Trying to update the kilogram
Seven are the basic units of science, fundamental for their combination
because all other units are created. And six of these seven are defined from fundamental constants. The exception is kilogram.In the other six there is no problem. One meter is the distance traveled by light in 1/299792458 seconds. In short, light is a fundamental characteristic of nature and is a precise definition if used to define the metro. But the kilogram does not have that definition. The definition, physical, is a fraction of the matter found in the Paris International Bureau of Weights and Measures. It is made of platinum and iridium alloys, but when the powder is pasted, for example, the reference kilogram becomes heavier and when cleaned it lightens.
American, French and British scientists want to change this situation. Two new ways of defining kilogram have been proposed, both theoretical. One would use gravity and a magnetic field to define the kilogram, while the other would use a certain number of mass atoms. However, the approval of the approved does not imply the entry into force of the new definition at least until October 2007.
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