Relational dynamics and Page-Wootters formalism in group field theory

Group field theory posits that spacetime is emergent and is hence defined without any background notion of space or time; dynamical questions are formulated in relational terms, in particular using (scalar) matter degrees of freedom as time. Unlike in canonical quantisation of gravitational systems,...

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Main Authors: Andrea Calcinari, Steffen Gielen
Format: Article
Language:English
Published: Verein zur Förderung des Open Access Publizierens in den Quantenwissenschaften 2025-01-01
Series:Quantum
Online Access:https://quantum-journal.org/papers/q-2025-01-27-1610/pdf/
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author Andrea Calcinari
Steffen Gielen
author_facet Andrea Calcinari
Steffen Gielen
author_sort Andrea Calcinari
collection DOAJ
description Group field theory posits that spacetime is emergent and is hence defined without any background notion of space or time; dynamical questions are formulated in relational terms, in particular using (scalar) matter degrees of freedom as time. Unlike in canonical quantisation of gravitational systems, there is no obvious notion of coordinate transformations or constraints, and established quantisation methods cannot be directly applied. As a result, different canonical formalisms for group field theory have been discussed in the literature. We address these issues using a parametrised version of group field theory, in which all (geometry and matter) degrees of freedom evolve in a fiducial parameter. There is a constraint associated to the freedom of reparametrisation and the Dirac quantisation programme can be implemented. Using the "trinity of relational dynamics", we show that the resulting "clock-neutral" theory is entirely equivalent to a deparametrised canonical group field theory, interpreted in terms of the Page-Wootters formalism. Our results not only show that the deparametrised quantisation is fully covariant and can be seen as encoding the dynamics of joint quantum matter and geometry degrees of freedom, they also appear to be the first application of the Page-Wootters formalism directly to non-perturbative quantum gravity. We show extensions to a setting in which many independent gauge symmetries are introduced, which connects to the "multi-fingered time" idea in quantum gravity and provides a somewhat novel extension of the Page-Wootters formalism.
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spelling doaj-art-46fbdf35b19948ecb2875a2ad30f3f812025-01-27T15:13:17ZengVerein zur Förderung des Open Access Publizierens in den QuantenwissenschaftenQuantum2521-327X2025-01-019161010.22331/q-2025-01-27-161010.22331/q-2025-01-27-1610Relational dynamics and Page-Wootters formalism in group field theoryAndrea CalcinariSteffen GielenGroup field theory posits that spacetime is emergent and is hence defined without any background notion of space or time; dynamical questions are formulated in relational terms, in particular using (scalar) matter degrees of freedom as time. Unlike in canonical quantisation of gravitational systems, there is no obvious notion of coordinate transformations or constraints, and established quantisation methods cannot be directly applied. As a result, different canonical formalisms for group field theory have been discussed in the literature. We address these issues using a parametrised version of group field theory, in which all (geometry and matter) degrees of freedom evolve in a fiducial parameter. There is a constraint associated to the freedom of reparametrisation and the Dirac quantisation programme can be implemented. Using the "trinity of relational dynamics", we show that the resulting "clock-neutral" theory is entirely equivalent to a deparametrised canonical group field theory, interpreted in terms of the Page-Wootters formalism. Our results not only show that the deparametrised quantisation is fully covariant and can be seen as encoding the dynamics of joint quantum matter and geometry degrees of freedom, they also appear to be the first application of the Page-Wootters formalism directly to non-perturbative quantum gravity. We show extensions to a setting in which many independent gauge symmetries are introduced, which connects to the "multi-fingered time" idea in quantum gravity and provides a somewhat novel extension of the Page-Wootters formalism.https://quantum-journal.org/papers/q-2025-01-27-1610/pdf/
spellingShingle Andrea Calcinari
Steffen Gielen
Relational dynamics and Page-Wootters formalism in group field theory
Quantum
title Relational dynamics and Page-Wootters formalism in group field theory
title_full Relational dynamics and Page-Wootters formalism in group field theory
title_fullStr Relational dynamics and Page-Wootters formalism in group field theory
title_full_unstemmed Relational dynamics and Page-Wootters formalism in group field theory
title_short Relational dynamics and Page-Wootters formalism in group field theory
title_sort relational dynamics and page wootters formalism in group field theory
url https://quantum-journal.org/papers/q-2025-01-27-1610/pdf/
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