The Manhattan Project Shows Scientists’ Moral and Ethical Responsibilities

After the first-ever explosion of an atomic bomb on July 16, 1945 near Socorro, N.M., J. Robert Oppenheimer, director of the Los Alamos Laboratory, recited a line from the Bhagavad Gita: “Now I am become death, the destroyer of worlds.”

Less than a month later, a quarter of a million lives were lost to the technology created by the Manhattan Project: people vaporized, buildings torn to dust, survivors dying in agony weeks or months later. There’s the lesser-known fact that about 50,000 Koreans, prisoners of Imperial Japan, died in the attacks.

The human toll is hard to comprehend. To many Americans, the bombings were justified, a necessity for ending the war. As a physicist, I have to wonder: how could my predecessors have participated in something used for such violent ends? Did no one think about walking away?

To answer that, it’s important to understand Oppenheimer and his colleagues. Oppenheimer has captivated the American imagination as the brilliant physicist who wrestled with the implications of his creation; in the same week that he helped top brass optimize the explosion of the bomb, he was heard muttering “those poor little people” on his morning walk. After the war, Oppenheimer sat with President Truman to talk about international control of nuclear weapons, telling him: “I feel I have blood on my hands.”

Oppenheimer would become an advocate for nuclear peace and oppose the construction of the hydrogen bomb, but not without consequence. He was publicly humiliated in a security hearing where a colleague testified against him and his security clearance was revoked.

History has rehabilitated Oppenheimer as a tragic moral actor, with director Christopher Nolan of Inception and Interstellar fame recently announcing the production of an Oppenheimer biopic. What astonishes me, however, is the obscurity into which Oppenheimer’s colleague Joseph Rotblat has been cast. A Polish physicist, Rotblat worked with the British Mission to the Manhattan Project. Despite his reservations, he believed that stopping Nazi Germany justified the work. In March 1944, however, he had dinner with General Leslie Groves, Jr., director of the project, who remarked that its objective was to subdue the Soviet Union. Disgusted, Rotblat departed the project a few months later and would spend his life working toward atomic nonproliferation. For this, Rotblat shared the 1995 Nobel Peace Prize.

“Science became identified with death and destruction,” Rotblat said in his Nobel lecture as he described the inception of the atomic age. The comparison with Oppenheimer’s famous line is stark: two men who both knew the danger of their work yet chose different paths. The world recognized Rotblat’s impact, but I find few people, physicists or not, have heard his name.

Why does this matter? Anybody who bothers to do the research can see for themselves whether using atom bombs were necessary for ending the war: intercepted Japanese wires indicated they were preparing to surrender; American intelligence showed that the Germans were not close to developing a nuclear bomb; Truman’s Secretary of State admitted wanting to end the war with Japan before Stalin became involved. Many project scientists favored only a demonstrative use, such as an explosion over the Pacific, which would terrify without harming. But how many Americans, whose view of history is crafted by popular narratives to support U.S. policy decisions, know all this?

How we tell history changes how it is understood. The national project predicates itself on maintaining a specific, widely disseminated version of history. In turn, it shapes our understanding of ourselves. Our decisions of who to look up to and who to talk about have consequences for the way we place ourselves relative to our predecessors and contemporaries—and the decisions that we, in turn, make. 

It means a lot if we don’t talk about Rotblat and instead center Oppenheimer. Oppenheimer’s voice, early on, would have made an impact, Rotblat believed. Instead, Oppenheimer tried to live with the bomb. Conversely, Rotblat simply ended his work with the Manhattan Project once he realized what its true purpose was. If our research leads to technology that shapes international affairs, then its politics are commensurate with the science. Rotblat spoke to this point in his Nobel lecture by quoting Lord Zuckerman, another advocate for nuclear nonproliferation: “When it comes to nuclear weapons … [i]t is he, the technician, not the commander in the field, who is at the heart of the arms race.” 

The Manhattan Project demonstrates that physicists must wrestle with the tight bonds of our research with national security. As civilian funding in science shrinks, the incentive to pursue support from the military grows. In fiscal year 2021, the National Science Foundation received $8.5 billion in total—half the $17 billion that the Department of Defense (DoD) received just for science and technology research. The DoD often funds basic research, with the hope that someday it could be useful for the military. Improvements in atomic clocks, which undergird GPS, can improve navigation for weapons and targeting, for example. Understanding turbulence can help the Air Force improve aircraft efficiency. Plasma physics helps to build new, long-range weapons. Such connections muddy the waters. I think if most physicists were asked to build a weapon, they would object. But if the military meets you on your own terms, offering to fund your basic research, the decision is difficult. 

It is even more challenging for students. The DoD maintains the National Defense Science and Engineering Graduate (NDSEG) Fellowship, which has awarded over 4,000 fellowships. In the application, the DoD details the needs of different branches of the military and asks students to connect their skills with a particular military interest. With many benefits in tow, the NDSEG is considered one of the most prestigious graduate fellowships. The DoD also offers the SMART Scholarship, a full-ride scholarship open to undergraduate and graduate students, conditional on postgraduation employment with the DoD. As tuition soars and as the cost of living for graduate students rises, these morally complex career decisions are increasingly being made for, rather than by, young Americans.

Still, we must speak and act in accordance with our conscience. We must push science to advocate for peace. We can learn from Rotblat. He didn’t make the decision to leave the Manhattan Project lightly, not to mention that the United States presented him with a false dossier alleging that he left to leak information to the Soviets. The decisions we make today are not so grand or liable to run us in as much trouble. If we turn down a grant or seek alternative research funding, who will bat an eye?

Collective action has power, but it starts with the individual. Today, we resign ourselves to the state we find the world in. We tell ourselves that we mustwork within a world dominated by the military-industrial complex, rationalizing that this is how it is. What is stopping us from doing what we believe to be right? We can’t rest easy knowing, “This is wrong,” but doing nothing. Thoughts without commensurate action effect no material change. We must have the courage to reimagine history and our place in it. In doing so, we don’t have to feel resigned. We don’t have to see our place in the world as destroyers, but instead, as creators of a better one.