by Chris Impey
June 30, 2023
Introduction:
Read more here: https://theconversation.com/a-subtle-s ... es-208815(The Conversation) An international team of astronomers has detected a faint signal of gravitational waves reverberating through the universe. By using dead stars as a giant network of gravitational wave detectors, the collaboration – called NANOGrav – was able to measure a low-frequency hum from a chorus of ripples of spacetime.
I’m an astronomer who studies and has written about cosmology, black holes and exoplanets. I’ve researched the evolution of supermassive black holes using the Hubble Space telescope.
Though members of the team behind this new discovery aren’t yet certain, they strongly suspect that the background hum of gravitational waves they measured was caused by countless ancient merging events of supermassive black holes.
Using dead stars for cosmology
Gravitational waves are ripples in spacetime caused by massive accelerating objects. Albert Einstein predicted their existence in his general theory of relativity, in which he hypothesized that when a gravitational wave passes through space, it makes the space shrink then expand periodically.
Researchers first detected direct evidence of gravitational waves in 2015, when the Laser Interferometer Gravitational-Wave Observatory, known as LIGO, picked up a signal from a pair of merging black holes that had traveled 1.3 billion light-years to reach Earth.