Representatives from 57 nations are assembled at the general conference on weights and measures in Versailles. Tomorrow -- Nov. 16 -- they will vote to decide on the fate of the kilogram. Sure, we will still have the good old kilogram to kick around but how it is measured will be based on something more consistent. The consistency will ensure that if aliens visit us we won’t be embarrassed by our current measurement standard.
According to an article from The Guardian, the roots of modern measurement can be traced back to the mid-18th century. A meter was defined as one ten-millionth of the distance from the North Pole to the equator. A kilogram was the mass of a liter of water. To make the units more practical, each was enshrined in a physical object, a metal bar for the meter and a weight for the kilogram. These measurements are kept in a vault in Paris.
However, the platinum doo-dad used to represent the kilogram gets grimy and the cylinder gets ever so slightly heavier. When it is cleaned, the kilogram loses weight as tiny amounts of alloy are removed.
The Guardian article goes on to note that it is enough to irk metrologists. “If aliens ever visit Earth what else would we talk about other than physics?” says Stephan Schlamminger, a physicist at the US National Institute of Standards and Technology, who is in Versailles for the vote. “If we want to talk about physics we have to agree on a set of units, but if we say our unit of mass is based on a lump of metal we keep in Paris, we’ll be the laughing stock of the universe.”
Apparently this is a done deal -- the vote is just to make it official. So, for the first time since 1889 the kilogram will be measured in a whole new way. Specifically, the kilogram makeover will derive mass from the Planck constant, a number deeply rooted in the quantum world.
Learn more by reading “In the balance: scientists vote on first change to kilogram in a century.”
