When physicists first measured gravity waves with the LIGO detector four years ago, it was sensational. The signal came from two black holes that had
swallowed each other. Now, scientists have discovered that since then, it has happened nine times. Gravity waves were predicted by Albert Einstein in his relativity theory. Einstein provided us with a new understanding of space when he added time as a fourth dimension. His theory involves that the 4D space-time is distorted by gravity waves that travel through the universe. We can only measure the biggest ones that occur in the most violent events of the universe such as the fusion of black holes,
and even then, it requires extremely sensitive detectors. The LIGO detectors consist of long tunnels, in which laser light travels back and forth between mirrors.
When a gravity wave passes by, it moves the mirrors less than the diameter of an atom, as recorded by the detectors. Among the new observations is the fusion of two black holes of 50 and 34 solar masses. They are located nine billion light years away, and the collision happened some five billion years ago. Since then, the gravity waves have traveled towards us.
Scientists hope that more gravity wave measurements could solve the mystery of the black holes. It remains unclear, how often they fuse, and if the collisions were more common in the past. The biggest cosmic collision ever measured was between two black holes with a combined weight of 84 solar masses.
166,000,000 sextillion tonnes – corresponding to 84 times the Sun’s mass – is the total weight of the two biggest black holes, the fusion of which scientists have observed.