In a packed talk on Tuesday afternoon at the American Physical Society's annual March meeting in Las Vegas, Ranga Dias, a physicist at the University of Rochester, announced that he and his team had achieved a century-old dream of the field: a superconductor that works at room temperature and near-room pressure. Interest was so intense in the presentation that security personnel stopped entry to the overflowing room more than fifteen minutes before the talk. They could be overheard shooing curious onlookers away shortly before Dias began speaking. The results, published today in Nature, appear to show that a conventional conductor ?" a solid composed of hydrogen, nitrogen and the rare-earth metal lutetium ?" was transformed into a flawless material capable of conducting electricity with perfect efficiency. While the announcement has been greeted with enthusiasm by some scientists, others are far more cautious, pointing to the research group's controversial history of allege