Plamen Stefanov is a professor at the Department of Mathematics at Purdue University. He earned his Ph.D. degree from the University of Sofia in 1988. After that, he has held visiting positions in France, Finland, Brazil, Canada and USA. His research interests are in Analysis and Applied Math, including Microlocal Analysis and Applications, Inverse Problems, Integral Geometry, Scattering Theory, and PDEs. His most recent work is in the field of Inverse Problems and more specifically, inverse problems in geometry, and problems related to medical imaging and seismology. In particular, he and his collaborators obtained significant results about recovery of a Riemannian metric on a compact manifold with boundary from the boundary distance function or the lens relation at the boundary. This problem is motivated by the fundamental problem in seismology: recover the inner structure of the Earth from the travel times of propagation of seismic waves.