Albert Einstein was a German-born theoretical physicist and Nobel laureate who revolutionized modern physics. He developed the theory of relativity, including special relativity in 1905 and general relativity in 1915, transforming understandings of space, time, and gravity. In his annus mirabilis of 1905, he published four influential papers on the photoelectric effect (earning him the 1921 Nobel Prize in Physics), Brownian motion, special relativity, and mass-energy equivalence (E=mc²). He contributed to quantum theory, statistical mechanics, and cosmology, introduced stimulated emission (the basis for lasers), and pursued a unified field theory, though he famously critiqued quantum mechanics' probabilistic nature with the phrase 'God does not play dice.' Einstein held professorships at institutions including the University of Zurich, Charles University in Prague, ETH Zurich, and the Prussian Academy of Sciences in Berlin before emigrating to the United States in 1933 to escape Nazi persecution, where he joined the Institute for Advanced Study in Princeton until his retirement in 1945. A vocal pacifist, democratic socialist, civil rights supporter (including NAACP membership), and Zionist, he advocated for world government, signed the Russell-Einstein Manifesto against nuclear arms, and co-authored the Einstein-Szilárd letter urging U.S. atomic research. Of secular Ashkenazi Jewish heritage with pantheistic beliefs, he influenced the philosophy of science and became a cultural icon named Time's Person of the Century in 1999. Einstein died from a ruptured abdominal aortic aneurysm in Princeton Hospital. His legacy endures in gravitational waves, black holes, GPS technology, and modern physics, with over 300 scientific papers published.