Juan Maldacena: Geometry as Entanglement, and the Emergence of Spacetime

In this episode of Theories of Everything, host Curt Jaimungal interviews Juan Maldacena, the theoretical physicist behind the most-cited paper in the field and architect of the AdS/CFT correspondence. Maldacena explains that spacetime in general relativity is not made of anything more fundamental, but quantum considerations suggest it may emerge from quantum degrees of freedom living on the boundary of spacetime. The conversation explores black hole interiors, where singularities represent places physics currently cannot describe, and the recent island formula breakthroughs by Pennington and Witten that resolve how black holes preserve quantum information. Maldacena reveals he is actively working to resolve fundamental incompatibilities surrounding wormholes in quantum gravity, describing them as 'leaky pipes' where different theoretical frameworks do not fit together. He argues that quantum gravity requires observers to be included in the system, stating there is no 'view from nowhere' and that measurements are fundamentally embedded in spacetime structure. On cosmology, Maldacena expressed skepticism about DESI results suggesting dark energy's equation of state might be below -1, calling such a finding potentially the biggest news in 100 years but predicting it will not survive scrutiny. The episode closes with Maldacena sharing that as a graduate student he struggled with feelings of inadequacy, advising students to persist, question lore in their fields, and understand concepts deeply rather than repeating what everyone says.

• Maldacena argues quantum gravity requires physical observers embedded in the system, rejecting any 'view from nowhere' in the theory's formulation.
• He disclosed he is working to resolve fundamental incompatibilities around wormholes, where different theoretical ideas conflict and represent one of quantum gravity's hottest unsolved problems.
• Maldacena revealed a PhD student of his proposed a major generalization of black hole entropy formulas which he initially rejected, calling it one of his failures as an advisor when others later published it.
• He expressed skepticism about DESI dark energy results showing w less than -1, predicting they will not hold but acknowledging such a finding would be the biggest physics news in a century.
• The island formula by Pennington and Witten provides a finite way to compute black hole entropy including quantum corrections, resolving paradoxes about information loss in Hawking radiation.
• Maldacena explained that spacetime may emerge from quantum entanglement, with his ER=EPR conjecture suggesting wormholes and entangled states are dual descriptions of the same phenomenon.
• He admitted feeling inadequate as a graduate student and advised students to persist, deeply understand concepts their own way, and question accepted lore in their fields.