The fundamental constants that govern the laws of nature are being determined with increasing accuracy. A new paper outlines the proceedings from this year's Workshop on the Determination of the ...

The redefinition of several physical base units planned for 2018 requires precise knowledge of the values of certain fundamental physical constants. Scientists are working hard to meet the deadlines ...

For more than a century, a single metal cylinder in a Paris vault quietly defined what a kilogram was. After 130 years, ...

If scientists had sacred objects, this would be one of them: a single, closely guarded 137-year-old cylinder of metal, housed in a vault outside of Paris. It is a prototype that precisely defines a ...

As cheat sheets go, it is a long one. Every four years, a task force of the Committee on Data for Science and Technology (CODATA), headquartered in Paris, releases a short-hand description of 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 ...

Nick van Remortel demystifies natural unit systems — and advises what to do when you see a mass expressed in GeV. Several unit systems for describing the natural world exist. The International System ...

Constants are supposed to be, well, constant. In physics there are a number of fundamental constants, such as the speed of light, Planck's constant, and the charge of an electron that are essential to ...

THROUGHOUT MUCH of human history, man has been the measure of many, if not all, things. Lengths were divided up into feet, palms, spans and smaller units derived from the human hand. Other measures ...

It must be a baker's worst nightmare: a world where a kilo ain't a kilo anymore. Next May 20, the universal standard for a kilogram gets its first upgrade in 130 years. There'll be screams a la ...