Relational Time as a Stochastic Variable in ADM Gravity
arXiv:2502.05829 · doi:10.1002/prop.70024
Abstract
The problem of time in canonical quantum gravity remains one of the most significant challenges, primarily due to the "frozen" formalism emerging from the Wheeler-DeWitt equation. Within the ADM formalism, we introduce a novel approach in which a scalar field is treated as a stochastic clock. By imposing a divergence-free condition on the scalar momentum, we integrate out quantum gravitational fluctuations and derive an effective noise term via the Hubbard-Stratonovich transformation. This noise drives dynamic adjustments in spacetime foliations, enabling a Schrodinger-like evolution that preserves diffeomorphism invariance and, upon noise averaging, maintains unitary evolution. Interestingly, by introducing stochastic variations in the foliations, the quantum indeterminacy of the clock recasts time as a diffusive process emerging from quantum fluctuations, where correlations between matter and geometry replace an absolute time parameter. This provides a potential pathway for understanding quantum time evolution while maintaining background independence in canonical quantum gravity.
20 pages, 2 figure