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An introduction to the new SI



Peter J. Mohr, Sandra Knotts, William D. Phillips


Plans are underway to redefine the International System of Units (SI) around 2018. The new SI specifies the values of certain physical constants to define units. This article explains the new SI in a way that could be used to present it to high-school physics classes.
The Physics Teacher


SI, defining constants, SI redefinition, new SI
Created December 20, 2016, Updated October 9, 2019