1879-1955, German-born physicist who published three papers in 1905 that had a profound effect on the development of physics. In one paper, he proposed the theory of special relativity (see relativity). In a second paper, he explained the photoelectric effect. In the third paper he provided evidence for the physical existence of atom-sized molecules. With the rise of fascism in Germany, Einstein moved to the U.S., where his correspondence with President Franklin D. Roosevelt concerning atomic energy contributed to the establishment of the Manhattan Project.