The National Institute of Standards and Technology (NIST) has released the 2014 recommended values of fundamental physical constants, published by CODATA. These values are crucial for the planned 2018 redefinition of the International System of Units (SI).
Key improvements include:
1. The Planck constant (h) now has a relative uncertainty of 12 parts per billion (ppb), a three-fold improvement over 2010 values, meeting CGPM’s criteria for consistency and accuracy.
2. The Boltzmann constant (k) exceeds the CGPM’s relative uncertainty criteria, enabling its use in redefining the kelvin unit.
Other notable improvements include a ten-fold reduction in uncertainty for the mass of the electron and improved precision in the magnetic moment of the proton.
These 2014 values align with the requirements for the 2018 SI redefinition, with new recommended values based on the updated SI expected to have significantly smaller uncertainties in most cases. This marks a significant milestone in metrology, with the 2014 values possibly representing the last official set of fundamental constants based on the current SI.
Source: https://www.nist.gov/news-events/news/2015/10/fundamental-constants-latest-and-last
Keywords: NIST, fundamental physical constants, CODATA
