The National Institute of Advanced Industrial Science and Technology (AIST) showed Japan's meter and kilogram prototypes to the press on Monday, ahead of the 150th anniversary later this month of the ...

Since 1889, Le Grand K, a sleek cylinder of platinum-iridium metal, has ruled from its underground vault in Paris. An absolute monarch, it was the very definition of 1 kilogram of mass. Scientists ...

Is a meter a meter and a second a second? Yes, but they will be defined differently from May 20th on. This marks the beginning of a new era for science. New rules have been in force since May 20th: ...

A kilogram is a kilogram, right? … right? Well, yes and no. For over a century, the kilogram has been defined by a cylinder of platinum and iridium housed in a super secure vault in Paris. Copies of ...