Marina Evseevna Ratner (Russian: Мари́на Евсе́евна Ра́тнер; October 30, 1938 – July 7, 2017) was a professor of mathematics at the University of California, Berkeley who worked in ergodic theory. Around 1990, she proved a group of major theorems concerning unipotent flows on homogeneous spaces, known as Ratner's theorems. Ratner was elected to the American Academy of Arts and Sciences in 1992, awarded the Ostrowski Prize in 1993 and elected to the National Academy of Sciences the same year. In 1994, she was awarded the John J. Carty Award from the National Academy of Sciences.
Marina E. Ratner
Marina Ratner in 1988
|Died||July 7, 2017 (aged 78)|
|Alma mater||Moscow State University|
|Awards||Ostrowski Prize (1993)|
|Institutions||University of California, Berkeley|
|Doctoral advisor||Yakov Sinai|
Ratner was born in Moscow, Russian SFSR to a Jewish family, where her father was a plant physiologist and her mother a chemist. Ratner's mother was fired from work in the 1940s for writing to her mother in Israel, then considered an enemy of the Soviet state. Ratner gained an interest in mathematics in her fifth grade. From 1956 to 1961, she studied mathematics and physics at Moscow State University. Here, she became interested in probability theory, inspired by A.N. Kolmogorov and his group. After graduation, she spent four years working in Kolmogorov's applied statistics group. Following this, she returned to Moscow State university for graduate studies were under Yakov G. Sinai, also a student of Kolmogorov. She completed her PhD thesis, titled "Geodesic Flows on Unit Tangent Bundles of Compact Surfaces of Negative Curvature", in 1969.  She emigrated from the Soviet Union in 1971 after obtaining a Ph.D. to Israel and taught at the Hebrew University 1971–1975. She began to work with Rufus Bowen at Berkeley and later emigrated to the United States and became a professor of mathematics at Berkeley. Her work included proofs of conjectures dealing with unipotent flows on quotients of Lie groups made by S. G. Dani and M. S. Raghunathan. For this and other work, she won the John J. Carty Award for the Advancement of Science in 1994. 
- In Memoriam: University of California, Berkeley website.
- Larry Riddle, Biography of Marina Ratner
- Dave Witte Morris, Ratner's Theorems on Unipotent Flows, ISBN 0-226-53984-9
- Membership list, American Academy of Arts and Sciences, retrieved 2015-06-13.
- "John J. Carty Award for the Advancement of Science". National Academy of Sciences. Archived from the original on 29 December 2010. Retrieved 25 February 2011.
- "Marina Ratner biography". www-history.mcs.st-and.ac.uk. Retrieved 2019-02-09.
- Marina Ratner at the Mathematics Genealogy Project
- Hartsock, John (1987-12-03). "Soviet refusenik to be released". UPI.
- Cook, M.; Gunning, R. C. (2013). Mathematicians: An Outer View of the Inner World. Princeton: Princeton University Press.
- "John J. Carty Award for the Advancement of Science". www.nasonline.org. Retrieved 2019-02-09.
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