Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Cosmic evolution from phase transition of 3-dimensional flat space   Flat space cosmology spacetimes are exact time-dependent solutions of
3-dimensional gravity theories, such as Einstein gravity or topologically
massive gravity. We exhibit a novel kind of phase transition between these
cosmological spacetimes and the Minkowski vacuum. At sufficiently high
temperature (rotating) hot flat space tunnels into a universe described by flat
space cosmology.

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The categories of this paper are: hep-ph
13
The categories of this paper are: quant-ph
9
The categories of this paper are: nlin
2
The categories of this paper are: math
4
The categories of this paper are: cond-mat
18
The categories of this paper are: econ
16
The categories of this paper are: stat
10
The categories of this paper are: q-bio
12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys
6
The categories of this paper are: astro-ph
21
The categories of this paper are: adap-org
22
The categories of this paper are: chao-dyn
36
The categories of this paper are: cmp-lg
24
The categories of this paper are: dg-ga
17
The categories of this paper are: q-fin