John Donoghue: The Physicist Who Says We've Already Quantized Gravity
Theories of Everything with Curt Jaimungal
S‑matrix, Unitarity, and Unstable States
He explains only normal stable particles appear in asymptotic states, preserving S-matrix unitarity despite ghosts.
Professor John Donoghue explains why quantum physics and gravity actually work perfectly together. He tackles quadratic gravity, effective field theory, and random dynamics, arguing that grand unification and naturalness aren't required for a theory of everything. As a listener of TOE you can get a special 20% off discount to The Economist and all it has to offer! Visit https://www.economist.com/toe SUPPORT: - Support me on Substack: https://curtjaimungal.substack.com/subscribe - Support me on Crypto: https://commerce.coinbase.com/checkout/de803625-87d3-4300-ab6d-85d4258834a9 - Support me on PayPal: https://www.paypal.com/donate?hosted_button_id=XUBHNMFXUX5S4 JOIN MY SUBSTACK (Personal Writings): https://curtjaimungal.substack.com LISTEN ON SPOTIFY: https://open.spotify.com/show/4gL14b92xAErofYQA7bU4e TIMESTAMPS: - 00:00:00 - Limits of Quantum Mechanics - 00:06:35 - Effective Field Theory - 00:12:24 - Gravity: Geometry or Force? - 00:18:46 - QFT and Gravity Tension - 00:24:59 - Quadratic Gravity Theory - 00:34:16 - Dueling Arrows of Causality - 00:41:57 - Random Dynamics and Anti-Unification - 00:48:13 - The Naturalness Problem - 00:53:40 - Questioning Hidden Assumptions LINKS MENTIONED: - John's lectures: https://www.youtube.com/@johndonoghue469/featured - John's papers: https://arxiv.org/a/donoghue_j_1.html - The Renormalization Group and Critical Phenomena [Paper]: https://www.nobelprize.org/uploads/2018/06/wilson-lecture-2.pdf - Anthropic Considerations in Multiple-Domain Theories [Paper]: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.80.1822 - Old "Ghost" Theory of Quantum Gravity Makes a Comeback [Article]: https://www.quantamagazine.org/old-ghost-theory-of-quantum-gravity-makes-a-comeback-20251117/ - Unitarity, Stability and Loops of Unstable Ghosts [Paper]: https://arxiv.org/pdf/1908.02416 - An Effective Field Theory of Gravity for Extended Objects [Paper]: https://arxiv.org/abs/hep-th/0409156 - Not Quite a Black Hole [Paper]: https://arxiv.org/pdf/1612.04889 - On Quadratic Gravity [Paper]: https://arxiv.org/pdf/2112.01974 - Quadratic Gravity [Paper]: https://arxiv.org/pdf/1804.09944 - Renormalization of Higher Derivative Quantum Gravity [Paper]: http://www.weylmann.com/stelle.pdf - Quantum Theory in a Nutshell [Book]: https://www.amazon.com/Quantum-Field-Theory-Nutshell-nutshell/dp/0691140340 - Field Theory: A Modern Primer [Book]: https://www.amazon.com/Field-Theory-Modern-Frontiers-Physics/dp/0201546116 - Origin of Symmetries [Book]: https://amzn.to/4qxnLzj - String Theory Iceberg [TOE]: https://youtu.be/X4PdPnQuwjY - Neil Turok [TOE]: https://youtu.be/zNZCa1pVE20 - Avshalom Elitzur [TOE]: https://youtu.be/pWRAaimQT1E - Sir Roger Penrose [TOE]: https://youtu.be/iO03t21xhdk - Ted Jacobson [TOE]: https://youtu.be/3mhctWlXyV8 - Leonard Susskind [TOE]: https://youtu.be/2p_Hlm6aCok - Jonathan Oppenheim [TOE]: https://youtu.be/NKOd8imBa2s - Peter Woit [TOE]: https://youtu.be/TTSeqsCgxj8 - Joseph Conlon & Peter Woit [TOE]: https://youtu.be/fAaXk_WoQqQ - Michael Levin [TOE]: https://youtu.be/c8iFtaltX-s
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