Accuracy 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 standard kilogram stands out in the line of units. After all, he is the only one who has a physical, really existing prototype. How much weigh and in which country the international standard of kilogram is stored, we will answer in this article.
Why do we need standards?
A kilogram, such as oranges, weighs the same in Africa and in Russia? The answer is yes, almost. And all thanks to the international standard definition system kilogram, meter, second and other physical parameters. Measurement standards are necessary for mankind 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 your iPhone breaks in the near future, it is very likely that this happened due to changes in the weight of the most important mass standard.
History of Standards
Each civilization had its own standards and standards, which succeeded each other over the centuries. In ancient Egypt, the mass of objects was measured in cantaras or kikkaras. 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 seemed to agree that a unit of measurement of mass, length, or other parameter would be comparable with a single contractual unit. Interestingly, even in the old days, poods could differ by a third from merchants from different countries.
Physics and Standards
Arrangements, often verbal and conditional, worked until a person seriously engaged in science and engineering. With the understanding of the laws of physics and chemistry, the development of industry, the creation of a steam boiler and the development of international trade, the need for more precise uniform standards has arisen. The preparatory work was lengthy and painstaking. Physicists, mathematicians, chemists around the world worked on the search for a universal standard. And first of all - the international standard of a 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 metric convention. This is an international treaty ensuring the unity of standards. Today, 55 countries have joined it as full members and 41 countries as associate members. Then the International Bureau of Weights and Measures and the International Committee of Weights and Weights were created, whose main task is to monitor the unity of standardization around the world.
Benchmarks of the First Metric Convention
The standard of the meter was a ruler of an alloy of platinum and iridium (9 to 1) with a length of one forty-millionth part of the Paris Meridian. The standard of a kilogram of the same alloy corresponded to the mass of one liter (decimeter cubic) of water at a temperature of 4 degrees Celsius (highest density) at standard pressure above sea level. The second standard was 1/86400 part of the duration of an average sunny day. All 17 countries participating in the convention received a copy of the standard.
Place Z
The prototypes and the original of the standard are today stored in the Chamber of Weights and Measures in the city of Sevres near Paris. It is in the suburbs of Paris that the place where the standard is stored kilogram, meter, candela (luminous intensity), ampere (amperage), kelvin (temperature) and moles (as a unit of matter, there is no physical standard). The system of measures and weights, which 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 system of standards that we use - SI (SI), from the French Systeme International d'Unites - includes seven basic values. 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 calculi using basic quantities. For example, the unit of force is kg x m / s 2 . All countries of the world, except the USA, Nigeria and Myanmar, use the SI system for measurements, which means comparing an unknown value with a standard. And the standard is the equivalent of physical meaning, which everyone agreed that it is absolutely accurate.
Kilo standard is how much?
It would seem 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 the standard kilogram of about 80 prototypes is a rather complicated question. But by chance, the optimal version of the alloy composition was chosen, which lasted more than 100 years. The standard kilogram of mass is made of an alloy of platinum (90%) and iridium (10%), and is a cylinder whose diameter is equal to the height and is 39.17 millimeters. Were also made and its exact copies, in quantities of 80 pieces. Copies of the standard kilogram located in countries party to the convention. The main standard is stored on the outskirts of Paris and covered with three sealed capsules. Wherever the kilogram standard is located, with a frequency of ten years, reconciliation with the most important international standard is carried out.
The most important standard
The international kilogram standard was cast in 1889 and is stored in Sevres in France in the safe of the International Bureau of Weights and Measures, covered with three sealed glass caps. Only three senior bureau representatives have the keys to this safe. Together with the main standard in the safe there are also six of his understudies or successors. Each year, the main measure of weight, which is taken as the standard kilogram, is solemnly removed for examination. And every year he becomes thinner and thinner. The reason for this weight loss is the detachment of atoms during sample extraction.
Russian version
A copy of the standard is in Russia. It is stored in the All-Russian Research Institute of Metrology named after Mendeleev in St. Petersburg. These are two platinum-iridium prototypes - No. 12 and No. 26. They are on a stand made of quartz, covered with two glass caps and closed in a metal safe. The air temperature inside the capsules is 20 ° C, humidity is 65%. Domestic prototype has a weight of 1, 000000087 kilograms.
The 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 in similar conditions, and calculations show that the standard kilogram in a hundred years loses weight of 3 x 10 −8 weight. But by definition, the mass of the international standard corresponds to 1 kilogram, and any changes in the real mass of the standard also lead to a change in the value of the kilogram itself. In 2007, it turned out that a kilogram cylinder began to weigh 50 micrograms less. And the decrease in his weight continues.
New technologies and a new benchmark for weight measures
To eliminate errors, a new structure of the kilogram standard is being searched. There are developments to determine the standard of a certain number of silicon-28 isotopes. There is a project “Electronic kilogram”. At the National Institute of Standards and Technology (2005, USA), a device was constructed based on measuring the power needed to create an electromagnetic field that can lift 1 kg of mass. The accuracy of this measurement is 99.999995%. There are developments on the definition of mass in relation to the rest mass of a neutron. All these developments and technologies will allow you to get away from being tied to the physical standard of mass, 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, they consider the most promising project in which the mass will not change over time. Such a standard would be a body of a cubic shape made of atoms of the carbon-12 isotope with a height of 8.11 centimeters. In such a cube there will be 2250 x 281489633 carbon-12 atoms. Researchers at the U.S. National Institute of Standards and Technology propose defining a kilogram standard using the Planck constant and the formula E = mc ^ 2.
Modern metric system
Modern standards are not at all what they were before. The meter, originally correlated with the circumference of the planet, today corresponds to the distance that a ray of light passes in one 299792458th second. But the second is the time during which 9192631770 oscillations of the cesium atom pass. The advantages of quantum accuracy in this case are obvious, because they can be reproduced anywhere in the world. As a result, the only standard that exists physically remains the standard of a kilogram.
How much does the benchmark cost?
Having existed for more than 100 years, the standard is already worth a lot, as a unique and artifact subject. But in general, to determine the price equivalent, it is necessary to calculate the number of atoms per kilogram of pure gold. The number will be obtained from the order of 25 digits, and this does not take into account the ideological value of this artifact. But it’s 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.
Interesting about measurements
In all time zones of the planet, time is determined relative to UTC (for example, UTC + 4: 00). What is noteworthy, the abbreviation has no decryption at all, it was adopted in 1970 by the international telecommunication union. Two options were proposed: English CUT (Coordinated Universal Time) and French TUC (Temps Universel Coordonné). They chose the medium neutral abbreviation.
At sea, the “knot” dimension is used. To measure the speed of the ship used a special lag with nodes at the same distance, which were thrown overboard and counted the number of nodes for a certain period of time. Modern appliances are much more perfect than a rope with knots, but the name remains.
The word meticulousness, the meaning of which is 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 originates in the names of measures of weight. For example, sterling in Britain called silver coins, and 240 of these coins weighed a pound. In Ancient Russia, “hryvnias of silver” or “hryvnias of gold” were in use, which meant a certain number of coins, expressed in weight equivalent.
A strange measurement of the power of cars in horsepower has a very real origin. The inventor of the steam engine, James White , decided so to demonstrate the advantage of his invention over traction transport. He calculated how much a horse can lift a load per minute and designated this number as one horsepower.