Abstract
We present a flat emergent universe (EU) in Einstein gravity with non-linear equation of state (nEoS) in the usual four and in higher dimensions. The EU is assumed to evolve from an initial Einstein’s static universe (ESU) in the infinite past. For a homogeneous Ricci scalar we determine the shape function and obtain a new class of dynamical wormholes that permits EU. The nEoS p= Arho -B sqrt{rho _o rho } is equivalent to three different cosmic fluids which is identified with barotropic fluid for a given A. We obtain EU models in flat, closed and open universes and tested the null energy condition (NEC). At the throat of the wormhole which is recognized as the seed of ESU, we tested the NEC for a given size of the neck. As the EU evolves from an asymptotic past and approaches t=0, it is found that NEC does not respect. This triggers the onset of interactions at t=t_i, and a realistic flat EU scenario can be obtained in four and in higher dimensions. The origin of the ESU at the throat of the wormhole is also explored via a gravitational instanton mechanism. We compare the relative merits of dynamical wormholes for implementing EU.
Highlights
=claAssρo−f dBy√naρmoρicaisl equivalent to three different cosmic fluids which is identified with barotropic fluid for a given A
In this paper we extend the analysis of dynamical wormholes in a higher dimensional General Theory of Relativity (GR) with non-linear equation of state to explore the origin of an emergent universe
In the emergent universe (EU) scenario [66,67,68,69] one of the basic assumption is that the present universe emerged from an Einstein static universe (ESU) in the infinite past. We demonstrate that such a early Einstein static universe at infinite past exists and it may be the throat of the wormhole which evolves
Summary
It is known that in GR, Lorentzian wormhole solution exists when the matter energy condition is violated. The matter sector of the Einstein gravity supporting such geometries violates the null energy condition (NEC) at the throat of the wormhole [27,28] for its existence. In this paper we extend the analysis of dynamical wormholes in a higher dimensional GR with non-linear equation of state (nEoS) to explore the origin of an emergent universe [66] The EU model is free from Big Bang singularity assuming that the universe originated from an Einstein static universe (ESU) which will be explored. We obtain EU model using dynamical wormhole solutions permitted in the GR with nEoS It accommodates ESU in the infinite past at the throat.
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