The cosmological backreaction: gauge (in)dependence, observers and
  scalars
  We discuss several issues related to a recent proposal for defining classical
spatial averages to be used in the so-called cosmological backreaction problem.
In the large averaging-volume limit all gauge dependence disappears and
different averages can be univocally characterized by the observers associated
with different scalar fields. The relation between such averaging procedure and
the standard one is emphasized and a gauge invariant way to select different
observers is presented. For finite averaging volumes we show that, within our
proposal, a residual gauge dependence is left, but is suppressed by several
effects.
