Abstract
We propose a simple scenario which explains why our Universe appears spatially flat, homogeneous and isotropic. We use the Einstein–Cartan–Kibble–Sciama (ECKS) theory of gravity which naturally extends general relativity to include the spin of matter. The torsion of spacetime generates gravitational repulsion in the early Universe filled with quarks and leptons, preventing the cosmological singularity: the Universe expands from a state of minimum but finite radius. We show that the dynamics of the closed Universe immediately after this state naturally solves the flatness and horizon problems in cosmology because of an extremely small and negative torsion density parameter, ΩS≈−10−69. Thus the ECKS gravity provides a compelling alternative to speculative mechanisms of standard cosmic inflation. This scenario also suggests that the contraction of our Universe preceding the bounce at the minimum radius may correspond to the dynamics of matter inside a collapsing black hole existing in another universe, which could explain the origin of the Big Bang.
Highlights
We show that the dynamics of the closed Universe immediately after this state naturally solves the flatness and horizon problems in cosmology because of an extremely small and negative torsion density parameter, ΩS ≈ −10−69
This scenario suggests that the contraction of our Universe preceding the bounce at the minimum radius may correspond to the dynamics of matter inside a collapsing black hole existing in another universe, which could explain the origin of the Big Bang
We considered the ECKS theory of gravity which is the closest theory with torsion to general relativity
Summary
The ECKS theory of gravity naturally extends Einstein’s general relativity to include matter with spin, providing a more complete account of local gauge invariance with respect to the Poincaré group [3,4,5,6,7,8,9,10,11] It is a viable theory, which differs significantly from general relativity only at densities of matter much larger than the nuclear density. The ECKS gravity is based on the Lagrangian density of the gravitational field that is proportional to the Ricci curvature scalar R, as in general relativity This theory removes the general-relativistic restriction of the symmetry of the affine connection Γik j , that is, of the vanishing of the torsion tensor Skij = (Γik j − Γ jki)/2. If the spin vanishes, (5) reduces to the standard Einstein equations
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