Why Can't We Unite Gravity and Quantum Physics?

Why can't we unite gravity and quantum physics in 1 complete theory? From vibrating strings to black-hole information, the search for a theory of everything leads to some of the strangest ideas in science. Follow 6 physicists through general relativity, string theory, loop quantum gravity, extra dimensions and holography. Then visit the real tests: colliding black holes and atomic clocks measuring time dilation across about 1 millimeter. Gravity and quantum theory already work together in useful, limited regimes. The unfinished task is a complete, experimentally established description. This documentary separates theoretical clues from measured results. Which clue would you investigate first: black holes, quantum geometry or precision experiments? Tell us why, like the video and subscribe to Matter of Why. CHAPTERS 00:00 Why physics still has 2 rulebooks 00:50 What Einstein and quantum theory already share 02:05 When spacetime becomes part of the problem 03:18 The quantum gravity we can already calculate 04:33 String theory and the graviton 05:51 Could extra dimensions be hidden? 07:03 Loop quantum gravity: quantizing geometry 08:12 Black holes and the information puzzle 09:27 Maldacena's holographic connection 10:44 Real tests: gravitational waves and atomic clocks 11:55 What would count as a breakthrough? 13:12 The unfinished theory of everything SCIENCE SOURCES CERN - Standard Model https://home.cern/science/physics/sta... CERN - Unified forces https://home.cern/science/physics/uni... John Donoghue - General relativity as an effective field theory (1994) https://arxiv.org/abs/gr-qc/9405057 Juan Maldacena - Holographic correspondence (1997) https://arxiv.org/abs/hep-th/9711200 Carlo Rovelli - Loop Quantum Gravity (1998) https://arxiv.org/abs/gr-qc/9803024 JILA/NIST - Relativity at millimeter scale (2022) https://www.nist.gov/news-events/news... LIGO/Virgo - Tests of general relativity with GW150914 https://arxiv.org/abs/1602.03841 Perimeter Institute - From Discretuum to Continuum https://perimeterinstitute.ca/researc... ORIGINAL TALKS Harry Cliff / TEDGlobal Geneva 2015 https://www.ted.com/talks/harry_cliff... Raphael Bousso / (c) 2024 CERN https://videos.cern.ch/record/3017728 Cumrun Vafa / (c) 2024 CERN https://videos.cern.ch/record/2300494 Carlo Rovelli / TEDAI 2024 https://www.ted.com/talks/carlo_rovel... Juan Maldacena / (c) 2024 CERN https://videos.cern.ch/record/3001297 Anna Ceresole / (c) 2026 CERN https://videos.cern.ch/record/3026905 ARCHIVE & VISUALIZATION CREDITS CERN - accelerator and detector archive https://videos.cern.ch/record/2716034 CERN - CMS construction and operation https://videos.cern.ch/record/1246799 CERN - CMS aerial footage https://videos.cern.ch/record/2027841 ESO. Editing & Drone Footage: Angelos Tsaousis. VLT aerial footage; excerpted and reframed. https://www.eso.org/public/videos/ann... License: CC BY 4.0 https://creativecommons.org/licenses/... NIST - Einstein, Time, and Very Small Things, with Jun Ye https://www.nist.gov/video/einstein-t... NASA/Goddard/Scott Noble; simulation data: d'Ascoli et al. 2018 https://svs.gsfc.nasa.gov/13086/ NASA/Bernard J. Kelly (Goddard/UMBC), Chris Henze (Ames), Tim Sandstrom (CSC Government Solutions LLC) https://svs.gsfc.nasa.gov/13197/ Original score: Two Rulebooks. Original explanatory graphics: Matter of Why. Scientific simulations and conceptual illustrations are used to explain the ideas. The cover is conceptual. No featured expert or institution endorses this documentary. #QuantumGravity #TheoryOfEverything #QuantumPhysics #GeneralRelativity #StringTheory #LoopQuantumGravity #BlackHoles #Spacetime #Physics #MatterOfWhy