Abraham Pais; Physicist, Einstein Biographer

COPENHAGEN â€”  Abraham Pais, an American physicist and science historian who wrote one of the most acclaimed biographies of Albert Einstein, has died. He was 81.

Pais, who was born in 1919 in Amsterdam, died Friday in Copenhagen of heart failure, colleagues at the University of Copenhagen’s Niels Bohr Institute said.

Pais helped build the conceptual foundations of the modern theory of elementary particles when he was a professor at Princeton University in New Jersey, and he worked with such physics luminaries as Bohr and Albert Einstein.

He was best known, however, as a science historian. His biography “Subtle Is the Lord: The Science and the Life of Albert Einstein,� is considered a definitive work about the Nobel laureate who developed the theory of relativity.

The biography was the winner of the 1983 American Book Award.

In reviewing the book for The Times in 1983, former Times science writer Lee Dembart called it a “loving, thoughtful, respectful and insightful book.� Dembart hailed the book as the first Einstein biography written in English and commented that its “detailed and technical discussion of Einstein’s science� was written “powerfully and movingly.�

“The reminiscences of Helen Dukas [Einstein’s longtime secretary], the quotations from letters and the firsthand observations of the author,� Dembart added, “give this book a closeness to subject that some other biographies lack.�

Pais also wrote a biography of Bohr, the Dane who was awarded the 1922 Nobel Prize in physics for his nuclear research.

Pais, who was Jewish, was forced into hiding when Nazi troops invaded his homeland in 1940. He was briefly imprisoned by the Gestapo in 1945 and many of his relatives, including his sister and her husband, died in concentration camps.

After World War II, Pais briefly lived in Copenhagen, where he worked with Bohr, who introduced him to J. Robert Oppenheimer, the father of the atomic bomb. Oppenheimer asked Pais to move to New Jersey to help strengthen Princeton’s physics division in 1946.

Pais, who became a U.S. citizen in 1954, joined Rockefeller University in New York City in 1963 as a physics professor and was later named Detlev W. Bronk professor emeritus.

In 1985, he met his second wife, Ida Nicolaisen, an anthropologist at the University of Copenhagen, and moved to the Danish capital. Pais, who had retired, joined the Niels Bohr Institute and wrote numerous books, including “Inward Bound: Of Matter and Forces in the Physical World, “ which expanded on his earlier scientific articles.

In a Times review of that 1986 book, author John L. Heilbron praised “Pais’ large and valuable inventory of conceptual advances.�

“His memoir of the postwar years is informed and enlivened,� Heilbron commented, “by his direct participation in the construction of modern theories of elementary particles.�

Pais’ last book, “The Genius of Science--A Portrait Gallery,� containing commentary on 12 American physicists, all of whom he knew personally, was published earlier this year.