By Will Dunham
WASHINGTON (Reuters) – Scientists presented evidence on Wednesday that gravitational waves, the perturbations of space-time predicted by Albert Einstein a century ago, are plunging the universe into low frequencies – creating the cosmic background hum.
The new findings show that space is riddled with these gravitational waves, which oscillate for years or more and appear to originate primarily from pairs of supermassive black holes that spin together before merging.
“Gravitational waves are created by astronomically dense objects in our universe, often orbiting each other,” said Oregon State University astronomer Jeff Hasbown, a scientific collaboration that conducted research and lead author of a paper describing the findings in the Astrophysical Journal Letters.
Einstein in the year In 1916, he proposed the existence of gravitational waves out of his ground-breaking theory of general relativity, which showed that gravity is a distortion of space and time by matter. In the year Until their discovery in 2016, scientists had only had indirect evidence of their existence since the 1970s.
Objects called pulsars – extremely dense, exploding stars spinning at the speed of a kitchen mixer – were crucial in the new research. Sixty-eight pulsars were used to gather evidence.
“We observe the passage of gravitational waves as a change in the timing of pulses from the cluster of pulsars in our galaxy,” Hasbon said.
The gravitational wave signal has been observed by more than 190 scientists from the United States and Canada with data from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) of the Physics Frontiers Center (PFC).
The researchers described the background of the universe’s gravitational waves as being the equivalent of hearing lots of people talking at a party and not being able to distinguish any of the voices.
Astronomers have long relied on studying light to learn more about the cosmos, but this approach has limitations because it does not provide insight into many aspects of the universe. Gravitational waves allow a more robust probe of the universe, as do ghost subatomic particles called neutrinos.
The discovery comes seven years after researchers first announced the existence of gravitational waves produced by two distant black holes – so dense that not even light can escape. The motion of black holes and other massive objects can cause gravitational waves.
That research includes the Laser Interferometer Gravitational-Wave Observatory (LIGO).
“We have strong evidence for gravitational waves in a new band of the gravitational wave spectrum. These frequencies are 10-12 orders of magnitude lower than those detected by LIGO, and the wavelengths are light years,” Hasbown said.
“The most vanilla explanation for these gravitational waves is a cluster of supermassive black hole binaries (black holes orbiting each other) in our cosmic neighborhood. Other explanations include new physics near the big bang,” Hasbown added, citing the event. It marks the origin of the universe 13.8 billion years ago.
(Reporting by Will Dunham; Editing by Jerry Doyle)