Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: New Constraints on Varying Alpha   I briefly present some current theoretical motivations for time or space
variations of the fundamental constants of nature and review current key
observational results. I focus on the fine-structure constant, and particularly
on measurements using quasars and the cosmic microwave background. I also
compare various observational results to the simplest model-building
expectations.

29
The categories of this paper are: funct-an
19
The categories of this paper are: eess
28
The categories of this paper are: alg-geom
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
35
The categories of this paper are: mtrl-th
9
The categories of this paper are: nlin
27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
16
The categories of this paper are: stat
26
The categories of this paper are: bayes-an
11
The categories of this paper are: hep-lat
30
The categories of this paper are: q-alg
1
The categories of this paper are: cs
4
The categories of this paper are: cond-mat
32
The categories of this paper are: atom-ph