Manhattan Project

Invented in the early 1930s, cyclotrons (“atom smashers") accelerate atoms through a vacuum to induce collisions at very high speeds—25,000 miles per second—via electromagnets. In 1936, John R. Dunning directed the development of Columbia University's own cyclotron in the basement of Pupin Hall. The project would take four years to complete. To produce the highest voltage possible, the team would employ a method developed by PhD student Herbert Anderson, using a pair of resonant concentric lines coupled to a high-power oscillator, marking the first use of this system. 

In December 1938, German chemists Otto Hahn and Fritz Strassman detected barium by bombarding uranium with neutrons, subsequently making the discovery of nuclear fission. Hearing the news, Niels Bohr¹ travels to New York to find Columbia physicist Enrico Fermi. But when Bohr reaches campus, he doesn’t find Fermi in his office, so he goes to the basement of Pupin Hall and encounters Anderson. Anderson recounted this experience years later in a 1965 interview with journalist Stephane Groueff:

Anderson: ...in January of 1939, Professor Bohr arrived with the news about fission. He arrived in New York and he came immediately to Columbia University, because he wanted to tell the news to Fermi. He did not find Fermi right away. He was looking for him and he found me instead. He was quite excited and he explained. He told everything to me.

Groueff: The first day he came to visit Columbia, you happened to be there?

Anderson: I happened to be there. He unburdened himself to me.

Groueff: You were just a young post-graduate student?

Anderson: I was just starting to do my doctoral research.

That month, the Columbia experimental team—consisting of John R. Dunning, Enrico Fermi, Herbert L. Anderson, Eugene T. Booth, G. Norris Glasoe, and Francis G. Slack—conducted the first nuclear fission experiment in the US using Pupin Hall’s very own cyclotron as they demonstrated the large energy release in the fission of uranium. A year later, Columbia physicists identified the exact fissionable material in uranium: the rare isotope uranium-235. To be used in a nuclear weapon, they reached the conclusion that uranium-235 must be separated from the more prevalent uranium-238 isotopes and concentrated. Dunning and Harold Urey then headed a Columbia team in the invention and perfection of the “gaseous diffusion” method of separating uranium isotopes. 

This critical breakthrough served as the building block for the Manhattan Project's K-25 gaseous diffusion plant in Tennessee, which at the time of its completion, was the world's largest building. Decades after the Manhattan Project changed the course of history, the core component of the Columbia University cyclotron is now a part of the Smithsonian's National Museum of American History collection.

Check out a pdf copy of the National landmark filing for Pupin Hall and a pdf draft of the press release, written at the time of the landmark designation. Extensive documentation on the Pupin Physics Laboratories can also be accessed at the National Archives Catalog listing. 

¹Willis Lamb, a distinguished faculty member from Columbia, claims he was the physicist who shared the news of the European fission experiment to Herbert Anderson, not Bohr.
https://www.aip.org/history-programs/niels-bohr-library/oral-histories/23200

The creation and aftermath of the Manhattan Project is complex. The most famous repercussion of the project was the development of nuclear weapons. The first weaponized use of atomic energy was detonated in the Japanese city of Hiroshima on August 6, 1946, and then three days later in the city of Nagasaki. Mass destruction in warfare had reached a terrifying new level. 

But as Cynthia Kelly, founder and president of the Atomic Heritage Foundation, explained in a 2023 article in Scientific American, knowledge and research produced by the Manhattan Project also led to groundbreaking discoveries in space exploration, medicine, and engineering. 

Columbia University has grappled with its own roots in the project's complicated history. In 2017, Shigeaki Mori, one of the last survivors of Hiroshima, visited Abhay Pasupathy and the Columbia physics department in Room 118—where the famous experiment took place. Pasupathy observed how “Mr. Mori said to me that he now felt at peace with science and was happy to see me there in the lab and see how far the world had come." 

To learn more about the experiences of survivors like Mr. Mori, visit the Hiroshima Peace Memorial Museum website.