The National Institute of Standards and Technology (NIST) has made significant advancements in measuring fundamental constants of nature, reducing uncertainties to levels that allow complete redefinition of the International System of Units (SI). The SI currently relies on physical artifacts for its base units, but NIST’s measurements of Planck’s constant and other constants have reached sufficient precision to define all SI units in terms of fundamental constants.
This breakthrough will benefit science, technology, and industry by providing more stable and reliable measurement standards. The seven base SI units – meter, kilogram, second, ampere, kelvin, mole, and candela – will be redefined using exact values of fundamental constants like the speed of light and the elementary charge.
NIST’s Peter Mohr, David Newell, and Barry Taylor led the international Task Group on Fundamental Constants, which updates these values every four years. The latest update, published in the Journal of Physical and Chemical Reference Data and Reviews of Modern Physics, reduces uncertainties in key constants to parts per billion levels, enabling the SI redefinition scheduled for 2018.
The redefined SI will improve accuracy in scientific equations and measurements across various fields, providing a more stable foundation for international measurement systems.
Keywords: Fundamental, Constants, Uncertainty, Metrology, Quantization
