Why in News?

• • Recently, the CSIR-National Physical Laboratory (NPL), which is India’s official reference keeper of units of measurements, released a set of recommendations to update the definition of the kilogram.

Highlights:

• • The kilogram joined other standard units of measure such as the second, metre, ampere, Kelvin, mole and candela that would no longer be defined by physical objects.
• • The measures are all now defined on the basis of unchanging universal, physics constants.
• The kilogram now hinges on the definition of the “Planck Constant”, a constant of nature
  that relates to how matter releases energy.
• • In 2018, at the General Conference on Weights and Measures (CGPM) in Versailles (France), delegates of International Bureau of Weights and Measures (BIPM) had voted to redefine the kilogram in terms of Planck constant.
• • Earlier, the kilogram derived its provenance from the weight of a block of a platinum- iridium alloy housed at the International Bureau of Weights and Measures in France.