Latest SI base units Stories
By Vayshenker, I Li, X; Livigni, D J; Lehman, J H; Bermudez, J C; Molina, J C; Ruiz, Z E We describe the results of a comparison of reference standards between the National Institute of Standards and Technology (NIST- USA) and Centro Nacional De Metrologia (CENAM-Mexico).
The kilogram is losing weight and many international scientists, including some at Sandia National Laboratories, agree that itâ€™s time to redefine it.
A kilogram just isn't what it used to be. The 118-year-old cylinder that is the international prototype for the metric mass, kept tightly under lock and key outside Paris, is mysteriously losing weight - if ever so slightly.