scholarly journals Growth of covariant perturbations in the contracting phase of a bouncing universe

2012 ◽  
Vol 86 (12) ◽  
Author(s):  
Atanu Kumar
Keyword(s):  
Bouncing Universe ◽  
Contracting Phase

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 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 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.

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