Oppenheimer: The Father of the Atomic Bomb

American theoretical physicist Julius Robert Oppenheimer is most famous for his contributions to the Manhattan Project, a U.S. military operation to develop the atomic bomb for use in World War II. The popular summer 2023 movie Oppenheimer, which won seven awards at the 2024 Oscars, is one of the many historical fiction films about Oppenheimer’s work as a leading scientist in the project. However, Oppenheimer is also renowned amongst the scientific community for his work in theoretical physics before beginning research on the atomic bomb and was nominated for the Nobel Prize three times in his lifetime. 

Oppenheimer established himself as a scientist early in his academic career. In 1925, Oppenheimer earned his bachelor’s degree in chemistry from Harvard University and went on to pursue physics at the University of Göttingen in Germany, conducting research under the advisory of physicist Max Born. In 1927, Born and Oppenheimer published “On the Quantum Theory of Molecules,” a paper detailing the Born-Oppenheimer approximation. The paper describes a method to determine an approximate location for electrons in a molecule. While describing their method, the scientists noted that the mass of an individual proton in the nucleus is far greater than the mass of an electron. Therefore, the nucleus could be considered stationary, which greatly simplifies the calculations that determine the location of electrons. This has helped scientists model molecules and study the way that electrons move, therefore advancing the fields of chemistry and physics and giving Oppenheimer the reputation that would eventually get him invited to participate in the creation of the atomic bomb. 

With World War II escalating all over the world in the early 1940s, President Franklin Roosevelt initiated the Manhattan Project, a military operation to manufacture nuclear weapons for the arms race against Germany, where scientists had already begun similar experiments. Oppenheimer was appointed the director of the Manhattan Project in 1942 and set up a new laboratory in Los Alamos, New Mexico. His research was focused on collecting enough of the isotope uranium-235 to be used in an atomic bomb. Atomic bombs work via nuclear fission, a process where scientists split the nucleus of an atom into two smaller nuclei, which releases a fatal amount of energy as heat and radiation. The split happens in a chain reaction—a neutron collides with an unstable atom, which releases more neutrons that collide with other atoms. The reaction can only take place if there’s a critical mass of the element, which is the amount of the element needed for the chain reaction to sustain itself—there need to be enough atoms for neutrons to collide with, and enough neutrons to continue colliding with the atoms. The atomic bomb used uranium-235 or, at other labs of the Manhattan Project, the more readily available plutonium-239.

Oppenheimer directed his lab’s resources to figuring out how to compress plutonium in a quantity high enough to facilitate the nuclear chain reaction. The design that the team came up with consisted of 32 hexagonal or pentagonal shaped explosives spherically surrounding a mass of plutonium at the center of the bomb. The explosives would be simultaneously detonated using an automated system, which would pressurize the plutonium at the center and set off the chain reaction. Scientists at Los Alamos conducted the Trinity test in July 1945, where the final plutonium implosion prototype,  “The Gadget”, was dropped in the New Mexico desert. Despite its remote location, the Trinity test changed the lives of hundreds of local New Mexicans, exposing them to large amounts of radiation and contaminating the local water and food supply. This would lead many to develop radiation-related illnesses such as cancer. 

After the war ended, Oppenheimer was appointed Chairman of the U.S. Atomic Energy Commission (AEC), a government agency that would oversee all atomic research done by American scientists. When he took a stance against the building of a hydrogen bomb—which would be hundreds to thousands of times more powerful and destructive than a uranium or plutonium bomb—many suspected him to be associated with the American Communist Party, and he lost his role as Chairman of the AEC in 1953. However, his fears were well-founded and many scientists shared the same opinion. A hydrogen bomb combines the forces of nuclear fission and nuclear fusion in a two-step process where the splitting of the atom provides the energy necessary for the atoms to fit back together. In order for nuclear fusion to happen, each nucleus needs to lose some mass, which is released as pure energy and creates an explosion. This happens most easily with hydrogen atoms because they only have one electron, which makes it relatively easy to overcome the electrostatic forces between atoms.

The first and only instances of atomic warfare to this date are the bombings of the Japanese cities Hiroshima and Nagasaki at the end of World War II, where total casualties were approximately 200,000 people. In the immediate aftermath, Oppenheimer was hailed as a national hero in the United States and was even awarded the Medal for Merit by President Truman in 1946. However, as the nation began to reflect on the events of World War II, an ongoing debate emerged about whether both bombings were necessary to end the war, as well as whether the bombs should have been used at all. Some consider it a failure of the government to recognize fundamental human values and wished to classify the bombings as war crimes, and others think that it was analogous to ripping the band-aid off, believing that not using the bomb would have prolonged the war and the casualties it caused. While Oppenheimer himself did express concern about future use of the atomic bomb, he never publicly issued an apology or expressed regret for his invention, but was he obligated to?

Oppenheimer is a complicated historical figure who raises important questions about science in society. The role he played in building such a devastating weapon and his politically controversial stance on building the hydrogen bomb bring up issues that are especially relevant in this age of technology, where new inventions like AI can be both instruments of great destruction and of great advancement. The same ethical questions arise about the role that scientists play in the government and the extent to which science can, or should, be weaponized—how can we as a society make sure that our knowledge doesn’t destroy us? As we look to the future, the guidelines for scientific discovery are blurrier than ever. What we ultimately decide to do with the information in our hands depends on our own principles and our ability to see how our discoveries can change the world—for better or for worse.