Manhattan Project Scientists: Leo Szilard

Black and white photo of a man gesturing to a chalkboard.
Leo Szilard was chief physicist at Chicago's Met Lab.


Quick Facts
Chief Physicist at Chicago's Met Lab
Place of Birth:
Budapest, Hungary
Date of Birth:
February 11, 1898
Place of Death:
San Diego, CA
Date of Death:
May 30, 1964
Place of Burial:

Born Leo Spitz in Budapest, Hungary in 1898, Szilard received his PhD in Physics at the University of Berlin in 1922, becoming close friends with Albert Einstein during this time. In 1933, during the rise of Nazi Germany, Szilard moved to England to study nuclear chain reactions. In 1940, he became a US citizen and began work at New York’s Columbia University. One year prior, Szilard, with the assistance of colleagues Albert Einstein, Edward Teller, and Eugene Wigner, wrote the famous “Einstein Letter” warning President Franklin Roosevelt of Germany’s potential plans to create an atomic weapon and urging the United States to do the same.

In 1942, Szilard began work on the Chicago Pile (CP-1) during his tenure as chief physicist at the Chicago Metallurgical Laboratory (Met Lab) under the direction of Arthur Compton. While Szilard was a key player in the development of the atomic bomb, he was very suspicious of having the Manhattan Project be under military control, preferring civilian control and urging the limited use of atomic weapons, in July of 1945 going so far as to request the bomb not be dropped on Hiroshima. His request never made it to President Truman’s desk.

In 1946, Szilard resigned from the Met Lab and continued research and teaching at the University of Chicago through the 1950s, all while advocating for limited nuclear weapons development and urging the peaceful use of nuclear power. Szilard died of a heart attack in California in 1964.

Manhattan Project National Historical Park

Last updated: September 26, 2023