Big bang stability and isotropisation for the Einstein-scalar field equations in the ekpyrotic regime

Fuente: arXiv
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Autori principali: Beyer, Florian, Garfinkle, David, Isenberg, James, Oliynyk, Todd A.
Natura: Preprint
Pubblicazione: 2026
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author Beyer, Florian
Garfinkle, David
Isenberg, James
Oliynyk, Todd A.
author_facet Beyer, Florian
Garfinkle, David
Isenberg, James
Oliynyk, Todd A.
contents It has been shown that, in spacetime dimensions $n\geq 3$, that the Kasner-scalar field solutions to the Einstein-scalar fields equations with potential $V_0 e^{-s ϕ}$, where $s<s_c=\sqrt{\frac{8(n-1)}{n-2}}$ and $V_0\in \mathbb{R}$, are nonlinearly stable to the past and terminate at a quiescent big bang singularity over the full range of sub-critical Kasner exponents. In particular, the spatially homogeneous and isotropic solutions, the Friedman-Lemaitre-Robertson-Walker (FLRW) spacetimes, to the Einstein-scalar field equations are stable in this sense for $s<s_c$ and $V_0\in\mathbb{R}$. While perturbations of the sub-critical Kasner-scalar field family of solutions, including the FLRW solutions, are asymptotically velocity term dominated (AVTD) near the big bang, they do not in general isotropise near the big bang singularity. Rather, they remain highly anisotropic, even for small perturbations of the isotropic FLRW solutions. In this article, we establish the stability of FLRW solutions to the Einstein-scalar field equations for the potential parameter values $s>s_c$ and $V_0<0$. Such scalar field potentials are known in the literature as \textit{ekpyrotic}. In particular, we prove that the FLRW solutions to the Einstein-scalar field equations are nonlinearly stable to the past and terminate at a quiescent, crushing AVTD big bang singularity. A distinguishing property of these perturbed spacetimes is that they isotropise towards the big bang.
format Preprint
id arxiv_https___arxiv_org_abs_2604_00297
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Big bang stability and isotropisation for the Einstein-scalar field equations in the ekpyrotic regime
Beyer, Florian
Garfinkle, David
Isenberg, James
Oliynyk, Todd A.
General Relativity and Quantum Cosmology
Analysis of PDEs
It has been shown that, in spacetime dimensions $n\geq 3$, that the Kasner-scalar field solutions to the Einstein-scalar fields equations with potential $V_0 e^{-s ϕ}$, where $s<s_c=\sqrt{\frac{8(n-1)}{n-2}}$ and $V_0\in \mathbb{R}$, are nonlinearly stable to the past and terminate at a quiescent big bang singularity over the full range of sub-critical Kasner exponents. In particular, the spatially homogeneous and isotropic solutions, the Friedman-Lemaitre-Robertson-Walker (FLRW) spacetimes, to the Einstein-scalar field equations are stable in this sense for $s<s_c$ and $V_0\in\mathbb{R}$. While perturbations of the sub-critical Kasner-scalar field family of solutions, including the FLRW solutions, are asymptotically velocity term dominated (AVTD) near the big bang, they do not in general isotropise near the big bang singularity. Rather, they remain highly anisotropic, even for small perturbations of the isotropic FLRW solutions. In this article, we establish the stability of FLRW solutions to the Einstein-scalar field equations for the potential parameter values $s>s_c$ and $V_0<0$. Such scalar field potentials are known in the literature as \textit{ekpyrotic}. In particular, we prove that the FLRW solutions to the Einstein-scalar field equations are nonlinearly stable to the past and terminate at a quiescent, crushing AVTD big bang singularity. A distinguishing property of these perturbed spacetimes is that they isotropise towards the big bang.
title Big bang stability and isotropisation for the Einstein-scalar field equations in the ekpyrotic regime
topic General Relativity and Quantum Cosmology
Analysis of PDEs
url https://arxiv.org/abs/2604.00297