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Isotropising anisotropic cyclic cosmologies

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Standard models of cosmology use inflation as a mechanism to resolve the isotropy and homogeneity problem of the universe as well as the flatness problem. However, due to various well known problems with the inflationary paradigm, there has been an ongoing search for alternatives. Perhaps the most famous among these is the cyclic universe scenario or scenarios which incorporate bounces. As these scenarios have a contracting phase in the evolution of the universe, it is reasonable to ask whether the problems of homogeneity and isotropy can still be resolved in these scenarios. In my talk, I will focus on the problem of the resolution of isotropy. In the contracting phase of the evolution, the mechanism of ekpyrosis is used in most cosmological scenarios which incorporate a contracting phase to mitigate the problem of anisotropies blowing up on approaching the bounce. I will start by studying anisotropic universes and I shall examine the effect of the addition of anisotropic pressures on the ekpyrotic phase. I will then consider evolving such anisotropic universes through several cycles with increasing expansion maxima at each successive bounce. This is the mechanism suggested to deal with the flatness problem. My aim will be to see if the resolution of the flatness problem also leads to a simultaneous resolution of the isotropy problem.

This talk is part of the DAMTP Friday GR Seminar series.

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