  We study the evolution of quantum fluctuations of a scalar field which is
coupled to the geometry, in an exponentially expanding universe.
  We derive an expression for the spectrum of intrinsic perturbations, and it
is shown that the intrinsic degrees of freedom are well behaved in the
infra-red part of the spectrum. We conclude that quantum fluctuations do not
change the dynamics of the spacetime in a way which makes its evolution
non-perturbative and stochastic.
  This result contradicts previous derivations which are based on the study of
a quantum field on a fixed geometry.
