The amazing discovery of graviational waves by the LIGO observatory recently was big not just because it helped us better understand the fundamentals of the universe, but also it had some surprises for us when it comes to black holes.

The discovery, which happened earlier this year, confirms Albert Einstein’s predictions. But it also increases our understanding of black holes as well by proving that black holes will sometimes circle each other before colliding and forming a larger black hole, potentially providing the “missing link” between small stellar black holes that formed from collapsed stars and the supermassive black holes at the centers of galaxies.

Scientists believe that black holes form from star death. Whena massive star runs out of fuel to burn, the mass collapses down to a point, creating a huge gravitational pull that prevents even light from escaping. The laws of physics as we understand them break down past a certain point.

But up until the discovery of gravitational waves, there had been no physical proof that black holes can circle each other as binary pairs and then collide with each other. Binary stars are common, and logic would suggest that they can collapse and become binary black holes, but until now there was no proof of that.

The problem is observing such binary black holes. The dynamics around them would be so chaotic that observing them with light-based telescopes would be unrealistic, which is why it took the LIGO detector to spot them. Now that we know what gravitational waves look and “sound” like, we can use them to perhaps find other instances of black holes collapsing into each other and expand our understanding about one of the most mysterious and fascinating forces in the entire universe.