Next step in gravity and cosmology: fundamental theory or data-driven models?

TL;DR

This paper discusses the debate between data-driven and fundamental theory-based cosmological models, examining their roles, strengths, and future research directions in understanding inflation, dark energy, and gravitational waves.

Contribution

It provides a comparative analysis of bottom-up and top-down cosmological models, highlighting their current status, predictive capabilities, and implications for future research.

Findings

Bottom-up models like $f(R)$, Horndeski, DHOST are widely used in data analysis.

Fundamental quantum gravity models offer a different approach but are less developed.

The paper emphasizes the importance of balancing both approaches for progress.

Abstract

We comment on the difference between bottom-up (i.e., data-driven, ad hoc) and top-down (i.e., derived from a fundamental theory of gravitational interactions) cosmological models, their respective status, predictive power and viability. We fuel the debate on whether present and future research on theoretical models of inflation, dark energy and gravitational waves should concentrate on bottom-up models such as $f(R)$, Horndeski or DHOST theories or on cosmological models of quantum gravity.