Metrology: quo vadis?

Metrology, the science of measurement, has become an essential part of the technical infrastructure of industrialized countries. In cooperation with the BIPM, the national metrology institutes realize, maintain, and disseminate the units of the SI (Systeme International d´Unites), so making accurate measurements available to all users. The discovery of the macroscopic quantum effects provided the means of reproducing certain electrical units with an uncertainty considerably smaller than that of direct realization according to their SI definition. The reproduction of units in this way has become an important method of improving their maintenance and dissemination. The article highlights the advantages of such a method: it is general, it will certainly be extended to units other than electrical ones and it will generally improve the paths of traceability resulting in a better worldwide metrological network