For the second time, a group of scientists has detected gravitational waves, bringing more physical proof of the phenomenon Albert Einstein anticipated in his general theory of relativity a century ago.
The waves were detected by the Laser Interferometer Gravitational-Wave Observatory, or LIGO, which is funded by the National Science Foundation and managed jointly by Caltech and MIT.
The discovery stands to open up a whole new frontier of research in astronomy and astrophysics — one that may even take scientists beyond Einstein's general theory of relativity, Dave Reitze, a professor of physics at the University of Florida, and the executive director of LIGO, told CNBC.
"Gravitational waves are a different kind of information, and it is a kind of information we have never had before, these two detections," Reitze said. "The gravitational wave is a way of understanding how massive objects like black holes and neutron stars, move and accelerate. And when they collide and merge with each other, the gravitational wave signals we see gives us deep insights into the mechanisms, the dynamics of those collisions."
"This is a new kind of astronomy, this is a new frontier for high energy astrophysics," he said. "It will let us look at these events in ways that nobody else can look at them."
The team made its second detection of waves on Dec. 26, and announced the results in a paper published Wednesday in the journal Physical Review Letters.
LIGO scientists were also the first to confirm the existence of the waves in September 2015 — they announced the results of that detection on Feb. 11.
In both cases, the waves were detected by the twin LIGO detectors — one in in Livingston, Louisiana, and another in Hanford, Washington.
In Einstein's general theory of relativity, space has a geometry that makes it curve around objects, and in turn influences how those objects move in space. The common visual analogy, which simplifies this concept, likens it to what happens when a bowling ball rolls around on a trampoline — the trampoline bends around the ball, but also pushes it in different directions.
Gravitational waves are thought of as "ripples" in space caused by the movement of very large objects through space. Einstein's theory suggested that massive objects would create these disturbances in space as they move.
As in their first discovery, the researchers say the signal they spotted this time came from two black holes about 1.4 billion light years away. These black holes, which were 14 and 8 times the size of the sun, orbited each other until they finally merged, producing an even more massive black hole 21 times larger than the sun, and sending the ripples out into space. The black holes in the original detection were about the same distance from Earth as the latest observation.
Reitze noted that the detectors were able to "hear" these gravitational waves while running at only half their full sensitivity, so "in the future, when we start running again, we are going to be seeing a lot of these binary black hole systems," he said. "We are going to learn a lot about black holes, using LIGO. Even if nothing else comes into our detectors, we are going to own black hole astronomy."
But he said, they do expect to see other sources of waves, such as collisions of neutron stars, or even, possibly, a supernova going off somewhere in the galaxy.
"We are going to add to the future of this field, which we call multi-messenger astronomy, and I think that is very exciting," he said. This field is roughly defined as the ability to gather information about space through many means beyond traditional astronomy.
"The future of gravitational astronomy is very bright," he said."We are going to be discovering things we know or expect to see, but we are also going to be discovering things we did not expect to see," he said.
"What would be my best hope is if we would start to see something in our data that might start to show that general relativity might not be right, at least in the regimes that we are looking at. So we would start to get a sense of what comes after general relativity. And that would be tremendously exciting. I am not going to bet against Einstein, but we could, and that would be fantastic."