(Mahr Federal: Providence, RI) -- In conjunction with the General Conference on Weights and Measures (CGPM), the kelvin, the basic unit of thermodynamic temperature, is currently being newly defined at the Physikalisch-Technischen Bundesanstalt (PTB) in Braunschweig, Germany, which is the counterpart of NIST in the United States. The goal of PTB’s portion of the program is a precise determination of the Boltzmann constant k, the conversion factor between thermal and mechanical energy. The project is being done with the help of a highly accurate reference formtester from Mahr, the MarForm MFU 110 WP, which includes both tactile and optical sensors, and provides accuracy into the nanometer range.

In October of 2011, the CGPM adopted a plan to redefine four of the seven base units of the International System of Units (SI) in terms of the invariants of nature—the fundamental physical constants or properties of atoms. A previous example of this was the redefinition of the meter in 1983, which links it to an exact value of the speed of light in a vacuum. The CGPM recommended that efforts be made by the various National Metrology Institutes to reduce the uncertainties of these constants.

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