Really Cold AtomsCAMBRIDGE, MASS. - Physicists in the U.S. say they have cooled sodium gas to thelowest temperature ever recorded – half-a-billionth of a degree above absolute zero. The researchers say the milestone beats the previous record by a factor of six, andmarks the first time a gas was cooled below one nanokelvin, or a billionth of a degree.One of the researchers is a Nobel laureate At absolute zero, -273 degrees C, atomic motion stops as the cooling zaps all theenergy from the particles. "To go below one nanokelvin is a little like running a mileunder four minutes for the first time," said Nobel laureate Wolfgang Ketterle, co-leaderof the physics team at the Massachusetts Institute of Technology. Ultra-low temperature gases could lead to more precise measurements by atomicclocks and sensors for gravity and rotation, according to David Pritchard, an atomoptics expert at MIT and co-leader of the team.
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