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tv   DW News  Deutsche Welle  August 24, 2019 7:00am-7:02am CEST

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kept in the safe of the international bureau of whites and measures from 889 until this year it was the defining unit of mass worldwide but for some unknown reason the paris kilogram decreased in white by 15000000 of a gram so scientists decided to take action in a historic move they redefined the kilogram. this time they're not using a metal object but a constant of nature the planck constant denoted by a small age described for the 1st time by max planck around 1900 so what is the planck constant. guns just guns and before you can think of it as the smallest possible unit of energy consider the energy coming out of a car battery or an electric socket on the walls and if you were to divide that into lots of small amounts the smallest possible amount would be the plug constant
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. it's a fundamental constants of nature it's involved in many aspects of physics. one reason why we can't take the plank constant as the definition of this mass is because the planck constant can be expressed in terms of the cube a gram and 2 other units that's why we were able to establish a relationship between the value of the cube a gram and the plank constant so any of. this can be done using a watch balance for example it's a highly complex instrument that's been used since the 1980 s. to measure the planck constant as precisely as possible. there are only a handful of these scales.

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