In the near future, some units of dimensions will be redefined
Scientists decided to re-define the units of measurement of some quantities, namely, current strength, amount of matter, temperature and mass. This proposal was approved at the General Conference on Weights and Measures, which took place in Paris. The final new definitions, as planned, will be adopted in 2014, immediately after the decision goes through all the formalities.
Today it is known that all units of dimensions in the SI system can be reduced to seven basic ones – ampere, mole, kilogram, kelvin, second, meter, candela (luminous intensity). Immediately three of this list are associated with the main constants.
For example, the definition of a second, which was finally approved in 1997, is a certain time interval, which is equal to 9192631770 periods of radiation of the atom of Cesium-133. Even though this definition is cumbersome, its use is very convenient in physics.
Up to this point, other quantities such as ampere, mole, kelvin and kilogram had a slightly different definition, proceeding from completely different considerations. If we take for example the kelvin, then it is associated with the triple point of water, and the kilogram is determined in relation to a special standard, which is located in the chamber of measures and weights. As part of the new proposal, unaffected units will also be redefined.
Following the accepted proposal, ampere is the unit of current at which the elementary charge is 1.60217653 x 10-nineteen pendant. The Kelvin will be defined so that the Boltzmann constant is 1.3806505 x 10-23 joules per kelvin, mol – so that Avogadro’s constant is exactly 6.0221415 x 1023 per mol-one and finally a kilogram – so that Planck’s constant is 6.6260693 x 10-34 joule seconds.