Scientists are preparing to measure the inertial rotation of Earth using an underground laser-based gyroscope. The goal is to reveal fluctuations in Earth's rate of rotation and confirm a component of the theory of relativity known as the Lense-Thirring effect.
"This effect is detectable as a small difference between Earth's rotation rate value measured by a ground based observatory and the value measured in an inertial reference frame," Jacopo Belfi, researcher at the Italian National Institute for Nuclear Physics, said in a news release. "This small difference is generated by Earth's mass and angular momentum and has been foreseen by Einstein's general theory of relativity."
In order for scientists to directly observe the Lense-Thirring effect, they must measure Earth's rotation rate vector with extreme precisions -- with a "relative accuracy better than one part per billion," Belfi said.
Astronomers at the INFN's Laboratori Nazionali del Gran Sasso hope their Gyroscopes in General Relativity program will allow them to do just that.
Eventually, the program will boast several ring laser gyroscopes buried beneath Earth's surface. So far, just one -- the single-axis GINGERino instrument -- has been installed in the subterranean lab. The installation was detailed this week in the journal Review of Scientific Instruments.
The gyroscopes, or RLGs, will be able to measure the rotation of Earth's surface with unprecedented precision -- and without interference from surface-level disturbances like those from hydrology, temperature or barometric pressure changes.
Initially, GINERino and its companions will be focused on measuring Earth's rotational forces within an astronomical and relativistic context. But scientists say the instruments could be used for research in geophysics and volcanology.
"One peculiarity of the GINGERino installation is that it's intentionally located within a high seismicity area of central Italy," Belfi added. "Unlike other large RLG installations, GINGERino can actually explore the seismic rotations induced by nearby earthquakes."