Stephen Semmes is Noah Harding Professor of Mathematics at Rice University. He is known for contributions to analysis on metric spaces, as well as harmonic analysis, complex variables, partial differential equations, and differential geometry. He received his B.S. at the age of 18, a Ph.D. at 21 and became a full professor at Rice at 25.
Semmes was awarded a Sloan Fellowship in 1987. In 1994, he gave an invited talk at the International Congress of Mathematicians.