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The standard big bang cosmology has been greatly successful in explaining many observational aspects of the real universe. However, two particular diffficulties faced by it are the so-called ``horizon'' and ``flatness'' problems. By…

General Physics · Physics 2007-05-23 Abhas Mitra

Universe structure emerges in the unreduced, complex-dynamic interaction process with the simplest initial configuration (two attracting homogeneous fields, quant-ph/9902015). The unreduced interaction analysis gives intrinsically creative…

General Physics · Physics 2007-05-23 Andrei P. Kirilyuk

We examine the possibility of "soft cosmology", namely small deviations from the usual framework due to the effective appearance of soft-matter properties in the Universe sectors. One effect of such a case would be the dark energy to…

Cosmology and Nongalactic Astrophysics · Physics 2021-09-22 Emmanuel N. Saridakis

A precise measurement of the curvature of the Universe is of primeval importance for cosmology since it could not only confirm the paradigm of primordial inflation but also help in discriminating between different early Universe scenarios.…

Cosmology and Nongalactic Astrophysics · Physics 2021-05-27 Eleonora Di Valentino , Luis A. Anchordoqui , Ozgur Akarsu , Yacine Ali-Haimoud , Luca Amendola , Nikki Arendse , Marika Asgari , Mario Ballardini , Spyros Basilakos , Elia Battistelli , Micol Benetti , Simon Birrer , François R. Bouchet , Marco Bruni , Erminia Calabrese , David Camarena , Salvatore Capozziello , Angela Chen , Jens Chluba , Anton Chudaykin , Eoin Ó Colgáin , Francis-Yan Cyr-Racine , Paolo de Bernardis , Javier de Cruz Pérez , Jacques Delabrouille , Celia Escamilla-Rivera , Agnès Ferté , Fabio Finelli , Wendy Freedman , Noemi Frusciante , Elena Giusarma , Adrià Gómez-Valent , Will Handley , Ian Harrison , Luke Hart , Alan Heavens , Hendrik Hildebrandt , Daniel Holz , Dragan Huterer , Mikhail M. Ivanov , Shahab Joudaki , Marc Kamionkowski , Tanvi Karwal , Lloyd Knox , Suresh Kumar , Luca Lamagna , Julien Lesgourgues , Matteo Lucca , Valerio Marra , Silvia Masi , Sabino Matarrese , Arindam Mazumdar , Alessandro Melchiorri , Olga Mena , Laura Mersini-Houghton , Vivian Miranda , Cristian Moreno-Pulido , David F. Mota , Jessica Muir , Ankan Mukherjee , Florian Niedermann , Alessio Notari , Rafael C. Nunes , Francesco Pace , Andronikos Paliathanasis , Antonella Palmese , Supriya Pan , Daniela Paoletti , Valeria Pettorino , Francesco Piacentini , Vivian Poulin , Marco Raveri , Adam G. Riess , Vincenzo Salzano , Emmanuel N. Saridakis , Anjan A. Sen , Arman Shafieloo , Anowar J. Shajib , Joseph Silk , Alessandra Silvestri , Martin S. Sloth , Tristan L. Smith , Joan Solà , Carsten van de Bruck , Licia Verde , Luca Visinelli , Benjamin D. Wandelt , Deng Wang , Jian-Min Wang , Anil K. Yadav , Weiqiang Yang

A Universe with finite age also has a finite causal scale. Larger scales can not affect our local measurements or modeling, but far away locations could have different cosmological parameters. The size of our causal Universe depends on the…

General Physics · Physics 2020-04-17 Enrique Gaztanaga

We consider a nonsingular deflationary cosmological model with decaying vacuum energy density in universes of arbitrary spatial curvature. Irrespective of the value of $k$, the models are characterized by an arbitrary time scale $H_I^{-1}$…

Astrophysics · Physics 2009-10-28 J. A. S. Lima , M. Trodden

We investigate the behaviour of the skewness parameters for an anisotropic universe in the framework of General Relativity. Non interacting dark energy is considered in presence of electromagnetic field. A time varying deceleration…

General Physics · Physics 2022-07-19 B. Mishra , Pratik P Ray , S. K. Tripathy , Kazuharu Bamba

The consensus of opinion in cosmology is that the Universe is currently undergoing a period of accelerated expansion. With current and proposed high precision experiments it offers the hope of being able to discriminate between the two…

Astrophysics · Physics 2011-02-09 P. S. Corasaniti , E. J. Copeland

We analyse the cosmological evolution of a generalised axion-like field that drives the late-time acceleration of the Universe. This model can exhibit tracking behaviour, which alleviates the coincidence problem. The cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-29 Carlos G. Boiza , Mariam Bouhmadi-López

In this paper we exploit the theory of the dynamical systems to study the dynamics of the standard cosmological model of the universe, which is known as the $\Lambda$CDM model. We assume that the matter content in our universe consists of…

General Physics · Physics 2022-09-07 Danijela Branković , Žarko Mijajlović

We construct a cosmological model which is physically reasonable, mathematically tractable, and extends the study of CDM models to the case where the equations of state (EoS) for matter and dark energy (DE) vary with time. It is based on…

General Relativity and Quantum Cosmology · Physics 2012-06-14 J. Ponce de Leon

We investigate the complete universe evolution in the framework of $f(T)$ cosmology. We first study the requirements at the kinematic level and we introduce a simple scale factor with the necessary features. Performing a detailed analysis…

General Relativity and Quantum Cosmology · Physics 2021-09-16 W. El Hanafy , Emmanuel N. Saridakis

Methods of dynamical systems have been used to study homogeneous and isotropic cosmological models with a varying speed of light (VSL). We propose two methods of reduction of dynamics to the form of planar Hamiltonian dynamical systems for…

General Relativity and Quantum Cosmology · Physics 2008-07-22 Marek Szydlowski , Adam Krawiec

We propose a cosmological model that makes a significant step toward solving the coincidence problem of the near similarity at the present of the dark energy and dark matter components. Our cosmology has the following properties: a) among…

Astrophysics · Physics 2008-11-26 Luca Amendola , Domenico Tocchini-Valentini

The $f(T,T_G)$ class of gravitational modification, based on the quadratic torsion scalar $T$, as well as on the new quartic torsion scalar $T_G$ which is the teleparallel equivalent of the Gauss-Bonnet term, is a novel theory, different…

General Relativity and Quantum Cosmology · Physics 2014-08-19 Georgios Kofinas , Genly Leon , Emmanuel N. Saridakis

Cosmological observations strongly suggest the presence of dark energy which comprises the majority of the current energy density of the universe. The equation of state relating the pressure and energy density of this dark energy, p = w…

Astrophysics · Physics 2007-05-23 Eric Gawiser

An accelerated universe should naturally have a vacuum energy density determined by its dynamical curvature. The cosmological constant is most likely a temporary description of a dynamical variable that has been drastically evolving from…

General Relativity and Quantum Cosmology · Physics 2015-10-28 Joan Sola

The ghost-free theory of massive gravity with two dynamical metrics has been shown to produce viable cosmological expansion, where the late-time acceleration of the Universe is due to the finite range of the gravitational interaction rather…

Cosmology and Nongalactic Astrophysics · Physics 2014-10-29 Adam R. Solomon , Yashar Akrami , Tomi S. Koivisto

We consider the description of cosmological dynamics from the onset of inflation by a perfect fluid whose parameters must be consistent with the strength of the enhanced quantum loop effects that can arise during inflation. The source of…

General Relativity and Quantum Cosmology · Physics 2010-04-14 N. C. Tsamis , R. P. Woodard

The late-time cosmological dynamics of disformal gravity are investigated using dynamical systems methods. It is shown that in the general case there are no stable attractors that screen fifth-forces locally and simultaneously describe a…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-23 Jeremy Sakstein