ITHACA, N.Y. — Hans Bethe, a giant of 20th-century physics who played a central role in the building of the atomic bomb and won a Nobel Prize for discovering the process that powers the sun and the stars, has died at 98.
Bethe, who died Sunday, stood alongside such figures as Enrico Fermi, Robert Oppenheimer, Leo Szilard and Edward Teller as a member of the corps of scientists who ushered in the atomic age.
During the World War II race to build the bomb, Bethe was head of the Manhattan Project’s theoretical physics division at Los Alamos, N.M.
“Bethe was the last of the giants of Los Alamos,” said Gerald Brown, a physics professor at the State University of New York at Stony Brook.
A breakthrough every decade
Bethe, who fled Nazi Germany and joined the Cornell University faculty in 1935, also made major discoveries about how atoms are built up from smaller particles, about what makes dying stars blow up, and how the heavier elements are produced from the ashes of these supernovas.
He averaged a scientific breakthrough every decade or so, beginning during the golden age of physics between the world wars.
Bethe also played key roles in the 1963 nuclear test ban treaty and the 1972 anti-ballistic missile treaty.
Even though the A-bomb designers knew its calamitous potential, the weapon’s reality “was worse than we expected,” Bethe reflected in an interview with The Associated Press in 1996. “After Hiroshima, many of us said: ‘Let’s see that it doesn’t happen again.”’
“One of the things that was very special about Hans was his strong moral motivation,” said astrophysicist John Bahcall of the Institute for Advanced Study in Princeton, N.J. “He did things because he believed they were right and not because they were convenient or helpful to him or promoted his career. His work on the bomb was motivated by a desire to preserve freedom and open society in the face of a spreading Nazi tyranny, which he knew about firsthand.”
Fled Nazism, then wrote 'Bethe's Bible'
Born in Strasbourg in 1906, Bethe (pronounced BAY-tuh) fled Germany in 1933 after losing a university post because his mother was Jewish.
Bethe emerged in an era bursting with discoveries about the fundamental building blocks of matter. In the infancy of modern atomic theory, he spelled out what was known and unknown in nuclear physics in a classic series of papers dubbed Bethe’s Bible.
He also investigated the structure of atoms, molecules and solids, devised techniques for calculating the properties of nuclear matter and laid the groundwork for the development of quantum electrodynamics.
In 1938, leading nuclear physicists were invited to solve a mystery that had long stumped the best scientific minds: the source of the sun’s energy. Just six weeks later, Bethe came up with his “carbon cycle” formula: He showed that virtually all the energy produced by the most brilliant stars stems from a fusion reaction in which hydrogen serves as the fuel and carbon as the catalyst.
His work eventually won him the Nobel in physics in 1967.
At Los Alamos, Bethe earned the nickname “The Battleship.”
“He worked like a bulldozer,” Brown said. “If he ran into a temporary wall, he would just go around it. With his immense confidence and his knowledge, he was arguably the most powerful scientist of the century.”
Studying supernovas and numbers
After retiring from teaching in 1975, Bethe turned to astrophysics, a field he previously had only dipped into. With his grasp of so many areas of theoretical physics, Bethe was persuaded by Brown, an astrophysicist, to delve into the mysteries of mighty star explosions, or supernovas. They collaborated on a 1979 paper that upended long-held assumptions about the density of a collapsing star’s core.
Bethe worked into his 90s at Cornell University’s Newman Laboratory of Nuclear Studies, devoting many solitary afternoons to his passion: numbers.
“I think it’s very useful for keeping me young,” he said in a 1996 interview.
At Bethe’s zenith, his mind was a wonder to behold. He could not program the simplest computer, but had no trouble digesting reams of supercomputer readouts. For help, he reached into his briefcase for a slide rule he had carried around for 70 years.
He also had a habit of taking a 30-minute bath each morning.
“You sleep and things get somewhat unscrambled in your mind,” he said in 1996. “Then in the bath, I can become conscious of that.”
Long love affair with science
Science had fascinated Bethe since boyhood.
“You see, most philosophical questions were quite well answered by the old Greeks, and even better by people from 1500 to 1800,” he said. As for deciphering human character, “I don’t think Shakespeare has ever been surpassed.”
“Science is always more unsolved questions, and its great advantage is 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.
“It is the most wonderful feeling when you come to a real answer. This is it, and this is correct! In science, you know you know.”
Bethe’s survivors include his wife, Rose; a son, Henry; and a daughter, Monica.
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