Farewell to the old definition of measuring units: the most familiar from today, like the old kilo, go to the attic with meter, second, ampere, kelvin, mole and candle to make room for the new definition criteria. "It's a revolution that won't cause shocks," explains Diederik Wiersma, president of the national metrology institute. Over time, however, the change will benefit the measures relating to very small quantities.
No longer are physical reference points, such as the Grand Kilo, the platinum-iridium cylinder for the kilogram, to establish the new measurement rules, but mathematical laws as universe constants. It will be accurate in areas like the electronics industry, the pharmaceutical industry, and applications for nanotechnology.
A "more democratic" system-No consequence, instead, for those who go shopping: as it has done so far, the scale will continue to score one kilogram. "It's a great day today," INIM's science director Maria Luisa Rastello said. "Now the units of the International Measurement System refer to a fundamental constant, that is, they are based on a number that is found everywhere: it is a huge difference from the past, especially for the kilo, which was still a preserved sample of material in a safe with three keys assigned to three people.
On November 16, 2018, the 26th General Conference on Weights and Measures approved the new International Systemof the measures, in which Italy played an important role. The new system replaces the one known as the International System since 1960, in which, with the exception of the kilogram, almost all physical references were gradually abandoned.
In 1967 the second was the first unit of measurement to be defined on the basis of a constant (cesium atom transition), whereas in 1979 it was the turn of the candle, defined on the basis of the visibility coefficient. The meter left the old platinum-iridium bar in 1983 and then the krypton wavelength to be defined based on light speed. There was no kilogram, ampere, kelvin and mole, which are defined with the Planck constant, the electron charge, the Boltzmann constant for the Kelvin and the Avogadro number for the mole, respectively.