scholarly journals Addendum: EPRL/FK Asymptotics and the Flatness Problem (2018 Class. Quantum Grav. 35 095003)

Author(s):  
Jonathan Steven Engle ◽  
Wojciech Kaminski ◽  
José Ricardo Camões de Oliveira
Keyword(s):  
2020 ◽  
Vol 102 (10) ◽  
Author(s):  
Pietro Donà ◽  
Francesco Gozzini ◽  
Giorgio Sarno

2021 ◽  
pp. 383-387
Author(s):  
Norbert Schwarzer
Keyword(s):  

2019 ◽  
Vol 34 (32) ◽  
pp. 1950262
Author(s):  
Raj Bali

Analytical solutions for radiation-dominated phase of Quasi-Steady-State Cosmology (QSSC) in Friedmann–Robertson–Walker models are obtained. We find that matter density is positive in all the cases [Formula: see text]. The nature of Hubble parameter (H) in [Formula: see text] is discussed. The deceleration parameter [Formula: see text] is marginally less than zero indicating accelerating universe. The scale factor [Formula: see text] is graphically shown with time. The model represents oscillating universe between the above-mentioned limits. Because of the bounce in QSSC, the maximum density phase is still matter-dominated. The models represent singularity-free model. We also find that the models have event horizon i.e. no observer beyond the proper distance [Formula: see text] can communicate each other in FRW models for radiation-dominated phase in the frame work of QSSC. The FRW models are special classes of Bianchi type I, V, IX spacetimes with zero, negative and positive curvatures, respectively. Initially i.e. at [Formula: see text], the models represent steady model. We have tried to show how a good fit can be obtained to the observations in the framework of QSSC during radiation-dominated phase. The present model is free from singularity, particle horizon and provides a natural explanation for the flatness problem. Therefore, our model is superior to other models.


2002 ◽  
Vol 65 (8) ◽  
Author(s):  
Daniel J. H. Chung ◽  
Edward W. Kolb ◽  
Antonio Riotto

2002 ◽  
Vol 17 (03) ◽  
pp. 175-184 ◽  
Author(s):  
DONAM YOUM

We study a varying electric charge brane world cosmology in the RS2 model obtained from a varying-speed-of-light brane world cosmology by redefining the system of units. We elaborate conditions under which the flatness problem and the cosmological constant problem can be resolved by such cosmological model.


2002 ◽  
Vol 11 (06) ◽  
pp. 921-932 ◽  
Author(s):  
SUBENOY CHAKRABORTY ◽  
NARAYAN CHANDRA CHAKRABORTY ◽  
UJJAL DEBNATH

In this paper, we have studied Brans–Dicke (BD) Cosmology in an anisotropic Kantowski–Sachs space–time model; considering variation of the velocity of light. We have addressed the flatness problem considering both cases namely (i) when the Brans–Dicke scalar field φ is constant (ii) when φ varies, specially for radiation dominated era perturbatively and non-perturbatively and asymptotic behaviour have been studied.


2020 ◽  
Vol 495 (4) ◽  
pp. 3571-3575
Author(s):  
Phillip Helbig

ABSTRACT Several authors have made claims, none of which has been rebutted, that the flatness problem, as formulated by Dicke and Peebles, is not really a problem but rather a misunderstanding. Nevertheless, the flatness problem is still widely perceived to be real. Most of the arguments against the idea of a flatness problem are based on the change with time of the density parameter Ω and normalized cosmological constant λ and, since the Hubble constant H is not considered, are independent of time-scale. An independent claim is that fine-tuning is required in order to produce a Universe which neither collapsed after a short time nor expanded so quickly that no structure formation could take place. I show that this claim does not imply that fine-tuning of the basic cosmological parameters is necessary, in part for similar reasons as in the more restricted flatness problem and in part due to an incorrect application of the idea of perturbing the early Universe in a gedankenexperiment; I discuss some typical pitfalls of the latter.


2003 ◽  
Vol 18 (19) ◽  
pp. 3315-3323 ◽  
Author(s):  
Subenoy Chakraborty ◽  
Narayan Chandra Chakraborty ◽  
Ujjal Debnath

A quintessence scalar field in self-interacting Brans–Dicke theory is shown to give rise to a nondecelerated expansion of the present universe for open, flat and closed models. Along with providing a nondecelerating solution, it can potentially solve the flatness problem too.


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