World-leading Australian physicist Professor Susan Scott played a key role in the first-ever observation of gravitational waves, proving an outcome of Einstein’s iconic theory of general relativity and paving the way to a new understanding of the universe. In 2020, she was the first female physicist to win Australia’s top science prize.
Over a century ago, Albert Einstein predicted the existence of gravitational waves – invisible, super-fast ripples in space-time created by events like exploding stars and colliding black holes – but his theory went unproven for decades. When Australian mathematical physicist Professor Susan Scott began working in this area in 1990, other scientists were sceptical about our ability to ever measure gravitational waves, or even show that they existed.
In September 2015, Scott – a leading global expert in general relativity – was a key part of an international team of 1,000 that finally succeeded in directly observing gravitational waves. It was a ground-breaking achievement that won the 2017 Nobel Prize in Physics and launched a new era of scientific discovery.
“We can now unlock parts of the universe that previously weren’t accessible,” says Scott. “We’re going to discover all these new things about how the universe works and how it started.”
Gravitational waves squeeze and stretch everything in their path, literally causing tiny ripples in the fabric of reality. But by the time they reach Earth, they’re so faint that measuring them had been impossible with existing technology.
Between 1994 and 2002, an international team built the US-based Laser Interferometer Gravitational-Wave Observatory (LIGO), with critical input from Australian researchers. In 2008, Australia was one of four nations that signed up to the Advanced LIGO Project to enhance the original detectors. But this pioneering technology was only one part of the equation.
“Quite apart from the massive technology developments that needed to take place in those years, we also needed to work out ways of digging gravitational wave signals out of the incredible amount of noise in the detectors,” says Scott.
Scott initiated the Australian effort in gravitational wave science in 1998, building mathematical models to pick up signals. She leads the Australian National University’s General Relativity Theory and Data Analysis Group, who also developed many of the key components for the data analysis system that was used to detect the first signals in 2015.
The night the LIGO detectors first observed gravitational waves, Scott barely slept. While it was a huge achievement for humanity, it was really just the beginning of a new chapter in science. And the work of Scott and her colleagues has helped put Australia front and centre in exploring this new frontier.
A new dawn of discovery
“This has revolutionised astronomy because we’ve opened this new window to the universe, and we can provide information that astronomy hasn’t been able to throughout the history of humans,” says Scott. “Some things can only be seen with gravitational waves.”
Since 2015, Scott’s work has focused on expanding our knowledge even further. She is a head investigator of the Australian Research Council Centre of Excellence for Gravitational Wave Discovery (OzGrav), through which Australia will continue to play a major role in gravitational wave astronomy, as we unravel more mysteries of the universe.
“We have been very fortunate over these decades to have the Australian Government, through the Australian Research Council, fund our ongoing projects, even though there were no immediate benefits,” says Scott. “I don’t think we could have done it otherwise.”
Blazing trails Down Under
In October 2020, Scott was part of a team of four experimental physicists to win the Prime Minister’s Prize for Science, Australia’s most prestigious science award, for critical contributions to the first direct detection of gravitational waves. Scott was the first female physicist to win it, and relishes the opportunity to inspire women in a male-dominated field.
“It’s very hard as a young woman entering such a field to imagine how you’re going to have any success, because there are no role models,” she says. “And so it's very important to me to be a role model.”
Scott’s career was shaped by two experiences that showed her that women could succeed in male-dominated arenas – her education at a Melbourne all-girls’ school and her time at Somerville College, Oxford University’s oldest women’s college.
Also critical to her success has been collaboration across disciplines and beyond the borders of academia. In 2007, Scott was part of a team that ran two international conferences on general relativity and gravitational waves in Sydney.
“It all came together there,” she says. “We were able to spark interest with industry, the community and government, as well as showcasing the work we were doing to overseas audiences to really cement Australia’s place in this field.
“Having been to many conferences overseas, I know that scientists love to come to Australia,” says Scott. “Because not only will there be an excellent conference, but they also get to visit places related to their work, and then do incredible things they’ve always wanted to do. So it's an amazing package to come here for an international conference.”
Looking ahead, Scott will continue shining a light into the universe’s darkest corners.
“In the future, with greater sensitivity of our detectors, we're going to be able to look back to the beginning of the universe, because we can see further back with gravitational waves than we can with light,” says Scott.
“I feel like now the floodgates have opened… We can understand the universe so much more,” she says. “I’m just riding that wave of trying to be part of uncovering as much of that as we can.”
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