Gravitational waves announcement: Scientists hail ‘spectacular’ new detection of ripples in spacetime

Gravitational ripples in the fabric of spacetime, first predicted by Albert Einstein a century ago, have been detected for a second time by scientists - who believe the “spectacular” discovery could hearld a new era of understanding into the universe.

An international team of more than 1,000 researchers, including a number of British professors, observed two black holes collide and merge, unleashing titanic forces rarely seen before.

The event, which took place 1.4 billion light years away, caused an amount of energy roughly equivalent to the mass of the sun to be converted into gravitational waves.

The waves were "captured" by the twin Ligo (Laser Interferometer Gravitational-wave Observatory) detectors in US communities the Livingston, Louisiana, and Hanford, Washington, last December but the news has only now been made public.

Gravitational waves were predicted in Einstein's theory of general relativity, which argues that gravity occurs due to the curving space and time. The waves stretch and compress anything in their path, whether it be humans or entire planets, as the fabric of spacetime is distorted.

Dr Stephen Fairhurst, one of the team members from Cardiff University, said: "This event heralds the true beginning of gravitational wave astronomy and the opening of a new window on the universe.

"The different masses and observable spins that we witnessed in the Boxing Day event show that we're starting to collect vital information about the population of black holes that exist in the universe.

"Future gravitational wave observations will allow us to understand how black holes form from the death of massive stars, and test whether they are really as predicted by Einstein's theory."

Scientists hope gravitational waves will offer a completely different view of the universe, allowing them to study events that might be hidden from traditional optical and radio telescopes. By analysing the latest detection, scientists were able to tell that the colliding black holes were 14 and eight times larger than the sun.

Professor Sheila Rowan, director of the University of Glasgow's Institute for Gravitational Research, who also took part in the discovery, said: "We know from this second detection that the properties being measured by Ligo will allow us to start to answer some key questions with gravitational astronomy.

“In future we will be able to study this and better understand cosmic history, aiming to fill in the 'missing links' in our knowledge."

The findings have been accepted for publication in the journal Physical Review Letters.

Dr Chad Hanna, from Pennsylvania State University in the US, who co-led the detection team, said: "We now have far more confidence that mergers of two black holes are common in the nearby universe.

"Now that we are able to detect gravitational waves, they are going to be a phenomenal source of new information about our galaxy and an entirely new channel for discoveries about the universe."

The Ligo Scientific Collaboration consists of more than 1,000 scientists from 17 countries, including researchers from 10 UK universities – Glasgow, Birmingham, Cardiff, Strathclyde, West of Scotland, Sheffield, Edinburgh, Cambridge, King's College London and Southampton.

Each Ligo site has two tubes, both 2.5 miles (4km) long, arranged in an L shape.

A laser is beamed down each tube to monitor very precisely the distance between mirrors at each end. If a gravitational wave is present, it will alter the distance between the mirrors by a minute amount.

Professor Andreas Freise, from the University of Birmingham's School of Physics and Astronomy, whose team helped develop instrumentation for Ligo, said: "The Advanced Ligo detectors are a masterpiece of experimental physics. They are the most sensitive gravitational wave detectors ever built.

"We started with a well-known concept, a light interferometer, but it required new technologies that we have developed over several decades to create these extremely sensitive listening devices for gravity signals from the universe."

Dr Ed Daw, from the University of Sheffield's Department of Physics and Astronomy, who has been researching gravitational waves with Ligo since 1998, said: "The detection of the collision of one pair of black holes was amazing; the detection of a second one is spectacular, because it hints that there are lots more of these things out there.

"But it also raises more questions – what made these black holes? How many of these things are there? Can we start to really test general relativity in detail?"