Proceedings of the 81 WE-Heraeus-Seminar Held at the Physikzentrum Bad Honnef, Germany, 2-6 September 1991Gravitational lensing.- The general relativistic N-body problem.- Observable relativistic effects in the solar system.- New results for relativistic parameters from the analysis of llr measurements.- Very-Long-Baseline Interferometry in astro-, geo-, and gravitational physics.- A gradiometer experiment to detect the gravitomagnetic field of the earth.- The international atomic time and the PTB's clocks.- Gravity-wave astrophysics.- The GEOproject a long-baseline laser interferometer for the detection of gravitational waves.- The optics of an interferometric gravitational-wave antenna.- Mechanical aspects in interferometric gravity wave detectors.- Fermion and Boson stars.- Black holes with hair.- Gravitational fields of rapidly rotating neutron stars: Theoretical foundation.- Gravitational fields of rapidly rotating neutron stars: Numerical results.- A new laboratory experiment for testing Newton's gravitational law.- Matter wave interferometry and why quantum objects are fundamental for establishing a gravitational theory.Relativistic effects become increasingly important in observational astrophysics. This book covers this topic in the form of a collection of readable articles. The reader will find papers on gravitational lensing, the relativistic n-body problem, gravitational waves, interferometry and lunar laser-ranging measurements etc.Springer Book Archives