TEMPO.CO, Jakarta – Since 1889, Le Grand K, a fine platinum-iridium metal cylinder in an underground vault in Paris, is the definition of a pound of mass. Scientists from all over the world traveled there, bringing national kilogram standards to weigh comparisons.
Read: Note, today scientists will redefine the pounds
Read: Scientists change the definition of kilograms, here is the initial history of kilograms
"Air carriers have never gone wrong," said Robert Vocke Jr., a chemist at the National Institute of Standards and Technology (NI.S.T.) in Gaithersburg, MD.
However, it is no longer. Last Friday, November 16, 2018, in a small congress center located a few steps from the Versailles Palace, several dozen countries chose to replace the Le Grand K and redefine the kilo and three other units of normal size: kelvin, for the temperature ? and mole, which describes the amount of chemicals.
The vote fulfills an 18th century dream in which all seven units of the International System of Units, otherwise known as SI, will no longer be determined by material objects and will be defined only by abstract physical constants.
"This historic path began before the French Revolution and now, I think we have completed the trip," said Stephan Schlamminger, a NI.S.T. physicist, on 16 November 2018. "The democratization of the units," he said, is now over.
SI began at the end of the 18th century with only meters and kilograms. The idea is to standardize basic units of commercial and scientific measurement. In addition, for one kilogram of gold coins for the storage of universal values, each person must approve the exact definition of one kilogram.
In 1875, 17 countries signed the cash agreement in Paris, which set international standards for meters and pounds. The meter is defined as the distance between two scratches on a platinum-iridium metal rod. The normal kilo is Le Grand K. Both items will be stored in the International Weight and Size Office, with copies distributed in different countries. "People call it" forever, for all, "said Dr Schlamminger.
But he did not. Natural objects can be scratched, broken, or even destroyed. Scientists have begun to dream of a standardized unit of measurement that will always remain stable – a model with definitions built from the structure of the universe.
The meter achieved this in 1983 when it was redefined in terms of steady speed of light. Scientists had estimated the speed of light for centuries, but only after the 1970s, following experiments involving empty lasers, arranged a number: exactly 299,792,458 meters per second.
The meter is defined as the distance traveled by a light beam exactly 1 / 299,792,458 seconds. Seconds, another fundamental unit, have been set since 1967 as the time it takes to see the cesium-133 atom vibrate 9,192,631,770 times.
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