Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Thermodynamics of effective Minkowski spacetime in self-assembled
  hyperbolic metamaterials   Recent developments in gravitation theory indicate that the classic general
relativity is an effective macroscopic theory which will be eventually replaced
with a more fundamental theory based on thermodynamics of yet unknown
microscopic degrees of freedom. Here we consider thermodynamics of an effective
Minkowski spacetime which may be formed under the influence of external
magnetic field in a cobalt ferrofluid. It appears that the extraordinary
photons propagating inside the ferrofluid perceive thermal gradients in the
ferrofluid as an effective gravitational field, which obeys the Newton law.
Moreover, the effective Minkowski spacetime behaviour near the metric signature
transition may mimic various cosmological Big Bang scenarios, which may be
visualized directly using an optical microscope. Thus, some important features
of the hypothetic microscopic theory of gravity are reproduced in the
ferrofluid-based analogue model.

7
The categories of this paper are: hep-th
23
The categories of this paper are: solv-int
27
The categories of this paper are: comp-gas
19
The categories of this paper are: eess
22
The categories of this paper are: chao-dyn
26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con
21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th
24
The categories of this paper are: dg-ga
34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
2
The categories of this paper are: math
13
The categories of this paper are: quant-ph