scholarly journals Bouncing universe with non-minimally coupled quintom matter

2008 ◽  
Vol 669 (1) ◽  
pp. 9-13 ◽  
Author(s):  
M.R. Setare ◽  
J. Sadeghi ◽  
A. Banijamali
Keyword(s):  
Bouncing Universe

scholarly journals Bouncing universe with Quintom matter

2007 ◽  
Vol 2007 (10) ◽  
pp. 071-071 ◽  
Author(s):  
Yi-Fu Cai ◽  
Taotao Qiu ◽  
Xinmin Zhang ◽  
Yun-Song Piao ◽  
Mingzhe Li
Keyword(s):  
Bouncing Universe

scholarly journals Reconstruction of Mimetic Gravity in a Non-Singular Bouncing Universe from Quantum Gravity

Universe ◽  
2019 ◽  
Vol 5 (5) ◽  
pp. 107 ◽  
Author(s):  
Marco de Cesare
Keyword(s):  
Field Theory ◽  
Quantum Gravity ◽  
Effective Field ◽  
Time Varying ◽  
Reconstruction Procedure ◽  
Cosmological Background ◽  
Bouncing Universe ◽  
Physical Information ◽  
Group Field Theory ◽  
Mimetic Gravity

We illustrate a general reconstruction procedure for mimetic gravity. Focusing on a bouncing cosmological background, we derive general properties that must be satisfied by the function f(□ϕ) implementing the limiting curvature hypothesis. We show how relevant physical information can be extracted from power-law expansions of f in different regimes, corresponding e.g., to the very early universe or to late times. Our results are then applied to two specific models reproducing the cosmological background dynamics obtained in group field theory and in loop quantum cosmology, and we discuss the possibility of using this framework as providing an effective field theory description of quantum gravity. We study the evolution of anisotropies near the bounce, and discuss instabilities of scalar perturbations. Furthermore, we provide two equivalent formulations of mimetic gravity: one in terms of an effective fluid with exotic properties, the other featuring two distinct time-varying gravitational “constants” in the cosmological equations.

scholarly journals Quantum states of the bouncing universe

2013 ◽  
Vol 87 (12) ◽  
Author(s):  
Jean Pierre Gazeau ◽  
Jakub Mielczarek ◽  
Włodzimierz Piechocki
Keyword(s):  
Quantum States ◽  
Bouncing Universe

THE SPECTRUM OF SCALAR FLUCTUATIONS OF A BOUNCING UNIVERSE

2010 ◽  
Vol 25 (15) ◽  
pp. 3095-3105 ◽  
Author(s):  
M. CAMPISTA ◽  
M. NOVELLO ◽  
J. M. SALIM
Keyword(s):  
General Relativity ◽  
Gravitational Field ◽  
Standard Model ◽  
Hubble Parameter ◽  
Inhomogeneous Structure ◽  
Small Perturbations ◽  
Actual Distribution ◽  
Bouncing Universe ◽  
Cluster Of Galaxies ◽  
The Standard Model

In the last years, the idea of the existence of a collapsing phase previous to the actual expanding one has attracted attention in many different contexts (being very active!). There are many reasons for this, which concerns the standard model and its difficulties in dealing with a singularity which — in the words of the creator of general relativity — means the failure of the equations of general relativity to represent the gravitational field in those regions of extraordinary high curvature. However, we would like to point out just one: the possibility of deciding the existence of such primordial collapsing phase by observational tests due to the inprint it could be left in the inhomogeneous structure that constitutes the actual distribution of galaxies and cluster of galaxies. In this vein, the purpose of the present work is to analyze a particular bouncing universe and the evolution of small perturbations. To realize such analysis when the geometry has a bouncing (that is, the associated Hubble parameter — that measures the rate of the velocity of the expansion through [Formula: see text] — has a zero) the standard Lifshitz–Bardeen–Mukhanov variables/method is not the best one. Instead, we use the most well-behaved standard quasi-Maxwellian equations of perturbation introduced by Hawking and developed by Ellis et al. and Novello et al.

scholarly journals Dark matter in a bouncing universe

2014 ◽  
Vol 2014 (11) ◽  
pp. 001-001 ◽  
Author(s):  
Yeuk-Kwan E. Cheung ◽  
Jin U Kang ◽  
Changhong Li
Keyword(s):  
Dark Matter ◽  
Bouncing Universe
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