How did scientists discover evidence for dark energy? Neil deGrasse Tyson and comedian Paul Mecurio explore dark energy, Hubble tension, and the beginning and end of the universe with astrophysicist and Nobel laureate, Adam Riess. Learn the story of how Adam helped discover dark energy, and how he wrote equations expecting to measure deceleration only to watch his computer spit out negative mass, signaling acceleration instead. From calibrating candles to worrying about bad weather on Hubble observing nights, he walks through the beautiful mistake that held up. Learn how astronomers once wondered whether there was enough matter to slow the universe’s expansion, and how parallax, Gaia data, Cepheid variables, and the search for ever-brighter standard candles led them to Type Ia supernovae. He breaks down why these explosions are so uniform, how the Chandrasekhar limit works, and how dust tricks astronomers by dimming and reddening starlight. The conversation widens to dark energy’s role in the universe’s ultimate fate: the Big Freeze, Big Rip, or Big Crunch. We discuss the ΛCDM model, where 97% of the universe remains unknown. We explore Hubble tension, why early- and late-universe measurements refuse to overlap, and whether shifting dark energy, new particles, magnetic fields in the primordial plasma, or revised pre-CMB physics could reconcile the mismatch. With JWST confirming Hubble’s results, new facilities on the horizon, and the community hunting for overlooked assumptions, sometimes the universe moves the goalposts, and our job is to follow the thread. Thanks to our Patrons micpoc, Nathan, Matthew, Aislynn Schaffer, Mark Domino, Lou Wheeland, Matrograde, Elliott Natale, Machael Lipovski, Mathew Moore, Tony, Pablo P, Toni, Brian Futterman, quantumAnomaly, Robin Steiner, Errol Norwitz, Donovan Meek, Alan Geist, Sriganesh Arunanthi, Nuno Abreu, Ross Ziobro, Petr Doležal, Mandar Parikh, Bryan Tollin, Fooj, David Bozarth, Kolja Dobrindt, Sean Poplawski, Brad Durbin, Christian Nielsen, Zen Kurokawa, Lương Tiến, Joel Arbuckle, Chad L Ingham, Mark Morris, dylndmg, Derrick Korstick, EleanorRigbyy, Tarun C, Larry Infante, Jaclyn Anderson, Dave, Kayla Finch, The Bayside Volunteer Jam Band, Dale Allen Platt, Raymond Boulay, Lawrence Zeller, David, Kim Matthews, Jon Gefen, Mark A. Hasty, Clifford Dedmore, Mario De La Crus and Brianni Massin, jordan visina, Ryan Brown, Sebastian H, Daniel Voth, Karen Hollis, Josua Ennis, Julius Adams, Christie L Hall, Filip Risteski, scottdunbar_io, Samantha Davis, Don Franks, Corey Butler, Josh Jones, Daniel Vilasuso, J MR, joe, I Am Austin, bobmac69, Anthony cole, Zan, Erik LeRoy, Kevin George, Arman Adei, Christopher Pickett, John Morlock, AllTheScience, Juana Bee, Jeff Chastain, Jaimal Eiseman, Ed Matte, Lorkhan, D, roninraver, z67760, Orghanik Productions, and CubedWombat for supporting us this week. Timestamps: 00:00 - Introduction: Adam Riess 05:10 - The Mysterious Term in Einstein's Equations 11:08 - Finding Standard Candles 18:47 - Supernovas, Cepheids & Dust 23:32 - Discovering the Universe’s Accelerating Expansion 31:55 - The Emergence of Hubble Tension 37:59 - Is Dark Energy Shifting? 42:29 - Transforming Our Understanding & New Measurements 52:31 - Resolving Hubble Tension 55:42 - Error & Democratization of Science 59:32 - Chunky Space 01:00:52 - The Age Crisis 01:02.25 - A Cosmic Perspective 01:06:00 - Closing Check out our second channel, @StarTalkPlus Get the NEW StarTalk book, 'To Infinity and Beyond: A Journey of Cosmic Discovery' on Amazon: https://amzn.to/3PL0NFn Support us on Patreon: https://www.patreon.com/startalkradio FOLLOW or SUBSCRIBE to StarTalk: Twitter: http://twitter.com/startalkradio Facebook: https://www.facebook.com/StarTalk Instagram: https://www.instagram.com/startalk About StarTalk: Science meets pop culture on StarTalk! Astrophysicist & Hayden Planetarium director Neil deGrasse Tyson, his comic co-hosts, guest celebrities & scientists discuss astronomy, physics, and everything else about life in the universe. Keep Looking Up! #StarTalk #NeildeGrasseTyson