Causality and cosmic inflation

@article{Vachaspati1998CausalityAC,
  title={Causality and cosmic inflation},
  author={Tanmay Vachaspati and Mark Trodden},
  journal={Physical Review D},
  year={1998},
  volume={61},
  pages={023502}
}
In the context of inflationary models with a pre-inflationary stage, in which the Einstein equations are obeyed, the null energy condition is satisfied, and spacetime topology is trivial, we argue that homogeneity on super-Hubble scales must be assumed as an initial condition. Models in which inflation arises from field dynamics in a Friedmann-Robertson-Walker background fall into this class but models in which inflation originates at the Planck epoch may evade this conclusion. Our arguments… 

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