Professor Shing-Tung Yau is a Chinese-American mathematician. He is known for a wide variety of contributions to mathematics and theoretical physics. With Richard Schoen, he proved the positive mass conjecture, discovered the first black hole existence theorem due to the condensation of matter, and most recently, he and Mu-Tao Wang worked on defining “quasilocal mass,” which allows the measurement of gravitational energy on any finitely extended region. Making use of ideas from quasilocal quantities, they solved a long outstanding problem on understanding angular momentum in general relativity. Yau is a member of the National Academy of Sciences (NAS) and the American Association for the Advancement of Science (AAAS), and a recipient of the Fields Medal, the Crafoord Prize, the United States National Medal of Science, the Wolf Prize in Mathematics, and the Marcel Grossmann Award.