Speaker
Description
The very beginning of our universe is believed to be a rapid and silent expansion, called Inflation, during which the universe stayed cold, empty, and dark without heat or light. However, before the familiar hot and dense universe (the Hot Big Bang) begins, something extraordinary had to happen: the universe needs to get ignition. This brief but turbulent transition, known as reheating, transformed the vast, cold field energy left by inflation into a hot sea of particles, setting the stage for all later cosmic evolution. Instead of a simple decay process, reheating can involve rich nonlinear dynamics, including explosive particle production, inhomogeneity and the emergence of solitons. These intense and chaotic processes may leave traces in the form of gravitational waves or subtle signatures in the early matter distribution, which are potentially to be detected by the future observations. In this talk, I will explore how the universe gain its warmth, how the complicated dynamics set the precise initial conditions for the Hot Big Bang, and why this hidden era matters for understanding the cosmic history we observe today.