Do atemporal theories of quantum gravity presuppose the notion of time? A critical analysis of Henrik Zinkernagel's arguments against quantum fundamentalism

Abstract

This thesis is dedicated to examining three arguments against quantum fundamentalism (QF), the view that everything is fundamentally of a quantum nature and can be described exclusively in quantum theoretical terms. All three arguments rely on the timelessness of leading approaches to quantum gravity (QG), the successor theory of our two best physical theories, general relativity and quantum field theory. According to the first argument, by Svend Rugh and Henrik Zinkernagel, QF cannot explain how time emerges diachronically from a timeless quantum structure described by QG. I argue with Daniele Oriti that such a diachronic emergence is not strictly necessary, so the argument fails. According to the second argument, by Zinkernagel, timeless QG cannot be more fundamental than GR because its field of application is defined by a classical relativistic time concept. I propose two readings of the argument: the first fails, while the second is successful but requires accepting a broad set of epistemological commitments. The third argument adds that timeless QG does not imply that time is not fundamental, but instead that physics cannot describe it. I conclude that the last two arguments refute an epistemological but not ontological version of QF.