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A Fourth Gravitational Wave Has Been Detected (theguardian.com)
An anonymous reader quotes a report from The Guardian: Astronomers have made a new detection of gravitational waves and for the first time have been able to trace the shape of ripples sent through spacetime when black holes collide. The announcement, made at a meeting of the G7 science ministers in Turin, marks the fourth cataclysmic black-hole merger that astronomers have spotted using Ligo, the Laser Interferometer Gravitational-Wave Observatory. The latest detection is the first to have also been picked up by the Virgo detector, located near Pisa, Italy, providing a new layer of detail on the three dimensional pattern of warping that occurs during some of the most violent and energetic events in the universe.
A tiny wobble in the signal, picked up by Ligo's twin instruments and the Virgo detector on 14 August, could be traced back to the final moments of the merger of two black holes about 1.8 billion years ago. The black holes, with masses about 31 and 25 times the mass of the sun, combined to produce a newly spinning black hole with about 53 times the mass of the sun. The remaining three solar masses were converted into pure energy that spilled out as deformations that spread outwards across spacetime like ripples across a pond. Detecting these tiny distortions has required detectors sensitive enough to measuring a discrepancy of just one thousandth of the diameter of an atomic nucleus across a 4km laser beam. A paper about the latest discovery has been accepted for publication in the journal Physical Review Letters.
A tiny wobble in the signal, picked up by Ligo's twin instruments and the Virgo detector on 14 August, could be traced back to the final moments of the merger of two black holes about 1.8 billion years ago. The black holes, with masses about 31 and 25 times the mass of the sun, combined to produce a newly spinning black hole with about 53 times the mass of the sun. The remaining three solar masses were converted into pure energy that spilled out as deformations that spread outwards across spacetime like ripples across a pond. Detecting these tiny distortions has required detectors sensitive enough to measuring a discrepancy of just one thousandth of the diameter of an atomic nucleus across a 4km laser beam. A paper about the latest discovery has been accepted for publication in the journal Physical Review Letters.
How about, uh, the last 48 hours. Seriously guyz, to the extent that you're able to divulge, what the hell happened? https://www.theregister.co.uk/2017/09/27/faulty_data_center_takes_out_sourceforge/ Because we're glad you're back, but we really missed you.
The space that the photons are in is what changes size. To measure it they have two perpendicular "arms" in each detector. When the distance of space changes as a wave goes by, the change in each arm is different; they compare the two and that's when they can detect the ripples.
On the one hand you take life too seriously, and on the other, you do not take playful existence seriously enough. Seth
The mirrors they had for reflecting the beam back down the tunnel have been SIGNIFICANTLY upgraded. They can measure how much the reflector swings on its pendulum by the impact of said laser itself.
The Hanford LIGO facility can detect a tractor-trailer moving down I5. The effects of these and any other distortions or disturbances are very similar in nature to the waves they're trying to detect, so much of the early work was spent on identifying these and filtering them out. The mirror upgrades helped. (This all comes from a tour of the facility)
So, in essence, yes. Upgrades. Physical equipment, sensors, hell, probably even people.
Yes you read that correctly - 3 SOLAR MASSES were converted into energy, and the timescale is less than 0.1 seconds.
In the region right around the merger, the shear in space (how much it was shrinking and stretching) from the gravitational waves was ~50% (ie 1km becomes 2km).
It is awesome!