  Gravitational wave science should transform in this decade from a study of
what has not been seen to a full-fledged field of astronomy in which detected
signals reveal the nature of cataclysmic events and exotic objects. The LIGO
Scientific Collaboration and Virgo Collaboration have recently completed joint
data runs of unprecedented sensitivities to gravitational waves. So far, no
gravitational radiation has been seen (although data mining continues). It
seems likely that the first detection will come from 2nd-generation LIGO and
Virgo interferometers now being installed. These new detectors are expected to
detect ~40 coalescences of neutron star binary systems per year at full
sensitivity. At the same time, research and development continues on
3rd-generation underground interferometers and on space-based interferometers.
In parallel there is a vigorous effort in the radio pulsar community to detect
~several-nHz gravitational waves via the timing residuals from an array of
pulsars at different locations in the sky. As the dawn of gravitational wave
astronomy nears, this review, intended primarily for interested particle and
nuclear physicists, describes what we have learned to date and the prospects
for direct discovery of gravitational waves.
