“The mother ship is never wrong,” said Robert Vocke Jr, a chemist at the National Institute of Standards and Technology in Gaithersburg, Maryland. No longer. Friday, in a small conference centre just ...

An upcoming change to SI units – due to be officially approved this month – will mark the end of a long journey from defining quantities in terms of objects to using precise, unchanging and universal ...

In addition to Ampere, Kelvin, Mol and others, the kilogram is now defined by a natural constant. In concrete terms, this means that the original kilogram, which has been the measure of all things for ...

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

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 ...

Taking the first steps of what would be a major historical advance in the science of measurement, the U.S. National Institute of Standards and Technology is participating in a worldwide effort to ...

The official definition of a kilogram has been changing for well over a century, but this week it may be redefined for the final time. After years of debate and discussion, scientists from around the ...

The metric system of measurements, also known as the International System of Units (SI) has been in practice since 1889. In a historic decision on November 16, last year, more than 60 countries ...

A new definition of the kilogram is required, an international team of scientists contends. The current one is imprecise, they say, because it is not linked to an unvarying property of nature. The ...

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, ...