Submitted by Kanokkuan Chaicherdsakul, Texas graduate student.

It was the asumption that there was nothing but the inflaton and gravitation before reheating. However, to have reheating, there must be other fields or fluids besides the inflaton, and these do not suddenly come into existence during reheating. The reactions that produce matter during reheating can't be completely absent beforehand, so the questions are: (1) How the energy transfer from inflaton to matter took place? (2) How large the energy transfer really is? (3) What were the particles that were first created during reheating? (4) Does the particle production affect the large scale structure of the universe?

The only thing we know about the universe is the observation at the present time and the speculation that the universe is dominated by scalar fields at the very early time. But the connection to understand these two gap periods and how vacuum energy converts to matter and radiation remains obscure. So we need the most realistics model of inflation that best describe the existence of us without artificially imposing what's not there. So, the study of conservation law (i.e., adiabatic mode of cosmological inflation) and particle production during very early time may help us to understand our origin.