Our mastery of cold is something we take for granted, whether it s air conditioning and frozen food or the liquefied gases and superconductivity at the heart of cutting-edge technology. But what is cold? How do you achieve it, and how cold can it get? This two-part NOVA special brings the history of this frosty fascination to life with brilliant dramatic recreations of high moments in low-temperature research and the quest for ever-lower notches on the thermometer. The first hour, The Conquest of Cold, opens in the 1600s when the nature of cold and heat was a complete mystery. Were they different aspects of the same phenomenon? The experiments that settled these questions helped stoke the Industrial Revolution. In the second hour, The Race For Absolute Zero dramatizes the titanic rivalry between Scottish researcher James Dewar and Dutch physicist Heike Onnes, who plunged cold science to the forbidding realm at which oxygen and then nitrogen turn into liquids. The race continues toda