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arxiv: 0809.2022 · v1 · submitted 2008-09-11 · 🌀 gr-qc

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Cosmology without inflation

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classification 🌀 gr-qc
keywords contractingscalebouncecosmologicallargeperturbationsuniversebeen
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We propose a new cosmological paradigm in which our observed expanding phase is originated from an initially large contracting Universe that subsequently experienced a bounce. This category of models, being geodesically complete, is non-singular and horizon-free, and can be made to prevent any relevant scale to ever have been smaller than the Planck length. In this scenario, one can find new ways to solve the standard cosmological puzzles. One can also obtain scale invariant spectra for both scalar and tensor perturbations: this will be the case, for instance, if the contracting Universe is dust-dominated at the time at which large wavelength perturbations get larger than the curvature scale. We present a particular example based on a dust fluid classically contracting model, where a bounce occurs due to quantum effects, in which these features are explicit.

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Cited by 2 Pith papers

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    In bouncing cosmological backgrounds, event and particle horizons can appear or disappear independently of the local expansion rate because they are determined by the full spacetime history.

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    A matter bounce model driven by a scalar field with exponential potential fits Planck 2018 CMB data comparably to inflationary ΛCDM, with the potential slope λ directly setting the scalar spectral index ns.