Göttingen 2025 – scientific programme

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GR: Fachverband Gravitation und Relativitätstheorie

GR 5: CQG II

GR 5.2: Talk

Tuesday, April 1, 2025, 16:35–16:55, ZHG007

Low velocity test of the speed of gravity — Eva Hackmann and •Claus Lämmerzahl — ZARM and GOC, University of Bremen, Bremen, Germany

The weak field approximation of the Einstein field equations are similar to the Maxwell equations. Furthermore, in analogy to the Maxwell equations also the Einstein equations cann be given a pre-metric form with a constitutive tensor. On the one hand, from this constitutive tensor the wave propagation can be derived. On the other hand, the various parts of the constitutive tensor can be measured by observing particle motion in the gravitational field. Restricting to isotropic constitutive quantities one obtains as a particular consequence, that from the gravitational attraction together with the Lense-Thirring effect the constitutive tensor can be determined. That means the speed of gravity can be calculated from the constritutive tensor and compared to the speed of light which agree on the level of 1%. This provides an independent test of the speed of gravity compared with the measurements provided by multimessenger observations of gravitational wave events.

Keywords: speed of gravity; constitutive law; Lense-Thirring effect; gravitational force