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Friedmann–Lemaître–Robertson–Walker metric

About: Friedmann–Lemaître–Robertson–Walker metric is a research topic. Over the lifetime, 4113 publications have been published within this topic receiving 87752 citations. The topic is also known as: FLRW metric.


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TL;DR: In this article, the authors introduced the formalism of quantum cosmology in a Friedmann-Lemaitre-Robertson-Walker (FLRW) universe of arbitrary dimension filled with a perfect fluid with p = alpha rho equation of state.
Abstract: We introduce the formalism of quantum cosmology in a Friedmann-Lemaitre-Robertson-Walker (FLRW) universe of arbitrary dimension filled with a perfect fluid with p={alpha}{rho} equation of state. First we show that the Schutz formalism, developed in four dimensions, can be extended to a n-dimensional universe. We compute the quantum representant of the scale factor a(t), in the Many-Worlds, as well as, in the de Broglie-Bohm interpretation of quantum mechanics. We show that the singularities, which are still present in the n-dimensional generalization of FLRW universe, are excluded with the introduction of quantum theory. We quantize, via the de Broglie-Bohm interpretation of quantum mechanics, the components of the Riemann curvature tensor in a tetrad basis in a n-dimensional FLRW universe filled with radiation (p=(1/n-1){rho}). We show that the quantized version of the Ricci scalar are perfectly regular for all time t. We also study the behavior of the energy density and pressure and show that the ratio {sub L}/ {sub L} tends to the classical value 1/(n-1) only for n=4, showing that n=4 is somewhat privileged among the other dimensions. Besides that, as n{yields}{infinity}, {sub L}/ {sub L}{yields}1.

30 citations

Journal ArticleDOI
TL;DR: In this article, the entropy-corrected version of the new agegraphic dark energy model in the non-flat FRW universe is considered and the exact differential equation that determines the evolution of the entropycorrected dark energy density parameter in the presence of interaction with dark matter is derived.
Abstract: Here we consider the entropy-corrected version of the new agegraphic dark energy model in the non-flat FRW universe. We derive the exact differential equation that determines the evolution of the entropy-corrected new agegraphic dark energy density parameter in the presence of interaction with dark matter. We also obtain the equation of state and deceleration parameters and present a necessary condition for the selected model to cross the phantom divide. Moreover, we reconstruct the potential and the dynamics of the phantom scalar field according to the evolutionary behavior of the interacting entropy-corrected new agegraphic model.

30 citations

Journal ArticleDOI
TL;DR: In this article, the authors consider the evolution of FRW cosmological models and linear perturbations of tachyon matter rolling towards a minimum of its potential, and show that this linear stage changes to a strongly non-linear one very early, so that the usual quasi-linear stage observed at sufficiently large scales in the present Universe may not be realized in the absence of the usual particle-like cold dark matter.
Abstract: We consider the evolution of FRW cosmological models and linear perturbations of tachyon matter rolling towards a minimum of its potential. The tachyon coupled to gravity is described by an effective 4d field theory of string theory tachyon. In the model where a tachyon potential $V(T)$ has a quadratic minimum at finite value of the tachyon field $T_0$ and $V(T_0)=0$, the tachyon condensate oscillates around its minimum with a decreasing amplitude. It is shown that its effective equation of state is $p=-\epsilon/3$. However, linear inhomogeneous tachyon fluctuations coupled to the oscillating background condensate are exponentially unstable due to the effect of parametric resonance. In another interesting model, where tachyon potential exponentially approaches zero at infinity of $T$, rolling tachyon condensate in an expanding universe behaves as pressureless fluid. Its linear fluctuations coupled with small metric perturbations evolve similar to these in the pressureless fluid. However, this linear stage changes to a strongly non-linear one very early, so that the usual quasi-linear stage observed at sufficiently large scales in the present Universe may not be realized in the absence of the usual particle-like cold dark matter.

30 citations

Journal ArticleDOI
TL;DR: In this article, the authors consider the theory of quantum gravity that emerges from the fakeon idea and study its classicization, focusing on the FLRW metric, showing that the classical limit shares many features with the quantum theory it comes from, including the impossibility to write down complete, “exact” field equations, to the extent that asymptotic series and nonperturbative effects come into play.
Abstract: Under certain assumptions, it is possible to make sense of higher derivative theories by quantizing the unwanted degrees of freedom as fakeons, which are later projected away. Then the true classical limit is obtained by classicizing the quantum theory. Since quantum field theory is formulated perturbatively, the classicization is also perturbative. After deriving a number of properties in a general setting, we consider the theory of quantum gravity that emerges from the fakeon idea and study its classicization, focusing on the FLRW metric. We point out cases where the fakeon projection can be handled exactly, which include radiation, the vacuum energy density and the combination of the two, and cases where it cannot, which include dust. Generically, the classical limit shares many features with the quantum theory it comes from, including the impossibility to write down complete, “exact” field equations, to the extent that asymptotic series and nonperturbative effects come into play.

30 citations

Journal ArticleDOI
TL;DR: In this paper, a member of the class of anisotropic and inhomogeneous cosmological models constructed by Wainwright and Goode is investigated, which is shown to evolve exponentially rapidly towards the homogeneous and isotropic de Sitter universe model.

29 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023150
2022352
2021196
2020204
2019214
2018191