Keep Watching the Chilly Skies

Outer space is not far, some wit once observed. It’s only an hour’s drive away, should you be so lucky to have a car that goes straight up.

To get his view on outer space, McGill physics professor Matt Dobbs had to go considerably further. As a member of the South Pole Telescope (SPT) team, he spent the beginning of 2007 in Antarctica’s white wastes. The SPT is a partnership between McGill and eight American institutions. With an imposing 10-metre-wide antennae dish, the telescope is designed to scan the wallpaper of the universe: cosmic microwave background (CMB) radiation, the afterglow light from the Big Bang released long before planets, stars and galaxies formed.

CMB radiation suffuses the entire universe, but the South Pole is a particularly good place to see it. On the electromagnetic spectrum, CMB falls between heat radiation and radio waves, making it easily absorbed by water vapour in the atmosphere—and therefore tough to observe. The South Pole’s high elevation (read: thin atmosphere) and dry climate, however, makes for an ideal CMB-spotting environment.

CMB radiation backlights all the objects in the universe. When these objects are particularly large, like galaxy clusters, there is measurable distortion in CMB. (In the shadow theatre of the universe, CMB is the light, galaxies are the puppets, and distortion is the shadow.) The strength of this distortion does not fade over distance, making CMB an indispensable tool for discovering very, very remote galaxy clusters. By measuring small angular scale features in CMB, the telescope may help astronomers detect previously unknown clusters—invaluable data for demystifying the history of how the universe has grown.

Dobbs spent a frigid month helping to build the receiver and readout electronics for this enormous high-tech window to the sky. Working in the South Pole’s extreme weather was not easy; even brief forays outside could lead to frostbite. The local weather crew described conditions one day as “Skies: going to hell. Temperature: Going to hell in a handbasket. Tomorrow: Even worse.”

Nonetheless, Dobbs left the bottom of the world feeling, well, on top of the world. “As our plane lifted off and circled back over the station,” he wrote in his polar blog, “the pilot banked quickly to the left and back again so that the wing would dip down and give us our last view of the South Pole Telescope—commissioned and ready to bring back a year’s worth of exciting new science.”

The South Pole Telescope is funded by the National Science Foundation, the Kavli Foundation and the Gordon and Betty Moore Foundation. McGill participants received additional funding from the Fonds québécois de la recherche sur la nature et les technologies and the Natural Sciences and Engineering Research Council of Canada.