Gravitational waves are ripples in the curvature of spacetime. Predicted in 1916 by Albert Einstein on the basis of his theory of general relativity, gravitational waves transport energy as gravitational radiation.
On February 11, 2016, scientists announced that they had directly detected gravitational waves from a pair of black holes merging using the Advanced LIGO Interferometer.
If you look with visible light as far back as we can look in the universe, it is no longer transparent, it becomes opaque. If you could see gravitational waves, you can see past where you can no longer see with physical light. Right now, we can currently only see celestial objects that emit electromagnetic radiation — visible light, X-rays, gamma rays, and so on. But some objects — like colliding black holes or the smoking gun of the Big Bang — don’t emit any electromagnetic radiation. They emit gravity.
And that’s why, with this discovery, invisible objects in the universe may soon become visible. Focusing on gravitational waves, scientists were able to “see” or “hear” (both metaphors work) black holes in action for the very first time in scientific history.
The discovery of gravitational waves could “revolutionise astronomy”, Prof Stephen Hawking said as he congratulated scientists on their groundbreaking work.
“Gravitational waves provide a completely new way of looking at the universe. The ability to detect them has the potential to revolutionise astronomy. This discovery is the first detection of a black hole binary system and the first observation of black holes merging.”
Hawking, research director at Cambridge University’s Department of Applied Mathematics and Theoretical Physics, said: “The observed properties of this system is consistent with predictions about black holes that I made in 1970 here in Cambridge. Asked what more could be discovered if scientists scanned for gravitational waves, he said: “Apart from testing general relativity, we could hope to see black holes throughout the history of the universe. We may even see relics of the very early universe during the big bang at the most extreme energies possible.”