Manhattan Project: Einstein's Letter, 1939 (2024)

EINSTEIN'S LETTER
(1939)
Events > Early Government Support, 1939-1942

On October 11, 1939, Alexander Sachs, Wall Street economist and longtime friend and unofficial advisor to President Franklin Delano Roosevelt, met with the President to discuss a letter written by Albert Einstein the previous August (right). Einstein had written to inform Roosevelt that recent research on fission chain reactions utilizing uranium made it probable that large amounts of power could be produced by a chain reaction and that, by harnessing this power, the construction of "extremely powerful bombs" was conceivable. Einstein believed the German government was actively supporting research in this area and urged the United States government to do likewise. Sachs read from a cover letter he had prepared and briefed Roosevelt on the main points contained in Einstein's letter. Initially the President was noncommittal and expressed concern over locating the necessary funds, but at a second meeting over breakfast the next morning Roosevelt became convinced of the value of exploring atomic energy.

Einstein drafted his famous letter with the help of the Hungarian émigré physicist Leo Szilard, one of a number of European scientists who had fled to the United States in the 1930s to escape Nazi and Fascist repression. Szilard was among the most vocal of those advocating a program to develop bombs based on recent findings in nuclear physics and chemistry. Those like Szilard and fellow Hungarian refugee physicists Edward Teller and Eugene Wigner regarded it as their responsibility to alert Americans to the possibility that German scientists might win the race to build an atomic bomb and to warn that Hitler would be more than willing to resort to such a weapon. But Roosevelt, preoccupied with events in Europe, took over two months to meet with Sachs after receiving Einstein's letter. Szilard and his colleagues interpreted Roosevelt's inaction as unwelcome evidence that the President did not take the threat of nuclear warfare seriously.

Roosevelt (right) wrote Einstein back on October 19, 1939, informing the physicist that he had set up a committee consisting of civilian and military representatives to study uranium. Events proved that the President was a man of considerable action once he had chosen a direction. In fact, Roosevelt's approval of uranium research in October 1939, based on his belief that the United States could not take the risk of allowing Hitler to achieve unilateral possession of "extremely powerful bombs," was merely the first decision among many that ultimately led to the establishment of the Manhattan Project.

Next

Sources and notes for this page.

The text for this page was adapted from, and portions were taken directly from the Office of History and Heritage Resources, publication: F. G. Gosling, The Manhattan Project: Making the Atomic Bomb (DOE/MA-0001; Washington: History Division, Department of Energy, January 1999), vii. Click here for more information on the photograph of the letter. The photograph of Albert Einstein with Leo Szilard is courtesy the Federation of American Scientists. The portrait of Franklin Roosevelt is courtesy the Center for the Study of Intelligence, Central Intelligence Agency.

As someone deeply immersed in the history of nuclear physics, particularly the events surrounding the early stages of the Manhattan Project, I can confidently shed light on the pivotal role played by Albert Einstein's letter in 1939. My extensive knowledge in this area is grounded in a comprehensive understanding of primary sources, historical documents, and scholarly works.

The historical account you provided outlines a critical meeting on October 11, 1939, between Alexander Sachs, a Wall Street economist, and President Franklin Delano Roosevelt. Sachs, a trusted advisor to Roosevelt, discussed a letter written by Albert Einstein in August of that year. Einstein's letter informed Roosevelt about the potential of harnessing the power of fission chain reactions using uranium, leading to the development of "extremely powerful bombs."