Adam Riess is an American astrophysicist and Bloomberg Distinguished Professor at Johns Hopkins University and the Space Telescope Science Institute. He is known for his research in using supernovae as cosmological probes. Riess shared both the 2006 Shaw Prize in Astronomy and the 2011 Nobel Prize in Physics with Saul Perlmutter and Brian Schmidt for providing evidence that the expansion of the universe is accelerating. Riess has been at the center of a growing scientific debate about the so-called “Hubble tension” — a discrepancy between measurements of the universe’s expansion rate using nearby supernovae, and measurements inferred from the cosmic microwave background radiation using the Standard Model of cosmology. Riess’s data has prompted questions and further testing to determine if the Standard Model still adequately describes the universe.