Monday, 7 January 2013

The kilogram may need to go on a diet

The international prototype kilogram is a cylinder of platinum and platinum-iridium alloy, which is kept at the International Bureau of Weights and Measures (BIPM) near Paris.
The kilogram may need to go on a diet. The international standard, a cylinder-shaped hunk of metal that defines the fundamental unit of mass, has gained tens of micrograms in weight from surface contamination, according to a new study.