New Delhi: India on Monday adopted a global resolution to redefine four of the seven base units ― kilogramme, Kelvin, mole and ampere, a move expected to have far-reaching effects, including changes in textbooks.
Kilogramme (kg) is the standard unit of measurement of mass, which, when multiplied by the acceleration due to gravity, gives the product called weight although in popular perception, kg is a unit of measurement of weight (which is not true).
Kelvin is the standard unit of measurement of temperature. It is obtained by adding 273.15 to the measurement of temperature in celsius or centigrade.
Mole is the amount of substance that is made up of 6.02214076×1023 constituents like atoms, molecules, ions or electrons. This number is the Avogadro constant. Scientist Amedeo Carlo Avogadro hypothesised that under all circumstances, two samples of gas of equal volume, at the same temperature and pressure, contain the same number of molecules.
Ampere is the standard unit of measurement of electric current.
A resolution to redefine four of the seven base units was passed by representatives of 60 countries at the General Conference on Weights and Measures (CGPM) of the International Bureau of Weights and Measures (BIPM), Paris on 16 November last year.
However, it has been implemented across the world on 20 May ― World Meteorology Day, Shekhar Mande, Director General of the Council for Scientific and Industrial Research (CSIR), said.
Over 100 countries have adopted the metric system of measurements, also known as the International System of Units or Système Internationale (SI), which has been in practice since 1889.
What will happen as a result is that while the units will continue to be referred to by the same, respective names, these quantities will be compared to natural occurrences or phenomena to ascertain how much amount or volume they represent.
This is necessary because the comparison with a man-made substance fails to be a standard, as the artificial object can undergo wear and tear.
This is a switch from physical artefacts to quantum standards.
The other base units are ― second, metre and candela.
“The fundamental constants are invariants of time and space and have successfully replaced the artifact based units, and aptly opened up the new era for quantum world by linking all seven base units to fundamental constants or quantum standards,” said K Aswal, Director of the National Physical Laboratory (NPL), one of the oldest scientific institutes in the country that also takes care of setting meteorology standards domestically.
The purpose of a system units is to enable worldwide coherence of measurements. The International System of Units (SI) was formalised in 1960 and has been updated several times to account for development in measurement technology.
“Since the 1960s, we have to rely ever more heavily on advanced science and engineering in our day-to-day lives, and also in manufacturing, healthcare and science. The proposed changes in the unit definition have been designed to have no immediate consequences,” he said.
“The unit redefinitions represent a profound change of perspective and they are expected to form the foundations of improved measurements for decades to come as science and technology continues to develop in a way we cannot currently foresee,” Aswal said, however, this “may not change anything drastically”, but it will matter when it comes to measurements less than a kilogramme. For instance, measuring smaller diamonds.
The NPL has also sent recommendations on the proposed changes to be incorporated in the National Council of Educational Research and Training (NCERT) to implement them in contemporary education, he said.
Recommendations on the proposed changes have also been sent to the All India Council for Technical Education (AICTE), Indian Institutes of Technology (IITs), National Institutes of Technology (NITs), and other academic institutes to be incorporated in syllabi of metrology courses in graduate engineering and academic courses.