Testing gravity with photons and satellites

Our fundamental understanding of the physical universe is governed by two theories, quantum mechanics and general relativity. While there is no unified theory of quantum gravity, the two fundamental theories `peacefully coexist' in all experimentally feasible scenarios. Nevertheless there are very few situations where both quantum and general relativistic effects can be probed simultaneously. Experiments involving photons are the most promising candidates for near-future measurements that involve both theories. Recent progress towards quantum optics satellite experiments, such as QEYSSat, are a step up towards measurements of post-Newtonian effects on quantum objects. In light of these possibilities we need to carefully examine the various effects that may be detectable in a realistic experiment. Possible results of such experiments include corrections to post-Newtonian parameters, tests of the equivalence principle, and experimental insights about the interaction between quantum mechanical objects and gravity.