Multiverses and physical cosmology

@article{Ellis2003MultiversesAP,
  title={Multiverses and physical cosmology},
  author={George F R Ellis and Ulrich Kirchner and William R. Stoeger},
  journal={Monthly Notices of the Royal Astronomical Society},
  year={2003},
  volume={347},
  pages={921-936}
}
The idea of a multiverse – an ensemble of universes – has received increasing attention in cosmology, both as the outcome of the originating process that generated our own universe, and as an explanation for why our universe appears to be fine-tuned for life and consciousness. Here we carefully consider how multiverses should be defined, stressing the distinction between the collection of all possible universes, and ensembles of really existing universes that are essential for an anthropic… 

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