The Manhattan Project, the top-secret government program that led to the development of the atomic bomb, occupies a unique place in the history of science. But the legacy of the project's director, J. Robert Oppenheimer, is less clear-cut. Much of the debate that has swirled around Oppenheimer was prompted by his leftist ties in the 1930s. These connections, along with Oppenheimer's publicly expressed qualms about the bomb he helped develop, led to the loss of his security clearance in 1954 during the Red Scare that gripped America. It was a loss from which, his friends say, he never recovered.

Now, nearly 40 years after the physicist's death, comes Oppenheimer: Portrait of an Enigma (Ivan R. Dee, $25) by Jeremy Bernstein, a former science writer for the New Yorker. Bernstein has written a book that manages to be both insightful and maddening.

Bernstein spent two years at the Institute for Advanced Study at Princeton in the late 1950s when Oppenheimer was the director. The book benefits from Bernstein's access: The two men had several private talks, knew many of the same people and were raised in the same affluent, intellectual New York Jewish milieu.

The book contains some provocative observations about its subject, a scientific genius who read widely, spoke several languages, studied Sanskrit and wrote poetry. Yet Oppenheimer was divorced from current events: He read neither magazines nor newspapers and didn't learn about the stock market crash of 1929 until long after it happened.

Bernstein discusses Oppenheimer's insecurities, some of which were the product of anti-Semitism, his self-destructiveness reflected in the voracious cigarette habit that killed him, and the single-minded toughness he exhibited as lab director at Los Alamos when the outcome of the war was by no means certain.

Unfortunately Bernstein has also studded the biography with irrelevant details, most of them about himself, such as the summer camp and professional tennis match he attended. Yet for readers interested in Oppenheimer, the shortcomings of Bernstein's style are secondary to his portrait of an iconoclast whose stewardship at Los Alamos changed the course of history.

-- Sandra G. BoodmanSandra G. Boodman is a science reporter for The Post.