A cylindrical weight of platinum-iridium alloy marking a kilogram of weight has mysteriously become lighter, losing 50 micrograms of its original mass. It may not change People's Daily lives, but for those who do delicate work such as scientific research and statistics, a change in the 1kg standard would cause a lot of trouble. The weight is made of a platinum-iridium alloy and is 3.9 centimeters in diameter and height. In 1889, the first International Metrology Congress was determined as the standard of 1 kilogram, and in use today.
Don't look down upon this weight, it is so important that all the countries in the world that use the metric system of measurement rely on it to determine the mass of a kilogram. It is now housed in a three-storeyed lockbox in a castle and rarely sees light. Physicists at the International Agency for Quality and Measurement say the standard weight is 50 micrograms lighter than the average mass of many replicas.
He said: "What is strange is that the quality of these reproductions is the same as that of a standard 1kg weight, and many of them were made at the same time and kept under the same conditions, but their quality gradually varies. "We haven't identified any rational reasons for the change. It is not clear whether the material mass of the standard weights has become lighter or whether the current national universal weights have become heavier." For the future of the 1 kg standard determination method, it has been suggested that a new international standard weight of spherical crystals of silica-28 could be made instead of the existing cylindrical weight of platinum-iridium alloy.
The single texture of the new weight avoids the problem of ratio errors during the mixing of the two elements, allowing scientists to accurately determine the type and number of atoms in the weight.
