Hans Bethe, titan of physics and conscience of science, dies at 98

Related story: Bethe's colleagues reminisce

Emeritus Professor of Physics Hans A. Bethe in his campus office Dec. 19, 1996. On the blackboard is Bethe's "Carbon Cycle" equation for nuclear energy generation in stars. Michael Okoniewski

By David Brand

Professor emeritus Hans Bethe, a Nobel laureate who was the last of the giants of the golden age of 20th-century physics and the birth of modern atomic theory -- and one of science's most universally admired figures -- died quietly March 6 at his home in Ithaca. He was 98.

Bethe joined Cornell's physics department in 1935 after fleeing Nazi Germany because his mother was Jewish. He was one of the most honored members of the faculty in the university's 140-year history for his work in revolutionizing our perception of the real world. But he was equally admired for his reputation for integrity, humility and concern that made him the conscience of science.

President Jeffrey S. Lehman said: "The world has lost one of the great pioneers of 20th-century physics, and Cornell has lost a beloved teacher, mentor and friend. In the breadth of his insight, the rigor of his research, the depth of his social conscience and the steadfastness of his commitment to Cornell, Hans Bethe set the standard for engaged scientific citizenship that will serve as a beacon for generations to come."

Bethe's fellow Nobel laureate, physicist Robert C. Richardson, Cornell's vice provost for research, said: "Hans Bethe was a giant of 20th-century science. He has been revered by his Cornell colleagues. He left profound and enduring marks of his intellectual leadership on Cornell, the United States and the entire world. Bethe had an important influence upon me as a young faculty member when I arrived at Cornell in 1966. He demonstrated a clarity of thought that I could only hope to emulate some day."

Bethe's deep and abiding belief in science was unaffected by his work on developing the first atomic bomb. "The intellectual achievements of pure research are one of the things that make life worth living," he once said. Even when he had just witnessed the blinding flash from the detonation of the first nuclear explosion at Trinity site in the New Mexico desert on July 16, 1945, he professed only a concern about the atomic bomb's functioning. "I am not a philosopher," he explained.

Yet he was deeply committed to humanitarian values, as shown in his efforts to limit the use of nuclear weapons and his work to promote the peaceful use of nuclear energy. "Science is always more unsolved questions, and its great advantage is that you can prove something is true or something is false. You can't do that about human affairs -- most human things can be right from one point of view and wrong from another," he once said.

Eminent astrophysicist Edwin E. Salpeter, who arrived at Cornell in 1949 to study under Bethe, said of his former mentor, "He brought clarity to an amazing number of fields of science -- especially in astrophysics -- where he had to work in the face of uncertainty."

Despite the turmoil of history, Bethe remained committed to the idea of physics as a thing of beauty leading to discovery and understanding, a quest that he called "the spirit of physics." It was a spirit enunciated by his famously optimistic phrase "I can do that," always said in the face of opposition or adversity. Salpeter noted that Bethe's optimism sprang from knowing how to use the minimum mathematical complexity compatible with each problem he faced. "In his hands, approximations were not a loss of elegance but a device to bring out the basic simplicity and beauty of each field," he said.

During World War II Bethe was a key figure in the building of the first atomic bomb as head of the theoretical physics division at Los Alamos. But after the war he became a persistent champion of nuclear arms control, helping to persuade the White House to ban atmospheric nuclear tests in 1963 and antiballistic missile systems in 1972. He stood firm in his opposition to President Ronald Reagan's Strategic Defense Initiative, informally referred to as Star Wars.

Bethe also was a deeply committed, even sensitive, teacher, and from 1945 until his retirement from active teaching in 1975 he trained and inspired a large number of graduate students, including Freeman Dyson of the Institute for Advanced Study at Princeton.

His presence at Cornell was a magnet that attracted a world-class faculty to the physics department. After the war he became more involved in what he called "political physics," an attempt to educate the public and politicians about the consequences of nuclear weapons. He was on the President's Scientific Advisory Committee advising Presidents Eisenhower, Kennedy and Johnson on ways to limit nuclear proliferation and further development of atomic weapons.

Bethe was truly indefatigable. In his 90s, with his left arm and shoulder wasted by a degenerative muscle disease, he continued to arrive regularly at his office at the Newman Laboratory although, he admitted, "not every day do I find anything interesting." He always carried his old slide rule on which he could with ease perform calculations to the sixth power.

Hans Albrecht Bethe was born July 2, 1906, in Strasbourg, now in France but then part of Germany. He showed early genius as a mathematician, studying physics at the University of Frankfurt and doing research in theoretical physics at the University of Munich, where he received his doctorate in 1928. In 1930 and 1931 he received fellowships to the University of Cambridge and the Institute of Physics in Rome, where he worked with Enrico Fermi. He taught at Frankfurt and Munich. At the Technical University of Stuttgart he was assistant to Paul Ewald, professor of theoretical physics, who would become his father-in-law a decade later when Bethe married Rose Ewald, then a student at Smith College, who graduated from Cornell in 1941.

Bethe's father, a professor of physiology, was a Protestant, but his mother was Jewish. With Nazi race laws enacted after Hitler came to power, he was dismissed from his faculty position at the University of Tubingen. He left Germany, going first to England, then to America and Cornell in 1935.

Bethe later said of his arrival at Cornell: "I came to America expecting to be among strangers. I came home to Ithaca." He regarded it as home for the next 70 years.

Bethe propelled Cornell's physics department into the top rank. At Cornell during the late 1930s he wrote his famous reviews of nuclear physics and, in 1938, published his seminal paper on the theory of energy production in stars that explained how the sun shines. The work was to win him the Nobel Prize in 1967.

He published papers in every decade from the 1920s through the 2000s. In 1995 Bethe's colleagues, students and friends marked his 60 years at Cornell with a two-day tribute to his life and work. "If you know his work," said John Bahcall of the Institute for Advanced Study, "you might be inclined to think he is really several people, all of whom are engaged in a conspiracy to sign their work with the same name."

After World War II Bethe brought some of the most outstanding young physicists at Los Alamos to Cornell, among them Richard Feynman and Robert Wilson. Under their leadership Cornell became a world center for high energy elementary particle physics. Bethe and Feynman played a central role in developing quantum electrodynamics, work for which Feynman shared the Nobel Prize in 1965.

He was deeply in love with the mountains, and was also a stamp collector. "It is the one place in the world where all countries sit together peacefully," he said.

In addition to his wife, he is survived by two children, Henry, of Ithaca, and Monica, who lives near Kyoto, Japan, and three grandchildren.