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We point out a new phenomenon which seems to be generic in 4d effective theories of scalar fields coupled to Einstein gravity, when applied to cosmology. A lift of such theories to a Weyl-invariant extension allows one to define classical…

High Energy Physics - Theory · Physics 2015-06-03 Itzhak Bars , Shih-Hung Chen , Paul J. Steinhardt , Neil Turok

In this work we study an alternative scheme for an Emergent Universe scenario in the context of a Jordan-Brans-Dicke theory, where the universe is initially in a truly static state supported by a scalar field located in a false vacuum. The…

General Relativity and Quantum Cosmology · Physics 2019-05-01 Pedro Labrana , Hobby Cossio

We discuss the possibility of obtaining the present acceleration of the universe via f(R) gravity theories which recently attracted much attention. It is known that f(R) theories generally have room for this. In this work we stress that the…

High Energy Physics - Theory · Physics 2008-11-26 Tonguç Rador

Emergent modified gravity is a canonical theory based on general covariance where the spacetime is not fundamental, but rather an emergent object. This feature allows for modifications of the classical theory and can be used to model new…

General Relativity and Quantum Cosmology · Physics 2024-02-06 Erick I. Duque

We establish purely geometric or metric-based criteria for the validity of the separate universe ansatz, under which the evolution of small-scale observables in a long-wavelength perturbation is indistinguishable from a separate…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-01 Wayne Hu , Austin Joyce

In this essay we marshal evidence suggesting that Einstein gravity may be an emergent phenomenon, one that is not ``fundamental'' but rather is an almost automatic low-energy long-distance consequence of a wide class of theories.…

General Relativity and Quantum Cosmology · Physics 2014-11-17 Carlos Barcelo , Matt Visser , Stefano Liberati

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

Recently, a novel idea about our expanding Universe was proposed by T. Padmanabhan [arXiv:1206.4916]. He suggested that the expansion of our Universe can be thought of as the emergence of space as cosmic time progresses. The emergence is…

High Energy Physics - Theory · Physics 2012-11-13 Ke Yang , Yu-Xiao Liu , Yong-Qiang Wang

We present a cosmological model of an early-time scenario that incorporates a relaxation process of the would-be large vacuum energy, followed by a reheating era connecting to the standard hot big bang universe. Avoiding fine-tuning the…

High Energy Physics - Theory · Physics 2022-11-30 Paul Martens , Shinji Mukohyama , Ryo Namba

One of the challenges of constructing a successful cyclic universe scenario is to be able to incorporate the second law of thermodynamics which typically leads to Tolman's problem of ever shrinking cycles. In this paper we construct a…

High Energy Physics - Theory · Physics 2009-07-31 Tirthabir Biswas

We propose a simple scenario which explains why our Universe appears spatially flat, homogeneous and isotropic. We use the Einstein-Cartan-Kibble-Sciama (ECKS) theory of gravity which naturally extends general relativity to include the spin…

Cosmology and Nongalactic Astrophysics · Physics 2011-07-20 Nikodem J. Poplawski

Scenario of a bouncing universe is one of the most active area of research to arrive at singularity free cosmological models. Different proposals have been suggested to avoid the so called 'big bang' singularity through the quantum aspect…

General Relativity and Quantum Cosmology · Physics 2022-10-26 Indrani Banerjee , Tanmoy Paul , Soumitra SenGupta

Quasi-topological theories of gravity are known to resolve black-hole singularities. We investigate whether the same mechanism can remove cosmological singularities. Focusing on non-polynomial curvature quasi-topological gravities in $d=4$…

General Relativity and Quantum Cosmology · Physics 2026-03-19 Johanna Borissova , João Magueijo

The energy conditions of Einstein gravity (classical general relativity) do not require one to fix a specific equation of state. In a Friedmann-Robertson-Walker universe where the equation of state for the cosmological fluid is uncertain,…

General Relativity and Quantum Cosmology · Physics 2015-01-08 Matt Visser

Analyzing quantum cosmological scenarios containing one scalar field with exponential potential, we have obtained a universe model which realizes a classical dust contraction from very large scales, the initial repeller of the model, and…

General Relativity and Quantum Cosmology · Physics 2017-09-13 Samuel Colin , Nelson Pinto-Neto

General relativistic entropic acceleration theory may explain the present cosmic acceleration from first principles without the need of introducing a cosmological constant. Following the covariant formulation of non-equilibrium phenomena in…

General Relativity and Quantum Cosmology · Physics 2021-10-20 Juan Garcia-Bellido , Llorenc Espinosa-Portales

We examine the evolution of the Friedmann Universe within our recent model of space-time identified with an elastic continuous medium whose deformations are described by a vector field constrained to obey a generalized four-dimensional…

General Relativity and Quantum Cosmology · Physics 2015-12-22 Fayçal Hammad

The quest to understand better the nature of the initial cosmological singularity is with us since the discovery of the expanding universe. Here, we propose several non-flat models, among them the standard cosmological scenario with a…

General Relativity and Quantum Cosmology · Physics 2021-12-28 Andres Felipe Estupinan Salamanca , Sergio Bravo Medina , Marek Nowakowski , Davide Batic

For variable gravity models the strength of gravity, as measured by Newton's ``constant'' or the Planck mass, depends on the value of a scalar field, the cosmon. We discuss two simple four-parameter models with a quadratic or constant…

Cosmology and Nongalactic Astrophysics · Physics 2014-01-15 C. Wetterich

We argue that the emergent spacetime picture admits a background-independent formulation of cosmic inflation. The inflation in this picture corresponds to the dynamical emergence of spacetime while the conventional inflation is simply an…

High Energy Physics - Theory · Physics 2019-02-27 Hyun Seok Yang