Evolutionary Reformulation of Quantum Gravity

Abstract

We present a critical analysis of the Canonical approach to quantum gravity, which relies on the ambiguity of implementing a space-time slicing on the quantum level. We emphasize that such a splitting procedure is consistent only if a real matter fluid is involved in the dynamics.

Definition of a time variable with entropy of a perfect fluid in canonical quantum gravity

“…Different approaches have been developed, trying to recover a meaningful definition of time [1,[9][10][11][12]: a possible solution is to couple matter to the gravitational field. It can be shown that there is a strong duality between matter and reference frames ( [11,13,14]; see [15] and [16] for a clear example), as one can intuitively use fluid particles to label spacetime points, while general covariance can be recovered simply re-parametrizing the coordinate dependence.…”