SCIENTISTS HAVE SPENT the better part of the past four centuries, since the early days of the Enlightenment, discovering the truth about how the natural world works. A critical part of this endeavor ...

This release is available in German. A milestone in the international Avogadro project coordinated by the Physikalisch-Technische Bundesanstalt (PTB) has been reached: With the aid of a single crystal ...

Katie has a PhD in maths, specializing in the intersection of dynamical systems and number theory. She reports on topics from maths and history to society and animals. Katie has a PhD in maths, ...

An ongoing international effort to redefine the kilogram by 2018 has been helped by recent efforts from a team researchers from Italy, Japan and Germany to correlate two of the most precise ...

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 ...

How much is a kilogram? It turns out that nobody can say for sure, at least not in a way that won’t change ever so slightly over time. The official kilogram – a cylinder cast 118 years ago from ...

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 need for a physical constant quantifying a reference amount of substance is a manifestation of the atomic nature of matter. At the basis of the concept of a 'quantity constant' lies the law of ...

Relics in the form of rods, rulers, and weights go back thousands of years, suggesting that people have long cared about standardized measurements. Today, the International System of Units(SI) defines ...

The world’s measurement system will be based on updated values for four fundamental constants of nature. A revised SI ( the International System of Units ) based fully on accurate values of these ...

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, ...

How much is a kilogram? It turns out that nobody can say for sure, at least not in a way that won’t change ever so slightly over time. The official kilogram – a cylinder cast 118 years ago from ...