Controlled experiments are very rare if you are talking about gravity, since the force is so weak. Observational experiments (astronomy) is where most of the ev

Controlled experiments are very rare if you are talking about gravity, since the force is so weak. Observational experiments (astronomy) is where most of the evidence comes from. The most obvious inclusion of it for me is the radiative (also known as the photon) component of the matter density in Lambda CDM models (that is, they need to account for the proportion of the energy density of the universe which is related to electromagnetic fields to rule it out as dark matter).