Scientists are claiming a stunning discovery in their quest to fully understand gravity.
They have observed the warping of space-time generated by the collision of two black holes more than a billion light-years from Earth.
The international team says the first detection of these gravitational waves will usher in a new era for astronomy.
It is the culmination of decades of searching and could ultimately offer a window on the Big Bang.
The research, by the LIGO Collaboration, has been published today in the journal Physical Review Letters.
what does it mean?
"Ripples in the fabric of space-time"
• Gravitational waves are prediction of the Theory of General Relativity
• Their existence has been inferred by science but only now directly detected
• They are ripples in the fabric of space and time produced by violent events
• Accelerating masses will produce waves that propagate at the speed of light
• Detectable sources ought to include merging black holes and neutron stars
• LIGO fires lasers into long, L-shaped tunnels; the waves disturb the light
• Detecting the waves opens up the Universe to completely new investigations
That view was reinforced by Prof Stephen Hawking, who is an expert on black holes. He said he believed that the detection marked a key moment in scientific history:
"Gravitational waves provide a completely new way at 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."
"Apart from testing (Albert Einstein's theory of) General Relativity, we could hope to see black holes through the history of the Universe. We may even see relics of the very early Universe during the Big Bang at some of the most extreme energies possible."
Prof Karsten Danzmann, from the Max Planck Institute for Gravitational Physics and Leibniz University in Hannover, Germany, a European leader on the collaboration said, the detection was one of the most important developments in science since the discovery of the Higgs particle, and on a par with the determination of the structure of DNA.
"There is a Nobel Prize in it - there is no doubt."