Gravitational waves detected for a second time

Four months after the historic first-ever detection of gravitational waves, scientists said Wednesday they have directly detected another gravitational wave washing over the Earth.

The gravitational waves, ripples in the fabric of spacetime, were observed for a second time on Dec. 26, 2015, at 03:38:53 UTC, scientists said at a press conference during the American Astronomical Society conference in San Diego, California.

Scientists said that the incredibly faint ripple that eventually reached Earth was the result of the spinning dance of a binary black hole pair on the brink of merging, although this duo weighed only 8 and 14 solar masses.

Their merger produced a single, more massive spinning black hole that is 21 times the mass of the sun, and transformed an additional sun's worth of mass into gravitational energy, they said.

The scientists detected the gravitational waves using the twin Laser Interferometer Gravitational-wave Observatory (LIGO) interferometers, located in Livingston, Louisiana, and Hanford, Washington.

In contrast, LIGO's historic first detection on Sept. 14, 2015 resulted from a merger of two black holes 36 and 29 times the mass of the sun.

The first detection of gravitational waves, announced on Feb. 11, 2016, was a milestone in physics and astronomy. It confirmed a major prediction of Albert Einstein's 1915 general theory of relativity and marked the beginning of the new field of gravitational wave astronomy.
Source:XINHUA