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Big Rip
About: Big Rip is a research topic. Over the lifetime, 3108 publications have been published within this topic receiving 98912 citations.
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TL;DR: In this paper, the Gauss-Bonnet dark energy model with scalar and Gauss invariant invariants is proposed and it is shown that the effective phantom phase of the late universe may occur in the presence of such a term when the scalar is phantom or for nonzero potential (for canonical scalar).
Abstract: We propose the Gauss-Bonnet dark energy model inspired by string/M-theory where standard gravity with scalar contains additional scalar-dependent coupling with a Gauss-Bonnet invariant. It is demonstrated that the effective phantom (or quintessence) phase of the late universe may occur in the presence of such a term when the scalar is phantom or for nonzero potential (for canonical scalar). However, with the increase of the curvature, the Gauss-Bonnet term may become dominant so that the phantom phase is transient and the $w=\ensuremath{-}1$ barrier may be passed. Hence, the current acceleration of the universe may be caused by a mixture of scalar phantom and/or potential or stringy effects. It is remarkable that scalar-Gauss-Bonnet coupling acts against the big rip occurrence also in phantom cosmology.
731 citations
TL;DR: According to the inflationary universe scenario, the Universe in the very early stages of its evolution was exponentially expanding in the unstable vacuum-like state as mentioned in this paper, and at the end of the exponential expansions (inflation) the energy of a classical scalar field transforms into the energy energy of hot dense matter, and the subsequent evolution of the Universe is described by the usual hot universe theory.
Abstract: According to the inflationary Universe scenario the Universe in the very early stages of its evolution was exponentially expanding in the unstable vacuumlike state At the end of the exponential expansions (inflation) the energy of the unstable vacuum (of a classical scalar field) transforms into the energy of hot dense matter, and the subsequent evolution of the Universe is described by the usual hot Universe theory Recently it was realised that the exponential expansion during the very early stages of evolution of the Universe naturally occurs in a wide class of realistic theories of elementary particles The inflationary Universe scenario makes it possible to obtain a simple solution to many long-standing cosmological problems and leads to a crucial modification of the standard point of view of the large-scale structure of the Universe
710 citations
TL;DR: Einstein equations with flat homogeneous hypersurfaces including effects of viscosity in radiation and anisotropic pressures were studied in this paper, where the authors considered flat hypersurface models with flat surfaces.
Abstract: Einstein equations with flat homogeneous hypersurfaces including effects of viscosity in radiation and anisotropic pressures
694 citations
TL;DR: In this paper, the authors show that there remains a wide range of cosmological models in good concordance with these constraints, and they point to models in which the matter density of the universe falls well below the critical energy density required to halt its expansion.
Abstract: OBSERVATIONS are providing progressively tighter constraints on cosmological models advanced to explain the formation of large-scale structure in the Universe. These include recent determinations of the Hubble constant1a¤-3 (which quantifies the present expansion rate of the Universe) and measurements of the anisotropy of the cosmic microwave background4,5. Although the limits imposed by these diverse observations have occasionally led to suggestions6 that cosmology is facing a crisis, we show here that there remains a wide range of cosmological models in good concordance with these constraints. The combined observations point to models in which the matter density of the Universe falls well below the critical energy density required to halt its expansion. But they also permit a substantial contribution to the energy density from the vacuum itself (a positive a¤˜cosmological constanta¤™), sufficient to recover the critical density favoured by the simplest inflationary models. The observations do not yet rule out the possibility that we live in an ever-expanding a¤˜opena¤™ Universe, but a Universe having the critical energy density and a large cosmological constant appears to be favoured.
672 citations
TL;DR: In this article, it was shown that quantum effects play the dominant role near a big rip, driving the universe out of a future singularity (or at least moderating it).
Abstract: As it follows from the classical analysis, the typical final state of a dark energy universe where a dominant energy condition is violated is a finite-time, sudden future singularity (a big rip). For a number of dark energy universes (including scalar phantom and effective phantom theories as well as specific quintessence models) we demonstrate that quantum effects play the dominant role near a big rip, driving the universe out of a future singularity (or, at least, moderating it). As a consequence, the entropy bounds with quantum corrections become well defined near a big rip. Similarly, black hole mass loss due to phantom accretion is not so dramatic as was expected: masses do not vanish to zero due to the transient character of the phantom evolution stage. Some examples of cosmological evolution for a negative, time-dependent equation of state are also considered with the same conclusions. The application of negative entropy (or negative temperature) occurrence in the phantom thermodynamics is briefly discussed.
606 citations