Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Three tests of general relativity via Fermat's principle and the phase
  of Bessel functions   Fermat's principle applied to a flat metric in the plane yields the phase of
a Bessel function in the periodic domain for a constant index of refraction.
Gravitational forces cause the index of refraction to vary and lead to a
modified phase of the Bessel function. A distinction is made between the forces
that cause acceleration: the gravitational force affects the optical properties
of the medium whereas the centrifugal force does not, the latter being built
into the phase of oscillations of the Bessel function. The time delay in radar
echoes from planets is determined from Fermat's principle where the velocity of
light is the phase velocity and the index of refraction varies on account of
the gravitational potential. The deflection of light by a massive body is shown
to be produced by a quadrupole interaction, and the perihelion shift requires
both the gravitational potential, producing a closed orbit, and the quadrupole,
causing the perihelion to rotate.

32
The categories of this paper are: atom-ph
36
The categories of this paper are: cmp-lg
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
23
The categories of this paper are: solv-int
7
The categories of this paper are: hep-th
16
The categories of this paper are: stat
24
The categories of this paper are: dg-ga
13
The categories of this paper are: quant-ph
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
10
The categories of this paper are: q-bio
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph