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arxiv: 2605.13777 · v2 · pith:JZBWYWLBnew · submitted 2026-05-13 · ✦ hep-th · gr-qc

Before the Bang: Wormholes at the Dawn of the Universe

Panos Betzios , Paul Ghiringhelli , Ioannis D. Gialamas , Olga Papadoulaki This is my paper

Pith reviewed 2026-05-20 20:18 UTC · model grok-4.3

classification ✦ hep-th gr-qc
keywords Euclidean wormholesno-boundary proposalquantum cosmologyinitial conditionsholographyearly universepath integral
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The pith

Euclidean wormholes enlarge the valid initial quantum states for the universe beyond the Hartle-Hawking no-boundary proposal.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper examines recent work on Euclidean wormholes as possible contributions to the universe's initial quantum state. It compares the wormhole approach to the Hartle-Hawking no-boundary proposal and notes both shared ideas and clear advances. Wormholes keep Euclidean saddles as useful for encoding properties of cosmological wavefunctions yet add more regular saddles suited to inflating universes. This helps address specific problems that arise in the no-boundary proposal. The main result is an expanded set of semiclassical initial conditions that is physically rich and consistent with holographic expectations from quantum gravity, making it useful for building early-universe models in complete theories.

Core claim

The principal achievement of the wormhole program is to enlarge the semiclassical initial-condition landscape in a way that is physically rich, conforms with holographic expectations and as such becomes increasingly relevant for early-universe model building within UV complete theories of quantum gravity. Wormholes retain the relevance of Euclidean saddles as encoders of properties of cosmological wavefunctions while broadening the class of regular saddles that are physically relevant for inflating universes and capable of resolving issues that plague the no-boundary proposal.

What carries the argument

Euclidean wormholes viewed as saddles that contribute to the path integral for the cosmological wavefunction and supply initial conditions for the universe.

If this is right

  • Wormholes broaden the class of regular saddles physically relevant for inflating universes.
  • They resolve issues that plague the no-boundary proposal.
  • They enlarge the semiclassical initial-condition landscape while conforming with holographic expectations.
  • The resulting states become relevant for early-universe model building in UV complete theories of quantum gravity.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Including wormhole contributions could shift the predicted likelihood of different amounts of early inflation compared with simpler proposals.
  • This framework may link to other quantum gravity methods that seek boundary-free descriptions of the universe's beginning.
  • Predictions from wormhole saddles could be checked against features in the cosmic microwave background for testable differences.

Load-bearing premise

The assumption that Euclidean wormholes form physically relevant saddles in the gravitational path integral that can resolve problems in the no-boundary proposal and supply valid starting points for inflating universes.

What would settle it

A explicit calculation of the wavefunction that includes wormhole saddles and shows that the resulting probabilities for inflating universes remain unchanged from the no-boundary case or conflict with known holographic constraints would undermine the claim.

Figures

Figures reproduced from arXiv: 2605.13777 by Ioannis D. Gialamas, Olga Papadoulaki, Panos Betzios, Paul Ghiringhelli.

Figure 1
Figure 1. Figure 1: Schematic illustration of the wineglass wormhole proposal for the birth of the [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Schematic illustration of the no-boundary proposal for the birth of the Universe. [PITH_FULL_IMAGE:figures/full_fig_p006_2.png] view at source ↗
read the original abstract

This essay discusses recent progress on Euclidean wormholes as candidate contributions to the Universe's initial quantum state. The comparison with the Hartle-Hawking no-boundary proposal highlights both a conceptual affinity and genuine advance: wormholes retain the relevance of Euclidean-saddles as encoders of properties of cosmological wavefunctions, while they broaden the class of regular saddles that are physically relevant for inflating universes and are capable of resolving issues that plague the no-boundary proposal. The principal achievement of the wormhole program is to enlarge the semiclassical initial-condition land-scape in a way that is physically rich, conforms with Holographic expectations and as such becomes increasingly relevant for early-universe model building, within UV complete theories of quantum gravity.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

1 major / 1 minor

Summary. The manuscript is an essay discussing recent progress on Euclidean wormholes as candidate contributions to the Universe's initial quantum state. It compares this approach to the Hartle-Hawking no-boundary proposal, highlighting conceptual affinity and an advance in broadening the class of regular saddles for inflating universes. The central claim is that the wormhole program enlarges the semiclassical initial-condition landscape in a physically rich way that conforms with holographic expectations and is relevant for early-universe model building in UV-complete quantum gravity theories.

Significance. If the central claims hold, the work would meaningfully expand the toolkit for constructing initial conditions in quantum cosmology by supplying additional Euclidean saddles that address limitations of the no-boundary proposal while aligning with holographic principles. This could influence model building in UV-complete theories, provided the physical relevance of the new saddles is established.

major comments (1)
  1. The central claim that Euclidean wormholes enlarge the semiclassical landscape by supplying physically relevant regular saddles that resolve no-boundary issues requires explicit support. The manuscript asserts this without providing derivations of the on-shell Euclidean action for wormhole geometries or checks for negative modes and stability, leaving the assertion that these saddles are dominant or physically preferred untested relative to the Hartle-Hawking saddle.
minor comments (1)
  1. The discussion of holographic conformity would benefit from explicit references to specific holographic models or dualities that the wormhole saddles are claimed to satisfy.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their careful reading and constructive comments on our essay. We respond to the major comment below.

read point-by-point responses

  1. Referee: The central claim that Euclidean wormholes enlarge the semiclassical landscape by supplying physically relevant regular saddles that resolve no-boundary issues requires explicit support. The manuscript asserts this without providing derivations of the on-shell Euclidean action for wormhole geometries or checks for negative modes and stability, leaving the assertion that these saddles are dominant or physically preferred untested relative to the Hartle-Hawking saddle.

    Authors: Our manuscript is an essay that surveys and contextualizes recent progress in the literature rather than a technical paper presenting new derivations. The on-shell Euclidean actions, negative-mode analyses, and stability checks for the relevant wormhole geometries are contained in the primary technical works we cite and discuss. The essay's purpose is to articulate how these established results collectively enlarge the semiclassical initial-condition landscape, retain the utility of Euclidean saddles, and align with holographic expectations while addressing certain limitations of the no-boundary proposal. We have revised the manuscript to include an explicit statement directing readers to the cited references for the technical details, thereby clarifying the evidential basis for the central claim without changing the essay's scope or format. revision: yes

Circularity Check

0 steps flagged

No circularity detected: conceptual essay summarizes progress without self-referential derivations or fitted predictions

full rationale

The manuscript is an essay-style discussion of Euclidean wormholes as contributions to the initial quantum state, comparing them to the Hartle-Hawking no-boundary proposal. It asserts conceptual affinity and an enlarged semiclassical landscape but supplies no equations, on-shell actions, stability analyses, or explicit predictions. No load-bearing steps reduce by construction to inputs, self-citations, or fitted quantities; claims rest on referenced prior work rather than internal redefinition. This is a normal non-finding for a review-style piece that does not attempt new derivations.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Based on abstract only; no specific free parameters, axioms, or invented entities can be identified. The discussion relies on standard concepts from quantum gravity and holography without introducing new postulates visible here.

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Reference graph

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