Does the big rip happen in LQC?

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SUMMARY

The discussion centers on the relationship between Loop Quantum Cosmology (LQC) and the concept of the Big Rip singularity. Participants assert that the Big Rip is not a generic outcome in LQC models, as LQC introduces gravity-induced corrections that prevent singularities at high energy densities. Key contributions include the work of Param Singh, which outlines how LQC can avoid the Big Rip by ensuring energy density remains bounded near the Planck scale. The conversation also touches on speculative ideas regarding dark energy and the potential for LQC to provide a framework for understanding cosmic evolution without leading to singularities.

PREREQUISITES
  • Understanding of Loop Quantum Gravity (LQG) principles
  • Familiarity with cosmological models, specifically the LambdaCDM model
  • Knowledge of singularity types in cosmology, including Big Rip and phantom energy
  • Basic grasp of quantum corrections in high-density scenarios
NEXT STEPS
  • Read Param Singh's paper "Are loop quantum cosmos never singular?" for detailed insights on singularities in LQC
  • Explore the implications of dark energy models on cosmic expansion and singularities
  • Investigate the role of the dark energy equation of state (w) in cosmological predictions
  • Study the differences between classical and quantum cosmological models, focusing on singularity resolution
USEFUL FOR

Researchers in theoretical physics, cosmologists studying the implications of quantum gravity, and anyone interested in the interplay between dark energy and cosmic evolution.

  • #31
Hmm, right on spot. Although this paper was not related to my question, it was what made me free associate with my question.

BTW, why Marcus is ignoring me? :(
 
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  • #32
Look at what I found:

http://arxiv.org/abs/0907.5591v3

Non-singular Ekpyrotic/Cyclic model in Loop Quantum Cosmology
Authors: Thomas Cailleteau, Parampreet Singh, Kevin Vandersloot
(Submitted on 31 Jul 2009 (v1), last revised 23 Oct 2009 (this version, v3))

Abstract: We study the role of non-perturbative quantum gravity effects in the Ekpyrotic/Cyclic model using the effective framework of loop quantum cosmology in the presence of anisotropies. We show that quantum geometric modifications to the dynamical equations near the Planck scale as understood in the quantization of Bianchi-I spacetime in loop quantum cosmology lead to the resolution of classical singularity and result in a non-singular transition of the universe from the contracting to the expanding branch. In the Planck regime, the universe undergoes multiple small bounces and the anisotropic shear remains bounded throughout the evolution. A novel feature, which is absent for isotropic models, is a natural turn around of the moduli field from the negative region of the potential leading to a cyclic phenomena as envisioned in the original paradigm. Our work suggests that incorporation of quantum gravitational effects in the Ekpyrotic/Cyclic model may lead to a viable scenario without any violation of the null energy condition.
 

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