Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gravity as an emergent phenomenon: experimental signatures   According to some authors, gravity might be an emergent phenomenon in a
fundamentally flat space-time. In this case the speed of light in the vacuum
would not coincide exactly with the basic parameter "c" entering Lorentz
transformations and, for an apparatus placed on the Earth's surface, light
should exhibit a tiny fractional anisotropy at the level 10^{-15}. We argue
that, most probably, this effect is now observed in many room-temperature
ether-drift experiments and, in particular, in a very precise cryogenic
experiment where this level of signal is about 100 times larger than the
designed short-term stability. To fully appreciate what is going on, however,
one should consider the vacuum as a true physical medium whose fundamental
quantum nature gives rise to the irregular, non-deterministic pattern which
characterizes the observed signal.

25
The categories of this paper are: patt-sol
29
The categories of this paper are: funct-an
17
The categories of this paper are: q-fin
2
The categories of this paper are: math
30
The categories of this paper are: q-alg
26
The categories of this paper are: bayes-an
0
The categories of this paper are: hep-ph
35
The categories of this paper are: mtrl-th
7
The categories of this paper are: hep-th
20
The categories of this paper are: acc-phys
22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas
13
The categories of this paper are: quant-ph
37
The categories of this paper are: supr-con
3
The categories of this paper are: physics
15
The categories of this paper are: nucl-ex