Silicon sphere - the roundest object on Earth - HD Stock-Video

Shot of the Silicon Sphere - the roundest object on Earth. Made by scientists at the Physikalisch-Technische Bundesanstalt in Germany, the sphere is being used to help redefine the kilogram. It is made out of a single crystal of silicon 28 atoms. By carefully measuring the diameter, the volume can be precisely specified. Since the atom spacing of silicon is well known, the number of atoms in a sphere can be accurately calculated. The aim is to redefine the kilo based on this calculation.