At the beginning of 1939, German chemist O. Hahn and physical chemist F. Strassman published a paper on the phenomenon of nuclear fission of uranium atoms. Within a few weeks, scientists from many countries verified this discovery and further suggested that it was possible to create conditions for this fission reaction to proceed on its own, thus opening up a broad prospect of using this new energy to create wealth for mankind. However, like many new scientific and technological discoveries in history, the development of nuclear energy was first used for military purposes, that is, to make a powerful atomic bomb, and its process was influenced and restricted by social and political conditions at that time.

At the beginning of September of the same year, Danish physicist N.H.D Bohr and his collaborator J.A. Wheeler theoretically expounded the process of nuclear fission reaction, and pointed out that the best element that can cause this reaction is the isotope uranium 235. Because of the war, physicist a Einstein wrote to the 32nd president of the United States, F.D. Roosevelt, suggesting the development of an atomic bomb, which attracted the attention of the American government. Britain also sent a team of scientists led by physicist J. chadwick to the United States to participate in the development of atomic bombs led by theoretical physicist J. R. Oppenheimer. At first, the United States only allocated $6,000. It was not until 194 1 February that Japan attacked Pearl Harbor and expanded its scale. In August, 1942 developed into a huge project code-named "Manhattan Project Area", which directly employed about 600,000 people and invested more than 2 billion US dollars. By the end of World War II, three atomic bombs had been built, making the United States the first country to have an atomic bomb.