An Enormous Gravity ‘Hum’ Moves Through the Universe

The discovery, recently announced by the team known as the North American Nanohertz Observatory for Gravitational Waves, or NANOGrav, shows that extra-large ripples in space-time are constantly squashing and changing the shape of space. These gravitational waves are cousins to the echoes from black hole collisions first picked up by the Laser Interferometer Gravitational-Wave Observatory (LIGO) experiment in 2015. But whereas LIGO’s waves might vibrate a few hundred times a second, it might take years or decades for a single one of these gravitational waves to pass by at the speed of light. 

The finding has opened a wholly new window on the universe, one that promises to reveal previously hidden phenomena such as the cosmic whirling of black holes that have the mass of billions of suns, or possibly even more exotic (and still hypothetical) celestial specters.

The results come from studies that stretch back more than a decade by four teams based in the U.S., Europe, Australia and China. In a coordinated data release, the teams present evidence for a background “hum” of gravitational waves that were detected by tracking changes in the impossibly regular beats of objects called pulsars.

“Finding for the first time the suggestion of background gravitational waves is fascinating,” said Juan García-Bellido, theoretical cosmologist at IFT. “It’s really Nobel Prize-winning research.”

Red the full article via Quanta Magazine.