Zusammenfassung
Summary
The most relevant papers by Einstein on his theory of gravity were published in 1915; for that reason this year we can celebrate the 100th anniversary of the »General Theory of Relativity« (GRT). This contribution appears for that reason. It deals with diverse tests of GRT, Newton’s law of gravity (5th force), different forms of the equivalence principle, the gravitational redshift, tests of metric theories of gravity like the measurement of planetary anomalous perihelion precession, the gravitational light bending and time delay, etc. It is described how such relativistic effects enter geodetic measurements and thus practical applications like monitoring of our natural environment.