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In this article, we introduce an innovative parametric representation of the Hubble parameter, providing a model-independent means to explore the dynamics of an accelerating cosmos. The model's parameters are rigorously constrained through…

Cosmology and Nongalactic Astrophysics · Physics 2024-04-16 M. Koussour , N. Myrzakulov , M. K. M. Ali

The evolution of a flat, isotropic and homogeneous universe is studied. The background geometry in the early phases of the universe is conjectured to be filled with causal bulk viscous cosmological fluid and dark energy. The energy density…

General Relativity and Quantum Cosmology · Physics 2012-04-23 A. Tawfik

We examine a simple theoretical model to estimate (by fine tuning condition) the value of the cosmological constant. We assume, in analogy with holographic principle, that cosmological constant, like classical surface tension coefficient in…

Astrophysics · Physics 2008-01-21 V. Pankovic , S. Ciganovic , J. Ivanovic , R. Glavatovic , P. Grujic

The standard model of modern cosmology provides a description of a wide range of astrophysical and astronomical data. However, despite this impressive success, several discrepancies have have persisted. Most strikingly, the emerging tension…

Popular Physics · Physics 2021-08-04 Luis A. Anchordoqui

On the basis of qualitative analysis of the system of differential equations of the standard cosmological model it is shown that in the case of zero cosmological constant this system has a stable center corresponding to zero values of…

General Relativity and Quantum Cosmology · Physics 2016-09-29 Yurii Ignat'ev

We generalize the fractal bubble model (FB), recently proposed in the literature as an alternative to the standard $\Lambda$CDM cosmology, to include a non-zero cosmological constant. We retain the same volume partition of voids and walls…

General Relativity and Quantum Cosmology · Physics 2012-01-30 Stefano Viaggiu

The assumption that a complete description of an early state of the universe does not privilege any position or direction in space leads to a unified account of probability in cosmology, macroscopic physics, and quantum mechanics. Such a…

Quantum Physics · Physics 2010-08-09 David Layzer

We introduce a new approach for cosmological parameter estimation based on the information-theoretical Jensen-Shannon divergence (${\cal D}_{\rm JS}$), calculating it for models in the restricted parameter space $\{H_0, w_0, w_a\}$, where…

Cosmology and Nongalactic Astrophysics · Physics 2020-12-04 Michelle Stephens , Sara Vannah , Marcelo Gleiser

We revisit a cosmological model where dark matter (DM) and dark energy (DE) follow barotropic equations of state, allowing deviations from the standard $\Lambda$CDM framework (i.e. $w_{dm} \neq 0$, $w_{de} \neq -1$), considering both flat…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-24 Dorian Araya , Cristian Castillo , Genly Leon , Juan Magaña , Angie Barr Domínguez , Miguel A. García-Aspeitia

In models where the constants of Nature can take more than one set of values, the cosmological wave function $\psi$ describes an ensemble of universes with different values of the constants. The probability distribution for the constants…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Alexander Vilenkin

A covariant Lagrangian formulation of a solution to the cosmological constant problem, based on vizualising the fluctuations of the vacuum energy as a non-equilibrium process with stochastic behaviour, is presented. The variational…

Astrophysics · Physics 2016-08-30 J. W. Moffat

A spherically symmetric comoving fluid solution of Einstein's equations is adapted for cosmological application by extending the geometry of standard FRW cosmology using a generalised curvature term. The resulting model retains many of the…

General Relativity and Quantum Cosmology · Physics 2009-09-15 Ron Wiltshire

We consider the properties of an ensemble of universes as function of size, where size is defined in terms of the asymptotic value of the Hubble constant (or, equivalently, the value of the cosmological constant). We assume that standard…

High Energy Physics - Theory · Physics 2009-11-07 James D. Bjorken

In this paper, a parametrization describing the kinematical state of the universe via cosmographic approach is considered, where the minimum input is the assumption of the cosmological principle, i.e. the Friedmann-Robertson-Walker metric.…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Lixin Xu , Yuting Wang

Within the quantum mechanical treatment of the decay problem one finds that at late times $t$ the survival probability of an unstable state cannot have the form of an exponentially decreasing function of time $t$ but it has an inverse…

Cosmology and Nongalactic Astrophysics · Physics 2017-09-29 Marek Szydlowski , Aleksander Stachowski , Krzysztof Urbanowski

We investigated a bulk viscous fluid universe with cosmological constant {\Lambda} by assuming that the bulk viscosity to be proportional to the Hubble parameter. We found that for an expanding universe, the (relative) matter density will…

General Relativity and Quantum Cosmology · Physics 2024-01-25 Jinwen Hu , Huan Hu

The Standard Model of Particle Physics (SMPP) is an enormously successful description of high energy physics, driving ever more precise measurements to find "physics beyond the standard model", as well as providing motivation for developing…

Astrophysics · Physics 2015-06-24 Douglas Scott

We propose the Kolmogorov stochasticity parameter, $\lambda$ for energy level spectra to classify quantum systems with corresponding classical dynamics ranging from integrable to chaotic. We also study the probability distribution function…

Chaotic Dynamics · Physics 2015-03-18 Shashi C. L. Srivastava , Sudhir R. Jain

A simple position probability density formulation is presented for the motion of a particle in a spherically symmetric potential. The approach provides an alternative to Newtonian methods for presentation in an elementary course, and…

Physics Education · Physics 2007-05-23 Lorenzo J. Curtis , David G. Ellis

Measurement of the universe expansion rate through the cosmic chronometers proves to be a novel approach to understanding cosmic history. Although it provides a direct determination of the Hubble parameters at different redshifts, it…

Cosmology and Nongalactic Astrophysics · Physics 2023-04-12 Faeze Jalilvand , Ahmad Mehrabi