IN the early morning hours of Aug. 6, 1945, the Enola Gay, a B-29 airplane named after the pilot's mother, dropped the first atomic bomb used in warfare. Three days later, a second bomb brought the end of World War II. When Hans Albrecht Bethe - head of the Manhattan Project's Theoretical Physics Division from 1942 to 1946 - saw photographs of the destroyed Japanese cities, he did not expect the newly won peace would last for 50 years.
"We estimated that we would have five, maybe 10 years together before the world would be devastated," Dr. Bethe said in a recent interview, recalling the discussion he and his wife Rose had shortly after leaving the Los Alamos lab where the bomb was developed.
"It is now, I think, very unlikely that an atomic war will ever happen," he says.
That is a result not only of the devastating nature of atomic and nuclear bombs, but also of the efforts of scientists since that fateful day to see that atomic power was put to peaceful uses and that international controls were established.
Bethe, who was born in Strasbourg, Germany, was among more than 100 scientists forced to leave that country under Hitler's anti-Jewish ordinances. By 1935, he was a highly respected physics professor at Cornell University in Ithaca, N.Y. Bethe felt that radar was the most likely technology to aid in the war effort.
In the summer of 1942, Bethe was working at the Radiation Laboratory at the Massachusetts Institute of Technology in Cambridge, Mass., when Robert Oppenheimer tried to enlist him to join a group of theoretical physicists at the University of California, Berkeley. Oppenheimer called them the "luminaries." Their job was to throw light on the design of an atomic bomb. Bethe, who hypothesized in 1938 that stars produce energy by converting hydrogen to helium (earning a Nobel Prize in 1967), was at the top of Oppenheimer's "luminary" list. But Bethe doubted the feasibility of such an undertaking and turned down the invitation.
Later that summer, when he and Rose stopped in Chicago on their way to California, Bethe visited Enrico Fermi's lab. "After seeing the work that Fermi was doing with stacks of graphite, then I was quite sure it could be done. Or reasonably sure," Bethe says, "but what a terrible thing to do." The development of the bomb was inevitable, he says, and he wonders what might have happened if it had been built in peacetime.
There was an enormous fear that Hitler would get the bomb first. "The Nazis were very interested in doing dirt to the Allies," Bethe says. "They succeeded in making missiles that did great damage in England. Germany failed at getting the bomb because they weren't able to concentrate that many people and that much money on the project."
To Bethe, the best part of life is the process of discovery. Los Alamos, he says, was not a time of discovery but a time of problem-solving. "There were very difficult design problems which could be solved only by very competent and devoted people."
Bethe does not regret his part in the Manhattan Project. In his opinion, the bomb saved a lot of lives. "Far more Japanese lives than American lives were saved, and that has not been talked about much," Bethe says, recalling the nightly fire bombings of Japan's cities. He speculates that the number killed by the atomic bomb could have been rivaled by the number killed from fire bombing that would likely have continued for several more months.
"It was certainly tragic for the people of Hiroshima and Nagasaki," he says, "but for Japan as a nation, it was much better to end the war this way."
Los Alamos had put a heavy burden on the scientists. Bethe and his colleagues formed the American Federation of Scientists to lobby for international control of nuclear power. "We thought it was our duty to make known this menace, try to influence the public and the government to exercise restraint," he says.
Niels Bohr originated the idea of international control, Bethe says. While others worked on the bomb, Dr. Bohr tried to persuade statesmen that international control of the atom was the only way to avoid a pernicious arms race, or worse, atomic war.
The US adopted the Acheson-Lilienthal Committee's 1946 recommendation to create an international authority that would develop atomic reactors for power and other peaceful uses as official policy. The Soviets rejected the recommendation when it was presented to the United Nations.
This marked only the beginning of Bethe's work in politics. As a member of the science advisory committee to the president, he helped persuade the US to ban atmospheric nuclear tests. He was also a persistent advocate for arms control. He opposed the antiballistic missile systems (ABMs) in the 1970s and "star wars" in the 1980s. "We cannot go to zero nuclear weapons because of adventurous nations like Iraq and North Korea," he says. "But if we had 50 instead of 20,000 nuclear weapons, we would be sufficiently prepared against rogue nations."
The fate of the nuclear stockpile in the former Soviet Union is of less concern to Bethe than the fate of those countries' scientists. "I think it is a miracle that Russian scientists, thousands of whom worked on nuclear weapons and are now living in poverty, have not been seduced to defect to a country like Iran," Bethe says. "As far as I know, none has defected."
Since retiring from his post at Cornell in 1975, Bethe has directed his energies toward the stars once again. These days he is trying to understand how stars erupt into supernovas, cataclysmic explosions that signal the end of a star's life. This is just the kind of problem Bethe most likes to solve.