  For simple inflationary models, we provide a consistent and complete scheme
by which the macro-physical details of early universe inflation may be
determined explicitly from the underlying micro-physical theory. We examine
inflationary dynamics within the context of a fully renormalized,
non-perturbative, and non-equilibrium quantum field theory using the closed
time path formalism. We study the non-perturbative dynamics using the
self-consistent Hartree approximation and the large N limit. In addition, we
include gravitation dynamically by means of the semi-classical approximation to
Einstein gravity, allowing the cosmological geometry to be determined
self-consistently by the evolution of the particle fields. We develop a simple
and numerically implementable regularization and renormalization scheme for
which the renormalization counterterms contain no explicit dependence on the
initial state.
  We concern ourselves first with the dynamics of new inflation models, showing
how the dynamics become quantum fluctuation driven. We then describe how these
quantum fluctuations may be reassembled into an effective field which behaves
classically and acts as the source for the gravitational background. This
allows us to determine the spectrum of primordial density perturbations in a
consistent manner. We also examine explosive particle production after
inflation through the processes of spinodal decomposition and parametric
amplification, showing that the non-perturbative backreaction on the inflaton
field prevents catastrophic particle production. We find a strong dependence of
particle production on the expansion rate and on the symmetry properties of the
inflaton.
