Adam Riess

Johns Hopkins University

Adam Riess is a Bloomberg Distinguished Professor at Johns Hopkins University and a senior member of the Space Telescope Science Institute. He shared the 2011 Nobel Prize in Physics with Saul Perlmutter and Brian Schmidt for discovering that the expansion of the universe is accelerating—a finding that revolutionized our understanding of cosmology and introduced the concept of dark energy into mainstream physics. Using distant Type Ia supernovae as standard candles, Riess and colleagues measured cosmic distances with unprecedented precision, revealing that the universe's expansion rate is increasing rather than decelerating as gravity alone would predict. Since the Nobel Prize, Riess has become a leading figure in the Hubble tension controversy, a growing discrepancy between measurements of the Hubble constant obtained from the early universe versus the local universe. His SH0ES (Supernova H0 for the Equation of State) program uses the Hubble Space Telescope and James Webb Space Telescope to refine the cosmic distance ladder, achieving sub-percent precision in Hubble constant measurements. This tension may indicate new physics beyond the standard cosmological model. Riess is a recipient of the Breakthrough Prize in Fundamental Physics, the Harvey Prize, and the Dan David Prize, among others. His continued efforts to resolve the Hubble tension represent one of the most important open questions in modern cosmology.