Washington, UNITED STATES
Dr. David Reitze, Executive Director of the LIGO Laboratory at Caltech, speaks about gravitational waves...
Dr. David Reitze, Executive Director of the LIGO Laboratory at Caltech, speaks about gravitational waves, ripples in space and time hypothesized by physicist Albert Einstein a century ago, in Washington February 11, 2016. The waves were detected by twin Laser Interferometer Gravitational-wave detectors (LIGO) in Louisiana and Washington states in September 2015. REUTERS/Gary Cameron