<p>Measurements over the past 100 years show that the international prototype - a cylinder of platinum-iridium alloy, which is just under four cms tall and wide, may have shed around 50 micrograms - the mass of a grain of sand over the last 100 years.<br /><br />Scientists are now looking for a way to define the unit without referring to a physical object, the Daily Mail reports.<br /><br />If they are successful, the "gold standard" kilogram, which since 1889 has been triple-locked under two bell jars at the International Bureau of Weights and Measures in Paris, will follow the prototype metre into history.<br /><br />Michael Stock, who works at the bureau, presented the latest research on the matter to the Royal Society in London Sunday.<br /><br />The experiments aim to define the kilogram based on a link between mass and the Planck constant - the fundamental unit of measurement in quantum physics.<br /><br />Stock said there were "reasonable chances" that the new definition will be introduced in 2015, when the General Conference on Weights and Measures is due to meet in Paris.<br /><br />"The international prototype has fulfilled its role quite well during the last century. However, measurements get more and more precise, and precise measurements require well-defined measurement units to express their results."<br /><br />"Another disadvantage is that the international prototype exists only at one place, in Paris," he added.</p>
<p>Measurements over the past 100 years show that the international prototype - a cylinder of platinum-iridium alloy, which is just under four cms tall and wide, may have shed around 50 micrograms - the mass of a grain of sand over the last 100 years.<br /><br />Scientists are now looking for a way to define the unit without referring to a physical object, the Daily Mail reports.<br /><br />If they are successful, the "gold standard" kilogram, which since 1889 has been triple-locked under two bell jars at the International Bureau of Weights and Measures in Paris, will follow the prototype metre into history.<br /><br />Michael Stock, who works at the bureau, presented the latest research on the matter to the Royal Society in London Sunday.<br /><br />The experiments aim to define the kilogram based on a link between mass and the Planck constant - the fundamental unit of measurement in quantum physics.<br /><br />Stock said there were "reasonable chances" that the new definition will be introduced in 2015, when the General Conference on Weights and Measures is due to meet in Paris.<br /><br />"The international prototype has fulfilled its role quite well during the last century. However, measurements get more and more precise, and precise measurements require well-defined measurement units to express their results."<br /><br />"Another disadvantage is that the international prototype exists only at one place, in Paris," he added.</p>