Shreya Vardhan

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Black holes present fundamental puzzles about how to combine classical gravity with quantum mechanics. Even with much recent progress on the black hole information paradox, a central question remains unresolved: why does classical gravity break down in setups like evaporating black holes, when it does not break down in our everyday experience? In this talk, I will address this question using ideas from quantum information, quantum complexity, and random matrix theory. Through holographic duality, a black hole is equivalent to a highly chaotic quantum many-body system. I will use this equivalence to probe the breakdown of semiclassical gravity in two ways. First, by using a random unitary model for the black hole, I will argue that semiclassical gravity is valid in a regime of bounded computational complexity, and breaks down due to high complexity. Second, in the model of 2D JT gravity, I will show how new mechanisms can cause a breakdown of semiclassical gravity in a surprising regime. This phenomenon arises from certain nonperturbative effects in random matrix theory, and can thus be understood from subtle but universal features of quantum chaos.

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Caltech
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Contact: Alexander Altland