William Phillips used liquid nitrogen and racquetballs to demonstrate the cooling of atoms during his lecture Sept. 25. Details...
Phillips, a Nobel Laureate scientist, gave students and faculty an entertaining and enlightening lecture on cooling and trapping atoms in McCrary Theatre. Phillips’ lecture, titled “Almost Absolute Zero: The Story of Laser Cooling and Trapping,” was part of the Voices of Discovery Science Speaker Series, sponsored by the departments of Science and Mathematics.
Phillips and his colleagues have focused their research on cooling atoms to almost absolute zero, the temperature at which atoms quit moving. Phillips explained the difference between hot and cold atoms by using liquid nitrogen as a visual aid. Repeatedly, he poured liquid nitrogen, which is 77 degrees above absolute zero, from the canister. When the nitrogen hits normal room air, which is about 300 degrees above absolute zero, it boils immediately. Phillips also placed a racquetball into a canister of liquid nitrogen for five minutes, and then threw the ball against a cinder block on the stage. Rather than bouncing, the ball shattered.
“If a gas is hot, its atoms are moving fast, and if the gas is cold, its atoms are slow,” said Phillips. He says cold atoms are preferable for scientists because they are easier to manipulate, and because they can be used for applications such as more accurate atomic clocks and atom lasers.
Phillips and his colleagues have been able to successfully slow the speed of atoms from 4,000 kilometers per hour to less than one kilometer per hour. The slowing or supercooling is accomplished by subjecting atoms in a vacuum to opposing beams of high energy laser light.
Phillips was part of a team of researchers that received the 1997 Nobel Prize in Physics for the development of methods to cool and trap atoms with laser light.
Phillips is a research scientist at the National Institute of Standards and Technology. He received his doctorate from the Massachusetts Institute of technology in 1976. Phillips was elected to the National Academy of Sciences in 1997 and received the Gold Medal award from the U.S. Department of Commerce in 1993.