Spin-rotation coupling effects on the structure formation in Godel universe and COBE data

摘要

A rotating universe represented by the Godel metric in spacetimes with Cartan torsion is investigated. The spin-torsion coupling is shown to contribute to the structure formation in an apppreciable way only at the early stages of the universe. To demonstrate these conjectures, we have made use of a spinning fluid model in Einstein-Cartan gravity. We also show that autoparallel equation in Riemann-Cartan spacetime leads to the evolution equation of the cosmological perturbation where the spin-rotation coupling contributes to the growth of inhomogeneities through a constant term. From this idea, one is able to estimate that torsion in the Planck era is around 10(15)s(-1) where COBE constraint on temperature fluctuations is used in this computation. A spin density of the universe of 10(53) g (.) cm(-1)s(-1) is also obtained in our framework. [References: 12]