Sean Carroll in Preposterous Universe:
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.
More here.