Around-the-World Relativistic Sagnac Experiment.

Area of Science:

• Relativity and Geophysics
• Satellite Navigation Systems

Background:

• The Hafele-Keating experiment in 1971 demonstrated the Sagnac effect using portable atomic clocks.
• The Sagnac effect is a consequence of Earth's rotation and is predicted by special relativity.
• Previous methods relied on physical transport of clocks, limiting precision and accessibility.

Purpose of the Study:

• To perform an around-the-world Sagnac effect experiment using electromagnetic signals.
• To compare the precision of electromagnetic signal-based measurements with traditional clock-based methods.
• To leverage Global Positioning System (GPS) technology for relativistic measurements.

Main Methods:

• Utilized GPS satellites transmitting signals observable from multiple remote ground stations.
• Conducted an around-the-world experiment by analyzing the timing of these electromagnetic signals.
• Compared signal travel times to detect the Sagnac effect, accounting for Earth's rotation.

Main Results:

• Successfully observed and quantified the Sagnac effect using GPS signals.
• The measured Sagnac effect was larger compared to experiments using portable atomic clocks.
• Achieved a high average accuracy of only 5 nanoseconds over a 3-month experimental period.

Conclusions:

• Electromagnetic signals from GPS satellites provide a viable and more precise method for verifying relativistic effects like the Sagnac effect.
• This approach offers a novel way to conduct global-scale relativity experiments.
• The high accuracy demonstrates the potential of modern navigation systems for fundamental physics research.