Astronomers rocked the cosmological world with the 1998 discovery that the universe is accelerating. Well-deserved Nobel Prizes were awarded to Saul Perlmutter, Brian Schmidt, and today’s guest Adam Riess. Adam has continued to push forward on investigating the structure and evolution of the universe. He’s been a leader in emphasizing a curious disagreement that threatens to grow into a crisis: incompatible values of the Hubble constant (expansion rate of the universe) obtained from the cosmic microwave background vs. direct measurements. We talk about where this “Hubble tension” comes from, and what it might mean for the universe. Adam Riess received his Ph.D. in astronomy from Harvard University. He is currently Bloomberg Distinguished Professor and Thomas J. Barber Professor of Physics and Astronomy at Johns Hopkins University and a Senior member of the Science Staff at the Space Telescope Science Institute. Among his many awards are the Helen B. Warner Prize of the American Astronomical Society, the Sackler Prize, the Shaw Prize, the Gruber Cosmology Prize, the MacArthur Fellowship, the Breakthrough Prize in Fundamental Physics, and the Nobel Prize. Blog post with audio player, show notes, and transcript: https://www.preposterousuniverse.com/podcast/2020/10/12/118-adam-riess-on-the-expansion-of-the-universe-and-a-crisis-in-cosmology/ Patreon: https://www.patreon.com/seanmcarroll Mindscape Podcast playlist: https://www.youtube.com/playlist?list=PLrxfgDEc2NxY_fRExpDXr87tzRbPCaA5x #podcast #ideas #science #philosophy #culture