May 20, the kilogram will no longer be defined by a piece in France

The change has been going on for years and on May 20, three more units of measurement – the ampere, the kelvin and the mole – will also have new definitions. These proved to be easier to update because they were not based on a mass of the Victorian era in France. The kilogram will now correspond to the mass of an exact number of photons, or light particles, of a particular wavelength. With this change, the kilogram will be defined in terms of seconds and meter, which are physical constants and are therefore more reliable than a man-made object.

For most of us, the new definitions will not change much, but for the scientific community, it is a historic moment. This will give researchers much more accurate tools for doing measurements that could help re-examine the laws of physics. As Terry Quinn, Honorary Director of the International Bureau of Weights and Measures (BIPM), previously told Engadget: "This is the most important decision the BIPM has made for perhaps 100 years, which is what -being a slight exaggeration, but at least since 1960 when they adopted the International System of Units. "