Math professor Serge Lang dies at age 78

Serge Lang, a noted mathematics professor emeritus and the most prolific modern writer in his field, died Monday at the age of 78.

Yale President Richard Levin said he did not know the circumstances of Lang’s death, but a colleague said he had been suffering from health problems. Lang, a member of the National Academy of Sciences who retired from Yale last year, was known for his activism in mathematical education and his controversial disputation of the link between HIV and AIDS.

“He was a forceful advocate for causes he believed in,” Levin said. “Sometimes he regarded himself as the conscience of the University.”

Mathematics professor Peter Jones said the volume of Lang’s work is believed to have surpassed that of 18th century mathematician Leonhard Euler, who held the record for total number of words written. Lang’s work includes hundreds of articles, books and textbooks, as well as “The File,” an anthology of academic inconsistencies that he distributed to friends and colleagues.

Economics professor John Geanakoplos, Lang’s longtime acquaintance and colleague, said “The File” was only part of his lifelong crusade against inaccuracy.

“There were famous people and causes that he found intellectually unscrupulous, and he wouldn’t rest until he got to the bottom of things,” Geanakoplos said.

In perhaps his most controversial claim, Lang argued that a causal link between HIV and AIDS has not been definitively established. Lang frequently handed out pamplets on campus at talks dealing with AIDS.

But Lang had more success in his campaign against Samuel Huntington, a Harvard political scientist nominated to the National Academy of Sciences. In an unorthodox campaign, Lang defeated Huntington’s nomination on the grounds that he used spurious mathematical reasoning.

Lang even went so far as to administer a “Huntington Test” to dozens of his students each year, said Avidit Acharya ’06, his friend and mentee. Lang had the students comment on passages from Huntington’s work to determine, as he would put it, whether they could “tell a fact from a hole in the ground,” Acharya said.

Lang’s demanding personality extended into the classroom, said Timothy Brandt ’06, a former student. Though Lang befriended his students, sometimes taking his class out to dinner at Yorkside Pizza and Restaurant, he did not withhold his criticism from them.

“He wasn’t afraid to tell you that you didn’t know what you were talking about, that you were full of it,” Brandt said.

Lang’s career research focused on algebra — for which he won the prestigious Frank Nelson Cole Prize — as well as algebraic geometry, number theory, and analysis. Jones said that he often stayed at his office late into the evening, and did not stop theorizing even when he got home. For years at a time, Jones said, Lang would call him each night to pose mathematical problems without pausing to identify himself or say hello.

Many of their discussions centered around the “heat kernel,” a mathematical concept that Lang believed could be used to approach research and instruction across a variety of mathematical branches. As with “The File,” he made publicizing the heat kernel his personal mission.

Despite Lang’s prolific research, teaching undergraduates was his principal passion. Geankoplos met Lang as a freshman at Yale in 1971, when Lang was touring the dining halls of various universities to evaluate their job offers.

“He decided that the best way to find out what the school was like was to sit down and have meals with the undergraduates,” Geanakoplos said. “He was tremendously engaged in what his students were doing and thinking.”