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 ...

When someone tells you they'll be "back in two shakes!" they are guaranteed to take much, much longer than that — at least if we're talking shakes in the sense used by physicists. The shake is a unit ...

Deluged by responses to his request for your favourite units, Robert P Crease discovers that non-SI units persist, and are sometimes even popular, among the physics community Setting the standard ...

Scales aren't changing and the weather won't be noticeably different, but on May 20 the definitions that underlie what your scale and thermometer report—along with standard definitions used in ...

With a dedicated monthly column, Nature Physics draws attention to metrology. And a set of Commentaries in this issue focuses on various aspects of thermometry. Physics is all about observations, ...