Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gravity as the breakdown of conformal invariance   We propose that at the beginning of the universe gravity existed in a limbo
either because it was switched off or because it was only conformally coupled
to all particles. This picture can be reverse-engineered from the requirement
that the cosmological perturbations be (nearly) scale-invariant without the
need for inflation. It also finds support in recent results in quantum gravity
suggesting that spacetime becomes two-dimensional at super-Planckian energies.
We advocate a novel top-down approach to cosmology based on the idea that
gravity and the Big Bang Universe are relics from the mechanism responsible for
breaking the fundamental conformal invariance. Such a mechanism should leave
clear signatures in departures from scale-invariance in the primordial power
spectrum and the level of gravity waves generated.

26
The categories of this paper are: bayes-an
32
The categories of this paper are: atom-ph
22
The categories of this paper are: chao-dyn
23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
8
The categories of this paper are: hep-ex
21
The categories of this paper are: adap-org
3
The categories of this paper are: physics
35
The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
6
The categories of this paper are: astro-ph
14
The categories of this paper are: math-ph
4
The categories of this paper are: cond-mat
10
The categories of this paper are: q-bio
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci