Everything you need to know about gravitational waves. In February 2016 scientists announced the first detection of gravitational waves by humans on Earth. This was a huge, world changing, discovery. The gravitational waves were caused by a pair of colliding black holes 1.3 billion light years away 1.3 billion years ago. This video summaries all the of the mind blowing facts about the gravitational waves and describes LIGO, the incredibly sensitive telescope that detected them.