On November 16, in Versailles, France, representatives from 57 countries are expected to make history. They will vote to dramatically transform the international system that underpins global science and trade. This single action will finally realize scientists’ 150-year dream of a measurement system based entirely on fundamental properties of nature.
The International System of Units, informally known as the metric system—the way in which the world measures everything from coffee to the cosmos—will change in a way that is more profound than anything since its establishment following the French Revolution.
It will be a turning point for humanity.
The SI — the modern metric system — has seven base units from which all other measurement units can be derived. In November 2018, four of them — the kilogram, kelvin, ampere and mole — are slated to be redefined in terms of constants of nature. The remaining three — the second, meter, and candela — are already based on universal constants.
Click on the SI symbols below for more information (greyed-out items coming soon).