As widely reported, including in this piece on the Caltech website, “[s]cientists are reporting the first evidence that our Earth and the universe around us are awash in a background of spacetime undulations called gravitational waves.”
As the article reminds us, “[g]ravitational waves were first proposed by Albert Einstein in 1916.” The new evidence confirming their existence is a result of “15 years’ worth of observations made by the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), a National Science Foundation-funded (NSF) Physics Frontier Center of more than 190 scientists from the United States and Canada.”
The article gives some background on NANOGrav:
“NANOGrav is an international collaboration dedicated to exploring the low-frequency gravitational-wave universe through radio pulsar timing. NANOGrav was founded in October 2007 and has grown to more than 190 members at more than 70 institutions. In 2015, it was designated a National Science Foundation (NSF) Physics Frontiers Center.”
The methodology of this long-term study has been summarised in lay terms as follows:
“NANOGrav used data from radio telescopes—the Arecibo Observatory in Puerto Rico, the Green Bank Telescope in West Virginia, and the Very Large Array in New Mexico—to monitor 68 dead stars, called pulsars, in the sky. The pulsars acted like a network of buoys bobbing on a slow-rolling sea of gravitational waves.”
and
“When gravitational waves travel across the cosmos, they stretch and squeeze the fabric of spacetime very slightly. This stretching and squeezing can cause the distance between Earth and a given pulsar to minutely change, which results in delays or advances to the timing of the pulsars’ flashes of light. To search for the background hum of gravitational waves, the science team developed software programs to compare the timing of pairs of pulsars in their network. Gravitational waves will shift this timing to different degrees depending on how close the pulsars are on the sky […]”
Reportedly, a “series of papers detailing the new NANOGrav results have been accepted for publication in The Astrophysical Journal Letters.”
Read the full article here.