Explanations of and in Time

Various approaches to quantum gravity render spacetime an emergent phenomenon, with the existence and properties of spacetime depending in some way on a non-spatiotemporal underlying reality. This chapter investigates the mode of dependence that is involved. I explain and defend my recent proposal to classify different kinds of dependencies in terms of the principles mediating the dependency, and apply this proposal to the emergence of spacetime in quantum gravity. While philosophers have typically interpreted spacetime emergence as involving something like metaphysical grounding, I show how premises that are widely endorsed lead us to classify the emergence of spacetime in loop quantum gravity as causal in nature. I recommend spacetime functionalism as a resolution of this puzzle that vindicates the natural view of spacetime emergence as non-causal. I then explore a different approach to spacetime emergence in quantum gravity, the ‘many-instant landscape’ scenario described by Henrique Gomes, and show how it fits into the chapter’s proposed framework for spacetime emergence.