Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Time dilation and length contraction without relativity: The Bohr atom
  and the semi-classical hydrogen molecule ion   Recently it was shown that classical "relativistic" particle dynamics was
implicit in physics going back to Maxwell. The demonstration utilized a simple
modification of a 1906 thought experiment by which Einstein established the
mass equivalence of energy, independently of the relativity postulates. The
modified thought experiment leads directly to correct expressions for the
momentum and kinetic energy of a particle at high speed. In the present paper,
one additional ingredient is added, namely, the Bohr quantization rule of the
old quantum theory. It is found that a semi-classical model of a hydrogen atom
and a hydrogen molecule ion exhibit, respectively, time dilation and length
contraction.

1
The categories of this paper are: cs
30
The categories of this paper are: q-alg
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
0
The categories of this paper are: hep-ph
33
The categories of this paper are: plasm-ph
4
The categories of this paper are: cond-mat
23
The categories of this paper are: solv-int
8
The categories of this paper are: hep-ex
34
The categories of this paper are: chem-ph
16
The categories of this paper are: stat
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
31
The categories of this paper are: ao-sci
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex