The life and work of Giovanni Giorgi. The rationalization of the units of measurement system

This column focuses on Giovanni Giorgi (Figure 1), the Italian scientist who clarified the necessity to augment the existing system of three fundamental units to a fourth electrical one, leading to the International System of Units (SI units) of measurement, now universally accepted. The statement of the physical problem is first briefly recalled. The confusing historical context at the end of the 19th century is examined, and the terms of the problems are clarified. The evolution of the concept of an absolute system, the rationalization of the system and the introduction of a fourth electrical unity, and the contributions of the other scientists before Giorgi (like Carl Friedrich Gauss, Wilhelm Eduard Weber, James Clerk Maxwell, and Oliver Heaviside) are reviewed, and the results of the subsequent various conferences held to organize the matter are considered. Then, Giorgi's intuition and the characteristics of his proposal are described. Finally, some notes about the life and the various scientific and technical activities of Giovanni Giorgi are summarized, showing the contributions given by him in different fields, such as relativity.