Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Why the Entropy of a Black Hole is $A/4$?   A black hole considered as a part of a thermodynamical system possesses the
Bekenstein-Hawking entropy $S_H =A_H /(4l_{\mbox{\scriptsize{P}}}^2)$, where
$A_H$ is the area of a black hole surface and $l_{\,\mbox{\scriptsize{P}}}$ is
the Planck length. Recent attempts to connect this entropy with dynamical
degrees of freedom of a black hole generically did not provide the universal
mechanism which allows one to obtain this exact value. We discuss the relation
between the 'dynamical' contribution to the entropy and $S_H$, and show that
the universality of $S_H$ is restored if one takes into account that the
parameters of the internal dynamical degrees of freedom as well as their number
depends on the black hole temperature.

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The categories of this paper are: math
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The categories of this paper are: solv-int
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The categories of this paper are: funct-an
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The categories of this paper are: cond-mat
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The categories of this paper are: math-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: econ
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The categories of this paper are: comp-gas
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The categories of this paper are: nlin
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The categories of this paper are: hep-th
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The categories of this paper are: cmp-lg
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The categories of this paper are: stat
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The categories of this paper are: q-bio
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The categories of this paper are: ao-sci
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The categories of this paper are: q-fin