The number of atoms in this silicon sphere is known given or taken 20 atoms each 10^9. The atom distance was measured by the X-ray interferometer on the left. Credit: Enrico Massa and Carlo Sasso ================================================================================================ An ongoing international effort to redefine the kilogram by 2018 has been helped by recent efforts from a team researchers from Italy, Japan and Germany to correlate two of the most precise measurements of Avogadro's number and obtain one averaged value that can be used for future calculations. Their results are published this week in the Journal of Physical and Chemical Reference Data. Avogadro's...