Pulsars hint at sea of gravitational waves

Astronomers might have spied their first hint of gravitational waves made by merging supermassive black holes. For more than a decade, the NANOGrav collaboration has been monitoring radio waves from 45 spinning stars, known as pulsars. Tiny deviations in the arrival times of the waves could reveal the cumulative ripples in space-time caused by merging supermassive black holes across the Universe. An analysis of more than 12 years of data shows preliminary evidence for the effect.