World Metrology Day is an
event occurring on 20 May celebrating the
International System of Units. The date is the anniversary of the signing of the
Metre Convention
The Metre Convention (french: link=no, Convention du Mètre), also known as the Treaty of the Metre, is an international treaty that was signed in Paris on 20 May 1875 by representatives of 17 nations (Argentina, Austria-Hungary, Belgium, Brazi ...
in 1875.
Metrology is the study of measurement.
The World Metrology Day project is currently realized jointly by the
BIPM and the
OIML.
2019
The 2019 Metrology Day is when the changes to the International System that were decided on in 2018 come into effect,
among them the replacement of the
international prototype of the kilogram with a
redefinition based on the
Planck Constant
The Planck constant, or Planck's constant, is a fundamental physical constant of foundational importance in quantum mechanics. The constant gives the relationship between the energy of a photon and its frequency, and by the mass-energy equivale ...
.
External links
WorldMetrologyDay.org– official website
See also
2019 redefinition of SI base units
In 2019, four of the seven SI base units specified in the International System of Quantities were redefined in terms of natural physical constants, rather than human artifacts such as the standard kilogram.
Effective 20 May 2019, the 144 ...
References
May observances
Unofficial observances
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