Daniel Harry Friedan

Expert in string theory and two-dimensional conformal field theory. Analysis of the two-dimensional renormalization group led to the Ricci flow equations, bringing important consequences in mathematics, including a proof of the Poincaré conjecture. With Callan and Martinec, generalized this result and showed that the conditions for two-dimensional conformal invariance implied Einstein's equations for the space-time metric-one of the deepest and most influential results in string theory. Studied the constraints of unitarity on two-dimensional (super) conformal field theories and produced a complete classification of such theories with small central charge. With Martinec and Shenker, formulated a new approach to covariant perturbation theory for superstrings. Honors include the Onsager Prize (2010) and the MacArthur Fellowship (1987).