Constraining Mach's principle with high precision astrometry

The analyses of high precision astrometric surveys, such as Gaia, implicitly assume a modern version of Mach's Principle: the local inertial frame of our Solar System should be non-rotating in the frame of distant quasars. On the contrary, Einstein's General Relativity allows a rotating universe. Thus, relaxing the assumption of Mach's Principle will allow placing a constraint on a class of rotating cosmologies by comparing high precision astrometry of quasars with well-measured solar system orbits. Constraining global rotation will test General Relativity, inflation, and the isotropy of cosmological initial conditions.