Experimental tests of general relativity: recent progress and future directions

Einstein's general theory of relativity is the standard theory of gravity, especially where the needs of astronomy, astrophysics, cosmology and fundamental physics are concerned. As such, this theory is used for many practical purposes involving spacecraft navigation, geodesy and time transfer. Here I review the foundations of general relativity, discuss recent progress in the tests of relativistic gravity, and present motivations for the new generation of high-accuracy tests of new physics beyond general relativity. Space-based experiments in fundamental physics are capable today to uniquely address important questions related to the fundamental laws of nature. I discuss the advances in our understanding of fundamental physics that are anticipated in the near future and evaluate the discovery potential of a number of the recently proposed space-based gravitational experiments.