... Gravitational wave search provides insights into galaxy evolution and mergers . ... galaxies . ... Astronomers pin down galaxy collision rate . The galaxy merger rate is one of the fundamental measures of galaxy evolution, yielding clues to how galaxies bulked up over time. ... The new study, led by Jennifer Lotz of the Space Telescope Science Institute in Baltimore, Maryland, analyzed galaxy interactions at different distances, allowing the astronomers to compare mergers over time. ... Lotz said. ...