Scientists have collected a second burst of gravitational waves sweeping through the Earth. The warping of space-time was sensed on Christmas Day in the US at the Advanced LIGO laboratories - the same facilities that made the historic first detection in September last year. Back then, the waves came from two huge coalescing black holes. This new set of waves, likewise, is ascribed to a black hole merger - but a smaller one.
Reporting the event in the journal Physical Review Letters, the international collaboration that operates LIGO says the two objects involved had masses that were 14 and eight times that of our Sun. The data indicates the union produced a single black hole of 21 solar masses, meaning they radiated pure energy to space equivalent to the mass of one star of Sun size. It is this energy, in the form of gravitational waves, that was sensed in the laser interferometers of the LIGO labs in Livingston, Louisiana, and Hanford, Washington State, at 22:38 Eastern Standard Time on 25 December (03:38 GMT, 26 Dec; Boxing Day in Europe).
Ripples in the fabric of space-time
* Gravitational waves are a prediction of the Theory of General Relativity
* It took decades to develop the technology to directly detect them
* 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
According to UK collaboration member Prof Bernard Schutz of Cardiff University, making a second detection proves the first was not just an isolated event, and that Advanced LIGO really does have the capability to open up a new cosmic realm to investigation. "It shows the first event wasn't just a fluke. It shows that the Universe is filled with black holes spiralling in together and merging and giving off these huge bursts of gravitational waves quite regularly. It's a violent Universe," he told BBC News. It has been one big celebration since scientists fulfilled their decades-long quest in September by detecting the warping of space generated from the merger of black holes 29 and 36 times our Sun's mass. Key LIGO pioneers have been lauded with prizes, and there are very short odds now on the achievement being crowned with a Nobel in October.
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