For decades, the Sleeping Beauty Problem has divided people between two answers. Head to https://brilliant.org/veritasium to start your free 30-day trial, and the first 200 of you will get 20% off an annual premium subscription. ▀▀▀ Many thanks to Dr. Mike Titelbaum and Dr. Adam Elga for their insights into the problem. ▀▀▀ References: Elga, A. (2000). Self-locating belief and the Sleeping Beauty problem. Analysis, 60(2), 143-147. - https://ve42.co/Elga2000 Lewis, D. (2001). Sleeping beauty: reply to Elga. Analysis, 61(3), 171-176. - https://ve42.co/Lewis2001 Winkler, P. (2017). The sleeping beauty controversy. The American Mathematical Monthly, 124(7), 579-587. - https://ve42.co/Winkler2017 Titelbaum, M. G. (2013). Ten reasons to care about the Sleeping Beauty problem. Philosophy Compass, 8(11), 1003-1017. - https://ve42.co/Titelbaum2013 Mutalik, P. (2016). Solution: ‘Sleeping Beauty’s Dilemma’, Quanta Magazine - https://ve42.co/MutalikQ2016 Rec.Puzzles - Some “Sleeping Beauty” Postings - https://ve42.co/SBRecPuzzles The Sleeping Beauty Paradox, Statistics SE - https://ve42.co/SBPSSE The Sleeping Beauty Problem, Reddit - https://ve42.co/SBPReddit Sleeping Beauty paradox explained, GameFAQs - https://ve42.co/SBPGameFAQ The Sleeping Beauty Problem, Physics Forums - https://ve42.co/SBPPhysicsForums ▀▀▀ Special thanks to our Patreon supporters: Tj Steyn, Meg Noah, Bernard McGee, KeyWestr, Elliot Miller, Brian Busbee, Jerome Barakos, M.D., Amadeo Bee, TTST, Balkrishna Heroor, Chris LaClair, John H. Austin, Jr., Eric Sexton, john kiehl, Anton Ragin, Benedikt Heinen, Diffbot, Gnare, Dave Kircher, Burt Humburg, Blake Byers, Evgeny Skvortsov, Meekay, Bill Linder, Paul Peijzel, Josh Hibschman, Mac Malkawi, Mike Schneider, jim buckmaster, Juan Benet, Ubiquity Ventures, Richard Sundvall, Lee Redden, Stephen Wilcox, Marinus Kuivenhoven, Michael Krugman, Cy 'kkm' K'Nelson, Sam Lutfi. ▀▀▀ Written by Emily Zhang, Derek Muller, Tamar Lichter Blanks Edited by Fabio Albertelli Animation by Ivy Tello, Fabio Albertelli, Jakub Misiek Additional video/photos supplied by Getty Images & Pond5 Music from Epidemic Sound Thumbnail by Ignat Berbeci Produced by Derek Muller, Petr Lebedev, Emily Zhang