.....Advertisement.....
.....Advertisement.....

Absolute Zero: a local perspective

-A A +A
By Roger Snodgrass

The second part of NOVA’s Absolute Zero series, “The Race for Absolute Zero” arrives on Tuesday, bringing the story of the scientific pursuit of the coldest temperatures in the universe up to the recent past.For an update with many related details, one need look no further than Los Alamos National Laboratory, where cryogenics – the production of low temperature phenomena and the study of their effects – has been an ongoing theme from the earliest days.As Laboratory Fellows Greg Swift and Joe Thompson recalled, research on plutonium in the early 1940s included studies of the metal’s cold-temperature characteristics and behavior, which was urgently needed for getting to know an entirely new element.  During the period when the hydrogen bomb was developed, laboratory scientists were called upon to liquefy deuterium as a fusion fuel, which required temperatures around 20 degrees Kelvin, or minus 253 degrees Celsius, a big step on the road to cold.Swift is one of the experts cited on NOVA’s Absolute Zero website. He has been recognized for his work in superfluids and for cooling materials with soundwaves. Thompson leads a team developing new physics from new compounds at extreme conditions, including cold temperatures. In the infinite regression to absolute zero, which is the hypothetical and ultimately unreachable temperature of 0 degrees Kelvin or minus 273 degrees Celsius, each step deeper into the cold has revealed new properties of matter, which have in turn often led to new tools with profound impacts on the modern world.As Swift said, “The cold pulls itself up by its own bootstraps.” LANL’s historic experience and the NOVA shows both demonstrate that the ability to create and sustain a cold condition can, through repetition and insulation, create and lock in successively colder states.The NOVA program connects the invention of refrigeration and air conditioning to the growth of urban populations by making skyscrapers possible, just as refrigeration allowed people to live at greater distances from food sources and in hotter environments.The lab’s work in supercooling deuterium led to pioneering methods for containing liquid forms of cold gasses, which in turn opened the way to outer space by providing liquid hydrogen fuel for space rockets.When the energy crisis first hit home in the 1970s during the Arab oil boycott, laboratory researchers began working on superconductors, which use the effects of cold temperatures to conduct electricity without resistance. That research has continued to improve materials and raise the temperatures at which superconductivity can become a practical, energy-saving reality.Superconductivity enabled by super-cold liquid helium has enabled the widespread use of magnetic resonance imaging (MRI) for diagnosing medical conditions, among many other new and new generations of technologies.Laboratory scientists achieved a milestone in 1948  when they were the first to liquefy the isotope helium 3 at 3 degrees Kelvin, which is the temperature at the edge of outer space.But that was still relatively warm in the scheme of things.As James Rickman noted in a recent article on the lab’s News Bulletin, “During the past 60 years, temperatures attainable in the laboratory have plunged from 20 degrees Kelvin to one-one millionth of a degree, creeping every closer to absolute zero.” Now actively in the race for the lowest temperatures today are Xinxin Zhao, of the lab’s Chemistry Division, and Malcolm Boshier, the scientific director of the lab’s interdisciplinary Quantum Institute.The second part of the Nova program will bring the story of supercold research up to the end of the 20th century with the attempt to achieve temperatures of a few billionths of a degree above absolute zero in order to see a substance known as “the super atom,” a new form of matter at the coldest temperature in the universe.Boshier is part of a team part of a team that is now attempting to make use of these “super atoms” known as Bose-Einstein condensate (BEC) to develop ultra-sensitive miniature sensors. Zhao uses lasers to cool and trap radioactive atoms at temperatures so low that he can test the foundations of the Standard Model that describes the interactions between subatomic particles. Their stories and the lab’s continuing contributions to the conquest of cold await the next chapter.Meanwhile, part two of  NOVA’s “Absolute Zero” will air at 8 p.m. on KNME, Channel 5.