Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On two pictures in the heuristic approach to gravity   We examine the heuristic approach to constant gravitational field by Dehnen,
H\"onl and Westpfahl, extending it everywhere beyond linear approximation. Then
it becomes flexible to accommodate possible modifications of General
Relativity. We have found that two pictures introduced in the related paper by
Thirring are helpful in better understanding some features of gravitation. In
particular, this approach suggest that the privileged system for constant
gravitational field must be the isotropic one and that the requirement of gauge
invariance in gravitation theory may be a luxury; it is sufficient to take care
that the nonphysical degrees of freedom do not invalidate calculations. It
follows from this approach that gravitational constant should depend on
gravitational field and some universality in the form of metric of an
asymmetric body is suggested.

13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
26
The categories of this paper are: bayes-an
33
The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
27
The categories of this paper are: comp-gas
15
The categories of this paper are: nucl-ex
14
The categories of this paper are: math-ph
4
The categories of this paper are: cond-mat
12
The categories of this paper are: nucl-th