The concept of kilogram, it would seem, does not carry anything new. After all, every day we are faced with this unit of measurement. 1000 grams - this is known to all. But do you really know everything about a kilogram?
What is a kilogram?
Obviously, a kilogram is a unit of mass. But not just a unit. A kilogram is registered in the International System of Units (SI) as one of seven basic units corresponding to the seven basic concepts of measuring space along with a meter (length), second (time), ampere (electric current), kelvin (thermodynamic temperature), and a mole (amount of substance ) and candela (luminous intensity).
The scientific definition of what a kilogram was adopted in 1901 by the III General Conference on Weights and Measures. It happened in Paris.
A kilogram is a unit of mass equal to the mass of the international prototype of a kilogram.
This is the sound of the international scientific definition adopted at the beginning of the 20th century and valid at the present time.
Where to find the international standard kilogram?
The international standard is stored in the International Bureau of Weights and Measures in Sevres, located near Paris. It looks like a platinum-iridium cylinder with the same diameter and height, which are 39.17 millimeters. Platinum in the alloy from which the kilogram standard is made is more than as much as 90%, while the addition of iridium is only 10%.
So, an ideal kilogram exists and can be touched?
It would seem that there is a standard kilogram, that is, an ideal kilogram, once and for all fixed and unchanged. Unfortunately, it only seems so. Over time, the standard gives differences in mass compared to its original weight in 1889, when it was decided to issue it on the basis of the Metric Convention of 1875. This is due to the fact that the metals of which it is made are exposed to the environment over time. The weight of the reference changes, albeit very slowly.
Therefore, in 2005 it was decided to give the kilogram a new definition. Now it should be based not on a tangible concrete quantity, but on a fundamental physical property. However, the scientific community came to a decision about what kind of value should be used to determine the kilogram only in 2011, and work began on redefining the kilogram and measures and quantities based on its determination, which should be completed in 2018.
Touching the standard kilogram is also impossible. It is stored in special conditions in order to minimize external influences affecting the change in its mass, and is withdrawn only for verification of its copies. The last verification took place in 2014.