After 100 years of searching, an international team of physicists has confirmed the existence of Einstein's gravitational waves. That's a HUGE deal, because it opens up a whole new way of viewing and understanding the Universe.
The gravitational wave signal was detected by physicists at LIGO on September 14 last year, and the historic announcement was made at a press conference this morning. It's without a doubt one of the biggest scientific discoveries of the past century, and experts are saying it's a shoo-in for a Nobel Prize.
Gravitational waves are so exciting because they were the last major prediction of Einstein's general theory of relativity that had to be confirmed, and discovering them will help us understand how the Universe is shaped by mass.
"Gravitational waves are akin to sound waves that travelled through space at the speed of light," said gravitational researcher David Blair, from the University of Western Australia. "Up to now humanity has been deaf to the universe. Suddenly we know how to listen. The Universe has spoken and we have understood."
What does that mean for us? Just think of all the breakthroughs that have come thanks to the discovery of x-rays - now that we can detect gravitational waves, we're going to have a whole new way to see and study the Universe.
But first of all, a little background on what gravitational waves actually are. According to Einstein's theory, the fabric of space-time can become curved by anything massive in the Universe. When cataclysmic events happen, such as black holes merging or stars exploding, these curves can ripple out elsewhere as gravitational waves, just like if someone had dropped a stone in a pond.
By the time those ripples get to us on Earth, they're tiny (around a billionth of the diameter of an atom), which explains why they were so hard to find.
But thanks to LIGO - the laser interferometer gravitational-wave observatory - we've finally been able to detect them. By bouncing lasers back and forth in two 4-km-long pipes, the observatory was able to measure incredibly small changes in spacetime.
So where did these gravitational waves come from? The physicists were able to trace the signal back to the merging of two black holes around 1.3 billion years ago.
"The discovery of this gravitational wave suggests that merging black holes are heavier and more numerous than many researchers previously believed," said LIGO researcher Eric Thrane, from Monash University in Australia. "This bodes well for detection of large populations of distant black holes ... It will be intriguing to see what other sources of gravitational waves are out there, waiting to be discovered."
But this is just the beginning of what gravitational waves can teach us - several other gravitational wave observatories and detectors are scheduled to come online in the next five years, and they'll allow us to start painting a picture of gravitational radiation across the Universe.
Just like we can currently listen to radio waves in order to find out what happened in the history of our Universe, we now have the ability to do the same with gravitational radiation. And what's most exciting is that we can't even begin predict right now what that could lead to.
To be, or not to be, that is the question...