Person1898 – 1964

Leo Szilard

Hungarian-born physicist who first conceived the nuclear chain reaction and persuaded Einstein to write to Roosevelt warning of the atomic bomb

Where they went

1
1939The Einstein–Szilard Letterkey figure
In August 1939 Einstein signed a letter drafted by Szilard warning President Roosevelt that Nazi Germany might build an atomic bomb first and that the United States should speed up its own research.
2
1942Chicago Pile-1 — The First Chain Reactionparticipant
On 2 December 1942, in the world’s first reactor — graphite and uranium stacked by Enrico Fermi beneath the stands of the University of Chicago’s football field — a man-made nuclear chain reaction sustained itself for the first time.

Albert Einstein1879 – 1955
German-born physicist who developed the theory of relativity, emigrated to the US in 1933 fleeing the Nazis, and in 1939 signed the letter urging Roosevelt to develop the atomic bomb
Franklin D. Roosevelt1882 – 1945
32nd US president (1933–1945) who led the New Deal and took the US to war after Pearl Harbor; he attended the Cairo and Yalta conferences
Enrico Fermi1901 – 1954
Italian-born physicist who, after receiving the 1938 Nobel Prize in Physics, emigrated to the US and achieved the first chain reaction with the world’s first reactor in Chicago in 1942

The Birth of the Atomic Bomb1938 – 1949
From the discovery of fission to the first Soviet bomb — Einstein’s letter, the Manhattan Project, the Trinity test, Hiroshima and Nagasaki, and the dawn of the nuclear age