scholarly journals Bianchi type I universe with viscous fluid and a term: A qualitative analysis

2006 ◽  
Vol 219 (2) ◽  
pp. 168-176 ◽  
Author(s):  
Bijan Saha ◽  
V. Rikhvitsky
Keyword(s):  
Viscous Fluid ◽  
Qualitative Analysis ◽  
Bianchi Type ◽  
Type I ◽  
Bianchi Type I ◽  
Bianchi Type I Universe

scholarly journals BIANCHI TYPE I UNIVERSE WITH VISCOUS FLUID

2005 ◽  
Vol 20 (28) ◽  
pp. 2127-2143 ◽  
Author(s):  
BIJAN SAHA
Keyword(s):  
Viscous Fluid ◽  
Bulk Viscosity ◽  
Bianchi Type ◽  
Anisotropic Universe ◽  
Type I ◽  
Cosmological Singularity ◽  
Bianchi Type I ◽  
Bianchi Type I Universe ◽  
Ending Process

We study the evolution of a homogeneous, anisotropic Universe given by a Bianchi type-I cosmological model filled with viscous fluid, in the presence of a cosmological constant Λ. The role of viscous fluid and Λ term in the evolution the BI spacetime is studied. Though the viscosity cannot remove the cosmological singularity, it plays a crucial part in the formation of a qualitatively new behavior of the solutions near singularity. It is shown that the introduction of the Λ term can be handy in the elimination of the cosmological singularity. In particular, in case of a bulk viscosity, a negative Λ provides a never-ending process of evolution, whereas, for some positive values of Λ and the bulk viscosity being inverse proportional to the expansion, the BI Universe admits a singularity-free oscillatory mode of expansion. In case of a constant bulk viscosity and share viscosity being proportional to expansion, the model allows both non-periodic and inflationary expansion independent to the sign of Λ term.

Energy–momentum distributions of Ruban universe in general relativity and teleparallel gravity

2019 ◽  
Vol 34 (03n04) ◽  
pp. 1950011 ◽  
Author(s):  
C. Aktaş
Keyword(s):  
General Relativity ◽  
Bianchi Type ◽  
Teleparallel Gravity ◽  
Type I ◽  
Universe Model ◽  
Zero Energy ◽  
Bianchi Type I ◽  
Momentum Distributions ◽  
Bianchi Type I Universe

In this study, we obtain Einstein, Bergmann–Thomson (BT), Landau–Lifshitz (LL), Møller, Papapetrou (PP) and Tolman energy–momentum (EM) distributions for Ruban universe model in general relativity (GR) and teleparallel gravity (TG). We obtain same results for Einstein, Bergmann–Thomson and Landau–Lifshitz energy–momentum distributions in GR and TG. Also, we get same results for Einstein and Tolman energy–momentum distributions in GR. The Møller energy–momentum results are different in GR and TG. Also, using Ruban universe model, we obtain LRS Bianchi type I solutions and we get zero energy–momentum results for this universe model in GR and TG. These results of LRS Bianchi type I universe model agree with Aygün et al., Taşer et al., Doğru et al., Banerjee–Sen, Tryon and Xulu in different gravitation theories.

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