Dr Greg Ashton studies some of the most captivating astronomical objects: black holes, where gravity is so strong not even light can escape. When black holes collide, they produce ripples in spacetime called gravitational waves. In 2015, the 4km long LIGO laser interferometers made the first-ever detection of gravitational waves from colliding black holes. Since then, we have seen nearly 100 collisions, enabling a new way to study the Universe: gravitational-wave astronomy. Greg Ashton is a gravitational-wave astronomer and member of the LIGO Scientific Collaboration. He co-chairs the Collaboration's largest observational science group, the Compact Binary Group, responsible for finding and analysing all the mergers between black holes and neutron stars. His research focuses on developing new approaches to extract the science from the data, from measuring the mass of the black holes to understanding what the signals tell us about the nature of Gravity and the evolution of our Universe.