Monday , November 30 2020

Repair of the metric system fills up to one kilogram of science

Atoms in the Silicon-28 area correct the Avogadro constant and redefine the abundance. Le Grand K, a copy of the kilogram standard is displayed in the industry view.


Adrian Cho

Like an old monarch, Le Grand K is ready to serve as a modern man. For 130 years, this glossy cylinder of platinum-iridium alloy is the world standard for mass. Calling the International Bureau of Weights and Measures (BIPM) in Sueur, France, weighing over 40 such weightboats all over the world. Now, in the revolution, Louis XVI, as much bloodthirsty as it can, he leaves his throne a real kilo.

Since the 26th General Conference (CGPM) of Versailles in France is to elect representatives of 60 member countries to redefine the International Organization System (CI), its four main units – Kilograms, Ampers, Celts and Moles – are indirectly determined by the fact that physical constants from the point of view of They are added to the other three main units – the second, the meter, and the candela – measured in the same way. There are no final physical artifacts used to detect the rewriter, Le Grand K.

The shift allows the units to be more stable and develop more precise and flexible methods for converting permanent structures into units of measurement. "This is the beauty of the revision," said BIPM physicist Estefania de Miranda. "You are not limited to just one technology." But sometimes, even the advocates of secret changes, admit that experts may not be confused. John Pratt, a physicist at the US National Institute of Standards and Technology, Maryland, states: "Cooling stairs: What should we do about teaching people?"

The new SI summarizes the trades used to determine the meter in terms of lighting speeds. Until 1983 the speed of light was measured independently by meters and seconds. However, in the same year, the 17th CGPM detected the speed of light at 299,792,458 meters per second. The meter was measured: the distance is 1 / 299.792.458 seconds. (The second was due to the oscillation of microwave radiation of cesium atoms in 1967.)

The new SI plays the same game with other units. For example, the kyramet determines the Planck constant that emerges from all parts of quantum mechanics. The constant is now fixed at 6.62607015×10-34 per square meter of square meters per second. Since the cream appears in this definition, there is a method of measuring kilograms instead of any experiments that previously measured its constant value.

Such experiments are much more difficult than calculating the light velocity, which is the basis of bachelor's theoretical physics. One technique employs a so-called Kibbel balance, similar to the mythical range of justice. On the one hand, the mass is balanced with the magnetic field, on the other hand, by the electric power generated by the electric coils. The current will be discharged for a significant equilibrium. Researchers can balance the mass of independent voltages that emerge when mass mass is removed and moving up and down in the magnetic field.

Metric makeup

Metric basic units are expected to be revised on fixed physical constants.

Metric block The number of Stable definition
Kilogram Mass Planck constant
Meter Speed Light velocity
Secondly Time Cesium radiation frequency
Ampere Current Payment for an Electronic Paid
Kelvin Temperature Boltzmann is stable
Mole The size of the substance Avogadro constant
Candela Intensity of light Brightness of a certain frequency


The True Tensile is included in the dosing and current of the electron and quantum mechanics involved in the charge of the Planck constant. Now, when setting these new constants, the new SI is designed to measure a slide with exactly 1 kilogram mass. Nieth physicist James Olthoff says: "It makes quantitative techniques for re-examination and SI standards for stress and current measurement." So far, SI has not determined the amplitude of the infinite longitudinal current transmitted by metric.

Gary Price, a metrologist at Sydney, Australia, advises the Commission on National Standards of Australia, using complex new definitions and does not hinder anyone without the advanced level of physics. In fact, it does not meet one of the basic requirements of the new SI unit system, ie it is necessary to specify the weight mass, the length that can be measured, and so on. "The new SI is not a weight and measure," Price says.

According to Oltrof, metrologists have intuitively redefined. For example, you can determine kilograms as the mass of a large number of atoms. But this standard will be worse, says Olthoff. Scientists have identified 12 grams of carbon-12 atoms, much more ironically for molecules, the atoms have a beautiful circular atom, and silicon-1 is a kilogram of 1 kilogram.

If approved, the new SI will take effect in May 2019. In a short period of time, little changes, says Pratta. NIST will continue to distribute weight by calibrating weight, but now it will do it with the Kibble balance. Finally, according to Prat, researchers can develop a balance of tablets that they use to calibrate their microbubbles.

The next step is the recurrence of the second thought. Metrics develop a realistic atomic clock using high-frequency optical radiation than current cesium standards. They should be the basis for a deeper understanding of the other in 2030, Mirandes says.

Regarding Le Grand K, BIPM will save it and calibrate it for the second time as mass standards, Mirandes says. This was a significant decline for the French king.

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