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تسجيل مستخدم جديدCreating the Universe Without a Singularity and the Cosmological Constant Problem
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E. I. Guendelman
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We consider a non singular origin for the Universe starting from an Einstein static Universe in the framework of a theory which uses two volume elements $sqrt{-{g}}d^{4}x$ and $Phi d^{4}x$, where $Phi $ is a metric independent density, also curvature, curvature square terms, first order formalism and for scale invariance a dilaton field $phi$ are considered in the action. In the Einstein frame we also add a cosmological term that parametrizes the zero point fluctuations. The resulting effective potential for the dilaton contains two flat regions, for $phi rightarrow infty$ relevant for the non singular origin of the Universe and $phi rightarrow -infty$, describing our present Universe. Surprisingly, avoidance of singularities and stability as $phi rightarrow infty$ imply a positive but small vacuum energy as $phi rightarrow -infty$. Zero vacuum energy density for the present universe is the threshold for universe creation. This requires a modified emergent universe scenario, where the universe although very old, it does have a beginning.
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