Metrologists make progress in redefining the kelvin

Science Daily : Scientists at the National Metrology Institute in Berlin have succeeded in redetermining the Boltzmann constant, via acoustic gas thermometry, which may lead to a redefinition of the base unit of temperature measurement, the kelvin. The kelvin has traditionally been determined by the triple point of water, a chemico-physical material property that can vary depending on contaminants or different isotopes of water. Thus metrologists are seeking a more precise definition of the kelvin by using a fundamental constant, much like they redefined the base unit of length, the meter, using the speed of light. The scientists, who have published their findings in the scientific journal Metrologia, hope that within the next two years they will be able to refine their method and reduce the uncertainty of the result such that the redefinition of the kelvin will be cleared.