AssetID: 52853406
Headline: Scientists Detect Ripples In The Fabric Of Space-Time
Caption: **RAW VIDEO** Scientists have found evidence of ripples in the very fabric of space-time itself. The motion of black holes and other massive objects through space can create ripples in the fabric of the universe, called gravitational waves. On Wednesday (28 June 2023) researchers announced the first evidence of a background of such long-wavelength gravitational waves in the cosmos. These waves are thought to have been created over eons by supermassive black holes, up to billions of times the mass of our Sun, circling each other before they merge. The background ripples detected by NANOGrav could help scientists better understand how gravitational waves are created and what happens to them as they propagate through the universe. They could also be used to study supermassive black hole mergers - events that can last for millions of years. Scientists think these mergers happen in most galaxies and influence their evolution. The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) presented the evidence in a series of papers published in the Astrophysical Journal Letters. NANOGrav is a National Science Foundation-funded Physics Frontiers Center of more than 190 scientists from the United States and Canada, including scientists at NASA’s Jet Propulsion Laboratory in Southern California and other NASA centers. The collaborative project has spent more than 15 years collecting high-precision data from ground-based radio telescopes, looking for these gravitational waves. Gravitational waves were first predicted by Albert Einstein in 1916. They would not be confirmed until 2015, when the Laser Interferometer Gravitational-Wave Observatory (LIGO) detected spacetime ripples passing through the Earth. Although the source of those gravitational ripples was a collision of two far-off black holes, the resulting spatial distortion that LIGO detected was smaller than the nucleus of an atom. By comparison, the apparent pulsar time shift measured by the NANOGrav team is a few hundred billionths of a second and represents a flexing of spacetime between Earth and the pulsars about the length of a football field. Those spacetime distortions were caused by gravitational waves so immense that the distance between two crests is 2-10 light-years, or about 9-90 trillion kilometers. "These are by far the most powerful gravitational waves known to exist," said West Virginia University astrophysicist Maura McLaughlin, co-director of the NANOgrav Physics Frontiers Center. "Detecting such gargantuan gravitational waves requires a similarly massive detector, and patience." Using 15 years of astronomical data recorded by radio telescopes at NSF-supported observatories — including Green Bank Observatory in West Virginia, the Very Large Array in Socorro, New Mexico, and Arecibo Observatory in Puerto Rico— the NANOGrav team created a "detector" of 67 pulsars distributed all across the sky and compared the ticking rate of pairs of those pulsars. Through a sophisticated data analysis, they deduced the presence of the gravitational wave background causing the distortion of space, and thus explained the apparent timing changes of the pulsars. This is the first evidence for gravitational waves at these low frequencies," said Vanderbilt University astrophysicist Stephen Taylor, chair of the NANOGrav collaboration and co-leader of the research effort. "The likely source of these waves are distant pairs of close-orbiting, ultra-massive black holes." "There is so much we have yet to understand about the physical nature of the universe and that's why the National Science Foundation supports daring team efforts like NANOGrav — to expand our knowledge for the benefit of society," said NSF Assistant Director for Mathematical and Physical Sciences Sean L. Jones. The team's results are providing new insights into how galaxies evolve and how supermassive black holes grow and merge. The widespread spacetime distortion revealed in their findings implies that extremely massive pairs of black holes may be similarly widespread across the universe, numbering perhaps in the hundreds of thousands or even millions. Eventually, the NANOGrav team expects to be able to identify specific supermassive black hole pairs by tracing the gravitational waves they emit. They may even uncover traces of gravitational waves from the very early universe. "While our early data told us that we were hearing something, we now know that it’s the music of the gravitational universe," said NANOGrav co-director and Oregon State University astrophysicist Xavier Siemens. "As we keep listening, individual instruments will come to the fore in this cosmic orchestra."
Keywords: space-time,gravity,science,physics,astronomy,gravitational waves,black holes,space,feature
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