GPS observables: theoretical motivations and origin of the Relativistic Positioning Systems
- Carlo Rovelli
Centre de Physique Theorique de Luminy, Aix Marseille University
Relativistic Positioning Systems may have concrete scientific and technological applications. But one of the sources of the idea of Relativistic Positioning Systems is entirely theoretical. They were introduced to solve a longstanding open issue in general relativity: finding gauge-invariant observables which are local in an appropriate physical sense, and sufficiently realistic. I will review this theoretical conceptual foundation of the idea of the Relativistic Positioning Systems.