What Is Quantum Mechanics Really Telling Us? | World Science Festival

Does quantum mechanics actually imply that every possible outcome of every decision happens somewhere in an expansive reality? And if so, what does that mean for probability, free will, and our understanding of the universe itself? Brian Greene sits down with David Deutsch, widely regarded as the father of quantum computing, to examine what many physicists are still reluctant to accept about their own theory. They explore why the many-worlds interpretation isn't just a philosophical curiosity, what the wave function is really telling us about reality, and how decision theory may rescue probability in a fully deterministic multiverse. Deutsch also introduces constructor theory, his framework for rethinking the foundations of physics entirely and explains why the questions we've been trained not to ask might be the most important ones in all of science. This program is part of the Rethinking Reality series, supported by the John Templeton Foundation. Participant: David Deutsch Moderator: Brian Greene #worldsciencefestival #briangreene #cosmology #astrophysics ABOUT WORLD SCIENCE FESTIVAL: The World Science Festival (WSF) is a multimedia organization bringing the most transformative ideas in science to global audiences. Through long- and short-form videos spanning physics, cosmology, quantum mechanics, biology, neuroscience, consciousness, medicine, space exploration, the dilemma of free will, artificial intelligence, engineering, robotics, and beyond. WSF gathers world-renowned scientists, artists, and thinkers for dynamic discussions, debates, lectures, performances, films, and immersive live experiences. Founded in 2008 and headquartered in New York City, the World Science Festival is a production of the World Science Foundation, a 501(c)(3) nonprofit organization. Our mission is to cultivate a public informed by science, inspired by its wonder, convinced of its value, and prepared to engage with its implications for the future. With live events reaching millions worldwide and hundreds of millions of digital views, WSF continues to expand its global impact through festivals, educational initiatives like World Science U, and digital content that explores the near and far future of our world. FOLLOW WORLD SCIENCE FESTIVAL: Website: https://worldsciencefestival.com/ Instagram: https://www.instagram.com/worldscifest/ TikTok: https://www.tiktok.com/@worldscifest X(Twitter): https://twitter.com/worldscifest Facebook: https://www.facebook.com/worldsciencefestival LinkedIn: https://www.linkedin.com/company/world-science-festival 00:00 Rethinking Reality: What’s Actually Real? 02:50 From Classical to Quantum: When Things Stop Making Sense 05:30 What’s Wrong with Probability in Physics? 08:10 Determinism vs Randomness (What’s Really True?) 10:40 The Multiverse Explained (Many Worlds Theory) 13:20 Do Multiple Versions of You Really Exist? 16:00 Probability Without Chance 18:40 When Decision Theory Meets Quantum Physics 21:30 How Do You Make Choices in a Quantum World? 24:30 Betting on Reality (How Decisions Actually Work) 27:30 Is Probability Even Real? 33:30 Thought Experiments That Break Your Intuition 36:30 Common Misunderstandings About the Multiverse 39:30 The “Quantum Suicide” Idea (And Why It’s Dangerous) 49:17 Probability as a Tool, Not Something Real 51:30 Responding to Critics (Albert & Wallace) 54:30 What Does It Mean to Be Rational? 57:05 The Mistake People Make About “Versions” of Themselves 01:01:00 Free Will vs Physics: Do We Really Choose? 01:04:30 Why It Feels Like We Have Control 01:12:00 Different Levels of Reality (And Why They Matter) 01:14:00 Constructor Theory Explained 01:22:20 Final Thoughts: Adapting to a Stranger Universe What Is Quantum Mechanics Really Telling Us? | World Science Festival https://www.youtube.com/channel/UCShHFwKyhcDo3g7hr4f1R8A