Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dust ball physics and the Schwarzschild metric   A physics-first derivation of the Schwarzschild metric is given. Gravitation
is described in terms of the effects of tidal forces (or of spacetime
curvature) on the volume of a small ball of test particles (a dust ball),
freely falling after all particles were at rest with respect to each other
initially. The possibility to express Einstein's equation this way and some of
its ramifications have been enjoyably discussed by Baez and Bunn [Am. J. Phys.
73, 644 (2005)]. Since the formulation avoids the use of tensors, neither
advanced tensor calculus nor sophisticated differential geometry are needed in
the calculation. The derivation is not lengthy and it has visual appeal, so it
may be useful in teaching.

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The categories of this paper are: hep-ph
1
The categories of this paper are: cs
28
The categories of this paper are: alg-geom
23
The categories of this paper are: solv-int
29
The categories of this paper are: funct-an
9
The categories of this paper are: nlin
24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
12
The categories of this paper are: nucl-th
36
The categories of this paper are: cmp-lg
21
The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex
15
The categories of this paper are: nucl-ex