Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Anisotropy of the Cosmic Background Radiation implies the Violation of
  the Strong Energy Condition in Bianchi type I Universe   We consider the horizon problem in a homogeneous but anisotropic universe
(Bianchi type I). We show that the problem cannot be solved if (1) the matter
obeys the strong energy condition with the positive energy density and (2) the
Einstein equations hold. The strong energy condition is violated during
cosmological inflation.

28
The categories of this paper are: alg-geom
30
The categories of this paper are: q-alg
9
The categories of this paper are: nlin
27
The categories of this paper are: comp-gas
2
The categories of this paper are: math
20
The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an
16
The categories of this paper are: stat
4
The categories of this paper are: cond-mat
35
The categories of this paper are: mtrl-th
32
The categories of this paper are: atom-ph
14
The categories of this paper are: math-ph
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
10
The categories of this paper are: q-bio
17
The categories of this paper are: q-fin