Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hyperbolic heat equation in Kaluza's magnetohydrodynamics   This paper shows that a hyperbolic equation for heat conduction can be
obtained directly using the tenets of linear irreversible thermodynamics in the
context of the five dimensional space-time metric originally proposed by T.
Kaluza back in 1922. The associated speed of propagation is slightly lower than
the speed of light by a factor inversely proportional to the specific charge of
the fluid element. Moreover, consistency with the second law of thermodynamics
is achieved. Possible implications in the context of physics of clusters of
galaxies of this result are briefly discussed.

2
The categories of this paper are: math
29
The categories of this paper are: funct-an
4
The categories of this paper are: cond-mat
3
The categories of this paper are: physics
25
The categories of this paper are: patt-sol
28
The categories of this paper are: alg-geom
23
The categories of this paper are: solv-int
10
The categories of this paper are: q-bio
20
The categories of this paper are: acc-phys
22
The categories of this paper are: chao-dyn
26
The categories of this paper are: bayes-an
1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph
35
The categories of this paper are: mtrl-th
0
The categories of this paper are: hep-ph
13
The categories of this paper are: quant-ph