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Full-Text Articles in Physics
Non-Parametric Reconstruction Of An Inflaton Potential From Einstein–Cartan–Sciama–Kibble Gravity With Particle Production, Shantanu Desai, Nikodem Poplawski
Non-Parametric Reconstruction Of An Inflaton Potential From Einstein–Cartan–Sciama–Kibble Gravity With Particle Production, Shantanu Desai, Nikodem Poplawski
Physics Faculty Publications
The coupling between spin and torsion in the Einstein–Cartan–Sciama–Kibble theory of gravity generates gravitational repulsion at very high densities, which prevents a singularity in a black hole and may create there a new universe. We show that quantum particle production in such a universe near the last bounce, which represents the Big Bang, gives the dynamics that solves the horizon, flatness, and homogeneity problems in cosmology. For a particular range of the particle production coefficient, we obtain a nearly constant Hubble parameter that gives an exponential expansion of the universe with more than 60 e -folds, which lasts about ∼10 …
Schwinger’S Variational Principle In Einstein-Cartan Gravity, Nikodem Poplawski
Schwinger’S Variational Principle In Einstein-Cartan Gravity, Nikodem Poplawski
Physics Faculty Publications
By applying Schwinger’s variational principle to the Einstein-Cartan action for the gravitational field, we derive quantum commutation relations between the metric and torsion tensors.
Cosmology With Torsion: An Alternative To Cosmic Inflation, Nikodem Poplawski
Cosmology With Torsion: An Alternative To Cosmic Inflation, Nikodem Poplawski
Physics Faculty Publications
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≈− …