An exposition on Friedmann cosmology with negative energy densities

@article{Nemiroff2015AnEO,
  title={An exposition on Friedmann cosmology with negative energy densities},
  author={Robert J. Nemiroff and Ravi Joshi and Bijunath R. Patla},
  journal={Journal of Cosmology and Astroparticle Physics},
  year={2015},
  volume={2015},
  pages={006-006}
}
How would negative energy density affect a classic Friedmann cosmology? Although never measured and possibly unphysical, certain realizations of quantum field theories leaves the door open for such a possibility. In this paper we analyze the evolution of a universe comprising varying amounts of negative energy forms. Negative energy components have negative normalized energy densities, Ω 1/3. Assuming that such energy forms generate pressure like perfect fluids, the attractive or repulsive… 
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