Detecting Gravitational Waves

5 September 2016


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The Songs of the Universe - Detecting Gravitational Waves

A public talk by Professor David Blair, Director of the Australian International Gravitational Research Centre (AIGRC), The University of Western Australia and Professor Hyung Mok Lee, Seoul National University and UWA Institute of Advanced Studies Visiting Fellow.

Einstein’s gravitational waves have been directly detected, one century after his original prediction. The waves are ripples of space and time that travel through empty space at the speed of light. The discovery, which was heard as a brief chirp, allows us to anticipate a musical universe that reveals itself in all sorts of sounds. More and more sounds will become audible to gravitational wave detectors as the detectors are improved in the next few years.

Gravitational wave detection faced numerous obstacles. The first was the question of the reality of the waves. The next was the extreme weakness of proposed sources of gravitational waves, which made Einstein say that they were only of academic interest. Eventually the concept of the black hole, derived exactly 100 years ago, saved the day. However it was the extraordinary ingenuity and dedication of well over 1000 physicists who worked over many decades to invent concepts and then refine them, to create practical detectors.

Researchers at The University of Western Australia contributed to the first detection by using high power lasers at the Gingin Gravitational Research Centre  to study a newly discovered way that laser light scatters from sound waves in mirrors, that cause detectors to become unstable. Their method for preventing instability allowed the sensitivity to be turned up enough for the first detection.

Gravitational wave detectors are pinnacles of technology. It took numerous innovations and massive efforts to make them sufficiently sensitive. Their detection is a triumph of innovation and persistence over skepticism.

The discovery of Einstein’s waves confirms that space itself is a continually rippling medium, and that geometry itself is fluctuating. It confirms that a substantial amount of matter in the universe has been lost into black holes, and that black holes are growing. Many fundamental questions have now come within reach. 

In this special UWA Research Week event, Professor David Blair will tell the story of the century long quest to detect Einstein’s waves. Using simple language that everyone can understand, his talk will reveal the obstacles, the innovations, the technology and new ways of thinking about our place in the universe. 

Professor Hyung Mok Lee is a leading Korean astrophysicist and science communicator. He correctly predicted that the first detection of gravitational waves would be from merging pairs of black holes. His talk will tell the story of the formation of black holes, how they came to be merging, and how their ripples spread across the cosmos for one billion years before they reached the solar system in September 2015.