Bethe, Hans

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Hans Albrecht Bethe (1906–2005) was a Nobel physicist and leader in efforts to promote social and ethical responsibilities among scientists and engineers. Born in Strassburg, Germany (now Strasbourg, France), on July 2, Bethe received his doctorate from the University of Munich in 1928 and began teaching at Cornell University in 1935, where he continued throughout his career. Bethe died in Ithaca, New York, on March 6. In 1938 he published three papers on nuclear physics that became known as "Bethe's Bible," and he received the 1967 Nobel Prize for discoveries concerning energy production in stars.

During World War II, the U.S. government recruited Bethe to work on military technologies, and in 1943 he was made director of the theoretical physics division in the Manhattan Project at Los Alamos, New Mexico, where he helped develop the first atomic bomb. The use of nuclear weapons created a strong sense of social responsibility in Bethe, and during the Cold War he worked to reduce the danger posed by nuclear weapons.

In 1945 Bethe became one of the original supporters of the Federation of Atomic (later American) Scientists, which focused on educating others about the implications of nuclear weapons. Bethe also served as a member of the President's Science Advisory Committee from 1956 to 1964. Beginning in 1957, he headed a presidential study of nuclear disarmament, known as the "Bethe panel," and served the following year as scientific advisor to the U.S. delegation at the Geneva nuclear test-ban talks. Bethe was "one of the heroes" in the campaign that culminated in the limited nuclear test-ban treaty signed by the United States, Great Britain, and the Soviet Union on August 5, 1963 (Schweber 2000).

Complex Ethical Response to Nuclear Weapons

During this time, Bethe developed a complex response to the ethical dilemma created by his dual roles as an advisor to the Los Alamos National Laboratory and as a political and moral critic of the development of nuclear technologies—a tension that challenged many scientists and engineers. For fifty years, Bethe led the struggle to address such questions as: When should various nuclear technologies be developed? What is the proper role of scientists and engineers in a democracy? What moral and political responsibilities do they have for the use of the knowledge they create? Although Bethe believed that scientists should always feel responsible for the consequences of their work, he argued for no simple answers.

Bethe's response is founded on a distinction between pure and applied science and the criterion of political necessity. For Bethe, knowledge is a good in itself, and pure scientific research should proceed even when it might be used for immoral purposes. It is only at the point of application "that people should debate the question: Should we or should we not develop this? But the gathering of scientific knowledge preceding that debate, and certainly pure science itself should not be stopped" (Bethe 1983, p. 5).

Development in turn should be guided by necessity. For instance, during World War II, Bethe was convinced of the necessity of the atomic bomb because of the Nazi threat. The hydrogen bomb, however, was a weapon of such magnitude to be of little practical military value. "It was unnecessary. It should not have been done. And we would now be very much better off if [it] had never been invented" (Bethe 1983, p. 3).

Yet once Edward Teller (1908–2003) and Stanislaw Ulam (1909–1984) realized how to build the hydrogen bomb, Bethe believed that it needed to be developed before the Soviets. Caught in this dilemma, he wrote, "If I didn't work on the bomb somebody else would. ... It seemed quite logical. But sometimes I wish I were more consistent an idealist" (Edson 1968, p. 125). He maintains that the only justification for the hydrogen bomb is to prevent its own use (Bethe et al. 1950).

Who Should Make Decisions about Controversial Projects?

Bethe was careful to distinguish between the duties of the individual scientist and those of the scientific community as a whole. He was aware that a single individual is powerless to change the trajectory of weapons development. When asked whether it is justified to participate in immoral research projects just because others will do the research anyway, he replied, "No, but that is just to save my own soul. My refusal does not save the world" (Bethe 1983, p. 7). A group of scientists, not a single individual, needs to make decisions about what research to pursue and which findings to publish. Especially within the cold war context, the scientific community should not refuse to work on weapons as a group, because that would set them up as a superpolitical body that is the sole judge of their actions.

According to Bethe, elected representatives should make decisions about weapons research and other controversial projects. But scientists ought to have a large influence in these decisions. "By working on these weapons one earns the right to be heard in suggesting what to do about them" (Schweber 2000, p. 170). This in turn creates a dilemma for scientists, because in order to earn the right to be heard they must be willing to work for the government in developing weapons systems. Decisions about the use of technology are both scientific and political in nature, and such decisions should not be driven solely by technical feasibility (Bethe 1983).

In the 1980s, Bethe argued against the Strategic Defense Initiative (SDI) (a system, dubbed "Star Wars" by opponents, proposed by president Ronald Reagan in 1983 that would use space-based technology to protect the United States from attacks by strategic nuclear missiles), claiming that it would be much easier to simply reduce nuclear arsenals rather than developing a massive missile defense shield. In 1995 Bethe published an open letter to all scientists claiming that a new political era had made the further development of nuclear weapons unnecessary. He called "on all scientists in all countries to cease and desist from work creating, developing, improving and manufacturing further nuclear weapons— and, for that matter, other weapons of potential mass destruction such as chemical and biological weapons."


SEE ALSO Atomic Bomb;Nuclear Ethics;Weapons of Mass Destruction.


Bethe, Hans. (1983). "The Ethical Responsibilities of Scientists." Center Magazine 16(5): 2–11. A collection of Bethe's thoughts in this area with comments and counterarguments by an interdisciplinary panel of scholars.

Bethe, Hans, et al. (1950). "Let Us Pledge Not to Use an H-Bomb First." Bulletin of Atomic Scientists 6(3): 75. Signed by Bethe and eleven other prominent physicists.

Edson, L. (1968). "Scientific Man for All Seasons." New York Times Magazine March 10, pp. 29, 122–127. A brief look at Bethe's accomplishments and concerns.

Schweber, Silvan S. (2000). In the Shadow of the Bomb: Bethe, Oppenheimer, and the Moral Responsibility of the Scientist. Princeton, NJ: Princeton University Press. The best source for Bethe's involvement in the social and political aspects of nuclear weapons, chronicling his and Oppenheimer's roles in postwar developments and restrictions of nuclear arms.


Bethe, Hans. "Letter to the Science Community." Pugwash Online. Available from A plea to end the development of all weapons of mass destruction, originally issued July 23, 1995.

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