Cyclic cosmology and geodesic completeness

@article{Kinney2021CyclicCA,
  title={Cyclic cosmology and geodesic completeness},
  author={William H. Kinney and Nina K. Stein},
  journal={Journal of Cosmology and Astroparticle Physics},
  year={2021},
  volume={2022}
}
We consider recently proposed bouncing cosmological models for which the Hubble parameter is periodic in time, but the scale factor grows from one cycle to the next as a mechanism for shedding entropy. Since the scale factor for a flat universe is equivalent to an overall conformal factor, it has been argued that this growth corresponds to a physically irrelevant rescaling, and such bouncing universes can be made perfectly cyclic, extending infinitely into the past and future. We show that any… 
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