Alexandra Bellow | Biography

Ergodic theory, Alexandra Bellow's field of specialization, deals with the long term averages of the successive values of a function on a set when the set is mapped into itself, and whether these averages equal (converge to) a reasonable function on the set. The theory applies to probability and time series, and to the concept of entropy in physics and information theory. Bellow has proved significant results in this field.

Alexandra Bellow was born in Bucharest, Romania, on August 30, 1935. Her father, Dumitru Bagdasar, had studied medicine in the United States. He was a famous neurosurgeon who founded a school of neurosurgery in Romania in that year. Her mother, Florica Bagdasar, was a psychiatrist specializing in the treatment of mentally retarded children. The Romanian philosopher Nicolae Bagdasar was Bellow's uncle. After World War II, the politics of Romania were extremely unstable as the communists took control of the country. Bellow's parents supported the communists, and in 1946, her father was appointed minister of health in the Groza government. Bellow's father was soon accused of "defection," removed from the ministry, and imprisoned. He died in 1946, reportedly of cancer. Bellow's mother succeeded him as minister of health. According to the New York Times, she was the first woman to hold a ministerial position in Romania. However, by 1948 she was removed from that post. Bellow told Ruth Miller (a biographer of her second husband, Saul Bellow) that her mother was accused of "cosmopolitanism" and was prohibited from doing any work or practicing medicine.

In spite of these problems, Bellow studied mathematics at the University of Bucharest. In 1956, she married Cassius Ionescu Tulcea, a professor of mathematics at the university. She received a M.S. in mathematics in 1957. In that year, Bellow and her husband came to the United States to study at Yale University. He was a research associate at Yale while they were students. They both received Ph.D.s in mathematics from Yale in 1959. Bellow's thesis was titled "Ergodic Theory of a Random Sequence." After graduation, Bellow became a research associate at Yale from 1959 to 1961 and at the University of Pennsylvania from 1961 to 1962. She taught at the University of Illinois at Urbana as an assistant professor from 1962 to 1964, then as associate professor from 1964 to 1967. In 1967, Bellow went to Northwestern University as a professor. Her husband held positions at the same schools, although not exactly in the same years. Both remained at the mathematics department at Northwestern for the rest of their careers. Their book, Topics in the Theory of Liftings, appeared in 1969. They were divorced in that year.

Starting in 1971, Bellow published papers on ergodic theory. In 1974 she married the writer Saul Bellow, and in the following year they traveled to Israel, where she taught and worked with colleagues in mathematics at the University of Jerusalem. Saul Bellow won the Nobel Prize for literature in 1976. In the late 1970s Bellow published several papers on asymptotic martingales. Bellow edited, with D. Kolzow, the proceedings of a conference on Measure Theory held in Oberwolfach in 1975. She was an editor for the Transactions of the American Mathematical Society from 1974 to 1977, associate editor of the Annals of Probability from 1979 to 1981, and associate editor for Advances in Mathematics since 1979. Bellow's 1979 paper with Harry Furstenberg on applying number theory to ergodic theory contains the Bellow-Furstenberg Theorem.

Bellow was a Fairchild scholar at CalTech in 1980, and also visited the University of California at Los Angeles. She was divorced from Saul Bellow in 1986. Bellow received an award from the Alexander von Humboldt Foundation, which sponsors visits to Germany by scholars, in 1987. In 1989, she and Roger L. Jones of De Paul University organized a conference on "Almost Everywhere Convergence in Probability and Ergodic Theory" at Northwestern University and edited the conference proceedings. In that same year, Bellow married Alberto P. Calderon, a distinguished mathematician and civil engineer retired from the University of Chicago, whose fields of research are partial differential equations, functional analysis and harmonic analysis.

In 1991, Bellow gave the Emmy Noether Lecture for the Association for Women in Mathematics. Bellow, Jones, and others have collaborated on eight recent papers that deal primarily with partial sequences of observations. This work consists of their attempts to identify when averages based on partial observations are probably valid for the whole population, when they are not valid, and by how much. A 1996 paper in this series had six authors, unusual for a paper in mathematics, which was featured in the Mathematical Reviews. It describes averages that behave very badly. Jones describes Bellow as an excellent collaborator who is extremely knowledgeable, "very clever and very careful," and, according to another colleague, "never seems to make a mistake." Jones also reports that Bellow enjoyed her teaching and was a very good instructor who supervised at least four Ph.D. students. A conference was scheduled at Northwestern in October 1997 on the occasion of Bellow's retirement. Bellow plans to continue her research in mathematics.