These units, together with the astronomical second (based on the mean solar day) as the unit of time, constituted a mechanical unit system. Following the introduction of the ampere, the kelvin and the ...

The need for a smaller, more transportable version of ANSTO's 1,500-liter atmospheric radon-222 monitor, and with a calibration traceable to the International System of Units, prompted the team to ...

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 ...

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 ...

The United States's version of the Imperial system is based on an older British version. MaxPixel At press time, only three of the world's countries don't use the metric system: the United States, ...

Meet the metric system’s newest prefixes: ronna-, quetta-, ronto- and quecto-. Science News spoke with Richard Brown, head of metrology at the National Physical Laboratory in Teddington, England, ...

In a landmark decision, representatives from 60 countries voted to redefine the International System of Units (SI), changing the world's definition of the kilogram, the ampere, the kelvin and the mole ...

New prefixes for the world’s largest and smallest numbers have been confirmed by a vote at the General Conference on Weights and Measures (CGPM) in Versailles, France, on Friday. The suggested ...

The International System of Units (with the abbreviation of SI units) is one of the foundations of modern science. It consists of seven base units from which all others can be derived. These are the ...

For the first time in more than 30 years, new terms have been officially added to the International System of Units (SI). The four new prefixes – ronna, quetta, ronto and quecto – describe very large ...

The next time you pick up a bag of spuds from the supermarket or fill up the car with petrol, you can thank a treaty signed 150 years ago for the metric system that underpins daily life. On May 20, ...