American physicist and mathematician who is the leading theorist behind superstring theory. Superstring theory is an attempt at a "theory of everything" that can meld quantum mechanics and Albert Einstein's general relativity theory. Witten and others have shown how tiny particles called strings can form all of the elementary particles we see today, such as protons, electrons, and quarks, and account for gravity. Witten also developed the Seiberg-Witten equations with Nathan Seiberg; these have revolutionized the study of four-dimensional objects. He is a winner of the Fields Medal, the Nobel Prize of mathematics.