When gravitational waves were first detected a few weeks ago, excitement spread throughout the scientific community, and the prediction made by Einstein's general theory of relativity 100 years was finally confirmed. Furthermore, humanity now has a new way of observing the universe, opening up an infinite number of possibilities for future discoveries.
How were these waves created? Scientists believe that they stem from a collision of two black holes around 30 times the mass of the sun, which sent ripples through spacetime that contained energy three times more massive than the sun. For around 1.3 billion years, these waves travelled through the depths of space until they were detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO).
Even more interesting, the signal of the captured wave revealed a sound that resembled a "thump" and lasted approximately two-tenths of a second. Much like sound waves are created when two cars crash into each other, the ancient collision of two black holes created gravitational waves that echoed into space.
In order to detect these waves and the sounds that stem from them, LIGO uses multiple detectors around the world.
"It's like listening to music. You might have the bass in the left channel, the snares in the right," said Scott Hughes, a theoretical physicist at the Massachusetts Institute of Technology (MIT).
Listening to these sounds tells us stories about the universe that only gravitational waves can tell us. Prior to their discovery, these stories would be lost in the cosmic noise that was created by the Big Bang.
Although you might think that the sound of two black holes colliding into each other would make a much more intense, chaotic sound, there is a physical reason for the absence of these characteristics.
"At some level black holes are simple objects. They're able to be described by their mass and their spin, so they're relatively simple objects," LIGO Hanford's lead scientist Mike Landry said. "You haven't got matter there. You have mass but no matter. They're just objects of pure space-time."
Ultimately, the scientists are satisfied with what they have so far and hope to use the findings to open up a whole new path for exploring the universe.
"We were very fortunate to have such a clear signal," Landry said. "We could also imagine that the very first signal would be an ambiguous one. It turned out to be very, very clear and unambiguous, which was great."
