Introduction to part III

Abstract

Combining measurements with observations of the large scale structure coming from surveys which will probe the Universe in different scale regimes as compared to the size of the horizon, is a crucial step. Cosmology is (among others) our gravity laboratory. Hence, detailed investigation of the cosmological applications of various theories of gravity, and the extraction of suitable observational discriminators, can provide valuable knowledge. The impacts of deviations from General Relativity on cosmological observables stats by studying the cosmic microwave background (CMB) and cosmic large-scale structure (LSS). Different modified gravity theories can be degenerate with regard to both the background cosmology and the growth rate of linear perturbations. We list the various observational discriminators used in cosmology, aiming to predict possible smoking guns of modified gravity.