The committee to collect data in the field of science and technology (www.CODATA.org) produces every four years a list with redefined values of several physical constants. In the 2010 list, for example, you can find redefined values of constants, including the uncertainty parameters. So you can find the value of the fine structure constant, which is used in atomic physics, with reduced uncertainty. Furthermore, there is the specified Planck constant, which relates the energy of electromagnetic radiation to its frequency. These changes also affected the Avogadro number, showing the number of particles in one mole of a substance, and the Boltzmann constant, the binding energy and temperature. Redefined values of the constants, especially of the Avogadro constant and the Boltzmann constant were seen by physicists as a signal to update the international system of units (SI), which will be discussed in 2014. This will primarily affect the five units - amperes, moles, kilogram, kelvin and pascal. Proposals to refine the values of the majority of them have good prospects.
The stumbling block of the discussion was the reference value of one kilogram, because the reference value is likely to change and therefore regularly causes debates among the scientific community. Some experts propose to define kilogram, based on the value of the Planck constant. In addition, it is proposed to give a new name for the kilogram. Due to the fact that a kilogram is the only SI base unit having a multiplier - kilo. So there will be competition for the best name for the updated basic unit of mass, as noted above, it will be tied to the Planck constant, rather than the platinum-ridium standard kilogram stored in the Paris Chamber of Weights and Measures. It is most likely that there will win a title referring to “Stein” and derived units. “Stein”, rather, “ein Stein” is the German word for a stone - an object with mass. On the other hand, it is a part (a root)of the name of the genius physicist Einstein, who was not included for various reasons in the "pantheon" of units - volts, ampere, watt, kelvin (celsius, rankine, fahrenheit), newton, joule, pascal (see below), ohm, farad, weber, tesla, henry, siemens, becquerel, gray, sievert. Replacing kilograms with stein will correct this injustice.
Another significant change will affect a pressure unit - pascal. The dispute here is that this unit is too small, and it is almost always necessary to use multipliers like kilo, mega and giga. Because of this, you can recognize in science and technology still a strong use of alternative units of pressure, for example, bars or torr, etc. This diversity also often leads to errors in calculations. There is a plan to redefine pascal - the basic unit of pressure into the "new pascal" equivalent 100,000 old pascal. This will set a transition period in which it will be possible to use both the old and new units of pressure, and then the old pascal will be withdrawn from step by step form calculations.
More: http://twt.mpei.ru/ochkov/SI
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