Fermilab’s Scott Dodelson on Cosmology’s Crisis

Scott Dodelson spent ten years on the Dark Energy Survey testing the standard model of cosmology. It passed and missed by 2.5 sigma. The Director of Fermilab’s Cosmic Physics Division on why the theory he helped build may be wrong, why nobody can find dark matter, and what it takes to change a scientific consensus. Subscribe if you want science with evidence, not speculation. Dodelson is Director of the Cosmic Physics Division at Fermilab, Professor of Astronomy and Astrophysics at the University of Chicago, and author of Modern Cosmology, the textbook a generation of cosmologists learned the field from. Lambda-CDM predicts how the early universe’s tiny fluctuations grew into the structure we see today. The Dark Energy Survey was designed to check that prediction. The answer came back two and a half sigma off. That is both the most precise measurement ever made of how the universe grew, and a crack he cannot stop looking at. His question is not whether the model is close. It is whether close is enough to trust. We get into the Sigma-8 tension and what it actually takes for a scientific community to change its mind, the Dodelson-Widrow mechanism and his 1994 proposal that sterile neutrinos produced in the early universe could constitute dark matter, and the Neptune vs. Vulcan history of getting dark matter right and wrong. Asked which of those two situations we are in now, Dodelson’s answer is: I have no idea. What you’ll hear: Why the April 24, 1992 CMB discovery may have been the only science story ever to lead the New York Times front column The Dodelson-Widrow mechanism: how ordinary neutrinos in the early universe may have oscillated into the dark matter we see today Why Brian told Neil deGrasse Tyson to his face that we have already detected dark matter What it means when a theory can accommodate any result and whether inflation has that problem Why the particle physics community still does not trust cosmology’s neutrino mass measurements What cosmology looks like in 2036 if Lambda-CDM breaks Killing the model is my dream. 0:00 None of it has been found in a lab. How many free passes do we get? 0:44 Dodelson helped build Lambda-CDM. His dream is to kill it. 2:10 10 years. One prediction. Two and a half sigma off. 5:42 "You're in charge" — what mentorship in science actually looks like 6:56 April 24, 1992: cosmology stopped being speculation 9:48 Geoff Burbidge went to his grave a steady-state believer 11:04 What a neutrino is and why it barely interacts with anything 12:36 Brian told Neil deGrasse Tyson we already detected dark matter 18:08 How ordinary neutrinos may have become dark matter 23:24 Lambda-CDM predicts Manhattan's density 13.7 billion years later 26:42 Two and a half sigma: technically a 1% chance the theory is right 28:04 Neptune was dark matter. Vulcan wasn't. Which one are we in now? 31:20 Dark matter, inflation, dark energy: none found in a lab 36:46 If both cracks are the same crack, Lambda-CDM is finished Get the transcript, fascinating bonus content, and my Monday M.A.G.I.C. Message: https://briankeating.com/yt Have a .edu email and live in the USA? You automatically win a meteorite: https://BrianKeating.com/edu Subscribe: https://www.youtube.com/DrBrianKeating?sub_confirmation=1 Support Into the Impossible on Patreon, get my weekly M.A.G.I.C. Message, unfiltered bonus content, and live monthly Office Hours with me: https://www.patreon.com/drbriankeating Join this channel for perks, monthly Office Hours, and your name in the Member Roster at the end of every episode: https://www.youtube.com/channel/UCmXH_moPhfkqCk6S3b9RWuw/join Featured Guest: Scott Dodelson Substack: https://scottdodelson.substack.com/about Scott Dodelson on LinkedIn: https://www.linkedin.com/in/scott-dodelson-b6ba429/ Scott Dodelson on Twitter/X: https://x.com/ScottDodelson Modern Cosmology (book): https://www.sciencedirect.com/book/monograph/9780128159484/modern-cosmology Dark Energy Survey final results: https://www.darkenergysurvey.org/news-and-results/darchives/ Dodelson and Widrow 1994, Sterile neutrinos as dark matter: https://arxiv.org/abs/hep-ph/9303287 Previous ITI episode with Kyle Dawson on DESI: https://youtu.be/LPx4oiwGp2k?si=u_ZJWfJG5AhvBAEv  My books: Losing the Nobel Prize (memoir): http://amzn.to/2sa5UpA Think Like a Nobel Prize Winner: https://a.co/d/03ezQFu Focus Like a Nobel Prize Winner: https://a.co/d/hi50U9U Galileo’s Dialogue (first-ever audiobook): https://a.co/d/iZPi9Un Twitter/X: https://x.com/BrianKeating Substack: https://briankeating.substack.com Blog: https://briankeating.com/blog Audio-only: https://briankeating.com/podcast #intotheimpossible #briankeating #cosmology #darkmatter #darkenergy #physics #LambdaCDM #podcast Learn more about your ad choices. Visit megaphone.fm/adchoices