Albert Einstein's involvement in the Manhattan Project, which was the United States' research and development project during World War II to create atomic weapons, was indirect. Although Einstein's scientific contributions laid the groundwork for nuclear energy and the potential for atomic weapons, he was not directly involved in the project's implementation or decision-making process.
In 1939, Einstein and his Hungarian-American colleague, Leo Szilard, co-authored a letter to President Franklin D. Roosevelt. The letter warned of the possibility that Nazi Germany might be developing atomic weapons and suggested that the United States should initiate its own research into nuclear fission. This letter, known as the Einstein-Szilard letter, is often credited with motivating the U.S. government to establish the Manhattan Project.
However, Einstein himself did not participate in the project. His pacifist beliefs and concerns about the destructive potential of atomic weapons made him reluctant to contribute directly to military research. He was not involved in the project's planning, construction of facilities, or the actual development of the atomic bombs. Instead, Einstein continued his work as a professor at the Institute for Advanced Study in Princeton, New Jersey.
After the bombings of Hiroshima and Nagasaki in August 1945, which demonstrated the devastating power of atomic weapons, Einstein expressed regret about his indirect involvement in the project. He became an advocate for nuclear disarmament and emphasized the need for international cooperation and the prevention of future wars. Einstein's opinions on the project can be summarized as recognizing the potential danger of atomic weapons and advocating for their control and peaceful use in the future.