Reinventing antiquated theories is physics professor Art McDonald’s bread and butter.
McDonald said most of his work is done at the Sudbury Neutrino Observatory’s lab located two kilometres underground in an active nickel mine near Sudbury. The observatory’s $100-million project has put McDonald on the map.
Through his work at the observatory, which involves nearly 130 scientists worldwide, McDonald has proven that neutrinos—particles smaller than neutrons—have a mass, something which was previously assumed to be impossible. The fact that neutrinos have mass directly affects the expansion of the universe, McDonald said. He said the discovery affects such basic laws of physics that it will change the textbooks used to teach physics in high school.
“As a result of our measurements, we’ve basically rewritten the textbooks in physics,” he said. “We’ve defined properties of particles called neutrinos that were simply not known before, and that changes what’s called the Standard Model for elementary particles. “
One of this discovery’s results is the increased knowledge scientists have about the nuclear reactions that power the sun, McDonald said, adding that the models of the sun now used by scientists are much more accurate than previous models.
As the project’s director, McDonald travels around the world to give lectures and speeches, attend conventions and oversee meetings to discuss their ongoing research. This semester alone, McDonald will visit Louisiana, Japan, New Zealand, California, Princeton and Waterloo.
“When you’re able to make significant changes to the laws of physics, people want to hear about it. I’m not the only one from our collaborations who are travelling internationally,” he said. “The fact that I’m only teaching one term makes it possible for me to schedule all of these.” Although McDonald said he sometimes misses teaching large classes, his schedule doesn’t allow that kind of time commitment. He teaches an upper-level lab course and oversees several graduate and fourth-year undergraduate research projects.
In 2007, McDonald was the co-recipient of the Benjamin Franklin Medal for physics and was appointed to the Order of Canada. McDonald said his work on subatomic particles has made him one of the most sought-after scientists in his field.
“In 2003, we had more citations for our papers than any other papers in physics. We were listed by Discover Magazine as one of the top two scientific breakthroughs of the year 2002,” he said. “It is very common for me to have one or two conference calls [daily] with international participants in those projects.” “Up until this past year, I was in Sudbury a couple of days every couple of weeks. … I’m still there once a month. I’m also involved in giving invited talks all over the world. I’ve got six invited talks before June.” Federal and provincial government organizations as well as several non-governmental research groups fund McDonald’s research, he said, adding that about 25 per cent of his research has been ed by U.S. and U.K. agencies.
McDonald got his start at Dalhousie University in Halifax, where he got both is B.Sc. and his M.Sc. He then moved to the opposite end of the continent, completing his PhD at the California Institute of Technology. He also holds four honourary degrees from various universities.
Before coming to Queen’s, McDonald worked as a researcher at the Chalk River Laboratories and was a professor at Princeton University from 1982 to 1989. At Queen’s, he’s the Gordon and Patricia Chair of Particle Astrophysics, the director of the Sudbury Neutrino Observatory and a professor.
McDonald is working on a new project with the observatory in search of dark matter. Dark matter’s a hypothetical form of matter of unknown composition that can’t be observed directly because it doesn’t emit or reflect enough electromagnetic radiation. The new project—entitled Dark Matter Experiment with Argon and Pulse-shape discrimination—studies weakly interacting massive particles, which make up about 23 per cent of the universe. The particles don’t interact with electromagnetism, making them impossible to see directly, linking them to dark matter.
McDonald said the particles are interesting because people don’t know much about them.
“We think [the particles] were produced in the original Big Bang, and there has not been enough energy in our universe since then to produce them again. We see that they’re there because the galaxies are held together by this extra gravitational force,” he said. “It’s very fundamental measurements that will change textbooks. The implications are very big.”
Art McDonald will be giving a lecture called “Studying the universe from 2km underground: SNO and the new SNOLAB” on Sunday afternoon in Goodes Hall, room 301, from 2 to 3:30 p.m.
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