Symmetry and Evolution in Quantum Gravity

  title={Symmetry and Evolution in Quantum Gravity},
  author={Sean B. Gryb and Karim Th{\'e}baault},
  journal={Foundations of Physics},
We propose an operator constraint equation for the wavefunction of the Universe that admits genuine evolution. While the corresponding classical theory is equivalent to the canonical decomposition of General Relativity, the quantum theory contains an evolution equation distinct from standard Wheeler–DeWitt cosmology. Furthermore, the local symmetry principle—and corresponding observables—of the theory have a direct interpretation in terms of a conventional gauge theory, where the gauge symmetry… 
Schrodinger Evolution for the Universe: Reparametrization
Starting from a generalized Hamilton-Jacobi formalism, we develop a new framework for constructing observables and their evolution in theories invariant under global time reparametrizations. Our
Bouncing unitary cosmology I. Mini-superspace general solution
We offer a new proposal for cosmic singularity resolution based upon a quantum cosmology with a unitary bounce. This proposal is illustrated via a novel quantization of a mini-superspace model in
Bouncing unitary cosmology II. Mini-superspace phenomenology
A companion paper provides a proposal for cosmic singularity resolution based upon general features of a bouncing unitary cosmological model in the mini-superspace approximation. This paper analyses
Lagrangian Description for Particle Interpretations of Quantum Mechanics: Single-Particle Case
A Lagrangian description is presented which can be used in conjunction with particle interpretations of quantum mechanics. A special example of such an interpretation is the well-known Bohm model.
Time Remains
On one popular view, the general covariance of gravity implies that change is relational in a strong sense, such that all it is for a physical degree of freedom to change is for it to vary with
Ju n 20 16 Ψ-Epistemic Quantum Cosmology ?
This paper provides a prospectus for a new way of thinking about the wavefunction of the universe: a Ψ-epistemic quantum cosmology. We present a proposal that, if successfully implemented, would
Regarding the ‘Hole Argument’ and the ‘Problem of Time’
Conceptual and formal inadequacies within the representative language of canonical gravity will be shown to be at the heart of both the canonical hole argument and the problem of time.
In Search of Time Lost: Asymmetry of Time and Irreversibility in Natural Processes
In this survey, we discuss and analyze foundational issues of the problem of time and its asymmetry from a unified standpoint. Our aim is to discuss concisely the current theories and underlying


Einstein gravity as a 3D conformally invariant theory
We give an alternative description of the physical content of general relativity that does not require a Lorentz invariant spacetime. Instead, we find that gravity admits a dual description in terms
Modern Canonical Quantum General Relativity
The open problem of constructing a consistent and experimentally tested quantum theory of the gravitational field has its place at the heart of fundamental physics. The main approaches can be roughly
The cosmological constant and general covariance
Quantum Theory of Gravity. I. The Canonical Theory
Following an historical introduction, the conventional canonical formulation of general relativity theory is presented. The canonical Lagrangian is expressed in terms of the extrinsic and intrinsic
How commutators of constraints reflect the spacetime structure
Unimodular theory of canonical quantum gravity.
  • Unruh
  • Physics
    Physical review. D, Particles and fields
  • 1989
Einstein's theory of gravity is reformulated so that the cosmological constant becomes an integration constant of the theory, rather than a coupling'' constant, and the key weakness'' of this formulation is that one must introduce a nondynamic background spacetime volume element.
Scale anomaly as the origin of time
We explore the problem of time in quantum gravity in a point-particle analogue model of scale-invariant gravity. If quantized after reduction to true degrees of freedom, it leads to a
General relativity: Dynamics without symmetry
The concept of conditional symmetry is introduced for a parametrized relativistic particle model and generalized to geometrodynamics. Its role in maintaining a one‐system interpretation of the
Introduction to Modern Canonical Quantum General Relativity
This is an introduction to the by now fifteen years old research field of canonical quantum general relativity, sometimes called "loop quantum gravity". The term "modern" in the title refers to the