Who Were the Manhattan Project Scientists?

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Who Were the Scientists Working on the Manhattan Project?

The Manhattan Project represented a revolution in military technology that has had ripple effects from August 1945 to the present. Now in 2023, the motion picture "Oppenheimer" dramatizes the stories of scientists working to develop the atomic super weapon that would help the U.S. secure victory over the Axis powers during World War II.

This project came as the result of Albert Einstein learning that Germany was developing atomic weapons. Einstein relayed this critical information in a letter—known as the Einstein Letter—to President Franklin Roosevelt, and soon thereafter, the development of the atom bomb was elevated to the highest priority national security project. The secret atomic weapons development project, dubbed the Manhattan Project, was launched in December 1941. Several hundred scientists were called to a laboratory in Los Alamos, New Mexico to aid the United States in developing the atomic bomb, with the below individuals having the most notable roles in the project.  The Manhattan Project cost $2 billion in 1940s dollars out of a total American expenditure of $300 billion for all of World War II.

J. Robert Oppenheimer

Oppenheimer was an American theoretical physicist that is widely renowned as the father of the atomic bomb. Oppenheimer was born in 1904, and his profound intelligence could be observed in his early academic achievements, like being invited to lecture at the New York Mineralogical Club at the age of 12 and graduating from Harvard with a degree in chemistry in just three years. Following his graduation, Oppenheimer pursued graduate study in physics under Max Born, a highly distinguished theoretical physics professor from Germany. After receiving his doctorate in 1927, Oppenheimer returned to the United States where he worked as a physicist until eventually being sought out to lead the Manhattan Project.

In 1942, Oppenheimer was chosen by the United States Army to manage the laboratory that aimed to weaponize atomic energy and was given a budget of $2 million as the Army recognized the importance of developing an atomic weapon before Germany. Oppenheimer had stated that developing a sound method for implosion and purifying plutonium was the hardest aspect of the Manhattan Project. However, due to his ingenious capabilities as a scientist and leader, Oppenheimer was able to assist his fellow scientists with overcoming these particular challenges. Prior to joining the Manhattan Project, Oppenheimer had spent over a year researching fast neutrons, and he also developed the logistical calculations needed to determine the amount of radioactive material required to produce a bomb, as well as the means to measure an atom bomb’s overall efficiency. Oppenheimer’s understanding of fast neutrons and the logistics behind producing an atom bomb helped the Manhattan Project achieve its goal in 1945.

Leo Szilard

Leo Szilard was a Hungarian physicist that worked closely with Einstein to draft the aforementioned Einstein Letter to President Roosevelt that prompted the president to establish the Manhattan Project. He earned a degree in physics at the University of Berlin, alongside Albert Einstein. Szilard did most of his early work and research in Germany, but as the National Socialist German Workers’ Party, otherwise known as the Nazi Party, began to gain control over the nation, Szilard grew wary and departed Europe. Szilard tried to convince his colleagues that the possibility of harnessing atomic energy was a potential danger, and when German scientists discovered neutron-induced fission of uranium in 1939, his concerns were further validated.

Once President Roosevelt launched the Manhattan Project, Szilard became an integral part of the team that sought to develop the atomic bomb. After a thorough investigation of uranium fission, Szilard partnered with Enrico Fermi and his team of engineers to develop the first self-sustaining nuclear chain reaction. They accomplished this feat in 1942, creating an important component for producing a functional atomic weapon.

Hans Bethe

Hans Bethe was born in Strasbourg, Alsace-Lorraine in 1906 and served as Chief of Theoretical Division for the Manhattan Project after leaving Germany following the rise of the Third Reich. As one of the most important theoretical physicists of his generation, Bethe was responsible for discovering several crucial aspects of physics that made the atomic bomb possible. For instance, he showcased that the reaction that occurs in the heart of massive stars—the chemical process that gives off heat and energy—is nuclear fusion. With this theory in mind, he proposed several ways that hydrogen nuclei could be fused with helium nuclei, which proved to be fundamentally important to the completion of the atomic bomb while also expanding knowledge of the science of nuclear fission and fusion. In addition to this, Bethe helped the Manhattan Project team develop the formula needed for calculating the explosive yield of an atomic bomb, as well as assisted with creating the formula for calculating the critical mass of uranium-235—the radioactive material found in the earliest atomic bombs used against Hiroshima in 1945.

Ernest O. Lawrence

Ernest Lawrence is an American-born nuclear physicist who participated in the Manhattan Project after receiving his doctorate degree from the University of California, Berkeley in 1928. Before being chosen for the atomic bomb project, Lawrence focused his intentions on founding the academic research laboratories that would allow him to strongly pursue advancements in nuclear physics. In these labs, Lawrence invented the cyclotron in 1929. This device accommodated the acceleration of nuclear particles to velocities high enough to disintegrate atoms and form new elements without using high voltage currents. This technology grew more powerful over time and was useful in the production of the atomic bomb.

As the Program Chief of the Manhattan Project, Lawrence was given domain over research concerning the electromagnetic separation of atoms to be used in the atomic bomb. Lawrence’s intellect, labs, and offices were all instrumental pieces to the success of the Manhattan Project. By the end of World War II, Lawrence joined many of his fellows in their efforts to suspend atomic bomb testing, specifically when he attended the Geneva Conference in 1958.

Klaus Fuchs

Klaus Fuchs, a German theoretical physicist, was a notorious spy working for the Soviet Union who was embedded within the Manhattan Project. Prior to the ascension of the Third Reich, Fuchs fled Germany. Fuchs was interned in Quebec as a German refugee for a short time in 1940, but after his release, he became a British citizen in 1942. When the British selected their delegation of scientists to participate in the Manhattan Project, Fuchs was on the list. However, during his time with the program, Fuchs delivered atomic secrets to the Soviets.

Even though he delivered information to the Soviets during the Manhattan Projects, Fuchs contributed many important theories to the development of the atomic bomb, such as helping develop the means needed to implode the critical fissionable core within the first atom bomb designs. His work on one of the initial implosion atomic bombs—codenamed “Fat Man,” which was used to destroy Nagasaki—was praised by the United States Army. Due to this accomplishment, Fuchs was granted high-level security clearance and explicit access to many of the key details of the Manhattan Project. However, Fuchs’ long-harbored communist sympathies came to head, leading him to deliver detailed secrets about the energy yield of an atomic explosion, implosion methods, and the Trinity Test that occurred in July 1945. Some experts estimate that the information that Fuchs delivered enabled the Soviet Union to develop their own atomic bombs at least one year sooner than would otherwise be expected. In 1949, Fuchs was ousted as a spy and sentenced to 14 years in prison (though he served only nine).

Glenn Seaborg

Glenn Seaborg was an American-born chemist who earned his Ph.D. at the University of California, Berkeley. Together with Edwin McMillan, Seaborg discovered plutonium—a critical component of nuclear weapon technology—in 1941. After discovering plutonium, Glenn was granted a leave of absence from his research position at Berkeley so that he could participate in the Manhattan Project, where he led the team that handled plutonium work at the University of Chicago’s Metallurgical Laboratory. His team was responsible for producing the plutonium-239 needed to create the “Fat Man” bomb, and he was also able to develop a functional method of separating, concentrating, and isolating plutonium. After the atomic bombs were dropped, Seaborg became a member of the Atomic Energy Commission. When he was elected chairman of the Atomic Energy Commission in 1971, he used the position to campaign for the peaceful use of atomic energy, opposing further testing of nuclear weapons.

The Manhattan Project forever changed the global landscape. Since then, atomic energy has been a highly controversial topic, with countless organizations and governments attempting to suppress its widespread use and others aiming to capitalize on the military and industrial superiority that effectively applied nuclear technology can create. Many of the individuals involved in the Manhattan Project, including those listed above, have worked to regulate the devastatingly powerful technology by founding or joining councils, committees, and similar organizations determined to limit the weaponization of atomic energy.

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