An operator-algebraic quantization of the characteristic initial-value problem yields a candidate on-shell algebra for a gravitational subregion bounded by two null hypersurfaces.
Leigh.Quantum Null Geometry and Gravity.July15,2024.arXiv: 2407.11132 [gr-qc, physics:hep-th, physics:quant-ph]
6 Pith papers cite this work. Polarity classification is still indexing.
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abstract
In this work, we demonstrate that quantizing gravity on a null hypersurface leads to the emergence of a CFT associated with each null ray. This result stems from the ultralocal nature of null physics and is derived through a canonical analysis of the Raychaudhuri equation, interpreted as a constraint generating null time reparametrizations. The CFT exhibits a non-zero central charge, providing a mechanism for the quantum emergence of time in gravitational systems and an associated choice of vacuum state. Our analysis reveals that the central charge quantifies the degrees of freedom along each null ray. Throughout our investigation, the area element of a cut plays a crucial role, necessitating its treatment as a quantum operator due to its dynamic nature in phase space or because of quantum backreaction. Furthermore, we show that the total central charge diverges in a perturbative analysis due to the infinite number of null generators. This divergence is resolved if there is a discrete spectrum for the area form operator. We introduce the concept of `embadons' to denote these localized geometric units of area, the fundamental building blocks of geometry at a mesoscopic quantum gravity scale.
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Derives a thermal fluctuation formula for causal-diamond boundary area with a linear term of Verlinde-Zurek scaling interpreted as statistical evidence for discrete quanta of geometry.
Authors define proper observables and Goldstone probes on the Ashtekar-Streubel phase space at null infinity, showing supertranslation charges act correctly on shear and deriving distributional Dirac brackets with non-local corrections.
The noise spectrum an interferometer would see from quantum spacetime jitter is computed for vacuum, thermal, squeezed, and scalar-backreaction states; all are Planck-suppressed.
Phase space of arbitrary null cut in Minkowski spacetime is symplectomorphic to infrared phase space of asymptotically flat gravity, mapping cut fluctuations to leading soft graviton mode and supertranslation Goldstone mode to cut size times null time offset.
The angle-averaged soft and Goldstone modes of 4D asymptotically flat gravity are symplectically identified with the radial-size and area-edge modes of a spherically symmetric Minkowski causal diamond.
citing papers explorer
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Quantization of Gravity on Null Hypersurfaces
An operator-algebraic quantization of the characteristic initial-value problem yields a candidate on-shell algebra for a gravitational subregion bounded by two null hypersurfaces.
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Quantum Geometry from Area Fluctuations
Derives a thermal fluctuation formula for causal-diamond boundary area with a linear term of Verlinde-Zurek scaling interpreted as statistical evidence for discrete quanta of geometry.
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An algebra of proper observables at null infinity: Dirac brackets, Memory and Goldstone probes
Authors define proper observables and Goldstone probes on the Ashtekar-Streubel phase space at null infinity, showing supertranslation charges act correctly on shear and deriving distributional Dirac brackets with non-local corrections.
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Geometric noise spectrum in interferometers
The noise spectrum an interferometer would see from quantum spacetime jitter is computed for vacuum, thermal, squeezed, and scalar-backreaction states; all are Planck-suppressed.
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Mapping the Infrared Phase Space of Gravity to Finite Subregions
Phase space of arbitrary null cut in Minkowski spacetime is symplectomorphic to infrared phase space of asymptotically flat gravity, mapping cut fluctuations to leading soft graviton mode and supertranslation Goldstone mode to cut size times null time offset.
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From Asymptotically Flat Gravity to Finite Causal Diamonds
The angle-averaged soft and Goldstone modes of 4D asymptotically flat gravity are symplectically identified with the radial-size and area-edge modes of a spherically symmetric Minkowski causal diamond.