LIGO boffins set to reveal grav-wave corker

A press conference for a Nature paper? Guess that's a 'yes,' then

After weeks of speculation, the stage is set for Laser Interferometer Gravitational-wave Observatory (LIGO) boffins to announce their findings.

The LIGO Scientific Collaboration has briefly popped its head over the parapet to say it'll come clean about what it has (or hasn't) found on Thursday at the National Science Foundation.

LIGO uses identical detectors in the US states of Louisiana and Washington. The detectors themselves are simple enough: lasers fired down 4km (2.48-mile) paths at right angles to each other, with interferometers at the intersection looking for changes in path length that should be caused by a passing gravitational wave.

Using multiple sources means if only one detector catches a signal, it's discarded as a fluke since a true gravitational wave will affect both detectors.

Grav waves are minute ripples in the fabric of spacetime. They are created by accelerating objects – like the waves created when you run your fingers through the water's surface of a still lake – and are incredibly hard to detect because they are so faint. Our only hope of spotting a gravitational wave in the wild is by picking up one from a massive event – such as two black holes crashing into each other.

Confirming the existence of grav waves will be a huge breakthrough for physicists.

In January, physicist Lawrence Krauss sparked controversy when he seemed to pre-announce LIGO's first results:

Things quieted down again until the end of last week, when Science said it had seen an email saying Krauss was right. Quoting from the email, the mag wrote "spies who have seen the paper say they have seen gravitational waves from a binary black hole merger ... Apparently the signal is spectacular."

The two black holes are claimed to be equivalent to 29 and 36 solar masses, and the signal is described as being of 5.1 sigma (which is a high enough confidence that it would be classed as a "discovery," if it's confirmed).

The press conference is timed to coincide with the release of the LIGO collaboration's paper in Nature.

As Bryan Gaensler, director of the Dunlap Institute for Astronomy and Astrophysics at the University of Toronto, tweeted:

Physicists have been looking for gravitational waves ever since they were predicted by Einstein 100 years ago. ®


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