While we were busy celebrating the over 1400 points jump on the Sensex, on 20th May, the day-to-day measurements that we use – kilo, gram, meter have undergone a change.
The International Metrology Day was celebrated on 20th May and the day was marked with a complete revision of these standards. There is no noticeable change, not that you will show heavier or lighter, it is just that the change has been seamless.
Definitions of the seven base units of the SI (Système International d’Unités, or the International System of Units) are now completely different for kilogram (kg), metre (m), second (s), ampere (A), kelvin (K), mole (mol) and candela (cd). The main problems with the previous definitions were, in the case of the kg, they were not stable or for that matter, the unit of electric current, the ampere, could not be realised.
It’s a bit technical - all the units are now defined in a common way using what the BIPM calls the “explicit constant” formulation. A universal constant is taken and its numerical value is fixed at the best-measured value, without uncertainty. From today the kilogram is defined using the Planck constant, something that doesn’t change from quantum physics.
Well, we, common people, understanding this is errrr, pretty darn remote. So lets just know that the definitions have changed.