# New views on the low-energy side of gravity

## TL;DR

This paper explores low-energy modifications of gravity using quantum informational approaches, questioning the traditional geometric description and examining implications for cosmology and dark energy.

## Contribution

It introduces a quantum subsystem perspective to gravity, proposing alternative localization schemes and potential breakdown of the metric manifold at large scales.

## Key findings

- Standard localization aligns with semi-classical gravity.
- Alternative localization schemes have significant implications.
- Infra-red breakdown of the metric manifold may impact cosmological models.

## Abstract

Common wisdom associates all the unraveled and theoretically challenging aspects of gravity with its UV-completion. However, there appear to be few difficulties afflicting the effective framework for gravity already at low energy, that are likely to be detached from the high-energy structure. Those include the black hole information paradox, the cosmological constant problem and the rather involved and fine tuned model building required to explain our cosmological observations. I review some on-going research that aims to generalize and extend the low-energy framework for gravity. In a quantum informational fashion, regions of space at a given time are treated and described as quantum subsystems, rather than submanifolds. The idea is to define a region of space through the quantum degrees of freedom of the matter fields "living therein". I show how the correspondence sub-system/sub-manifold is realized in standard semi-classical gravity ("standard localization") and discuss the implications of alternative localization schemes. By exploiting further the subsystem description, I then consider the possibility that the usual GR metric manifold description might break down in the infra-red. This has implications on the description of the Universe on the largest scales and on dark energy.