Instant Folded Strings, Dark Energy and a Cyclic Bouncing Universe

Fuente: arXiv
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Main Authors: Itzhaki, Nissan, Peleg, Uri, Steinhardt, Paul J.
Format: Preprint
Published: 2025
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author Itzhaki, Nissan
Peleg, Uri
Steinhardt, Paul J.
author_facet Itzhaki, Nissan
Peleg, Uri
Steinhardt, Paul J.
contents We present a wholly self-consistent, complete cyclic bouncing cosmology based on components drawn from string theory and constructed in a way that is under perturbative control throughout (e.g., with temperature much less than the string scale and string coupling $g_s \ll 1$ at all times). The cyclic evolution is governed by standard dilaton-gravity in $(3+1)$-dimensions with a perturbatively generated potential and a coupling between the dilaton and a second field that becomes massless at $ϕ= ϕ_{ESP}$, resulting in an enhanced symmetry point (ESP) that prevents the dilaton from running all the way to zero coupling. A central role is played by instant folded strings (IFSs) - fundamental strings with the unusual property of being much lighter than the string mass while extending far beyond the string length, and violating the Null Energy Condition (NEC). IFSs are produced classically when the string coupling grows with time, which occurs at two critical points in each cycle. In turn, they fulfill a dual function: enabling cosmological bounces and initiating transient epochs of dark-energy domination that naturally transition into slow contraction. The resulting cosmology eliminates the cosmic singularity and multiverse problems of big bang inflationary models and robustly predicts time-varying IFS-induced dark energy and the absence of primordial B-mode polarization in the cosmic microwave background.
format Preprint
id arxiv_https___arxiv_org_abs_2508_09745
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Instant Folded Strings, Dark Energy and a Cyclic Bouncing Universe
Itzhaki, Nissan
Peleg, Uri
Steinhardt, Paul J.
General Relativity and Quantum Cosmology
Cosmology and Nongalactic Astrophysics
High Energy Physics - Theory
We present a wholly self-consistent, complete cyclic bouncing cosmology based on components drawn from string theory and constructed in a way that is under perturbative control throughout (e.g., with temperature much less than the string scale and string coupling $g_s \ll 1$ at all times). The cyclic evolution is governed by standard dilaton-gravity in $(3+1)$-dimensions with a perturbatively generated potential and a coupling between the dilaton and a second field that becomes massless at $ϕ= ϕ_{ESP}$, resulting in an enhanced symmetry point (ESP) that prevents the dilaton from running all the way to zero coupling. A central role is played by instant folded strings (IFSs) - fundamental strings with the unusual property of being much lighter than the string mass while extending far beyond the string length, and violating the Null Energy Condition (NEC). IFSs are produced classically when the string coupling grows with time, which occurs at two critical points in each cycle. In turn, they fulfill a dual function: enabling cosmological bounces and initiating transient epochs of dark-energy domination that naturally transition into slow contraction. The resulting cosmology eliminates the cosmic singularity and multiverse problems of big bang inflationary models and robustly predicts time-varying IFS-induced dark energy and the absence of primordial B-mode polarization in the cosmic microwave background.
title Instant Folded Strings, Dark Energy and a Cyclic Bouncing Universe
topic General Relativity and Quantum Cosmology
Cosmology and Nongalactic Astrophysics
High Energy Physics - Theory
url https://arxiv.org/abs/2508.09745