Current understanding of the Big Bang is incomplete. Gaps in the cosmological model need some explanation in order to verify what we think we know about the Universe as it exists today. Inflation, a period of accelerated expansion in the early stages of the Universe, is one theory we apply to the Big Bang model in order to cover these gaps in our understanding. However, inflation is not a perfect fix. Though inflationary theory does well to ‘solve’ the major issues with Big Bang cosmology (i.e. the horizon, flatness, and monopole problems), there is still little explanation for the region of time in which the Universe goes from being cold due to accelerated expansion to having thermalized and formed cohesive Standard Model particles. Preheating is a nonlinear process that follows the final stages of inflation in which the energy responsible for driving the expansion of space-time is redeposited into the Universe in the form of radiation and matter. Modelling these nonlinear processes allows us to simulate and study the deviation of these results from traditional inflationary models; we can then determine whether nonlinearity maintains the fundamental truths of cosmological theory and use this to leverage further investigations of the origins of the Universe as we see it today.
Jackson, Natalie and Giblin, Tom, "Effects of Nonlinear Processes in Cosmological Preheating" (2022). Kenyon Summer Science Scholars Program. Paper 561.