Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Fixing extensions to General Relativity in the non-linear regime   The question of what gravitational theory could supersede General Relativity
has been central in theoretical physics for decades. Many disparate
alternatives have been proposed motivated by cosmology, quantum gravity and
phenomenological angles, and have been subjected to tests derived from
cosmological, solar system and pulsar observations typically restricted to
linearized regimes. Gravitational waves from compact binaries provide new
opportunities to probe these theories in the strongly gravitating/highly
dynamical regimes. To this end however, a reliable understanding of the
dynamics in such a regime is required. Unfortunately, most of these theories
fail to define well posed initial value problems, which prevents at face value
from meeting such challenge. In this work, we introduce a consistent program
able to remedy this situation. This program is inspired in the approach to
"fixing" viscous relativistic hydrodynamics introduced by Israel and Stewart in
the late 70's. We illustrate how to implement this approach to control
undesirable effects of higher order derivatives in gravity theories and argue
how the modified system still captures the true dynamics of the putative
underlying theories in 3+1 dimensions. We sketch the implementation of this
idea in a couple of effective theories of gravity, one in the context of
Non-commutative geometry, and one in the context of Chern-Simons modified
General Relativity.

31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
27
The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio
35
The categories of this paper are: mtrl-th
15
The categories of this paper are: nucl-ex
29
The categories of this paper are: funct-an
36
The categories of this paper are: cmp-lg
8
The categories of this paper are: hep-ex
17
The categories of this paper are: q-fin
26
The categories of this paper are: bayes-an
20
The categories of this paper are: acc-phys
28
The categories of this paper are: alg-geom
24
The categories of this paper are: dg-ga
1
The categories of this paper are: cs
9
The categories of this paper are: nlin