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It's been pointed out already at Cosmo forum that a revolution, or at least a minor insurrection, is brewing in cosmology. This paper is part of that. It comes from a different direction compared to some of the other research in nonsingular cosmology. For instance it is not specifically a Loop cosmology bounce paper. But indeed there seem to be half a dozen converging lines of thought in nonsingular or bounce cosmo. One useful thing the authors do is compile a substantial body of references to other work. They provide their own ideas of how a quantum bounce removes the singularity and also removes the need for inflation. The riddles that inflation scenarios were made up to answer go away by themselves, according to Peter and Pinto-Neto, making inflation scenarios unnecessary extra baggage. Since the conjectured physical mechanisms underlying inflation scenarios are entirely made up, support for the scenarios depends on there being no other more natural way of addressing the several puzzles. Peter and Pinto-Neto devote themselves to yanking out the rug.
http://arxiv.org/abs/0809.2022
Cosmology without inflation
Patrick Peter, Nelson Pinto-Neto
8 pages, Phys. Rev. D 78, 063506 (2008)
"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."Among their many other publications, the authors have a couple of earlier papers specifically related to this:
http://arxiv.org/abs/hep-th/0203013
http://arxiv.org/abs/hep-th/0610205
Peter previously did string research. He now works in astrophysics (Paris), Pinto-Neto's main interest is cosmology (Rio De Janeiro)
http://arxiv.org/abs/0809.2022
Cosmology without inflation
Patrick Peter, Nelson Pinto-Neto
8 pages, Phys. Rev. D 78, 063506 (2008)
"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."Among their many other publications, the authors have a couple of earlier papers specifically related to this:
http://arxiv.org/abs/hep-th/0203013
http://arxiv.org/abs/hep-th/0610205
Peter previously did string research. He now works in astrophysics (Paris), Pinto-Neto's main interest is cosmology (Rio De Janeiro)
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One thing that would be very helpful is people coming us with TESTS of whether inflation actually occurred. And in fact just yesterday I saw a paper by Paul Steinhardt that addresses this.