'Gravitational waves detected 100 years after Einstein's prediction'

Scientists said on Thursday they have detected the existence of gravitational waves, which were predicted by Albert Einstein's theory of general relativity 100 years ago.

The detected gravitational waves were produced during the final fraction of a second of the merger of two black holes to produce a single, more massive spinning black hole, they said at a news conference in Washington, Xinhua reported.

The gravitational waves were detected on September 14, 2015, at 5.51 a.m. by both of the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington.

Based on the observed signals, LIGO scientists estimated that the black holes for this event were about 29 and 36 times the mass of the sun, and the event took place 1.3 billion years ago.

About three times the mass of the Sun was converted into gravitational waves in a fraction of a second -- with a peak power output about 50 times that of the whole visible universe.

"Our observation of gravitational waves accomplishes an ambitious goal set out over five decades ago to directly detect this elusive phenomenon and better understand the universe, and, fittingly, fulfils Einstein's legacy on the 100th anniversary of his general theory of relativity," said David Reitze, executive director of the LIGO Laboratory.

Rainer Weiss, professor of physics from the Massachusetts Institute of Technology, is one of the scientists who originally proposed LIGO as a means of detecting gravitational waves in the 1980s.

"It would have been wonderful to watch Einstein's face had we been able to tell him," he added.

The existence of gravitational waves was first demonstrated indirectly in the 1970s and 1980s by American scientists who found a binary pulsar whose orbit was slowly shrinking over time because of the release of energy in a way Einstein's theory predicted.

Two of the scientists were awarded the 1993 Nobel Prize in Physics.

The new discovery, accepted for publication in the journal Physical Review Letters, was made by the LIGO Scientific Collaboration (LSC), a group of more than 1,000 scientists from universities around the US as well as in 14 other countries.

"This detection is the beginning of a new era: The field of gravitational wave astronomy is now a reality," said Gabriela Gonzalez, LSC spokesperson and professor of physics and astronomy at the Louisiana State University.