How Canadian scientists contributed to Nobel Prize-winning discovery

Just three men won this year's Nobel Prize in Physics, but there were thousands of people involved in the gravitational wave discovery, including a Canadian team of astrophysicists.

'It took many, many, many people from many disciplines,' researcher says

This illustration shows the merger of two black holes and the gravitational waves that ripple outward as the black holes spiral toward each other. In reality, the area near the black holes would appear highly warped, and the gravitational waves would be difficult to see directly. (T. Pyle/LIGO)

Just three men won this year's Nobel Prize in Physics, but there were thousands of people involved in the gravitational wave discovery, including a Canadian team of astrophysicists.

"It took many, many, many people from many disciplines to build something extraordinary together," says Aaron Zimmerman, a postdoctoral student at the Canadian Institute for Theoretical Astrophysics (CITA) at the University of Toronto.

Zimmerman says the Royal Swedish Academy of Sciences recognized this in giving out the prize to Rainer Weiss, Barry Barish and Kip S. Thorne for "decisive contributions" to the detection and observation of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory (LIGO).

"They acknowledged that it was LIGO as an experiment and as a collaboration that made this discovery, even if the prize went to some of the drivers at the heart of things," Zimmerman said in an interview with CBC News.

Scientists detect gravitational waves for 1st time

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Einstein theory proven more than 100 years later

The discovery of gravitational waves — ripples in space-time produced when cosmic objects change shape — proved a major prediction made in Einstein's general theory of relativity 100 years earlier.

Zimmerman and his CITA colleagues are part of the LIGO scientific collaboration that today involves around 1,200 scientists in 15 countries.

There were many who came before them, including Kipp Cannon, the first person in Canada to be a member of the collaboration.

"So much about our understanding of gravity changed immediately with the discovery that it's hard to remember what life was like before," Cannon told CBC News.

Cannon established the U of T investigative group in 2010 and headed it up until his departure in 2016. While there, he developed software that could sift through the massive amounts of data coming in from the LIGO detectors to try to separate signal from noise.

He said his system cut down the "latency" time between collecting the data and finding a signal in it, and also algorithmically ranked the signals to call attention to those that were more likely to yield results.

'Decades of really intense work'

Harald Pfeiffer, who took over for Cannon as principal investigator, specialized in theoretical work — figuring out what exactly Einstein's equations predicted, what shape(s) would gravitational waveforms take — and then comparing the LIGO detector's measurements with the predictions.

"It's a capstone for several decades of really intense work — on the experiment, on the theory, putting all the pieces together ... that enabled the first discovery," Pfeiffer said in an interview from Germany, where he is doing work at the Max Planck Institute.

Pfeiffer made use of the SCINET supercomputer at U of T, just one instrument in a worldwide network of highly specialized equipment and knowledge: LIGO's lasers were built at the Max Planck Institute, for instance; another university group developed the mirror coatings they use, believed to be the world's most reflective; yet another group fabricated the "immensely thin" fibres on which the mirrors hang.

Members of the CITA team at the University of Toronto are, left to right, Jaykumar Patel, Harald Pfeiffer, Heather Fong, Carl-Johan Haster, Katerina Chatziioannou, Prayush Kumar and Aaron Zimmerman. (Diana Tyszko/CITA/Canadian Press)

The gravitational waves detected by LIGO were produced by the collision of two black holes — cosmic dead zones that emit no light or electromagnetic rays. Gravitational waves prove they exist; the undetectable has become detectable.

Pfeiffer says this will present "an entirely new way by which we can observe and learn about the universe."

That's where Zimmerman comes in.

"If you can develop this experiment to detect gravitational waves, what you've really built is sort of a black hole telescope — you now have a telescope that can look out in the universe and see the invisible," he said.

Building on Cannon's work, his team at CITA specializes in data analysis.

"We're still in the early stages of finding out what the universe has in store for us, but this is a new sense we've turned on to investigate, to see what's out there."