"The round object in the world" may become a new measure of kilogram

In a world where everything tends to be better, faster, higher and stronger, scientists from the Australian Avogadro Project reached a new peak: created the round object in the world.

They did not do it for the fact of, and in an attempt to solve the & quot; problem kilograms & quot ;. Unlike other measures that could theoretically be measured anywhere through various physical laws and properties pounds still remains tied to a particular physical object: cylinder of platinum-iridium alloy , created in 1889.

For example, the "meter" can be defined as distance traveled by light in a tiny fraction of a second . In turn, the "second" can be measured using a half-life of the atom. "Kilogram" is still measured as the physical mass of the sample, which is hidden in a safe vault the Paris Chamber of Weights and Measures .

For an unknown reason, and in spite of all sorts of precautions, the mass of the standard cylinder changes over time. In other words, today kilogram sample weighs less than its melting after 125 years ago. This is confirmed on the basis of comparisons with 40 samples, copies of the cylinder stored in different countries.

To solve the problem of creating a constant standard kilogram, Australian Centre for Precision Optics , in which the project is based Avogadro, has created an almost perfect sphere of silicon is very high purity and stability. Calculating the size and weight of the sphere, scientists can determine the exact number of silicon atoms in it, thus creating a constant time reference mass.

Scientists have decided to give the standard форму sphere , because it is devoid of corners and edges, which can be damaged to the same sphere has only one parameter - diameter - to be measured to calculate its volume.

Manufacturing sphere took place in several stages. First in Russia, with the help of centrifuges for uranium enrichment, was received very pure silicon-28 isotope. The party of this material was sent to the German National Metrology Institute, where from it, after six unsuccessful attempts, raised cylindrical crystal without defects. Next, it was cut into pieces of 5 kg and sent to Australia.

To make the silicon cylinders spherical Australians used two rotating rotor, which gradually hand polished workpiece. This process took several months. Followed by a computer measurement with a laser and detected irregularities were removed intentionally.

If you increase this area to the size of the Earth, on its surface will ripple depth of 5.12 mm and a diameter of 3-5 m.

To be fair to mention another method of creating standard kilogram, the so-called & quot; watt balance & quot; (Watt balance). The method consists in the fact that special installation calculates the force that is needed to counterbalance the load of one kilogram, and determines how much it is watts of electricity.





Source: habrahabr.ru/post/212795/