Today is World Metrology Day!
The theme for World Metrology Day 2019 is The International System of Units – Fundamentally better. This theme was chosen because on 16 November 2018, the General Conference on Weights and Measures agreed revisions to the International System of Units (the SI). In the revised SI, four of the SI base units – the kilogram, the ampere, the kelvin and the mole – are redefined in terms of constants. These changes come into force on Monday as part of World Metrology Day 2019.