Recently it has been shown that quantum fields can be regular on the inner, Cauchy horizon of a rotating BTZ black hole, which appears to indicate a failure of strong cosmic censorship. We argue that, instead, what these results imply is that the inner horizon remains non-singular when leading-order backreaction of the quantum fields is computed, but, after next-order backreaction … Read More

Abstract: I will discuss several models of evaporating AdS black holes. In all models, it is possible to use the holographic entanglement entropy prescription to compute the dependence of entropy on time. In two cases, the dynamics are unitary, and a semiclassical calculation is sufficient to show this. In the third toy model, the dynamics are manifestly non-unitary; in this … Read More

Abstract: A fundamental issue in the AdS/CFT correspondence is the wormhole growth paradox. Susskind’s conjectured resolution of the paradox was to equate the volume of the wormhole with the circuit complexity of its dual quantum state in the CFT. We study the ramifications of this conjecture from a complexity-theoretic perspective. Specifically we give evidence for the existence of computationally pseudorandom … Read More

We discuss aspects of magnetically charged black holes in the Standard Model. For black holes smaller than a tennis ball, the electroweak symmetry is restored in the near horizon region. The lowest Landau level for the charged fermions leads to a large number effectively light degrees of freedom, which greatly enhance the effects of Hawking radiation. They are interesting primordial … Read More

Abstract: We argue that given holographic CFT1 in some state with a dual spacetime geometry M, and given some other holographic CFT2, we can find states of CFT2 whose dual geometries closely approximate arbitrarily large causal patches of M, provided that CFT1 and CFT2 can be non-trivially coupled at an interface. Our CFT2 states are “dressed up as” states of … Read More

I will explore the idea that certain theories of gravity in Anti-de Sitter space are dual to an average over an ensemble of quantum theories, rather than to a specific quantum theory. I will describe an average over Narain’s family of two-dimensional conformal field theories which describe free bosons on a torus, and compute the partition function using the Siegel-Weil … Read More

Entropy and energy are found to be closely tied on our quest for quantum gravity. We point out an interesting connection between the recently proposed outer entropy, a coarse-grained entropy defined for a compact spacetime domain motivated by the holographic duality, and the Bartnik-Bray quasilocal mass long known in the mathematics community. In both scenarios, one seeks an optimal spacetime … Read More

For the first time, a gravitational calculation was recently shown to yield the Page curve for the entropy of Hawking radiation, consistent with unitary evolution. However, the calculation takes as essential input Hawking’s result that the radiation entropy becomes large at late times. We call this apparent contradiction the state paradox. We exhibit its manifestations in standard and doubly-holographic settings, … Read More

The QES prescription is a rule for computing entanglement entropies in quantum gravity that has become one of the central tools in holography. In particular, it was crucial to recent progress on understanding the Page curve for evaporating black holes. However, as I will show, a naïve application of the QES prescription for arbitrary bulk states is paradoxical, even at … Read More

Abstract: I will describe a bulk procedure that generates a sequence of coarse-grained holographic states by disentangling degrees of freedom at short distances. This is manifested as a flow in the bulk which approaches quantum extremal surfaces. This procedure generalizes an earlier classical construction by including bulk quantum corrections. ========= You will have to login into your Zoom account in … Read More