Eiichiro Komatsu is a cosmologist who enjoys both theoretical and observational work. He has been Director of the Physical Cosmology division at the Max Planck Institute for Astrophysics in Garching, Germany, since 2012. Prior to this he was a professor in the Department of Astronomy and Director of Texas Cosmology Center at the University of Texas at Austin. He obtained his Ph.D. from Tohoku University in Sendai, Japan, in 2001. In recent years he has been trying to find ways to prove that the Universe underwent a period of quasi-exponential, accelerated expansion called “inflation” before the big bang, and to understand why and how the expansion of the current Universe is also accelerating.