Albert Einstein was a German-born theoretical physicist who developed the theory of relativity, one of the two pillars of modern physics. His work is also known for its influence on the philosophy of science. He received the 1921 Nobel Prize in Physics for his services to theoretical physics, and his discovery of the law of the photoelectric effect. Einstein's work also had a major impact on the development of atomic energy. He is widely regarded as one of the most influential scientists of the 20th century and is considered one of the greatest minds in history. He is also known for his mass–energy equivalence formula E = mc2, which has been dubbed "the world's most famous equation".