Gravitational Waves
Kip Thorne, the Feynman Professor of Theoretical Physics at the California Institute of Technology, listens during a news conference in Washington, Feb. 11, 2016, to discuss the detection of gravitational waves, ripples in space and time hypothesized by physicist Albert Einstein a century ago. REUTERS/Gary Cameron

Scientists have detected gravitational waves for the first time. Gravitational waves are small ripples in space and time that cross the universe. First hypothesized by physicist Albert Einstein a century ago, this landmark discovery opens a new window for studying the cosmos.

Space