2019/07/31 by John D. Barrow, J. D. Barrow, Christos G. Tsagas +3 · 27 citations
Physics and Astronomy · #Advanced Differential Geometry Research #Cosmology and Gravitation Theories #Dynamical systems theory #Equilibrium point #Homogeneous #Isotropy #Lyapunov function #Noncommutative and Quantum Gravity Theories #Saddle #Saddle point #Stability theory #Torsion (gastropod) #astro-ph.CO #gr-qc
paper · pdf · doi:10.1140/epjc/s10052-019-7270-x
published in The European Physical Journal C 79(9) (Springer Science+Business Media) · Minor changes. Published in EPJC
openalex publication_date 2019/09/01 · arxiv created 2019/09/17 · openalex created_date 2019/09/19 · arxiv updated 2019/10/02 · openalex updated_date 2026/08/05
Abstract We consider Friedmann-like universes with torsion and take a step towards studying their stability. In so doing, we apply dynamical-system techniques to an autonomous system of differential equations, which monitors the evolution of these models via the associated density parameters. Assuming relatively weak torsion, we identify the system’s equilibrium points. These are found to represent homogeneous and isotropic spacetimes with nonzero torsion that undergo accelerated expansion. We then examine the linear stability of the aforementioned fixed points. Our results indicate that Friedmann-like cosmologies with weak torsion are generally stable attractors, either asymptotically or in the Lyapunov sense. In addition, depending on the equation of state of the matter, the equilibrium states can also act as intermediate saddle points, marking a transition from a torsional to a torsion-free universe.