World Metrology Day
May 20 · Level 6 · #926 of 2238
World Metrology Day celebrates the science of measurement—the reason a kilogram means the same thing in a shop, a factory and a laboratory. It marks the signing of the Metre Convention in 1875, which laid foundations for international cooperation on measurement.
How it is celebrated: metrology institutes organize talks, visits and meetings with specialists. Examples from trade, medicine and industry show how reliable measurements shape everyday life.
Since 2019, the kilogram has been defined using the Planck constant rather than the mass of a metal artifact. A familiar unit now rests on a fundamental constant of physics.