Measuring global gravity-inertial effects with ring laser interferometers

We discuss advances achieved over the past 20 years in physical experiments on measuring the gravity-inertial background of Earth's surface associated with astrodynamical, geodynamical, and geophysical effects generated by Earth's internal gravity and thermodynamics and by its diurnal and orbital rotation. We discuss a unique instrument, a large-scale Sagnac ring laser interferometer, with a record high sensitivity to variations in the rotation rate and inclination of the laboratory reference frame, as well as to the rotational asymmetry of the optical refractive index of a medium, including a vacuum. These tools allow obtaining knowledge that is simultaneously valuable for elementary particle physics, quantum field theory, laser physics, astrometry, global geodynamics, and seismology. Applications may consist in an early forecast of global cataclysms such as earthquakes and progress in the metrology of angular measurements.