A physical model for dimensional reduction and its effects on the observable parameters of the universe

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2005

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Karaca, Koray

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In this thesis, assuming that higher spatial dimensions existed only during the inflationary prematter phases of the universe, we construct a (1+D)-dimensional (D>3), nonsingular, homogeneous and isotropic Friedmann model for dimensional reduction. In this model, dimensional reduction occurs in the form of a phase transition that follows from a purely thermodynamical consideration that the universe heats up during the inflationary prematter phases. When the temperature reaches its Planck value Tpl,D, which is taken as the maximum attainable physical temperature, the phase of the universe changes from one prematter era with D space dimensions to another prematter era with ( D-1) space dimensions where T_pl,D is higher. In this way, inflation gets another chance to continue in the lower dimension and the reduction process stops when we reach D=3 ordinary space dimensions. As a specific model, we investigate the evolution of a (1+4)-dimensional universe and see that dimensional reduction occurs when a critical length parameter l_4,3 reaches the Planck length of the lower dimension. Although the predictions of our model for the cosmological parameters are beyond the ranges accepted by recent measurements for closed geometry, for a broad range of initial conditions they are within the acceptable ranges for open geometry

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Physics.

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http://etd.lib.metu.edu.tr/upload/12606125/index.pdf
https://hdl.handle.net/11511/15154

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

K. Karaca, “A physical model for dimensional reduction and its effects on the observable parameters of the universe,” Ph.D. - Doctoral Program, Middle East Technical University, 2005.