly in Europe.
Don talked a lot about his sabbatical at the University of Rome in 1968-1969. His entire family went along with him. They brought back with them a great appreciation for Italy, especially its food. He and Claire were well known for their Italian dinner parties which introduced diners to authentic Italian food beyond the classic “spaghetti and meatballs”. In 2017, Don and Claire took their adult children back to tour Italy. He continued to speak fondly of that trip and his Rome sabbatical until his last days.
In June 2001, a conference, entitled “Nonlinear Phenomena in Science”, was held at the Free University of Amsterdam to honor Don on the occasion of his 70th birthday. In 2013 Don was elected to the Inaugural Class of Fellows of the American Mathematical Society.
Don retired in June 2002. Shortly thereafter, he was recruited by Doug Arnold (IMA Director) and Fadil Santosa (Deputy Director) to join the IMA as their first Director of the IMA Postdoctoral Program. In this role, he supervised the selection of postdocs and their onboarding upon arrival at the IMA in the Fall. He stayed in this role until 2010.
Don’s place in mathematics is secured. He will be missed for his quick quips, which he dispatched with an endearing twinkle. He will be remembered for his many contributions to the life and the functioning of the mathematics department. With his passing, the department has lost a very dear friend and colleague.