Nonperturbative effects of vacuum energy on the recent expansion of the universe
Leonard Parker,Alpan Raval +1 more
TLDR
In this article, it was shown that the vacuum energy of a free quantized field of very low mass can significantly alter the recent expansion of the universe, which is consistent with the possibility of inflation in the early universe.Abstract:
We show that the vacuum energy of a free quantized field of very low mass can significantly alter the recent expansion of the universe. The effective action of the theory is obtained from a non-perturbative sum of scalar curvature terms in the propagator. We numerically investigate the semiclassical Einstein equations derived from it. As a result of non-perturbative quantum effects, the scalar curvature of the matter-dominated universe stops decreasing and approaches a constant value. The universe in our model evolves from an open matter-dominated epoch to a mildly inflating de Sitter expansion. The Hubble constant during the present de Sitter epoch, as well as the time at which the transition occurs from matter-dominated to de Sitter expansion, are determined by the mass of the field and by the present matter density. The model provides a theoretical explanation of the observed recent acceleration of the universe, and gives a good fit to data from high-redshift Type Ia supernovae, with a mass of about 10^{-33} eV, and a current ratio of matter density to critical density, Omega_0 <0.4 . The age of the universe then follows with no further free parameters in the theory, and turns out to be greater than 13 Gyr. The model is spatially open and consistent with the possibility of inflation in the very early universe. Furthermore, our model arises from the standard renormalizable theory of a free quantum field in curved spacetime, and does not require a cosmological constant or the associated fine-tuning.read more
Citations
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Extended Theories of Gravity
TL;DR: Extended Theories of Gravity as discussed by the authors can be considered as a new paradigm to cure shortcomings of General Relativity at infrared and ultraviolet scales, which is an approach that, by preserving the undoubtedly positive results of Einstein's theory, is aimed to address conceptual and experimental problems recently emerged in astrophysics, cosmology and High Energy Physics.
Journal ArticleDOI
The Case for a Positive Cosmological Λ-Term
TL;DR: In this article, the authors review both observational and theoretical aspects of a small cosmological Λ-term and discuss the current observational situation focusing on cosmology tests of Λ including the age of the universe, high redshift supernovae, gravitational lensing, galaxy clustering and the cosmic microwave background.
Journal ArticleDOI
An Alternative to quintessence
TL;DR: In this paper, the authors consider a FRW cosmological model with an exotic fluid known as Chaplygin gas and show that the resulting evolution of the universe is not in disagreement with the current observation of cosmic acceleration.
Journal ArticleDOI
Is Cosmic Speed-Up Due to New Gravitational Physics?
TL;DR: In this article, it was shown that cosmic acceleration can arise due to very tiny corrections to the usual gravitational action of general relativity, of the form{R}^{\ensuremath{-}n}$ with $ng0.$.
Journal ArticleDOI
The Cosmological Constant
TL;DR: In this paper, a review of the physics and cosmology of the cosmological constant is presented, focusing on recent developments, and a pedagogical overview of cosmology in the presence of such a constant is given.
References
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TL;DR: Combinations involving trigonometric and hyperbolic functions and power 5 Indefinite Integrals of Special Functions 6 Definite Integral Integral Functions 7.Associated Legendre Functions 8 Special Functions 9 Hypergeometric Functions 10 Vector Field Theory 11 Algebraic Inequalities 12 Integral Inequality 13 Matrices and related results 14 Determinants 15 Norms 16 Ordinary differential equations 17 Fourier, Laplace, and Mellin Transforms 18 The z-transform
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