Episode overview

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

Theories of Everything · 4 May 2026 · 4 Egleze moments

What happened in this episode?

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.

What are the key points?

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.

Which topics are covered?

Science

How is this page sourced?

Programme: Theories of Everything
Published: 4 May 2026
Original episode: Open the original source ↗

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4 moments from this episode

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Science

Maldacena Reveals Conceptual Crisis Around Wormholes in String Theory

at 38:55 · Attributed speaker claim

I'm trying to understand wormholes. Wormholes are a bit like leaky pipes in the sense that not everything is fitting together. There are many ideas that surround wormholes and they're not all compatible with each other. The question is, we probably need to modify some ideas or we need to, maybe they have some subtleties that we haven't understood.

Maldacena disclosed he is actively working to resolve fundamental incompatibilities in how wormholes are treated across different theoretical frameworks. Wormholes are essential for deriving the island formula and black hole entropy calculations, yet they also suggest constants of nature should be averaged over, conflicting with string theory models where constants are fixed. This represents one of the hottest unsolved problems in quantum gravity.

Read this moment → Check original at 38:55 ↗

Science

Maldacena Questions Whether Dark Energy Below Negative One Would Survive Scrutiny

at 58:20 · Attributed speaker claim

Some of the DESY fits have suggested that the value of the dark energy could be, of the equation of state could go below -1. That would be a more severe blow to our understanding of physics. I suspect that that probably will not be true. There are deep principles, the principles of no negative null energy. So these principles that enforce causality, that enforce traversability or large or traversability of wormholes. I find them very sacred. If it was true that they're violated, it would be super interesting and it would be the biggest news in the last 100 years.

Maldacena expressed skepticism about recent DESI cosmology results suggesting the dark energy equation of state parameter w might be less than -1. Such a finding would violate fundamental principles of causality and energy conditions that Maldacena considers sacred. He predicted the result will not hold up under further analysis, but acknowledged that if confirmed, it would represent the biggest physics discovery in a century.

Read this moment → Check original at 58:20 ↗

Science

Leading Physicist Admits He Once Told Students Their Great Ideas Were Wrong

at 1:11:50 · Attributed speaker claim

Many times I've told my students that what they said were wrong and they ended up being great ideas. A person called Eitor Leikowicz came with an interesting generalization of this formula for the Ryu and Takayanagi that we were talking about. And I said, well, I thought it was probably wrong. And not justified. But in the end it was correct. Unfortunately he didn't publish it. The other people published it. So that was one of my failures as an advisor.

Juan Maldacena revealed that one of his PhD students proposed a major generalization of the Ryu-Takayanagi formula for black hole entropy, which Maldacena initially rejected as incorrect. The idea turned out to be valid but the student never published, and others later claimed credit. Maldacena described this as one of his failures as an advisor, offering a rare glimpse into how breakthrough physics can be dismissed even by top experts.

Read this moment → Check original at 1:11:50 ↗

Science

Maldacena Claims Observers Are Required in Quantum Gravity Theory

at 1:20:55 · Attributed speaker claim

There is no view from nowhere in quantum gravity. You require an observer. When you consider a slightly more complicated discussion where you include an observer that is moving in this space, so you don't just do the empty space, but you do the space with the observer, then the entropy becomes positive. Putting an observer, a real observer that is there in the system, solves this problem with the imaginary numbers that were appearing.

Juan Maldacena, author of the most-cited paper in theoretical physics, argues that quantum gravity cannot be formulated from a perspective outside the system. In perturbative quantum gravity calculations for de Sitter space, certain entropy quantities yield imaginary or negative values unless a physical observer is included in the equations. This suggests that measurement and observation are fundamentally embedded in the structure of spacetime at the quantum level, not external to it.

Read this moment → Check original at 1:20:55 ↗