Recognition of work in measuring long-term dynamic systems.
By: Jeff Milgram
For his work measuring long-term dynamic systems like the weather and the stock market, Princeton University mathematics Professor Yakov G. Sinai has won one of two prestigious Nemmers Prizes, Northwestern University announced this week.
University of Minnesota economics Professor Edward Prescott was the other winner. They each will receive $125,000 stipends.
Saying he was "absolutely" surprised, Professor Sinai said, "I got a telephone call from the provost (Lawrence B. Dumas) that I won the award."
Professor Sinai’s work deals with measuring dynamic systems, or systems that change over time, such as weather, the motion of planets and economic systems, easy to measure in the short term, but difficult to understand and predict in the long term.
His work has influenced statistical mechanics and probability theory.
Professor Sinai, who was on the faculty of Moscow State University from 1971 to 1993, when he came to Princeton, was the first to come up with a mathematical foundation for determining the number that defines the complexity of a given dynamic system. His mathematical system is called Kolmomgorov-Sinai entropy.
"The concept of entropy enables us to measure random and chaotic behavior in systems," Professor Sinai said. "There are many real-world applications weather, the stock market and even social sciences."
Northwestern mathematics Professor Dr. Zhihong Jeff Xia, a member of the Nemmers selection committee, said Professor Sinai’s work brings order out of chaos.
"There are precise solutions to these equations for very short periods of time. But if you want to look at long-term behavior, like weather for the next five days to a week, then the system becomes very complicated. This is when we see something called chaos," Dr. Xia said.
"Kolmomgorov-Sinai entropy measures complexity, which is the first step. Then comes finding patterns. Even though a system is complex, there are always patterns you just need to look at it the right way. Sinai was the first one to recognize and study these patterns," said Dr. Xia.
Professor Sinai also has won the Wolfe Foundation prize in mathematics.
Dr. Prescott’s work has focused on business cycles and economic fluctuations. He has demonstrated that standard growth behavior historically studied by microeconomists also can explain business cycle fluctuations that macroeconomists have sought to understand.
His theory that a substantial part of business cycles is simply the best response of the economy to policy changes that affect the economy’s productivity is widely accepted in the field of economics.
"It is a privilege for Northwestern to recognize these scholars," said Northwestern University President Henry S. Bienen. "Their work has helped to shed light on important issues in mathematics and economics that ultimately have relevance to all of us."
The Nemmers Prizes are awarded to scholars who display outstanding achievement in their discipline as demonstrated by major contributions to new knowledge or the development of significant new modes of analysis. Initiated in 1994, they are made possible through bequests from the late Erwin E. Nemmers, a former member of the Northwestern University faculty, and his brother, the late Frederic E. Nemmers, both of Milwaukee.
The prizes are awarded every other year.