New physics and astronomy with the new gravitational-wave observatories

Gravitational-wave detectors with sensitivities sufficient to measure the radiation from astrophysical sources are rapidly coming into existence. By the end of this decade, there will exist several ground-based instruments in North America, Europe, and Japan, and the joint American-European space-based antenna LISA should be either approaching orbit or in final commissioning in preparation for launch. The goal of these instruments will be to open the field of gravitational-wave astronomy: using gravitational radiation as an observational window on astrophysics and the universe. In this article, we summarize the current status of the various detectors currently being developed, as well as future plans. We also discuss the scientific reach of these instruments, outlining what gravitational-wave astronomy is likely to teach us about the universe.