Physicists Find That ‘Absolute Zero’ May Not Be Quite So Absolute
Physicists don’t tend to use universal language freely, so since Lord Kelvin dubbed the base measure of his temperature scale “absolute zero,” that should be a sign that there is reason for the “absolute” nature of the measure to be taken seriously.
Unlike the centigrade scale, where 0 degrees marks the freezing point of fresh water, or the Fahrenheit scale, where 0 is the stable temperature of a mix of water, ice, ammonium chloride and sea salt, 0 Kelvin—absolute zero—is, theoretically, the coldest thing imaginable. This is the temperature when all motion comes to a crawl, when molecules stop quivering and atoms stop moving.
In Nature, Zeeya Merali reports on the work of Stefan Braun and colleagues, a group of physicists that managed to overthrow Kelvin’s absolutism by creating “an atomic gas with a sub-absolute-zero temperature for the first time.”