Sergei V. Ketov is a world expert in quantum field theory, gravitational theory and string theory. He obtained his Master's degree (1982) and Ph.D. (1986) in Theoretical Physics after his studies and research at Tomsk State University and Lebedev Physical Institute in Moscow, USSR. He later worked at the Soviet Academy of Sciences and got his habilitation (1990) at Budker Institute of Nuclear Physics in Novosibirsk, USSR. In 1990, he became a Visiting Professor of Physics at the University of Maryland in College Park, USA. Since 1992, he has been a member of "Akademischen Rat" at the Institute for Theoretical Physics of Hannover University in Germany. Since 2002, he has been an Associate Professor and Head of the Theoretical High Energy Physics Lab at Tokyo Metropolitan University, and a member of the Institute for the Physics and Mathematics of the Universe (IPMU) at the University of Tokyo in Japan. His current research topics mainly include cosmology and supergravity.