Using a state-of-the-art device for measuring mass, researchers have made their most precise determination yet of Planck's constant, an important value in science that will help to redefine the ...

The metric system is on track for a mass makeover. In an effort to provide accurate measurements at all scales, scientists are preparing to redefine four basic units by the end of 2018. The shift will ...

A new definition of the kilogram is required, an international team of scientists contends. The current one is imprecise, they say, because it is not linked to an unvarying property of nature. The ...