  We investigate the averaging problem in cosmology as the problem of
introducing a distance between spaces.
  We first introduce the spectral distance, which is a measure of closeness
between spaces defined in terms of the spectra of the Laplacian. Then we define
a space S, the space of all spaces equipped with the spectral distance. We
argue that this space S can be regarded as a metric space and that it also
possess other desirable properties. These facts make the space S a suitable
arena for spacetime physics.
  We apply the spectral framework to the averaging problem:
  We sketch the model-fitting procedure in terms of the spectral
representation, and also discuss briefly how to analyze the dynamical aspects
of the averaging procedure with this scheme.
  In these analyses, we are naturally led to the concept of the apparatus- and
the scale-dependent effective evolution of the universe. These observations
suggest that the spectral scheme seems to be suitable for the quantitative
analysis of the averaging problem in cosmology.
