Robert J. Zimmer, Who Promoted Free Speech on Campus, Dies at 75

“I actually started college as a physics major,” Mr. Zimmer once confessed. “I switched to mathematics when I tried unsuccessfully for 45 minutes to get an oscilloscope to show a sine wave.”

As a mathematician and an author, he specialized in “ergodic theory, Lie groups and differential geometry,” according to a university biography.

He taught at the United States Naval Academy from 1975 to 1977 and began teaching at the University of Chicago in 1977. He was named a full professor in 1980. He also taught for two years at the University of California, Berkeley.

At Chicago, he served as the chairman of the math department, the deputy provost for research and the vice president for research of the Department of Energy’s Argonne National Laboratory in Lemont, Ill., which the university oversees. From 2002 to 2006, he was a math professor and provost at Brown University. He then returned to the University of Chicago as its 13th president.

His marriage in 1974 to Terese Schwartzman, the former director of strategic initiatives for the Urban Education Institute, ended in divorce. In addition to his wife, Professor Bartsch-Zimmer, who is the director of the university’s Institute on the Formation of Knowledge and whom he married in 2011, and his son Benjamin, the chief executive of a biotechnology firm, Mr. Zimmer is survived by two other sons from his first marriage: David, a lawyer, and Alex, a filmmaker. He is also survived by a brother, Richard B. Zimmer; his mother, Harriet (who is 104 and still lives in the West Village apartment where Mr. Zimmer was raised); and two grandchildren.

At the end of the 2021 academic year, while recovering from brain surgery, Mr. Zimmer stepped down as president to become chancellor. He retired and was named chancellor emeritus in July 2022.

As a private institution, the University of Chicago was under no obligation to abide by the First Amendment’s guarantee of free speech. But, Bret Stephens wrote in a New York Times opinion essay in 2017, the real crux of Mr. Zimmer’s case for free speech, offensive or not, was that it was “our salvation from intellectual mediocrity and social ossification.”