Thursday, 16 June 2016

An international team of scientists including 21 researchers from UWA has made a major breakthrough: a second detection of gravitational waves, following their world-first discovery of gravitational waves last September.

The second detection suggests that by increasing the power of the laser light used to detect the waves, scientists will soon be hearing a symphony of gravitational sounds from the universe.

If that happens, scientists will be able to answer a major question about the universe: How many back holes are out there?

Gravitational waves are waves of energy, ripples in the fabric of space-time. The discovery of the first wave last year proved a prediction by Einstein 100 years ago.

Professor David Blair from UWA’s School of Physics said the scientists feared the first signal may have been the only one they would hear in their lifetime.

“But on Boxing Day at 11.38am Perth time, we heard two more black holes intercept, one eight times the weight of the sun, the other fourteen times,” Professor Blair said.

“The new signal created a black hole about twice the size of Perth, weighing 22 times the mass of the sun.

“The first signal gave us a single brief musical chirp. The second one consisted of a longer rising tone that reached a crescendo just above middle C. The new detection proves that there are many more black holes merging than we ever expected. As we tune up our detectors there will be symphony of gravitational sounds.

“Like the first signal, the second signal came from a billion light years away, but a location of the waves will only be able to be pinpointed by setting up more detectors across the earth.”

Professor Blair said the discoveries would change the way humans studied the universe and were the start of gravitational-wave astronomy.

“We may come across things we never expected to hear and the possibilities are endless. Many unusual objects such as quark stars and cosmic strings could be out there, and many signals such as gamma ray bursts may only be explainable by listening to gravitational waves,” he said.

The team is currently working on techniques for making detectors more sensitive, including techniques tested at Gingin in WA which will help the US observatories increase their laser power.

Gravitational wave detectors are the most sensitive instruments ever created. Some of the techniques invented for detecting gravitational waves are being used by the UWA team for making new sensors and for detecting minerals buried deep underground.

The gravitational waves were detected by twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, USA. The LIGO Observatories are funded by the National Science Foundation (NSF), and were conceived, built, and are operated by Caltech and MIT.

Both discoveries were made by the LIGO Scientific Collaboration (which includes the GEO600 Collaboration and the Australian Consortium for Interferometric Gravitational Astronomy) and the Virgo Collaboration using data from the two LIGO detectors.

Media references

Jess Reid (UWA Media and Public Relations Adviser) (+61 8) 6488 6876
David Stacey (UWA Media and Public Relations Manager) (+61 8) 6488 3229 / (+61 4) 32 637 716
Professor David Blair (UWA Australian International Gravitational Research Centre) (+61 8) 6488 2736


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