In today’s world, when scientists daily develop new technologies in the fields of medicine, astronautics and military affairs, even the slightest deviation from the standards of the international system of SI units can cause a catastrophe. In order for all countries to maintain a unified idea of the weight of a kilogram, the length of a meter and the properties of other quantities, their standards are kept in France, and all countries are compared by copy. If the standards of meter and second are the fundamental laws of physics, then for a kilogram this is a piece of metal. In order to avoid problems, scientists intend to abandon the standard of the XIX century.
The actual standard of the kilogram was created in 1889. It is stored at the headquarters of the International Bureau of Weights and Measures BIPM and is a cylinder made of an alloy of platinum and iridium in the ratio of 90% to 10%. With a height and diameter of 39.17 mm, it is stored under two sealed glass caps and is often referred to in publications as Le Grand K.
Le Grand K
In order to compare the concepts of the kilogram between the countries that adopted the metric convention, 80 copies of the standard were created. Their mass is compared with the mass of the standard every 40 years, and it was noticed that the difference in their mass reaches 50 micrograms. Even misunderstanding between countries at this level can be a source of disaster. The cause of the difference can be anything, for example, metal absorption of molecules from the air or weathering.
In order to solve the problem and avoid disasters, on November 16, 2018, the BIPM Bureau will hold a special meeting. Within its framework, a final decision will be made on whether the replacement of the current standard with a more modern counterpart, which does not change its properties after time, is necessary.
The 130-year-old Le Grand K is expected to be replaced by a device called the Kibble Balance. It allows you to create an “electronic” kilogram, whose mass is proportional to the product of current and voltage. Thanks to him, countries will know the mass of a kilogram with the same accuracy with which the Planck constant is measured. Unfortunately, it will take a long time to install the device in the laboratories of the countries participating in the metric convention due to its high cost.
What do you think, what can the difference in understanding the mass of a kilogram lead to?