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Bubble Universes With Different Gravitational Constants

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arxiv 1504.05788 v1 pith:DQKE7JWP submitted 2015-04-21 gr-qc astro-ph.COhep-th

Bubble Universes With Different Gravitational Constants

classification gr-qc astro-ph.COhep-th
keywords bubbleconstantsdifferentgravitationaluniversecurvatureeffectprimordial
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
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We argue a scenario motivated by the context of string landscape, where our universe is produced by a new vacuum bubble embedded in an old bubble and these bubble universes have not only different cosmological constants, but also their own different gravitational constants. We study these effects on the primordial curvature perturbations. In order to construct a model of varying gravitational constants, we use the Jordan-Brans-Dicke (JBD) theory where different expectation values of scalar fields produce difference of constants. In this system, we investigate the nucleation of bubble universe and dynamics of the wall separating two spacetimes. In particular, the primordial curvature perturbation on superhorizon scales can be affected by the wall trajectory as the boundary effect. We show the effect of gravitational constant in the exterior bubble universe can provide a peak like a bump feature at a large scale in a modulation of power spectrum.

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Cited by 1 Pith paper

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. Primordial Black Hole Formation in $f(R)=R+\alpha R^2$ Gravity: Perturbative and Non-Perturbative Analysis

    gr-qc 2026-01 reject novelty 4.0

    The paper claims a positive R² curvature term accelerates dust collapse and lowers the primordial-black-hole formation threshold, but the quantitative shift and the derived bound on α are not actually computed.