Jonathan Oppenheim: Why Gravity Might Not Be Quantum After All

Jonathan Oppenheim (UCL) challenges quantum gravity orthodoxy, arguing spacetime remains fundamentally classical. He examines quantum‑classical hybrid dynamics, path integrals, and the role of observation in collapse, offering fresh perspectives on the foundations of physics.

- 00:00 - Intro
- 01:08 - Quantum Mechanics and Classical Mechanics
- 06:05 - Quantizing Gravity
- 10:30 - How Gravity is Different
- 16:07 - Classical-Quantum Gravity
- 21:42 - Quantum Mechanics
- 25:23 - Example of Continuous Master-Equation
- 28:45 - Observation Causes a Collapse
- 35:20 - Path Integrals
- 49:34 - Intuitions
- 59:32 - Is Spacetime Classical?
- 01:03:05 - Outro / Support TOE

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RESOURCES:

- Sean Carroll on TOE: https://www.youtube.com/watch?v=9AoRxtYZrZo
- Jonathan's first appearance on TOE: https://www.youtube.com/watch?v=NKOd8imBa2s
- Jonathan's paper on hybrid classical-quantum dynamics: https://arxiv.org/pdf/2203.01332
- Jonathan's paper on a post-quantum theory of classical gravity: https://journals.aps.org/prx/pdf/10.1103/PhysRevX.13.041040
- Jonathan's website: https://www.ucl.ac.uk/oppenheim/
- List of all of Jonathan's published papers: https://arxiv.org/search/?query=Oppenheim%2C+Jonathan&searchtype=author&abstracts=show&order=-announced_date_first&size=50
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Theories of Everything with Curt Jaimungal features long-form, technically detailed interviews with leading researchers in physics, mathematics, consciousness, and philosophy, exploring topics at the level of active research. For academics, graduate students, and anyone seeking depth beyond popular science.

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