Precision is never superfluous. That is why a system of international measurements has been created and exists throughout the world, expressed in the standards of all measurements known to man. And only the kilogram standard stands out in the range of units of measurement. After all, it is he who is the only one who has a physical real-life prototype. How much it weighs and in which country the international standard of a kilogram is stored, we will answer in this article.
Why do we need standards?
A kilo, like oranges, weighs the same in Africa and Russia? The answer is yes, almost. And all thanks to the international system for determining the standards of the kilogram, meter, second and other physical parameters. Measurement standards are necessary for humanity to ensure economic activity (trade) and construction (unity of drawings), industrial (unity of alloys) and cultural (unity of time intervals) and many other areas of activity. And if inIf your iPhone breaks in the near future, it is very likely that this happened due to changes in the weight of the most important standard of mass.
History of standards
Each civilization had its own standards and standards, which changed each other over the centuries. In ancient Egypt, the mass of objects was measured in kantars or kikkars. In ancient Greece, these were talents and drachmas. And in Russia, the mass of goods was measured in pounds or spools. At the same time, people of different economic and political systems, as it were, agreed that the unit of mass, length, or other parameter would be comparable to a single contractual unit. Interestingly, even a pood in ancient times could differ by a third among merchants from different countries.
Physics and standards
Arrangements, often verbal and conditional, worked until a person took up science and engineering seriously. With the understanding of the laws of physics and chemistry, the development of industry, the creation of the steam boiler, and the development of international trade, there was a need for more precise uniform standards. The preparatory work was long and painstaking. Physicists, mathematicians, chemists all over the world worked to find a universal standard. And first of all - the international standard of the kilogram, because it is from the measure of weight that other physical parameters (Ampere, Volt, Watt) are repelled.
Metric convention
A significant event took place on the outskirts of Paris in 1875. Then for the first time 17 countries (including Russia) signed the metricconvention. This is an international treaty that ensures the unity of standards. Today, 55 countries have joined it as full members and 41 countries as associate members. At the same time, the International Bureau of Weights and Measures and the International Committee of Weights and Measures were created, the main task of which is to monitor the unity of standardization around the world.
Standards of the first metric convention
The standard of the meter was a ruler made of an alloy of platinum and iridium (9 to 1) with a length of one forty-millionth part of the Paris meridian. The kilogram standard of the same alloy corresponded to the mass of one liter (cubic decimeter) of water at a temperature of 4 degrees Celsius (the highest density) at standard pressure above sea level. The standard second was 1/86400 of the average solar day. All 17 countries participating in the convention received a copy of the standard.
Place Z
Prototypes and the original of the standard are today stored in the Chamber of Weights and Measures in Sèvres near Paris. It is on the outskirts of Paris that the place where the standard of kilogram, meter, candela (light intensity), ampere (current intensity), kelvin (temperature) and mole (as a unit of matter, there is no physical standard) is stored. The system of weights and measures that is based on these six standards is called the International System of Units (SI). But the history of standards did not end there, it was just beginning.
SI
The standard system we use - SI (SI), from the French Systeme International d'Unites - includes seven base units. This is a meter (length),kilogram (mass), ampere (current), candela (light intensity), kelvin (temperature), mole (amount of substance). All other physical quantities are obtained by various mathematical calculations using basic quantities. For example, the unit of force is kg x m/s2. All countries in the world, except the United States, Nigeria and Myanmar, use the SI system for measurements, which means comparing an unknown quantity with a standard. And a standard is the equivalent of a physical value that everyone agrees is absolutely accurate.
Reference kilo is how much?
It would seem something simpler - the standard of 1 kilogram is the weight of 1 liter of water. But in fact, this is not entirely true. What to take as a kilogram standard from about 80 prototypes is a rather complicated question. But by chance, the optimal variant of the composition of the alloy was chosen, which lasted more than 100 years. The standard of a kilogram of mass is made of an alloy of platinum (90%) and iridium (10%), and is a cylinder, the diameter of which is equal to the height and is 39.17 millimeters. Its exact copies were also made, in the amount of 80 pieces. Copies of the kilogram standard are located in the countries participating in the convention. The main standard is stored in the suburbs of Paris and is covered with three sealed capsules. Wherever the kilogram standard is located, reconciliation with the most important international standard is carried out every ten years.
The most important standard
The international standard of the kilogram was cast in 1889 and is stored in Sevres in France in the safe of the International Bureau of Weights and Measures, coveredthree sealed glass caps. Only three high-ranking representatives of the bureau have the keys to this safe. Along with the main standard, there are also six of its doubles or successors in the safe. Every year, the main measure of weight, which is taken as the standard of the kilogram, is solemnly removed for examination. And every year he gets thinner and thinner. The reason for this weight loss is the detachment of atoms when removing the sample.
Russian version
A copy of the standard is also in Russia. It is stored in the All-Russian Research Institute of Metrology. Mendeleev in St. Petersburg. These are two platinum-iridium prototypes - No. 12 and No. 26. They are on a quartz stand, covered with two glass caps and closed in a metal safe. The air temperature inside the capsules is 20 °C, the humidity is 65%. The domestic prototype weighs 1.000000087 kilograms.
Kilogram standard is losing weight
Reconciliation of the standard showed that the accuracy of national standards is about 2 µg. All of them are stored under similar conditions, and calculations show that the kilogram standard loses 3 x 10−8weight in a hundred years. But by definition, the mass of the international standard corresponds to 1 kilogram, and any changes in the actual mass of the standard lead to a change in the very value of the kilogram. In 2007, it turned out that the kilogram cylinder began to weigh 50 micrograms less. And his weight loss continues.
New technologies and a new standard of measure of weight
To eliminateerrors, a new structure of the kilogram standard is being searched. There are developments to determine the standard of a certain amount of silicon-28 isotopes. There is a project "Electronic kilogram". The National Institute of Standards and Technology (2005, USA) designed a device based on measuring the power required to create an electromagnetic field capable of lifting 1 kg of mass. The accuracy of such a measurement is 99.999995%. There are developments of the definition of mass in relation to the rest mass of the neutron. All these developments and technologies will make it possible to get away from being tied to a physical mass standard, to achieve higher accuracy and the possibility of reconciliation anywhere in the world.
Other promising projects
And while the world's luminaries of science are determining which way to solve the problem is more reliable, the most promising is the project in which the mass will not change over time. Such a standard would be a cubic body of carbon-12 isotope atoms with a height of 8.11 centimeters. In such a cube there will be 2250 x 281489633 carbon-12 atoms. Researchers from the US National Institute of Standards and Technology propose to determine the kilogram standard using Planck's constant and the formula E=mc^2.
Modern metric system
Modern standards are not at all what they used to be. The meter, originally related to the circumference of the planet, today corresponds to the distance that a ray of light travels in one 299792458th of a second. But a second is the time during which 9192631770 passesvibrations of the cesium atom. The advantages of quantum precision in this case are obvious, because they can be reproduced anywhere on the planet. As a result, the only standard that exists physically remains the kilogram standard.
How much does the standard cost?
Having existed for more than 100 years, the standard is already worth a lot, as a unique and artifact item. But in general, to determine the price equivalent, it is necessary to calculate the number of atoms in a kilogram of pure gold. The number will be obtained from about 25 digits, and this is without taking into account the ideological value of this artifact. But it is too early to talk about the sale of the kilogram standard, because the world community has not yet got rid of the only remaining physical standard of the international system of units.
I wonder about measurements
In all time zones of the planet, time is determined relative to UTC (for example, UTC+4:00). Remarkably, the abbreviation has no decoding at all; it was adopted in 1970 by the International Telecommunication Union. Two options were proposed: the English CUT (Coordinated Universal Time) and the French TUC (Temps Universel Coordonné). We chose a medium neutral abbreviation.
At sea, the knot measurement is used. To measure the speed of the ship, a special log with nodes at the same distance was used, which was thrown overboard and counted the number of nodes for a certain period of time. Modern devices are much more advanced than a rope with knots, but the name remains.
Word meticulousness, meaningwhose extreme accuracy and accuracy came to languages from the name of the ancient Greek standard of weight - scruple. It was equal to 1.14 grams and was used when weighing silver coins.
The name of monetary units also often originate in the names of weight measures. So, silver coins were called sterling in Britain, and 240 of these coins weighed a pound. In Ancient Russia, “silver hryvnias” or “gold hryvnias” were in use, which meant a certain number of coins expressed in weight equivalent.
The strange measurement of car horsepower has a very real origin. The inventor of the steam engine, James White, decided to demonstrate the advantage of his invention over traction transport in this way. He calculated how much a horse can lift a load per minute and designated this amount as one horsepower.
