Brian Greene is an American theoretical physicist and string theorist, known for his work in the field of superstring theory. He is a professor at Columbia University and has authored several popular science books, including "The Elegant Universe" and "The Fabric of the Cosmos," which aim to explain complex scientific concepts to a general audience. In addition to his research and writing, Greene is a co-founder of the World Science Festival, an annual event that celebrates science through discussions, performances, and interactive experiences. His efforts have made significant contributions to public understanding of physics and the universe.