Inflation and the principle of equivalence

A formal, mathematical statement of the principle of equivalence in general relativity is that one must always be able to find – at each location within a curved spacetime – the local free-falling frame against which one can measure the acceleration-induced time dilation and degree of curvature rela...

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Main Author: Melia Fulvio
Format: Article
Language:English
Published: De Gruyter 2024-11-01
Series:Open Physics
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Online Access:https://doi.org/10.1515/phys-2024-0077
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author Melia Fulvio
author_facet Melia Fulvio
author_sort Melia Fulvio
collection DOAJ
description A formal, mathematical statement of the principle of equivalence in general relativity is that one must always be able to find – at each location within a curved spacetime – the local free-falling frame against which one can measure the acceleration-induced time dilation and degree of curvature relative to flat spacetime. In this article, we use this theorem to prove that a de Sitter expansion, required during cosmic inflation, does not satisfy this condition and is therefore inconsistent with the PoE. To emphasize the importance – and reality – of this outcome, we contrast it with the analogous derivation for the Schwarzschild metric, which instead satisfies this requirement completely. We point out that this failure by de Sitter results from its incorrect handling of the Friedmann–Lemaître–Robertson–Walker (FLRW) lapse function, gtt{g}_{{\rm{tt}}}. Our conclusion calls into question whether a period of inflated expansion could have even been possible in the context of FLRW cosmologies, and is noteworthy in light of recent, high-precision measurements showing that inflation could not have solved the temperature horizon problem while simultaneously producing the observed primordial power spectrum.
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spelling doaj-art-4617fb0d21f24aac8dfdbad58d40fdbd2024-12-02T12:05:11ZengDe GruyterOpen Physics2391-54712024-11-012213475610.1515/phys-2024-0077Inflation and the principle of equivalenceMelia Fulvio0Department of Physics, The Applied Math Program and Department of Astronomy, The University of Arizona, AZ 85721, United States of AmericaA formal, mathematical statement of the principle of equivalence in general relativity is that one must always be able to find – at each location within a curved spacetime – the local free-falling frame against which one can measure the acceleration-induced time dilation and degree of curvature relative to flat spacetime. In this article, we use this theorem to prove that a de Sitter expansion, required during cosmic inflation, does not satisfy this condition and is therefore inconsistent with the PoE. To emphasize the importance – and reality – of this outcome, we contrast it with the analogous derivation for the Schwarzschild metric, which instead satisfies this requirement completely. We point out that this failure by de Sitter results from its incorrect handling of the Friedmann–Lemaître–Robertson–Walker (FLRW) lapse function, gtt{g}_{{\rm{tt}}}. Our conclusion calls into question whether a period of inflated expansion could have even been possible in the context of FLRW cosmologies, and is noteworthy in light of recent, high-precision measurements showing that inflation could not have solved the temperature horizon problem while simultaneously producing the observed primordial power spectrum.https://doi.org/10.1515/phys-2024-0077classical theories of gravitycosmological theoryearly universeinflationdark energy
spellingShingle Melia Fulvio
Inflation and the principle of equivalence
Open Physics
classical theories of gravity
cosmological theory
early universe
inflation
dark energy
title Inflation and the principle of equivalence
title_full Inflation and the principle of equivalence
title_fullStr Inflation and the principle of equivalence
title_full_unstemmed Inflation and the principle of equivalence
title_short Inflation and the principle of equivalence
title_sort inflation and the principle of equivalence
topic classical theories of gravity
cosmological theory
early universe
inflation
dark energy
url https://doi.org/10.1515/phys-2024-0077
work_keys_str_mv AT meliafulvio inflationandtheprincipleofequivalence