Professor emeritus, acclaimed mathematician Marina Ratner dies at 78

Dr. Marina Ratner, a professor emeritus in the campus’s math department, died July 7. She was 78.

Ratner was an acclaimed mathematician and was elected to the National Academy of Sciences. She was also awarded the Donald Sterling Noyce Prize for Excellence in Undergraduate Teaching in 2004.

Ratner was born in 1938 in the Soviet Union and received her doctorate from Moscow State University in 1969, according to the American Mathematical Society.

Ratner was invited to UC Berkeley in 1975, according to the New York Times. Ratner’s daughter, Anna Ratner, said her mother “really thrived” at UC Berkeley because “that’s when her career developed.”

“She aimed at solving a fundamental problem in dynamical systems, which would have all sorts of wonderful connections to other areas of mathematics, such as number theory,” explained Artur Avila, a mathematician at the National Center for Scientific Research in France and the Institute for Pure and Applied Mathematics in Rio de Janeiro, in an email.

According to her campus math department faculty page, Ratner’s primary fields of research were mathematical analysis and ergodic theory.

Amie Wilkinson, a mathematics professor at the University of Chicago, said in an email Ratner studied dynamical systems and motion in homogeneous spaces. In her research, she showed that “unipotent translation,” a type of motion, is “very rigid,” meaning that it is “restricted to follow very special directions in the space.”

“Her Theorem is very abstract and general, but it has all sorts of wonderful applications, especially in Number Theory,” Wilkinson said in an email. “The behavior of whole numbers can actually be connected to these motions in space.”

Wilkinson added that that acclaimed mathematicians Elon Lindenstrauss and Maryam Mirzakhani won the Fields Medal — a prestigious international honor awarded to mathematicians for work based on Ratner’s work.

Anna Ratner said Ratner’s career had “upward growth” and that she continued to produce outstanding work as she grew older.

Ratner could have won the Fields Medal herself for her work, according to Wilkinson and Avila, but she did not complete her research before the age of 40, which is a stipulation of the Fields Medal guidelines.

“A million people use her work to make major advances in number theory,” said Anatole Katok, a professor of mathematics at Penn State University.

Alexandre Chorin, a campus mathematics professor emeritus and former colleague of Ratner’s, called Ratner not only “an outstanding mathematician” but also an “extraordinarily fine professor.”

Anna Ratner said Ratner was a perfectionist, adding that “she would find the best ways to teach … (and) wasn’t afraid to speak up and improve on things.” She added that Ratner was always working, even when she didn’t appear to be doing so.

“It seemed like everybody really wanted to take her class. She tried really hard to explain things to the students and really cared for their understanding,” Anna Ratner said. “She really surprised her colleagues, (and her accomplishments) really opened up her field to young mathematicians to thrive.”

Contact Maya Ng-Yu at [email protected]