氮可唔可以低到絕對5K呢??

氮既溫度最低絕對可以遠低於5K
MIT team achieves coldest temperature ever
Public release date: 11-Sep-2003
MIT scientists have cooled a sodium gas to the lowest temperature ever recorded -- only half-a-billionth of a degree above absolute zero. The work, to be reported in the Sept. 12 issue of Science, bests the previous record by a factor of six, and is the first time that a gas was cooled below 1 nanokelvin (one-billionth of a degree).
The researchers also expect new phenomena to occur at such low temperatures involving, for example, how cold atoms interact with surfaces and how atoms move when they are confined to a narrow channel or layer. These gases form a remarkable state of matter called a quantum fluid, so studying their properties also provides new insights into the basic physics of matter.
At absolute zero (-273 degrees C or -460 degrees F), all atomic motion comes to a standstill since the cooling process has extracted all the particles' energy. By improving cooling methods, scientists have succeeded in getting closer and closer to absolute zero. At room temperature, atoms move at the speed of a jet airplane. At the new record-low temperature, atoms are a million times slower -- it takes them half a minute to move one inch.
In 1995, a group at the University of Colorado at Boulder and an MIT group led by Ketterle cooled atomic gases to below one microkelvin (one-millionth of a 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. The discovery of Bose-Einstein condensates was recognized with the 2001 Nobel Prize in physics, which Ketterle shared with his Boulder colleagues Eric Cornell and Carl Wieman.
Since this breakthrough, many groups worldwide now routinely reach nanokelvin temperatures; the lowest temperature reported before now was 3 nanokelvin. The new record set by the MIT group is 500 picokelvin, or six times lower.
At such low temperatures, atoms cannot be kept in physical containers, because they would stick to the walls. Furthermore, no known container can be cooled to such temperatures. Therefore, the atoms are surrounded by magnets, which keep the gaseous cloud confined.
For reaching the record-low temperatures, the MIT researchers invented a novel way of confining atoms, which they call a "gravito-magnetic trap." As the name indicates, the magnetic fields act together with gravitational forces to keep the atoms trapped.
I hope this can help your understanding.