News & Comment

Although the ohm is ‘only’ a derived SI unit, the assumption that it plays an unobtrusive role could not be further from the truth, as Karin Cedergren reveals.

The digital transformation doesn’t stop at metrology as Shanay Rab, Meher Wan and Sanjay Yadav explain.

The impact of legal metrology often remains unnoticed in our everyday lives. Pavel Klenovsky, Marc Wouters and Wilfried de Waal instruct us in trade and legal regulations.

The shift of the definition of the kilogram in 2019 away from an artefact to one relying on the Planck constant inspires technological innovation, as Naoki Kuramoto elucidates.

Juris Meija takes a look at the tumultuous past of the atomic unit of mass from its beginnings as an idea to its most recent revisions in a hotel bar.

A task group recommends values for many constants in fundamental theories of physics and chemistry. Eite Tiesinga and Peter Mohr tell some of the constants’ stories.

The coexistence of qualitative and quantitative scales characterizes advances in earthquake measurements. Although often confused, intensity and magnitude refer to very different things, as Leonardo Benini explains.

The establishment of a global metric system of units as agreed upon in the Metre Convention relies on international as well as national institutes and organizations, of which Stefanie Reichert gives an overview.

To celebrate the International Year of Basic Sciences for Sustainable Development, James Gallagher tells the story of the British thermal unit, a unit for heat.

The idea of radiocarbon existing at equilibrium within Earth’s atmosphere has established radiocarbon dating. Adam Fleisher takes a look at its beginnings, achievements and limitations.

The laws governing electrolysis developed by Michael Faraday, who originally trained as a bookbinder, led to the determination of the Faraday constant, as Daren Caruana recounts.

The measurement of pH is more complicated than it seems, recalls Andrea Taroni.

The uptake of graphene-based materials calls for standardization. Silvia Milana explains what this entails.

The unit length of DNA is a base pair, which serves as a ruler for DNA compaction and processing, as Michelle Wang explains.

Initially used to measure the brightness of radio sources, the jansky has spread to other areas of astronomy, as Natasha Hurley-Walker recounts.

A single equation can describe how fluids flow across a wide range of length scales, from ocean currents to swimming algae. The difference merely lies in the Reynolds number, says Julia Yeomans.

As the namesake of a variety of constants, distributions and equations, Ludwig Boltzmann has earned his place in the physics hall of fame. But as Ankita Anirban reveals, he cannot take sole credit for the most famous constant bearing his name.

What does it mean for an individual to be ‘important’ or for a connection to be ‘outstanding’? The answer depends on context, as Sarah Shugars and Samuel V. Scarpino explain.

Surface scientists love a good vacuum. The reason for this is captured by the work of Irving Langmuir and the little-known unit bearing his name, explains Daniel Payne.

The metric system is one of the enduring achievements of the French Revolution. Martin Milton recounts how it was also intended to unite nations.