I can formulate the purpose of my research as an attempt to look to the quantum gravity through both the theoretical and observational windows. My previous research was mainly dedicated to obtaining both observational predictions and theoretical constraints for the models of inflation which can be stated as 'minimal'. They contain only the fields which are proved to exist: Higgs field and gravity. As the results of this work, we proved the self-consistency and investigated the reheating mechanism in a model describing inflation driven by the interplay of Higgs and gravity. My recent research is more focused on the theoretical window to the nature of quantum gravity based on the scattering amplitudes and dispersive relations. The scattering amplitudes through the graviton exchange contain the IR singularities in forward limit. The divergences at $t\rightarrow 0$ can be cancelled in the dispersive relation only if the UV limit of the amplitude is tuned in a specific way which establishes the non-trivial connection between UV and IR forms of the amplitude. We show that this connection can be expressed in terms of the Laplace transform and it can give an information about the UV amplitude in the limit $t \log{s}\rightarrow 0$. We discuss the implications of this approach for QED with gravity.