Four of seven base SI units – the kilogram, the mole, the ampere and the kelvin – are set to be redefined. Delegates at the 24th Conference on Weights and Measures, held in France on 21 October, were persuaded that the existing definitions of these units were outdated and needed to be dragged into the 21st century.
The new definition is: ‘the kilogram is such that the Planck constant is exactly 6.6260693 x 10-34 joule-seconds’.
‘It will be some years before these proposals are adopted, but we have crossed the major hurdle‘ committee’s president, Ian Mills, emeritus professor of chemical spectroscopy at the University of Reading in the UK, says.
Read more at Royal Society of Chemistry.