Heidelberg 2022 – wissenschaftliches Programm

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AGPhil: Arbeitsgruppe Philosophie der Physik

AGPhil 11: Time and Temperature

AGPhil 11.2: Vortrag

Donnerstag, 24. März 2022, 16:45–17:15, AGPhil-H14

quantum gravity and time's arrow: why primitivism should leave the floor to (local) reductionism — •luca gasparinetti — Venice, Italy

According to some primitivist approaches about the debate on time's arrow, spacetime is characterized by an intrinsic and global anisotropy of time, i.e., the temporal direction is a primitive and no further analyzable feature of the universe's geometry (Earman 1974 and Maudlin 2007). However, in several approaches to quantum gravity (e.g., causal set theory, loop quantum gravity, string theory), most philosophers of physics, e.g., Huggett (2021), Le Bihan (2021), Wüthrich (2018), state that spacetime disappears at the fundamental level and emerges in some sense from a non-spatiotemporal structure. Thus, the following question arises: given the disappearance of spacetime from the fundamental structure, what are the consequences for the primitivist approach about time's arrow?

In this paper, I argue that primitivism about time's arrow is seriously challenged by what quantum gravity theorists state about spacetime. More specifically, since spacetime is emergent, the direction of time, if it exists, reduces on a more fundamental asymmetry. It follows that if time's arrow is not primitive, the primitivist approach is false in the context of a theory of quantum gravity. Hence, I conclude that quantum gravity theorists have at their disposal only (local) reductionism, i.e., time's arrow is an extrinsic and, local or global, anisotropy of time.