Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On Back-reaction in Special Relativity   Back-reaction of fields plays an important role in the generation of particle
masses and the mass-energy equivalence of special relativity, but the most
natural demonstrations using classical models result in apparent errors such as
the notorious "4/3" problem. Here we discuss the resolution of these
discrepancies within the underlying atomic description of matter, with the aim
of encouraging classroom discussion of back-reaction and its connection to
relativistic effects.

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The categories of this paper are: hep-ph
16
The categories of this paper are: stat
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys
22
The categories of this paper are: chao-dyn
6
The categories of this paper are: astro-ph
27
The categories of this paper are: comp-gas
36
The categories of this paper are: cmp-lg
10
The categories of this paper are: q-bio
25
The categories of this paper are: patt-sol
24
The categories of this paper are: dg-ga
8
The categories of this paper are: hep-ex
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom