Prior to expansion the inflaton field had a large potential energy. I wonder whether there are any considerations or calculations to evaluate how to this energy curves the space created by the big bang. Does it make sense at all to talk about critical vs. actual energy density, the value of the Hubble-Parameter, any time dependence of the scale factor, ... regarding that era? The big bang was hot and dense. Was does this mean, having in mind that the decay of the inflaton field into particles and radiation happened later? Naively but probaly wrong I would say hot and dense means positive curvature. But perhaps, as the nature of said scalar field isn't known, one can only speculate. Dense should mean pressure. Was there already negative pressure or only later, when the expansion was driven exponentially?