Supermassive black holes in the universe are merging with each other, and eventually the same fate awaits the black hole at the center of our galaxy. Located at the heart of nearly every galaxy, these mysterious cosmic structures absorb light and matter and cannot be seen with conventional telescopes. But now, for the first time in history, astrophysicists have managed to extract data directly from these titans, and this information comes in the form of gravitational waves that cause ripples in the fabric of space and time.

According to the data obtained by scientists, the “population” of merging massive black holes is estimated to be hundreds of thousands or even millions. Gravitational waves from these mergers become part of the background noise of the universe that scientists can detect from Earth.

Findings from the collaboration of more than 100 scientists from different countries help confirm that this is what happens when the supermassive black hole at the center of our galaxy, Sagittarius A*, crashes into the black hole at the center of the Andromeda galaxy.

“The Milky Way Galaxy is on a collision course with the Andromeda Galaxy, and the two galaxies should merge in about 4.5 billion years,” said Joseph Simon, an astrophysicist at the University of Colorado at Boulder and a NANOGrav collaborator who helped run it. New research with support from the National Science Foundation.

According to him, this merger will eventually cause the black hole at the center of Andromeda and Sagittarius A* to be at the center of the remerged galaxy, creating a so-called binary system. The scientists’ conclusions are presented in a series of articles published in the journal. Astrophysical Journal Letters.

“First of all, we didn’t know if supermassive black holes were merging, and now we have evidence that hundreds of thousands of black holes have merged,” said Chiara Mingarelli, an astrophysicist at Yale University and a member of NANOGrav.

According to the scientists, the results of the new study will help answer questions about how black holes grow and how often their host galaxies merge.

“This is one of the craziest objects in our universe,” said University of Washington physicist Masha Baryakhtar, who was not involved in the study. “Until now, there is no consensus among scientists as to how they got so big.”

According to Baryakhtar, if scientists better understand the merger history of supermassive black holes, it will help figure out how they arose in the first place.

An important aspect of these discoveries was the discovery of elusive gravitational waves and an understanding of how they arise.

Any moving object with mass creates these waves—an invisible disruption of the fabric of space and time, first theorized by Albert Einstein in 1916 and discovered nearly 100 years later. (Imagine the fabric of space and time as a taut trampoline on which heavy bowling balls roll.)

In 2015, scientists used the ground-based Laser Interferometer Gravitational-Wave Observatory (LIGO) to determine that short, high-frequency winds from less massive black holes are shaking the Earth less than the width of a subatomic particle. Scientists won the Nobel Prize for this discovery.

Sarah Vigeland, a physicist at the University of Wisconsin-Milwaukee who led the gravitational wave research for Nanograv, explained that LIGO can measure waves from colliding objects that change quickly, such as neutron stars.

“You get this burst of gravitational waves and then it’s over,” he said.