In 2004, the Laser Interferometer Gravitational Wave Observatory (LIGO) Science Collaboration reported the first searches for gravitational waves from the universe. LIGO, one of the largest projects ever undertaken by the National Science Foundation, has as its goal the detection and study of gravitational waves from large-scale astrophysical sources. Gravitational waves were predicted by Einstein almost 90 years ago but never been observed directly despite a number of experiments over the last 40 years. While strong indirect evidence comes from long-term precision astronomical measurements of the periastron shift of a pulsating binary neutron star system, it is only with the construction of large-scale interferometers that direct detection of gravitational waves is possible. Gravitational waves are tiny dynamical strains applied to space-time by motion of massive astrophysical systems such as binary black holes and neutron star systems. LIGO uses ultrahigh precision interferometry to detect the changes in positions of mirrors ("test masses") induced by the passage of gravitational wave. Direct observation of gravitational waves presents a formidable challenge, because the magnitude of the dynamic strain is expected to be less than 10^-22 near 100 Hz. In this talk, I will give an overview of LIGO, discussing the astrophysical goals and the challenges faced in reaching them with an emphasis on the starring role that lasers and optics play in the search for gravitational waves.

Contact: Luis A. Orozco.