Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Does the growth of structure affect our dynamical models of the
  universe? The averaging, backreaction and fitting problems in cosmology   Structure occurs over a vast range of scales in the universe. Our large-scale
cosmological models are coarse-grained representations of what exists, which
have much less structure than there really is. An important problem for
cosmology is determining the influence the small-scale structure in the
universe has on its large-scale dynamics and observations. Is there a
significant, general relativistic, backreaction effect from averaging over
structure? One issue is whether the process of smoothing over structure can
contribute to an acceleration term and so alter the apparent value of the
cosmological constant. If this is not the case, are there other aspects of
concordance cosmology that are affected by backreaction effects? Despite much
progress, this 'averaging problem' is still unanswered, but it cannot be
ignored in an era of precision cosmology.

3
The categories of this paper are: physics
8
The categories of this paper are: hep-ex
13
The categories of this paper are: quant-ph
9
The categories of this paper are: nlin
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con
20
The categories of this paper are: acc-phys
33
The categories of this paper are: plasm-ph
11
The categories of this paper are: hep-lat
24
The categories of this paper are: dg-ga
4
The categories of this paper are: cond-mat
28
The categories of this paper are: alg-geom
16
The categories of this paper are: stat
10
The categories of this paper are: q-bio