Breaking the Fabric: on AdS/CFT, Humeanism, and the Fate of Spacetime Inside Black Holes

This thesis discusses the philosophy behind models of quantum black holes in AdS/CFT. These models display a variety of foundationally and metaphysically interesting features, ranging from modifications to the semiclassical structure of spacetime, to wide ranging impacts on the metaphysics of laws of nature and the nature of spacetime emergence in Quantum Gravity. In particular, in this thesis I start by analyzing the resolution of the firewall paradox within these models, and argue that it depends on the introduction of certain non-local connections within the spacetime structure of General Relativity. I then discuss the relation between these constructions and the topic of causality conditions on evaporating black holes in General Relativity, and suggest that various theorems apparently contradicting these AdS/CFT models of black holes do not apply due to, also in this case, subtle modifications of the standard spacetime structure of General Relativity. On the metaphysics side, I use first of all these AdS/CFT models of quantum black hole to illustrate how Humeanism can be articulated in Quantum Gravity, suggesting in particular that spacetime relations should be substituted with amplitude relations to do so. I also argue that in AdS/CFT, black holes make standard approaches to spacetime emergence untenable. Indeed, my contention is that spacetime emergence does not make sense in these cases, and that spacetime itself does not exist. Rather, all we have at our disposal is the operational data associated to spacetime, and I argue that this is sufficient to avoid issues having to do with the disappearance of spacetime in Quantum Gravity. Finally, I argue that, given this understanding of how classical spacetime is represented in AdS/CFT, we should prefer a Humean metaphysics with regards to laws of nature, at least insofar as treating General Relativity as a scientific theory involving laws of nature is a desiderata.

Tesi e abstract solo in inglese