The Biggest Chill
Scientists have cooled sodium gas to the lowest temperature ever recorded–one half-billionth degree above absolute zero, which is the point where no further cooling is possible.
At absolute zero, which is -273 Celsius (-460 Fahrenheit), all motion stops, except for tiny atomic vibrations because the cooling process has extracted all energy from the particles.
It is the first time a gas has been cooled below one nanokelvin, which is one billionth of a degree above absolute zero.
The accomplishment is “like running a mile below four minutes for the first time,” said Dr. Wolfgang Ketterle, a physics professor at the Massachusetts Institute of Technology (MIT) and co leader of the research team, which was funded by the U.S. National Aeronautics and Space Administration and the National Science Foundation.
The success was published in a paper in today’s issue of the journal “Science.”
In 1995, a group at the University of Colorado, Boulder and a Massachusetts Institute of Technology group led by Ketterle cooled atomic gases to below one microkelvin, which is one-millionth degree above absolute zero.
In doing so, they discovered a new form of matter, the Bose-Einstein condensate, where the particles march in lockstep instead of flitting around independently and earned themselves the 2001 Nobel Prize in Physics.
Since the 1995 breakthrough, many groups have routinely reached nanokelvin temperatures, with three nanokelvin as the lowest temperature previously recorded.
This new temperature is six times lower than the previous record.
At such low temperatures, atoms cannot be kept in physical containers, because they would stick to the walls — and no known container can be cooled to such temperatures.
To circumvent this problem, magnets surround the atoms, which keep the gaseous cloud confined without touching it.
To reach the record low temperatures, the researchers invented a novel way of confining atoms, which they call a “gravito magnetic trap.” The magnetic fields acted together with gravitational forces to keep the atoms trapped.
“Ultra low temperature gases could lead to vast improvements in precision measurements by allowing better atomic clocks and sensors for gravity and rotation,” said Dr. David E. Pritchard, MIT physics professor, a pioneer in atom optics and atom interferometry, and co leader of the team.
Provided by theEnvironmental News Service.
