Paving the way for transforming the world’s measurement system, an international task force has determined updated values for four fundamental constants of nature. The updated values comprise the last scientific piece of the puzzle for redefining the modern metric system, known as the International System of Units (SI). If approved by an international body next year, the revised SI will enable authoritative measurements to be made anywhere on the planet.

The adjustments to the constants are small and won’t affect everyday life, but a revised SI based fully on accurate values of these constants underpins science and commerce and ensures uniformly precise measurements that scale smoothly from almost infinitesimal to enormous.

This wallet card displays the fundamental constants and other physical values that will define a revised international system of units. Credit: Stoughton/NIST

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