Time asymmetric extensions of general relativity

@article{Corts2015TimeAE,
  title={Time asymmetric extensions of general relativity},
  author={Marina Cort{\^e}s and Henrique Gomes and Lee Smolin},
  journal={Physical Review D},
  year={2015},
  volume={92},
  pages={043502}
}
We describe a class of modified gravity theories that deform general relativity in a way that breaks time reversal invariance and, very mildly, locality. The algebra of constraints, local physical degrees of freedom, and their linearized equations of motion, are unchanged, yet observable effects may be present on cosmological scales, which have implications for the early history of the universe. This is achieved in the Hamiltonian framework, in a way that requires the constant mean curvature… 

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