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A new duality relating density perturbations in expanding and contracting Friedmann cosmologies

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arxiv hep-th/0403026 v1 pith:MSRTVXJI submitted 2004-03-02 hep-th astro-phgr-qc

classification hep-thastro-phgr-qc
keywords epsilonscalarcontractingexpandingperturbationssamesolutionadmits
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abstract

For a 4-dimensional spatially-flat Friedmann-Robertson-Walker universe with a scalar field $\phi(x)$, potential $V(\phi)$ and constant equation of state $w=p/\rho$, we show that an expanding solution characterized by $\epsilon=3(1+w)/2$ produces the same scalar perturbations as a contracting solution with $\hat{\epsilon}=1/\epsilon$. The same symmetry applies to both the dominant and subdominant scalar perturbation modes. This result admits a simple physical interpretation and generalizes to $d$ spacetime dimensions if we define $\epsilon \equiv [(2d-5)+(d-1)w]/(d-2)$.

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Cited by 2 Pith papers

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

  1. Analytic Gravitational Wave Spectrum in Next-to-Minimal Bouncing Cosmology

    astro-ph.CO 2025-07 conditional novelty 6.0 of 10

    A five-phase bouncing cosmology yields a broken power-law gravitational wave spectrum whose amplitude bound automatically keeps the bounce energy below the Planck scale.

  2. Forecast Constraints on Bouncing Cosmology from High Frequency Gravitational Waves Using Superconducting LC Circuits and Resonant Cavities

    astro-ph.CO 2025-05 conditional novelty 4.0 of 10

    The paper forecasts that resonant-cavity and superconducting-circuit gravitational wave detectors could constrain the bounce energy scale of a generic bouncing cosmology far more tightly than astrophysical observatori...

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