What did the Einstein-Szilard letter warn President Roosevelt about in 1939?

Answer:

The Einstein-Szilard letter, sent in August 2, 1939, warned President Roosevelt about the danger that Germany could develop atomic bombs, and suggested that the United States should start its own nuclear program. It incited Roosevelt to take immediate action, which ultimately resulted in the beginning of the Manhattan Project and the development of the first atomic bombs.

Explanation:

The letter was signed by Einstein on August 2, and delivered to Roosevelt by economist Alexander Sachs. However, it only arrived on October 11 due to the president's concern about the German invasion of Poland, which would start World War II. After hearing a summary of Sachs from the letter Roosevelt authorized the creation of the Advisory Committee on Uranium. The first meeting of the committee was held on October 21, led by Lyman Briggs, president of the National Bureau of Standards. $ 6,000 were made available for experiments with the neutron, made by Enrico Fermi at the University of Chicago.

The letter is often seen as one of the origins of the Manhattan Project, the successful nuclear project that would produce the bombs launched in Hiroshima and Nagasaki in 1945.

Although not working on the atomic project, according to Linus Pauling, Einstein later regretted having signed the letter.