Chern worked at the Institute for Advanced Study (1943–45), spent about a decade at the University of Chicago (1949-1960), and then moved to University of California, Berkeley, where he co-founded the world-renowned Mathematical Sciences Research Institute in 1982 and was the institute's founding director. Renowned co-authors with Chern include Jim Simons, an American mathematician and billionaire hedge fund manager who has been acclaimed as "arguably the world's best investor" by Forbes. Chern's work, most notably the Chern-Gauss-Bonnet Theorem, Chern–Simons theory, and Chern classes, are still highly influential in current research in mathematics, including geometry, topology, and knot theory; as well as many branches of physics, including string theory, condensed matter physics, general relativity, and quantum field theory.