![An illustration showing the universe as a wobbly grid, with bright black holes warping the grid](https://cdn.mos.cms.futurecdn.net/7RL58SVbdvTYGmossrKF5g-320-80.jpg)
The universe is rippling with a faint 'gravitational wave background' created by colliding black holes, huge international study suggests
A 15-year search reveals the first evidence of a cosmic 'gravitational wave background' emitted by ancient, colliding black holes.