LONDON: Scientists have unanimously voted to change the way a kilogram is defined. A cylinder of polished platinum-iridium alloy known as “Le Grand K”, which is locked away safe in a Paris vault, it to be retired from its role as the true kilogram. Instead, attendees at the General Conference on Weights and Measures have opted to use a measurement based on electric currents to define this unit of weight. Representatives from 60 countries around the world gathered in Versailles, France, to witness the moment, with some scientists sporting tattoos on their arms to mark the occasion. The decision was greeted by rapturous applause, after the policy makers and scientists one by one signalled their approval of the new system. “The vote is a unanimous yes; I hope that such votes will be possible for many other issues in the world,” said Professor Sebastien Candel, president of the French Academy of Sciences, who oversaw proceedings.