Gravitational waves detected for 1st time, 'opens a brand new window on the universe'

Gravitational waves, ripples in space-time predicted by Einstein's general theory of relativity 100 years ago, have finally been detected.

"Ladies and gentlemen, we have detected gravitational waves. We did it," announcedDave Reitze, executive director of the U.S.-basedLaser Interferometer Gravitational-Wave Observatory (LIGO) at a news conference Thursday morning.

Scientists said gravitational waves open a door for a newway to observe the universe and gain knowledge about enigmaticobjects like black holes and neutron stars. By studyinggravitational waves they also hope to gain insight into thenature of the very early universe, which has remainedmysterious.

"I think we're opening a window on the universe," Reitze said.

"Until this moment we had our eyes on the sky and we couldn'thear the music," said Columbia University astrophysicist SzabolcsMarka, a member of the discovery team. "The skies will never be thesame."

Scientists detect gravitational waves for 1st time

9 years ago

Duration 0:51

Einstein theory proven more than 100 years later

Reitze said researchersdetected gravitational wavescoming from two black holes extraordinarily dense objects whose existence also was foreseen by Einstein that orbited oneanother, spiralled inward and smashed together. They said thewaves were the product of a collision between two black holes 30times as massive as the sun, located 1.3 billion light yearsfrom Earth.

"This is the first time that this type of system has ever been seen and this proves that binary black holes exist," he added.

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The scientific milestone, announced at a news conference inWashington, was achieved using a pair of giant laser detectorsin the United States, located in Louisiana and Washington state,capping a long quest to confirm the existence of these waves.

The announcement was made in Washington by scientists fromthe California Institute of Technology, the MassachusettsInstitute of Technology and the LIGO Scientific Collaboration, which includes scientists atCanadian Institute for Theoretical Astrophysics at the University of Toronto.

• Canadian LIGOscientist Mike Landry talks to Quirks & Quarks Feb. 13 at noon on CBC Radio One

Like light, gravity travels in waves, but instead ofradiation, it is space itself that is rippling. Detecting thegravitational waves required measuring 4 kilometre (2.5 mile)laserbeams to a precision 10,000 times smaller than a proton.

Hearing black holes merge

The two laser instruments, which work in unison, are knownas the Laser Interferometer Gravitational-Wave Observatory(LIGO). They are able to detect remarkably small vibrations frompassing gravitational waves. After detecting the gravitationalwave signal, the scientists said they converted it into audiowaves and were able to listen to the sounds of the two blackholes merging.

"We're actually hearing them go thump in the night," MITphysicist Matthew Evans said. "We're getting a signalwhicharrives at Earth, and we can put it on a speaker, and we canhear these black holes go, 'Whoop.' There's a very visceralconnection to this observation."

The scientists said they first detected the gravitationalwaves last Sept. 14.

"We are really witnessing the opening of a new tool fordoing astronomy," MIT astrophysicist Nergis Mavalvala said in aninterview. "We have turned on a new sense. We have been able tosee and now we will be able to hear as well."

Harald Pfeiffer and his team at the Canadian Institute for Theoretical Astrophysics at the University of Torontohelped make the software used to analyze the data and look for gravity waves.

In particular, they helped predict what gravity waves from different kinds of black hole collisionsmight look like.

"It's easier to find things if you know what you're looking for," Pfeiffer told CBC Newsahead of the announcement.

The LIGO work is funded by the National Science Foundation,an independent agency of the U.S. government.

Einstein in 1916 proposed the existence of gravitational waves as an outgrowth of his ground-breaking general theory ofrelativity, which depicted gravity as a distortion of space andtime triggered by the presence of matter. But until nowscientists had found only indirect evidence of their existence.

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Everything we know about the cosmos so far stems fromelectromagnetic waves such as radio waves, visible light,
infrared light, X-rays and gamma rays. But because such wavesencounter interference as they travel across the universe, theycan tell only part of the story.

Gravitational waves experience no such barriers, meaningthey can offer a wealth of additional information. Black holes,for example, do not emit light, radio waves and the like, butcan be studied via gravitational waves.

'Brand new window on the universe'

Scientists sounded positively giddy over the discovery.

"It is really a truly, truly exciting event," said AbhayAshtekar, director of Penn State University's Institute forGravitation and the Cosmos. "It opens a brand new window on theuniverse."

"The LIGO announcement describes one of the greatestscientific discoveries of the past 50 years," Cornell Universityphysicist Saul Teukolsky added.

Ashtekar said heavy celestial objects bend space and timebut because of the relative weakness of the gravitational forcethe effect is miniscule except from massive and dense bodieslike black holes and neutron stars. He said that when theseobjects collide, they send out ripples in the curvature of spaceand time that propagate as gravitational waves.

The detection of gravitational waves already has providedunique insight into black holes, with the scientists saying ithas demonstrated that there are plenty of black holes in therange of tens of solar masses, resolving the long debated issueof the existence of black holes of that size.

A black hole, a region of space so packed with matter thatnot even photons of light can escape the force of gravity, wasdetected for the first time in 1971. Scientists have known theexistence of small black holes and so-called supermassive blackholes are millions or billions of times as massive as the sun,but had debated the existence of black holes of intermediatesize.

Neutron stars are small, about the size of a city, but areextremely heavy, the compact remains of a larger star that diedin a supernova explosion.

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