KENNEWICK — For the first time the existence of gravitational waves have been detected 100 years after Albert Einstein predicted their existence.
Two black holes that collided 1.3 billion years ago created the wave detected at two special observatories at Hanford and in Louisiana, officials announced Thursday morning.
Einstein’s Messengers: The quest to find gravitational waves
A 2009 video describes how the LIGO observatory is trying to measure ripples in the fabric of space-time from monumental collisions between black holes.
National Science Foundation
Detection of gravitational waves holds promise to open up a new way for scientists to learn about the universe, much of which may be made up of matter unlike what we’re familiar with on Earth.
The detection also was the first proof that two black holes exist together.
“Ladies and gentlemen, we have detected gravitational waves. We did it!” said David Reitze, a physicist and executive director of the LIGO Scientific Collaboration. “I am so pleased to be able to tell you that.”
“It’s mind-boggling,” he said.
Being able to detect and measure waves should advance knowledge of astronomy and physics. New information on the nature of time and space and the creation of the universe could be revealed.
An operating run with improved equipment started in September and ended Jan. 12. For the last month scientists have been studying the data generated.
Officials announced at a news conference Thursday that the waves were detected Sept. 15. The waves were first observed at the observatory in Louisiana and then 70 seconds later at the Hanford facility north of Richland.
Violent events in space, like the collision and merger of black holes, or changes in the speed or direction of large objects create gravitational waves, or ripples through space and time. The waves carry huge amounts of energy, but dissipate to the point that they have been expected to be barely detectable once they pass through Earth.
The Laser Interferometer Gravitational-wave Observatory, or LIGO, at Hanford has been trying to detect the very slight change caused by gravitational waves As they move through objects, they should stretch them lengthwise and cause them to compress sideways. A circle would become an ellipse.
But the change is so small that it challenges existing technology’s ability to detect. The movement is about one thousandth of a diameter of a proton, which is the nucleus of a hydrogen atom. It would take 10 trillion such movements to equal the width of a human hair.
LIGO has been trying to detect that slight movement since 2002.
It operated until 2010 without detecting a gravitational wave. But its odds of detecting a gravitational wave improved significantly after the observatory shut down for five years for a total revamp.
When it started up in 2015, the sensitivity of its detection instruments had been increased by a factor of 10. LIGO initially had the sensitivity to detect gravitational waves from 100 galaxies. Now it can detect waves from up to 100,000 galaxies.
It’s a new kind of observatory, with no telescope required.
Two vacuum tubes extend for 2.5 miles across the Hanford shrub steppe at right angles. At the end of each, a mirror is suspended on fine wires.
A high power laser beam is split to go down each tube, bouncing off the mirrors at each end. If the beam is undisturbed, it will bounce back and recombine perfectly.
But if a gravity wave is pulsing through the Earth, making one of the tubes slightly longer and the other slightly shorter, the beam will not recombine as expected.
Scientists watching for a gravitational wave detect movement caused by many things other than a gravitational wave. They have to sort through vibrations caused by ocean waves on the Pacific Coast or water coming over McNary Dam in the spring.
That’s why there’s a twin facility. Findings at LIGO at Hanford can be compared with an identical LIGO 1,900 miles away in Louisiana. If a gravity wave passes through Earth, both LIGOs should detect it.
