MG12 - Talk detail
 

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Abstract

Regular and chaotic regimes in scalar field cosmology

We consider a dynamical system describing evolution of a closed isotropic Universe in the presence of a scalar field. Several types of dynamics can be identified: for a power-law scalar field potentials a transient chaos exists, for exponentially steep potentials it can disappear, for shallow potentials ($V \sim \phi^{\alpha}$ with $\alpha< 1.2$) islands of regular dynamics appear in the chaotic "sea". Some simple analitical criteria for chaos to exist in this system are described.

Dynamics of a flat multidimensional anisotropic Universe in the Gauss-Bonnet gravity

We investigate dynamics of (4+1) and (5+1) dimensional flat anisotropic Universe filled by a perfect fluid in the Gauss-Bonnet gravity. Several analitical solutions valid for particular values of the equation of state parameter $\gamma$ have been found. For other values of $\gamma$ structure of cosmological singularity have been studied numerically. We found that for $\gamma > 4/3$ the singularity is isotropic. Several important differences between (4+1) and (5+1) dimensional cases are discussed.

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