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Supermassive black holes all over the universe are merging (合并), a fate that will eventually come for the black hole at the center of our galaxy (银河系). These magic universal structures at the heart of nearly every galaxy consume light and matter and are impossible to see with traditional telescopes. But now, for the first time, astrophysicists have gathered knowledge directly from these huge universal structures, in the form of gravitational waves that move around through space and time.

Essential to these findings is the detection of complicated gravitational waves, and understanding how they are produced. Any object with mass that is moving causes these waves—invisible bending in time and space that were first theorized by Albert Einstein in 1916 but not detected until roughly 100 years later. In 2015, scientists used the ground-based Laser Interferometer Gravitational Wave Observatory to detect how short, high-frequency gravitational waves from one merger between less massive black holes move around the Earth by less than the width of a single subatomic particle (亚原子微粒).

The findings help confirm what will one day happen to the supermassive black hole at our galaxy’s center known as Sagittarius A, as it crashes into the black hole at the heart of the Andromeda galaxy. “The Milky Way galaxy is on a crash course with the Andromeda galaxy, and in about 4.5 billion years, the two galaxies are set to merge, said Joseph Simon, a member of Nanograv. That merger, he said, will eventually result in the black hole at the center of Andromeda and Sagittarius A sinking into the center of the newly combined galaxy.

“Before now, we didn’t even know if supermassive black holes merged, and now we have evidence that hundreds of thousands of them are merging, said Chiara Mingarelli, another member of Nanograv.

If scientists understand more about the history of the merging supermassive black holes, it could help know how they form in the first place, said Masha Baryakhtar, a physicist who wasn’t involved in the research.