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Mixmasters that bounce
arunavam edited this page Mar 15, 2021
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Bouncing cosmologies have been studied as alternatives to inflation. They face an isotropy problem as the anisotropies increase in the contracting phase. In this work, we study isotropy in the most general anisotropic, spatially homogeneous cosmology - called the Bianchi IX universe. We show that a quadratic equation of state which acts like a super-stiff fluid reminiscent of Ekpyrosis at high energies is able to produce a bounce in this universe. We also introduce a novel isotropisation mechanism using a negative anisotropic pressures that looks like shear viscosity and show that it isotropises the Bianchi IX cosmology and also mitigates the chaotic Mixmaster behaviour that these models are known for.