LIGO, the Laser Interferometer Gravitational-Wave Observatory, has done it again. Astronomers announced they have detected another gravitational wave tearing through spacetime. The occasion marks the third direct confirmation of Einstein’s theory of general relativity — and changes our understanding of black holes and other stellar phenomena.
Gravitational waves occur when extremely massive objects interact with the universe around them, such as when orbiting black holes merge with each other. This stellar dance produces tiny vibrations in the curvature of spacetime that travel at the speed of light and ripple throughout the cosmos.
The latest wave happened after two black holes collided with each other, resulting in one enormous black hole with the mass of 49 suns. This new stellar object is located approximately 3 billion light years from Earth, the farthest ever detected.
“Imagine two tornadoes that are going about each other,” said Laura Cadonati, a Georgia Tech physicist and LIGO deputy spokesperson, during a press conference Wednesday. Cadonati explained that while the two tornadoes may be rotating around each other, their individual spins may not be in the same direction. Like the tornadoes, LIGO’s observations suggest at least one of the black holes appeared to be spinning in the opposite direction of the collective twirl of the two black holes, which is something that scientists had hypothesized in the past but could not confirm.
“With the third confirmed detection of gravitational waves from the collision of two black holes, LIGO is establishing itself as a powerful observatory for revealing the dark side of the universe,” said David Reitze of Caltech, executive director of the LIGO Laboratory.
LIGO picked up its first couple of gravitational waves two years ago, though they didn’t announce them until February and June 2016, respectively. The observatory works by comparing measurements from a facility in Hanford, Washington, to another based in Livingston, Louisiana. The great distances between the laboratories assures local interference does not throw off the laser-based detectors, and possibly create a false positive.
Despite this distance, “glitches” can happen, and to cope, LIGO has crowdsourced a solution. Using a program called Gravity Spy, citizen scientists can help to locate these glitches by sifting through noise in the data and determining which stellar signals are flukes and which are real.