曼哈顿计划最重要的人物是爱因斯坦，费米，奥本海默及劳伦斯，贡献最大的大学是Columbia， UChigaco 及Berkele

On December 7, 1941, the Japanese military bombed Pearl Harbor, Hawaii, the headquarters of the United States Pacific Fleet. In response, the U.S. declared war on Japan the next day and officially entered WWII.

With the country at war and the realization that the United States was now three years behind Nazi Germany, President Roosevelt was ready to seriously support U.S. efforts to create an atomic bomb.

Costly experiments began at the University of Chicago, U.C. Berkeley, and Columbia University in New York. Reactors were built in Hanford, Washington and Oak Ridge, Tennessee. Oak Ridge, known as "The Secret City," was also the site of a massive uranium enrichment laboratory and plant.

Researchers worked simultaneously at all of the sites. Harold Urey and his Columbia University colleagues built an extraction system based on gaseous diffusion.

At the University of California in Berkley, the inventor of the Cyclotron, Ernest Lawrence, took his knowledge and skills to devise a process of magnetically separating the uranium-235 (U-235) and plutonium-239 (Pu-239) isotopes.

The research was kicked into high gear throughout 1942. On December 2, 1942, at the University of Chicago, Enrico Fermi created the very first successful chain reaction, in which atoms were split in a controlled environment. This accomplishment gave renewed vigor to the hopes that an atomic bomb was possible.