DARK MATTER: A COSMIC MYSTERY

In the process of measuring the speed of rotation of galaxies, astronomers made a startling, and completely unexpected, discovery.

Their calculations revealed that galaxies are rotating more than twice as fast as they should be, given their mass—which means that according to Einstein’s theory of gravity, they ought to be flying apart. Why aren’t they?

Physicists have since discovered that it’s because galaxies contain some “dark” form of matter that doesn’t emit or reflect enough light to be seen directly by conventional astronomical telescopes. Incredibly, it makes up close to 25 per cent of the universe.

What is this “dark matter”? How did it get here? What it is made of? What can it tell us about the origins of the universe and how it’s evolving?

TACKLING THE MYSTERY

Ontario is uniquely positioned to make the breakthrough discovery. The province has some of the brightest minds in physics today, including Dr. Tony Noble, lured back from the University of Zurich to Queen’s University, Dr. Art McDonald, attracted back from Princeton to Queen’s University, and Dr. David Sinclair, who returned from Oxford to Carleton University.

We also have a one-of-a-kind research facility two kilometres underground near Sudbury in CVRD-Inco’s Creighton Mine—and that’s what brought them home. It’s also what’s attracting scientists from around the world.

Consisting of the Sudbury Neutrino Observatory Underground Laboratory (SNOLAB), it’s the lowest radioactivity location in the world. So far, it’s enabled researchers to confirm that neutrinos, subatomic particles that pass through almost all matter without being stopped or deflected—and which make up a small part of dark matter—do have mass. It was a revolutionary finding that’s garnered international awards for the scientists involved, most notably Dr. McDonald, who recently won the Benjamin Franklin Medal in Physics, traditionally a stepping-stone to a Nobel Prize.

UNIQUE CRYOPIT WILL DETECT DARK MATTER PARTICLES

Ontario scientists hope to build on the success of their neutrino discoveries by using large volumes of ultra-cold (cryogenic) liquified argon and xenon gases to observe the missing dark matter particles for the first time.

“We’ll be using cryogenic liquids because they produce light when they’re hit by dark matter particles – and they’re relatively inexpensive so we can use large volumes,” explains Dr. Sinclair of Carleton University, founding director of the recently expanded SNOLAB. “That’s important because these interactions are extremely rare, so the more liquid there is, the more chances we’ll have to record them for analysis.”

This frontier research will take place at the new CRYOPIT, located in a large cavity at SNOLAB where the ultra-low radioactivity will essentially eliminate all background effects that might impact on the experiments.

ONTARIO’S SCIENTIFIC PRESTIGE IS GROWING

So, what does it all mean for Ontario? “Dark matter particles may be the next link to the theory of how everything came to be, which is the ultimate goal in particle physics,” says Dr. Noble. “If we’re successful in identifying them, it will solidify our pre-eminence in the field.”

Adds Dr. Sinclair, “The potential for further discovery is very exciting and it’s generating interest from all over the world. Stay tuned for news of further progress.”