Extends quantum reference frames to quantum reference fields in linearized quantum gravity and derives unitary maps implementing relational gauge-invariant observables between quantum perspectives.
Dust as a Standard of Space and Time in Canonical Quantum Gravity
8 Pith papers cite this work. Polarity classification is still indexing.
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abstract
The coupling of the metric to an incoherent dust introduces into spacetime a privileged dynamical reference frame and time foliation. The comoving coordinates of the dust particles and the proper time along the dust worldlines become canonical coordinates in the phase space of the system. The Hamiltonian constraint can be resolved with respect to the momentum that is canonically conjugate to the dust time. Imposition of the resolved constraint as an operator restriction on the quantum states yields a functional Schr\"{o}dinger equation. The ensuing Hamiltonian density has an extraordinary feature: it depends only on the geometric variables, not on the dust coordinates or time. This has three important consequences. First, the functional Schr\"{o}dinger equation can be solved by separating the dust time from the geometric variables. Second, the Hamiltonian densities strongly commute and therefore can be simultaneously defined by spectral analysis. Third, the standard constraint system of vacuum gravity is cast into a form in which it generates a true Lie algebra. The particles of dust introduce into space a privileged system of coordinates that allows the supermomentum constraint to be solved explicitly. The Schr\"{o}dinger equation yields a conserved inner product that can be written in terms of either the instantaneous state functionals or the solutions of constraints. Examples of gravitational observables are given, though neither the intrinsic metric nor the extrinsic curvature are observables. Disregarding factor--ordering difficulties, the introduction of dust provides a satisfactory phenomenological approach to the problem of time in canonical quantum gravity.
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Backreactions from inhomogeneous modes on homogeneous geometry are significant and sensitive to Fock representation in this deparametrized second-order adiabatic calculation.
Constructs a phase space for gravitational degrees of freedom on null ray segments with commuting localized observables via edge modes and dressing time, then introduces an effective classical theory with Virasoro deformations to capture diffeomorphism anomalies and distinguish gauge, physical, and
Perturbative dressing of local operators in QED and GR induces kinematic singularities and is mathematically equivalent to dynamical temporal gauge fixing.
In a path-integral model of timeless quantum systems, time evolution arises when a clock is prepared in a semiclassical state, showing that the cosine problem in quantum gravity follows from time-reversal invariance and neutral boundary conditions.
Algebraic equations from Hamiltonian constraints on vacuum spherically symmetric metrics describe non-homogeneous dust collapse and bounce, applied to quantum-inspired models to recover or find new bounce results.
A Hamiltonian is constructed that renders a deformed Poisson bracket spacetime theory canonical and covariant, enabling consistent coupling to scalar matter and dust.
Tachyon EFT near its minimum is mapped via collective field theory to a coherent-state subsector of Klein-Gordon theory, indicating quantum-level equivalence between open and closed string descriptions of unstable D-brane decay.
citing papers explorer
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Quantum Reference Fields Transformations in Linearized Quantum Gravity
Extends quantum reference frames to quantum reference fields in linearized quantum gravity and derives unitary maps implementing relational gauge-invariant observables between quantum perspectives.
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Quantum Cosmological Backreactions III: Deparametrised Quantum Cosmological Perturbation Theory
Backreactions from inhomogeneous modes on homogeneous geometry are significant and sensitive to Fock representation in this deparametrized second-order adiabatic calculation.
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Localization and anomalous reference frames in gravity
Constructs a phase space for gravitational degrees of freedom on null ray segments with commuting localized observables via edge modes and dressing time, then introduces an effective classical theory with Virasoro deformations to capture diffeomorphism anomalies and distinguish gauge, physical, and
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On Perturbatively Dressed Observables
Perturbative dressing of local operators in QED and GR induces kinematic singularities and is mathematically equivalent to dynamical temporal gauge fixing.
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The problem of time: a path integral view
In a path-integral model of timeless quantum systems, time evolution arises when a clock is prepared in a semiclassical state, showing that the cosine problem in quantum gravity follows from time-reversal invariance and neutral boundary conditions.
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Dust collapse and bounce in spherically symmetric quantum-inspired gravity models
Algebraic equations from Hamiltonian constraints on vacuum spherically symmetric metrics describe non-homogeneous dust collapse and bounce, applied to quantum-inspired models to recover or find new bounce results.
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Canonical form of a deformed Poisson bracket spacetime
A Hamiltonian is constructed that renders a deformed Poisson bracket spacetime theory canonical and covariant, enabling consistent coupling to scalar matter and dust.
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Mapping Tachyon effective field theory to a subsector of Klein-Gordon theory
Tachyon EFT near its minimum is mapped via collective field theory to a coherent-state subsector of Klein-Gordon theory, indicating quantum-level equivalence between open and closed string descriptions of unstable D-brane decay.