Transcript: In the Celsius temperature scale, zero degrees corresponds to the freezing point of water. However the molecules in ice are still moving microscopically, so there is thermal energy in the substance. It’s possible to be much colder then ice. Scientists therefore use a temperature scale where zero corresponds to the absolute cessation of microscopic motion. Zero on the Kelvin scale is much lower then zero on the Celsius scale. Zero on the Kelvin scale corresponds to minus 273 degrees Celsius. In the laboratory scientists have cooled substances to within one-millionth of a degree of absolute zero.