Gravitational waves detected from a second source

LIGO has detected gravitational waves for a second time, this time from a black hole merger about 1.4 billion light-years away.

Scientists have detected another round of gravitational waves, this time from a new source.

The first-ever detection of gravitational waves, described as ripples in space-time, occurred late last year.  According to NPR, the newly detected waves seem to have originated at the site of another black hole merger, and were detected with the Laser Interferometer Gravitational-Wave Observatory (LIGO).

“It looks like there are going to be more of these black holes out there than we imagined,” David Reitze of LIGO said.

Gravitational waves were first predicted by Albert Einstein a century ago.  His theory held that gravity distorts the fabric of space and time, and that a highly energetic event involving bodies of high mass, such as black holes colliding, would send out ripples through the universe.

There are two LIGO detectors, both located in the United States.  LIGO measures miniscule changes in the lengths of 2.5-mile-long detectors, which are fitted with lasers and mirrors to make precision measurements of subatomic lengths.

The most recently detected gravitational wave signal originated 1.4 billion light-years from Earth.  The black holes involved in the collision seem to have been about eight and fourteen times the mass of the sun, combining into a massive single black hole about 21 times the sun’s mass.  One solar mass was converted into gravitational waves that traveled all the way to LIGO.

“This is like Galileo turning his telescope to the sky 400 years ago,” Reitze said. “We’re now looking at the universe in an entirely new way, and we’re going to learn new things that we can’t learn any other way.”

The study has been accepted for publication in the journal Physical Review Letters.