Contribution of Japanese Scientists to Assigning −273.15 ºC as the Zero Point of Thermodynamic Temperature

Abstract

The challenge of determining the last two digits of absolute zero temperature attracted several groups of researchers around the world in the first half of the 20th century. It is little known that Japanese researchers, Jiro Oishi and Masao Kinoshita, were the ones who successfully settled the dispute over these two digits. Their work played a key role in defining the zero point on the thermodynamic temperature scale, and thus later in defining the unit of thermodynamic temperature, the kelvin, in terms of the absolute zero and the triple point of water. This current definition of kelvin is scheduled to be redefined based on the Boltzman constant. On the occasion of this turning point of the definition of the kelvin, it may be timely to reflect on the historic milestone work of Oishi and Kinoshita. The background and current status for changing the definition are also described.