Large Deviations and the Fate of the Universe

Tim Cohen (CERN)

July 03, 2024

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Abstract: The standard picture of inflation is characterized by a phase of exponential expansion followed by an epoch of reheating (aka the Big Bang). However, a natural consequence of inflationary models is the radical notion of “eternal inflation”, a hypothetical phase of the Universe where there are always patches that are inflating. In this talk, we apply the state of the art theoretical tool known as the Soft de Sitter Effective Theory to attempt to address if our Universe is eternally inflating. To our surprise, we find that the answer to this question requires knowledge of the complete microscopic theory, and is therefore incalculable within the effective description. Using the Soft de Sitter Effective Theory to determine the stochastic fluctuations of the inflation will inspire connections with the fascinating theory of Large Deviations, which in turn will allow us to diagnose the validity of our calculations and will point us in new directions for future explorations.