
Science & Tech
The facts on Canada’s cold weather
Antarctica was in the
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In Edmonton, it’s not uncommon to see temperatures dip below –20°C. And while most people own apparel warm enough to combat the chill, there is one place in the city where even the thickest toque wouldn’t keep away the cold: inside the refrigerators of John P. Davis’s laboratory for low-temperature quantum nanoscience, a.k.a. the coldest place in Canada.
The two huge cylindrical containers, which have been operational since August, are able to cool molecules down to just a few millikelvin above absolute zero, the theoretical limit of coldness at which matter contains no thermal energy at all. Working at just slightly above –273.15°C, Davis (above), an assistant professor in the physics department at the University of Alberta, can examine microscopic matter in a realm unmeasured by the average thermometer. In these frigid temperatures, the world works in ways we might never have imagined. “As you get colder, new phenomena are revealed,” says Davis. “You reduce the background thermal environment, and new physics is revealed.”
One example of “new physics” is superfluidity in helium. When cooled to temperatures just a few degrees above absolute zero, the gas begins exhibiting behaviour that can’t be described by classical physics models, including the ability to scale the walls of containers and to seep through extremely tiny holes.
Superfluidity can be described only by quantum mechanics, a branch of physics that works at minuscule scales and is used to describe things such as the behaviour of individual particles. One thing Davis and his team are trying to do is observe the quantum mechanical properties of comparatively larger objects (the largest of these are about 0.01 millimetres wide), something that’s possible at very low temperatures. Understanding what happens at these scales may be a step toward reconciling the quantum mechanics of microscopic objects with the classical mechanics of macroscopic objects, one of the most persistent challenges facing physicists.
Breakthroughs within these supercold containers would excite more than just theoretical physicists — a firm understanding of these phenomena could have real-world implications. For example, superconductors are materials that allow electricity to pass through them with zero resistance, making the transmission of energy significantly more efficient. Unfortunately, they function only at extremely cold temperatures, which is an expensive environment to maintain. (New York City currently has a superconducting power line that transmits about 150 times more electricity than traditional wires of the same diameter, but it must be kept at around –200°C.) The advent of a superconductor that could operate without having to be cooled down would mean a big leap forward in energy transmission. Davis describes room-temperature superconductors as a “Holy Grail of physics” and hopes that a better understanding of this science at low temperatures can translate into a comprehensive theory that is applicable at any temperature.
Davis’s small basement laboratory is a stark contrast to the high-speed world of particle physics. But while his refrigerators may be humble compared with the city-sized Large Hadron Collider sitting under the French-Swiss border near Geneva, Davis is comfortable at the cool end of the science spectrum. “I see low-temperature physics as the other side of physics,” he says. “Particle physics takes billions of dollars and thousands of scientists, but we do this ourselves. We build it ourselves, and we get it running ourselves. It’s very rewarding.”
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