POPSCI
On July 21, 2023, Christropher Nolan’s Oppenheimer entered wide release. The film follows J. Robert Oppenheimer, the scientist who directed the US program to create the world’s first atomic bombs. The movie, shot in part in New Mexico, tells a story of the bomb and the early Cold War focused closely on Oppenheimer, his personal relationships, and the revocation of his security clearance in 1954. The film depicts a fairly mainstream understanding of the scientist’s life, triumph, and foibles.
Because Nolan’s camera is kept narrowly focused on Cillian Murphy as Oppenheimer, much of the bomb’s impact and early history is kept largely off screen. The film draws directly from American Prometheus, a 2005 biography of Oppenheimer by Kai Bird and Martin J. Sherwin, which offers a thorough portrait. Los Alamos National Laboratory, where Oppenheimer oversaw the bomb’s development, was founded as part of the atomic bomb effort and today remains an important center of American nuclear weapons research.
Any fuller story of the bomb needs to venture beyond the boundaries of laboratory grounds and test ranges. Here are three details of nuclear weapons and their development not captured in the film.
The bombs of today are much more powerful
At the heart of an atomic bomb of any kind is a fission reaction. In this process, a mass of radioactive isotopes, like Uranium-235 or Plutonium 239, is compressed at high speed, breaking apart the atomic bonds in the isotopes and sending neutrons outwards with tremendous force.
It’s a fission bomb that forms the centerpiece of Oppenheimer. In an attempt to get scientists to stop openly talking about bomb production, the first atomic bomb was named “Gadget.” It was tested at Trinity on July 16, 1945.
It yielded an explosion equivalent to 20,000 pounds of TNT, or 20 kilotons. Fat Man, the bomb dropped on Hiroshima, Japan, on August 6, 1945, had a yield of 15 kilotons. Little Boy, the bomb dropped on Nagasaki, had a yield of 20 kilotons. These weapons had a massive impact. In the US, Gadget’s fallout caused health impacts still observed in people downwind today.
Initial estimates place the death toll from Hiroshima at 70,000 and the death toll from Nagasaki at 40,000 people. A later estimate puts the deaths at 140,000 for Hiroshima and 70,000 for Nagasaki. The methodology of both estimates is sound, and added to those estimates can be the tens of thousands injured by the bomb’s effects but not killed outright.
These numbers are the baseline for understanding how many people a fission weapon of such power can kill. Given the scale of an atomic blast, bombs will invariably kill civilians if used near any population center.
Another type of bomb, called the “Super” during the Manhattan Project, sought to use a small fission reaction to set off a larger fusion chain reaction. It’s also known as an H-Bomb, or more broadly a thermonuclear weapon, and the largest one ever detonated by the United States had a yield of 15 megatons. The largest H-bomb detonated by the Soviet Union yielded 50 megatons.
