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How a group of Canberra scientists helped to prove what Einstein couldn't

Professor David McClelland and Professor Susan Scott at the ANU Centre for Gravitational Physics.
Professor David McClelland and Professor Susan Scott at the ANU Centre for Gravitational Physics.  Photo: Jay Cronan

Albert Einstein may have predicted the existence of gravitational waves but even he couldn't foresee science advancing far enough to ever prove him right.

And among more than 1200 scientists who helped build the massive optical instrument which captured these mysterious waves as they washed past the Earth was a group of Canberran scientists.

The breakthrough of the century was made at the Advanced Laser Interferometer Gravitational-Wave Observatory in the United States.

Around 15 scientists at the Australian National University developed some of the key technologies which enabled the laser interferometer to detect the elusive waves , radiating from two giant black holes colliding 1.3 billion years ago.

Their main contribution was a lock aquisition system for the interferometer's mirrors, without which the interferometer could not measure the waves, Australian National University's Professor David McClelland said.

The ANU also created 30 small optics steering mirrors for routing the signal beam around the interferometer and into the detectors.

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Scientists from the CSIRO provided optical and thermal coating for some mirrors, among the most uniform and highly precise ever made.

ANU researchers also raked through the LOGO data for waves from young supernovas and used the university's Skymapper telescope to search for bursts of lights from the gravitational waves stemming from the colliding black holes.

The actual existence of these minute ripples in the curvature of space-time was the last outstanding prediction made in Einstein's 1915 theory of general relativity.

And while Einstein was doubtful a measurement fine enough to capture the wave could ever be calibrated, Professor McClelland said it began to look possible about 25 years ago.

"It took a number of evolution, revolutions in physics before we could even think about doing this work," he said.

"Modulation technologies, suspension technologies and even making the mirrors, back in Einstein's day none of that was possible. But by about 1990 we could see the ingredients were there."

ANU general relativity theorist Professor Susan Scott said where we can measure other waves like radio and light back to about 300,000 years after the birth of the universe, gravitational waves enable humans to reach right back to the Big Bang.

"It will give us an entirely new window on the universe. Now we have achieved detection, now we want to move forward and open a new window on the universe called gravitational astronomy," she said.

"This is just the beginning moment on that. We're going to be able to explore whole parts of the universe that we haven't even seen before because they don't emit in anything else, only in gravitational waves. Now we're at the dawn of a new age of astronomy."

The implications are massive – and not just for our understanding of the universe.

Professor McClelland said the technology has applications in much wider areas, and can even be used by satellites to measure how the water table is changing on the Earth's surface.

A Canberra start-up, Liquid Instruments, is using their technology to revolutionise land-based laboratory instruments, Professor McClelland said.

And the ANU will continue to be at the forefront of this emerging field, he said.

Dr Scott will now trawl the data for signals while her colleagues begin to explore how far they can develop this technology using quantum optics and "squeezing".

"The thing about when you start to measure signals from the universe is that you always want to build a better and better detector so you can see further and further into the universe and into the past," Professor McClelland said.

"We're going to discover things we can't even imagine at the moment. Like when Galileo first looked at the sky with a telescope in 1609, we had no idea what was out in the universe and that's the feeling we have now, we're right at the beginning."