Abstract Testing General Relativity (GR) is a key goal for several fields in modern physics, and is usually done in a way that is either theory or context specific. We improve on this situation by using the ‘Parametrized Post-Newtonian Cosmology’ (PPNC) approach as an holistic framework to obtain theory-agnostic constraints on deviations from GR using data from all astrophysical and cosmological scales. This allows us to combine observations of the Cosmic Microwave Background (CMB) with Baryon Acoustic Oscillations (BAOs) and Solar System observations of the Cassini probe and the ephemeris of Mars in a way which has not previously been possible. The full combination of these data sets constrains average deviations from GR over the history of the Universe to be less than ~10 %, with PPNC parameter values =0. 97{+0. 06 -0. 07} and =0. 97{+0. 05 -0. 05} at the 68 % confidence level (GR corresponds to = =1). Our results demonstrate the ability of the PPNC framework to successfully combine Solar System and cosmological tests of gravity into a single set of unified constraints, thereby getting the best of the constraining power from both environments. We expect our approach to be particularly useful for upcoming missions in both cosmology and astrophysics, which ultimately seek to constrain the same underlying gravitational interaction.
Thomas et al. (Wed,) studied this question.