Inflation and Reheating \({[M_P \rightarrow T_{RH}]}\)

The inflation and reheating phase of the Universe concern a period where the Universe changes very quickly from a vacuum/constant density domination, to a oscillation/matter domination, then radiation domination. These transitions are not only fast but also violent. We will analyze in detail each of these phases, insisting on the possibility of producing dark matter before reaching the thermal equilibrium. But before, one needs to understand the equation that will lead our expanding Universe: the Hubble law.