Gravitational waves found again, 3B light- years away

‘ It looks like Einstein was right’ about them

For just the third time ever, scientists have detected gravitational waves, the strange ripples in space- time first foreseen by Albert Einstein a century ago.

The phenomenon occurs when two black holes collide and merge with each other, releasing energy in the form of gravitational waves. The massive new black hole formed has a mass about 49 times that of our sun.

The exact location of the black hole is unknown, but it’s roughly 3 billion light- years away in a distant galaxy. Thus, what we’re “seeing” now actually happened 3 billion years ago, roughly onefourth the entire history of the universe.

The first and second detections of gravitational waves last year were milestones in physics and astronomy. The black hole in this event was “at a much greater distance than the first two,” said Su- san Scott of the Australian National University.

This latest detection, made Jan. 4, is described in a new paper accepted for publication in the journal Physical Review Letters.

The study again put Einstein’s theories to the test. Researchers looked for but found no evidence of an effect called dispersion, which occurs when light waves travel at different speeds depending on their wavelength. Einstein’s general theory of relativity forbids dispersion from happening in gravitational waves as they make their way toward Earth.

“It looks like Einstein was right — even for this new event, which is about two times farther away than our first detection,” said Laura Cadonati of Georgia Tech University. “We can see no deviation from the predictions of general relativity, and this greater distance helps us to make that statement with more confidence.”

AURORE SIMONNET/ SONOMA STATE/ CALTECH/ MIT/ LIGO An artist’s conception of two merging black holes like those detected by the Laser Interferometer Gravitationalwave Observatory.