Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Testing General Relativity on the Largest Scales in the Years 1915-1955:
  the Dawning of Modern Cosmology   Soon after he proposed three classic observational tests for the general
theory of relativity, Einstein realised that a consistent description of the
universe as a whole provided another important challenge for the theory. In
this essay, we recall how general relativity found important application in the
nascent field of cosmology, from the static models of Einstein and de Sitter to
the expanding cosmologies of Friedmann and Lemaitre. By the early 1930s, the
first tentative astronomical evidence of cosmic expansion had trigged a
paradigm shift to dynamic cosmologies, almost all of which were couched firmly
within the framework of general relativity. However, further progress was
impeded for some years by a paucity of observational data. In the 1950s, the
debate between steady-state and big bang models of the universe provided a new
stimulus for the quest to determine key parameters of relativistic models of
the cosmos by astronomical observation, setting the stage for today's precision
cosmology.

6
The categories of this paper are: astro-ph
35
The categories of this paper are: mtrl-th
32
The categories of this paper are: atom-ph
0
The categories of this paper are: hep-ph
33
The categories of this paper are: plasm-ph
21
The categories of this paper are: adap-org
8
The categories of this paper are: hep-ex
18
The categories of this paper are: econ
17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph
19
The categories of this paper are: eess