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), ...

Over the past 40 years, a number of discoveries in quantum physics have completely transformed our vision of fundamental metrology. This revolution starts with the frequency stabilization of lasers ...

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 ...

In addition to other scientific units, the kilogram also is now defined by a natural constant. This is made possible by single crystals grown from highly enriched silicon-28. In addition to Ampere, ...

Revamped definitions of scientific units are on their way. In the biggest overhaul of the international system of units (SI) since its inception in 1960, a committee is set to redefine four basic ...

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 ...