paper

Inflationary Models and Connections to Particle Physics

arXiv:astro-ph/0002188

Abstract

The basic workings of inflationary models are summarized, along with the arguments that strongly suggest that our universe is the product of inflation. The mechanisms that lead to eternal inflation in both new and chaotic models are described. Although the infinity of pocket universes produced by eternal inflation are unobservable, it is argued that eternal inflation has real consequences in terms of the way that predictions are extracted from theoretical models. The ambiguities in defining probabilities in eternally inflating spacetimes are reviewed, with emphasis on the youngness paradox that results from a synchronous gauge regularization technique. To clarify (but not resolve) this ambiguity, a toy model of an eternally inflating universe is introduced. Vilenkin's proposal for avoiding these problems is also discussed, as is the question of whether it is meaningful to discuss probabilities for unrepeatable measurements.

25 pages, including 5 figures, LaTeX 2.09. Review talk given at the Pritzker Symposium on the Status of Inflationary Cosmology, Chicago, Illinois, 29-31 January 1999. To appear in the proceedings. Based on astro-ph/0002156, but includes a new toy model to illustrate the difficulties in assigning probabilities in eternally inflating spacetimes, and a discussion of probabilities for unrepeatable measurements

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