LIGO team member Fulvio Ricci, a physicist at the University of Rome La Sapienzaa said there was a third “candidate” detection of an event in October, which Ricci said he prefers to call a “trigger”, but it was much less significant and the signal to noise not large enough to officially count as a detection. But by the time they reach Earth 1.4 billion years later, those waves have become very faint (like how the ripples from a stone dropped in a pond mellow out the further you get from the stone). The two cosmic entities had been circling around each other, progressively moving closer to collision. That long-ago violent collision set off reverberations through spacetime, a fusion of the concepts of time and three-dimensional space.
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Albert Einstein first predicted gravitational waves in 1916, following his theory of general relativity. As the LIGO team suggest, “together with GW150914, this event marks the beginning of gravitational-wave astronomy as a revolutionary new means to explore the frontiers of our Universe”. But you probably had no idea.
Two LIGO observatories based in Livingston, La. and Hanford, Wash. detected this event late on December 25, 2015. LIGO measures miniscule changes in the lengths of 2.5-mile-long detectors, which are fitted with lasers and mirrors to make precision measurements of subatomic lengths. One source of gravitational waves is two dense objects (like black holes or neutron stars) in orbit around each other.
The second wave was picked up by the LIGO detectors in Hanford, Washington and Livingston, Louisiana on December 26, 2015 at 9.09am IST through a signal from the coalescence of two black holes, with masses 14 and 8 times the mass of the sun, merging into a more massive, rapidly rotating black hole that is 21 times the mass of the sun. The observatories will begin their second detection period in the fall, officials said, with the Virgo detector coming online about halfway through that period. They made the announcement from the 228th American Astronomical Society meeting, and the work was published today in Physical Review Letters.
It’s the type of crash that may happen in our own Milky Way once every few hundred millions of years or so, but by looking at so many other galaxies, we can hear more, said Barnard College physicist Janna Levin, author of “Black Hole Blues And Other Songs From Outer Space”.
The University of Glasgow’s Institute for Gravitational Research led on the conception, development, construction and installation the mirrors in the heart of the LIGO detectors, which has been said to be crucial to the first observations.
Both discoveries resulted from the enhanced capabilities of Advanced LIGO, a major upgrade that increased the sensitivity of the instruments and the volume of the universe probed compared with the first-generation LIGO detectors.
The initial discovery of gravitational waves announced in February occurred in September, shortly after the LIGO detector was up and running.
“This is what we call gravity’s music”, González said.
Until now, scientists have used telescopes to detect light, or electromagnetic waves, traveling through space in order to learn about our universe.
Q: What are black holes?
“With the advent of Advanced LIGO, we anticipated researchers would eventually succeed at detecting unexpected phenomena, but these two detections thus far have surpassed our expectations”, said NSF Director France A. Córdova.
“Mysteries still to be explained include: how do such black hole systems form?” The two black holes, which were 14 and eight times the mass of our sun, merged about 1.4 billion years ago in a huge crunch. And they didn’t appear to be spinning, as models had suggested they would.
“It confirms – it super-confirms – that these events are not flukes”, astrophysicist Vicky Kalogera, who has been working with LIGO to analyze the signals, told Tech Insider.
By using gravitational waves, scientists might gain new insight into everything from how gravity works to how black holes form and collide.
“This is a more comforting event”, she says.
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For more information on this historic event, see the LIGO listing page for the finding of GW151226. “The fact that there’s more than one splash, and it’s possibly going to be a rainfall, is the big news”. The machine will be turned back on for six months later this year after its detection sensitivities have been improved.
