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Neutron star collision has changed our understanding of universe: scientists

THEORY PROVED:The observation of the collision is another feather in the cap for Albert Einstein, who predicted gravitational waves more than 100 years ago

AFP, PARIS

An undated illustration provided by the National Science Foundation shows an artist’s impression of two merging neutron stars.

Photo: AFP

For the first time, scientists have witnessed the cataclysmic crash of two ultra-dense neutron stars in a galaxy far away and concluded that such impacts forged at least half the gold in the universe.

Shock waves and light flashes from the collision traveled about 130 million light-years to be captured by detectors on Earth on Aug. 17, excited teams revealed at news conferences held around the globe on Monday as a dozen related science papers were published in top academic journals.

“We witnessed history unfolding in front of our eyes: two neutron stars drawing closer, closer ... turning faster and faster around each other, then colliding and scattering debris all over the place,” joint discoverer Benoit Mours of France’s CNRS research institute said.

The groundbreaking observation solved a number of physics riddles and sent ripples of excitement through the scientific community.

Most jaw-dropping for many, the data finally revealed where much of the gold, platinum, uranium, mercury and other heavy elements in the universe come from.

Telescopes saw evidence of newly-forged material in the fallout, the teams said — a source long suspected, now confirmed.

“It makes it quite clear that a significant fraction, maybe half, maybe more, of the heavy elements in the universe are actually produced by this kind of collision,” said physicist Patrick Sutton, a member of the US-based Laser Interferometer Gravitational-Wave Observatory (LIGO), which contributed to the find.

Neutron stars are the condensed, burnt-out cores that remain when massive stars run out of fuel, blow up and die. Typically about 20km in diameter, but with more mass than the sun, they are highly radioactive and ultra-dense — a handful of material from one weighs as much as Mount Everest.

It had been theorized that mergers of two such exotic bodies would create ripples in the fabric of space-time known as gravitational waves, as well as flashes of high-energy radiation called gamma ray bursts.

On Aug. 17, detectors witnessed both phenomena, 1.7 seconds apart, coming from the same spot in the constellation of Hydra.

“It was clear to us within minutes that we had a binary neutron star detection,” said David Shoemaker, another member of LIGO, which has detectors in Livingston, Louisiana, and Hanford, Washington. “The signals were much too beautiful to be anything but that.”

The observation was the fruit of years of labor by thousands of scientists.

Along with LIGO, they include teams from Europe’s Virgo gravitational wave detector in Italy, and a number of ground and space-based telescopes, including NASA’s Hubble.

“This event marks a turning point in observational astronomy and will lead to a treasure trove of scientific results,” said Bangalore Sathyaprakash from Cardiff University’s School of Physics and Astronomy, recalling “the most exciting [discovery] of my scientific life.”

“It is tremendously exciting to experience a rare event that transforms our understanding of the workings of the universe,” added France Cordova, director of the National Science Foundation, which funds LIGO.

The detection is another feather in the cap for physicist Albert Einstein, who predicted gravitational waves more than 100 years ago.

Three LIGO pioneers — Barry Barish, Kip Thorne and Rainer Weiss — were awarded the Nobel Prize in Physics this month for the observation of gravitational waves, without which the latest discovery would not have been possible.

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