Electric power, a fundamental concept in physics, denotes the rate at which electrical energy is transferred through an electric circuit over a specified duration. It is quantified in watts (W), ...

In a landmark decision, representatives from 60 countries voted to redefine the International System of Units (SI), changing the world's definition of the kilogram, the ampere, the kelvin and the mole ...

Revised definitions for four scientific units — the kilogram, the kelvin, the ampere and the mole — come into force today. The change, decided last year, means that all the base units of the ...

Taking the first steps of what would be a major historical advance in the science of measurement, the U.S. National Institute of Standards and Technology is participating in a worldwide effort to ...

Weighty matters: a platinum-iridium kilogram belonging to the US National Institute of standards and Technology. (Courtesy: J.L. Lee/NIST) Metrologists and policy-makers from 60 countries around the ...

New prefixes for the world’s largest and smallest numbers have been confirmed by a vote at the General Conference on Weights and Measures (CGPM) in Versailles, France, on Friday. The suggested ...

An upcoming change to SI units – due to be officially approved this month – will mark the end of a long journey from defining quantities in terms of objects to using precise, unchanging and universal ...

More than half a century after SI units became standard, pockets of resistance to their adoption still persist — at least in medicine (see also Nature 537, 279; 2016). Many specialists in the ...