RC Logr 20190522 075900

Wednesday, 22 May, 2019

«Le Grand KG», a small cylinder of 90% platinum and 10% iridium located in a Paris basement, that has been the prototype for a kilogram since 1889, is no more. It served as the IPK for 130 years, and was replaced on 20th May 2019 by a calculation based on the Planck constant. This video at NIST explains it. ℏ

Planck’s Constant: 6.626068 × 10^-34 m^2 kg / s