Oscillating universe in massive bigravity

12 May 2019  ·  Mousavi M., Darabi F. ·

In this paper, in the framework of massive bigravity, we study all possible cosmic evolutions by using a method in which the modified Friedmann equation is written in a form where the scale factor evolves like the motion of a particle under a "potential". Massive bigravity provides this potential with the most general mass interaction term which can create new circumstances to find different kinds of cosmological evolutions in the early universe... We classify all possible cosmic evolutions according to the classifications of the energy density as dust, radiation and dust with phantom. Oscillating universe and Einstein static state which exist initially may show a useful property of early universe, obtained in this model, in which the initial singularity is avoided. Bouncing universe extracted in the massive bigravity model can present a reasonable cosmic evolutionary behavior having a big bang initial point with expansion phase and switching to contraction phase leading to final big crunch point. The large-valued graviton mass $m$ in the early times causes a very small $a_{\rm{S}}$ (The Einstein static state scale factor) and $\lambda=\rho_{0}a_{0}^{3}$ a constant parameter constructed of the present day energy density and scale factor, respectively. read more

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General Relativity and Quantum Cosmology