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"It's starting to get colder down here. From about Christmas onwards, the temperature just drops and drops. Up until now it hasn't been much colder than a cold Montreal day — about -28 C. Now it's heading downwards and we're starting to wear our balaclavas and ski goggles for the walk to the dark sector lab."

For ¿´Æ¬ÊÓƵ University astrophysicist Matt Dobbs, January 29 was just another day at the office. At least during the final weeks of assembling the South Pole Telescope (SPT), Dobbs has been working in conditions that most North Americans would find daunting, if not unbearable. But most North Americans don't spend their days preparing to explore the nature of dark energy, the unexplained phenomenon responsible for the observed acceleration in the expansion of the universe. "We'll basically be taking a census of galaxy clusters and using them to trace out the growth history of the universe," said Dobbs, who has been keeping a blog of the final days before the SPT "sees first light," the term astronomers use to refer to the first time a new telescope is used to look up at the cosmos.

The SPT, one of many research activities undertaken for International Polar Year beginning in 2007, will look for massive clusters of galaxies by observing spectral distortions in the cosmos. Dark energy impedes the growth of galaxy clusters, so studying the population of clusters through cosmic time will provide scientists with insight into the nature of dark energy. "If we can map out galaxy clusters as a function of time, we'll have a better understanding of the role dark energy takes in the history of the universe," said Dobbs. ¿´Æ¬ÊÓƵ physics professor Gil Holder, who is also involved in the project, added, "Dark energy, accounting for about 70% of the energy density in the universe and as yet with no sound physical explanation, is perhaps the biggest mystery in cosmology and particle physics. We'll be providing a critical piece of that puzzle."

The project is a collaboration among eight U.S. institutions, including the University of Chicago, the University of California at Berkeley, the University of Illinois, Case Western Reserve University, NASA's Jet Propulsion Laboratory, the Harvard-Smithsonian Center for Astrophysics, the University of Colorado at Boulder, the University of California at Davis and one Canadian partner, ¿´Æ¬ÊÓƵ It is funded through the National Science Foundation Office of Polar Programs.