Modular Fluctuations in Cosmology

Fuente: arXiv
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Main Authors: Aalsma, Lars, Bak, Sang-Eon
Format: Preprint
Published: 2025
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author Aalsma, Lars
Bak, Sang-Eon
author_facet Aalsma, Lars
Bak, Sang-Eon
contents Verlinde and Zurek (VZ) have proposed that quantum gravity fluctuations in causal diamonds lead to observable effects. In particular, they argued that in quantum gravity causal diamonds have an uncertainty in their size that scales as $δL \sim \sqrt{\ell_p L}$, i.e. fluctuations are enhanced from the Planck scale. In this work, we explore the origin of the VZ scaling by studying scalar perturbations in inflationary cosmology. We reinterpret these cosmological perturbations as fluctuations of the modular Hamiltonian associated with a causal diamond, establishing a connection between modular fluctuations and observable primordial perturbations. Independent of assumptions about the modular Hamiltonian or the background spacetime, our results show that -- whenever an (effective) spherically symmetric perturbation is quantized -- it can lead to the VZ scaling. However, whether such a mode exists in the vacuum of any theory of quantum gravity remains an open question.
format Preprint
id arxiv_https___arxiv_org_abs_2503_04886
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Modular Fluctuations in Cosmology
Aalsma, Lars
Bak, Sang-Eon
High Energy Physics - Theory
General Relativity and Quantum Cosmology
High Energy Physics - Phenomenology
Verlinde and Zurek (VZ) have proposed that quantum gravity fluctuations in causal diamonds lead to observable effects. In particular, they argued that in quantum gravity causal diamonds have an uncertainty in their size that scales as $δL \sim \sqrt{\ell_p L}$, i.e. fluctuations are enhanced from the Planck scale. In this work, we explore the origin of the VZ scaling by studying scalar perturbations in inflationary cosmology. We reinterpret these cosmological perturbations as fluctuations of the modular Hamiltonian associated with a causal diamond, establishing a connection between modular fluctuations and observable primordial perturbations. Independent of assumptions about the modular Hamiltonian or the background spacetime, our results show that -- whenever an (effective) spherically symmetric perturbation is quantized -- it can lead to the VZ scaling. However, whether such a mode exists in the vacuum of any theory of quantum gravity remains an open question.
title Modular Fluctuations in Cosmology
topic High Energy Physics - Theory
General Relativity and Quantum Cosmology
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2503.04886