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China to adopt new kilogram definition from May 2019

Updated: Dec 12,2018 7:24 AM     Xinhua

BEIJING — China will adopt the new definition of the kilogram from May 20 next year, embracing a weighty change in the international system of units for the development of next-level measurement.

“The redefinition will enable physics, chemistry, and biology to gauge at the extreme level and revolutionize the industry of instruments and meters,” Xie Jun, an official with the State Administration for Market Regulation told a news conference on Dec 11.

Though the change will not have a visible impact on people’s daily lives, it is a game-changer for things like nuclear reactors, spacecraft and biological medicine, Xie said.

The move follows a decision by multinational scientists to do away with the old kilogram prototype and determine the unit with a constant from quantum physics from May 20 next year, which is World Metrology Day.

Since 1889, scientists have based their definition of the fundamental unit of mass on a physical object — a shining platinum-iridium cylinder and its replicas. A kilogram is equal to the heft of such an aging piece of metal, and discrepancies of as much as 50 micrograms have been found in some replicas.

Last month, members of the International Bureau of Weights and Measures from more than 60 nations and regions gathered in France and decided to update the definition with the “Planck constant,” a fundamental constant of quantum physics that is reliable across time and space.

China now ranks third in terms of calibration and measurement prowess in the world, Xie said, adding that the country has built a device to reproduce the newly-defined kilogram.

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