epa04491667 A picture made available on 16 November 2014 shows Scientist Arnold Nicolaus holding up a silicon sphere which weighs exactly one kilogram in front of the experimental assembly at the Physikalisch-Technische Bundesanstalt (PTB, physical and technical federal institute) in Braunschweig, Germany, 05 November 2014. Scientists of the PTB used the balls in an international project to redefine the prototype kilogram. EPA/JULIAN STRATENSCHULTE
