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GR: Fachverband Gravitation und Relativitätstheorie
GR 15: Classical Theory of General Relativity
GR 15.2: Vortrag
Donnerstag, 14. März 2024, 14:20–14:40, HBR 14: HS 2
General Relativistic Chronometry from Ground and in Space — •Dennis Philipp1,2, Eva Hackmann1, Jan Hackstein1, and Claus Lämmerzahl1,2 — 1ZARM, University of Bremen, Germany — 2Gauss-Olbers Center, University of Bremen, Germany
One of the main tasks of geodesy is to determine the gravity field of the Earth from measurements based on ground and in space.
General relativistic geodesy allows for an entirely new perspective and high-precision clock comparison has the potential to provide a new tool in the global determination of the Earth's gravito-electric potential based on the gravitational redshift. Toward this clock-based gravimetry, i.e., chronometry in stationary spacetimes, exact expressions for the relativistic redshift and the timing between observers in various configurations are discussed. These observers are assumed to be equipped with standard clocks and move along arbitrary worldlines. It is shown how redshift measurements, involving clocks on ground and/or in space, can be used to determine the (mass) multipole moments of the underlying spacetime geometry. Our results are in agreement with the Newtonian potential determination from, e.g., the energy approach in conventional geodesy. The framework of chronometric geodesy is presented and exemplified in different exact vacuum spacetimes for illustration. Gravity degrees of freedom, also involving gravito-magnetic contributions, are studied and potential experiments for their determination are investigated. Future gravity field recovery missions may use clock comparisons as an additional source for advanced data fusion.