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STORY: The new findings show that space is awash with these gravitational waves, which oscillate over years or longer and appear to originate primarily from pairs of supermassive black holes spiralling together before merging. Einstein in 1916 proposed the existence of gravitational waves as an outgrowth of his groundbreaking general theory of relativity, which depicted gravity as the distortion of space and time by matter. Until their detection in 2016, scientists had found only indirect evidence of their existence, beginning in the 1970s. Objects called pulsars - the extremely dense cores of exploded stars that spin at the speed of kitchen blenders - were crucial in the new research. Nearly 70 pulsars were used in gathering the evidence.

“As gravitational waves pass through the galaxy, they stretch and they squeeze it. And then these times of arrival of these pulses are changed. So one pulsar, as it's approaching the earth, its pulses will arrive a little earlier than we expect, as other pulsars will be away from the earth because it's being affected by the gravitational wave and those pulses arrive a little later,” said Oregon State University astrophysicist Xavier Siemens, a co-director of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), a collaboration of more than 190 scientists from the United States and Canada who worked to monitor the gravitational wave signals.

Gravitational waves allow for a more robust examination of the universe, as do ghostly subatomic particles called neutrinos. The discovery was announced seven years after researchers announced that they had first detected the existence of gravitational waves generated by two distant black holes - extraordinarily dense objects with gravity so strong that not even light can escape. The motion of black holes and other massive objects can cause gravitational waves.

“So if you imagine, you know, the collection of supermassive black holes that were that, you know, we were seeing correlations for as kind of like a choir or an orchestra... Imagine one of these orchestra members is a little bit close or is playing a little bit louder for some reason. That only happens with supermassive black holes,” Siemens told Reuters.