Can We Test Quantum Gravity? | World Science Festival

What if a groundbreaking experiment could finally reveal whether gravity is a quantum force? Brian Greene sits down with Vlatko Vedral, Professor of Quantum Information Science at the University of Oxford, to explore one of the deepest questions in modern physics: Is gravity fundamentally quantum, or does it remain classical even at the most fundamental level? They discuss Freeman Dyson's argument that gravity may never need to be quantized, Roger Penrose's proposal that gravity could play a role in shaping quantum mechanics, and Vedral's own ideas for experiments that might settle the issue. The conversation explores whether the many-worlds interpretation truly captures what quantum mechanics implies and examines a thought experiment inspired by Schrödinger's cat that challenges our understanding of observation, reality, and measurement. It's a look at one of physics' most compelling open questions and the remarkable ideas that could finally help answer it. This program is part of the Rethinking Reality series, supported by the John Templeton Foundation. Participant: Vlatko Vedral Moderator: Brian Greene Don't miss a video! Subscribe NOW: https://www.youtube.com/worldsciencefestival?sub_confirmation=1 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 Chapters: 00:00 Introduction: The Case for Quantum Gravity 00:23 Welcome to the Conversation: Brian Greene and Vlatko Vedral 00:51 From Einstein's Entanglement Debate to Quantum Computers Today 02:04 A Historical Parallel: Skepticism Before the Breakthrough 04:18 Freeman Dyson's Heresy: What If Gravity Isn't Quantum at All? 05:24 The Strongest Argument for Quantizing Gravity 08:05 Did Niels Bohr Get It Wrong About the Classical World? 09:54 Spontaneous Collapse Theories: Do They Actually Work? 13:04 Decoherence Explained: Many Outcomes, Not One 14:00 Many Worlds or "Q Numbers"? A Language Problem 17:09 Roger Penrose's Alternative: Gravitizing Quantum Mechanics 20:53 The Equivalence Principle Under Quantum Pressure 22:12 Why String Theorists Rarely Test Their Own Theory 23:38 The Experiment: Superposing Mass to Catch Gravity in the Act 26:04 How Small a Mass Do You Actually Need? 27:12 Two Interferometers: Testing for Gravitationally-Induced Entanglement 29:54 Real-World Progress: Splitting a Bose-Einstein condensate 32:33 Is Gravity Spacetime Itself, or Just Another Field? 34:38 How Quantum Entanglement Might Stitch the Fabric of Space 36:23 Reality Made of "Q Numbers" Instead of Ordinary Numbers 37:48 The Many-Worlds Probability Problem: The Born Rule 40:13 Self-Locating Uncertainty and the Trouble With Observers 42:00 Why No Special Status Is Needed for Conscious Observers 45:25 Living With "Spooky Action": Should We Stop Resisting Non-Locality? 47:36 Could Living Systems Be the Real Source of Collapse? 49:10 The Largest Object Ever Tested in a Quantum Superposition 52:53 Anton Zeilinger's Copenhagen Defense, and Its Limits 56:05 The Hardest Experiment: A Human Inside Schrödinger's Box 01:00:02 Is Information the True Currency of Reality? 01:02:36 The Next 5-10 Years: When Will We Know for Sure? 01:04:48 Could the Universe Be Built from "Bits of Geometry"? 01:06:31 Closing Thoughts Can We Test Quantum Gravity | World Science Festival https://youtu.be/5uBBz0upYoY