Rotating Hollow and Full Spheres: Einstein, Thirring, Lense, and Beyond

Concrete calculations of (linear) dragging effects on test masses were performed by Einstein in the period 1912–1913 by introducing the model of an infinitely thin mass shell. Einstein’s impact on the subsequent work of Thirring and Lense from 1918 on the induction of gravitational dragging forces by accelerated (rotating) masses is revealed. Generalizations to strong fields were performed not earlier than in 1966 by Brill and Cohen. Extensions to higher orders of the angular velocity ω of rotation by Pfister and Braun (1985–1989) led to a solution of the “centrifugal force problem” and to a “quasiglobal principle of equivalence.” The present experimental status of dragging phenomena is shortly reviewed, and cosmological and Machian aspects of gravitomagnetism are discussed.