• DOI:10.1103/PhysRevD.61.023502
• Corpus ID: 40641378

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}
}

• T. Vachaspati, M. Trodden
• Published 11 November 1998
• Physics
• Physical Review D

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 rest on causality and general relativistic constraints on the structure of spacetime. We discuss modifications to existing scenarios that may avoid the need for initial large-scale homogeneity. (c) 1999 The American Physical Society.