Caption:
Editorial use only . Albert Einstein during a lecture in Vienna in 1921. Photographed by Ferdinand Schmutzer (1870-1928). Albert Einstein (March 14, 1879 - April 18, 1955) was a German-born theoretical physicist who developed the general theory of relativity, effecting a revolution in physics. Einstein is often regarded as the father of modern physics and the most influential physicist of the 20th century. While best known for his mass-energy equivalence formula E = mc2, he received the 1921 Nobel Prize in Physics for his services to theoretical physics, and especially for his discovery of the law of the photoelectric effect. The latter was pivotal in establishing quantum theory within physics.