Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spontaneous Symmetry Breaking Breaks Time-Reversal Symmetry   The ideas related to the arrow of time are discussed briefly. I then focus on
the prevalent physical mechanism in the evolution of the universe and
developments in particle physics, spontaneous symmetry breaking, and show that
it explicitly breaks time-reversal symmetry. For simplicity, I do this in a
point mechanics gauge theory with symmetry group O(2). The proof of breakdown
of time-reversal symmetry relies on the use of a time step function to express
the Lagrangian valid for any time.

29
The categories of this paper are: funct-an
34
The categories of this paper are: chem-ph
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
16
The categories of this paper are: stat
18
The categories of this paper are: econ
8
The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci
19
The categories of this paper are: eess
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
6
The categories of this paper are: astro-ph
0
The categories of this paper are: hep-ph
15
The categories of this paper are: nucl-ex
20
The categories of this paper are: acc-phys