On Wednesday, Advanced Laser Interferometer Gravitational Waves Observatory (LIGO) has announced that they have detected ripples in space and time from two merging black holes. This breakthrough discovery follows LIGO's first detection of gravitational waves announced in February.

According to Gizmodo, the second gravitational wave detection of LIGO shows that these ripples came from two colliding small black holes, which weigh only 8 and 14 solar masses. The said black holes create one big black hole upon merging, which is 21 times the mass of the sun.

It could be noted that a century ago, Albert Einstein's General Theory of Relativity predicted the existence of gravitational waves. Einstein theorizes that space itself is flexible and wobbling. NPR notes that space-time is actually a lot stiffer but big events such as collision of large black holes could make it bend and shake due to the immense gravitational pull from the black holes.

David Shoemaker from MIT says that the first and second detections prove the existence of these gravitational ripples. He said, “Just the fact that we’ve now seen more than one [gravitational wave source] is very exciting. It takes us out of the ‘gee whiz, could it be true?’ mindset to yes, this is a tool that we can use.”

He further explained that the first detection of gravitational waves was huge. Meanwhile, the second one was a bit weaker as the collision came from two objects with smaller mass. However, what makes the second detection more convenient for scientists is the fact that weaker waves move slower, allowing ample time to study them.

Also, previous speculations that black hole collisions produce bursts of radiations have been disputed. The researchers confirmed, through observation of the second detection, that merging black holes do not produce gamma-rays nor X-rays, Forbes reports.

“The first event was realizing a dream. Now we have a second, and in the future we’ll have more. It means we’ve really entered the era of gravitational wave astronomy, and we can start to do statistics," said Federico Ferrini, director of the European Gravitational Observatory (EGO).