Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Analogy between freezing lakes and the cosmic radiation era   An equation describing a one-dimensional model for the freezing of lakes is
shown to be formally analogous to the Friedmann equation of cosmology. The
analogy is developed and used to speculate on the change between two
hypothetical "spacetime phases" in the early universe.

32
The categories of this paper are: atom-ph
30
The categories of this paper are: q-alg
28
The categories of this paper are: alg-geom
16
The categories of this paper are: stat
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
23
The categories of this paper are: solv-int
8
The categories of this paper are: hep-ex
24
The categories of this paper are: dg-ga
13
The categories of this paper are: quant-ph
21
The categories of this paper are: adap-org
22
The categories of this paper are: chao-dyn
14
The categories of this paper are: math-ph
19
The categories of this paper are: eess
37
The categories of this paper are: supr-con
33
The categories of this paper are: plasm-ph