Albert Einstein, who was born March 14, 1879 and died on April 18, 1955 was a German mathematician and physicist who developed the special and general theories of relativity, who in 1921, won the Nobel Prize for physics for his explanation of the photoelectric effect. Later during his research, he immigrated to the U.S. after being targeted by the Nazis. His work also had a major impact on the development of atomic energy. In his later years, Einstein focused on unified field theory. With his passion for discovering answers to questions, Einstein is generally considered the most influential physicist of the 20th century.