Emergent Semiclassical Time in Quantum Gravity. Full Geometrodynamics and Minisuperspace Examples

Abstract

I apply the preceding paper's semiclassical treatment to geometrodynamics. The analogy between the two papers is quite useful at the level of the quadratic constraints, while I document the differences between the two due to the underlying differences in their linear constraints. I provide a specific minisuperspace example for my emergent semiclassical time scheme and compare it with the hidden York time scheme. Overall, interesting connections are shown between Newtonian, Leibniz--Mach--Barbour, WKB and cosmic times, while the Euler and York hidden dilational times are argued to be somewhat different from these.