Masse, moti nascosti, etere e spazio nella meccanica hertziana

This paper is dedicated to the analysis of the connections between the «systems of hidden masses and motions» –that Hertz introduces in his Prinzipien der Mechanik in neuem Zusammenhang dargestellt (1894)–, William Thomson (Lord Kelvin)’s theory of vortex-atom and the vortex-aether models propounded by Maxwellians (particularly George F. FitzGerald). On this basis, the implicit adhesion of Hertz to a kinetic research program (similar to Kelvin & Tait’s programme) is discussed. Finally, it is shown how this affiliation as well as Hertz’s reference to the aether were incidental to the elimination of the concept of force and action at a distance. Following a Faraday-Maxwellian pattern, the concept is then replaced by a point-to-point action through the introduction of the ‘systems of hidden masses and motions’. According to Hertz, it is in this framework –revolving around the notions of aether, point-to-point action, and field theory– that the problem of physical space occurs. Together with the physicist’s seminal works, the main source that the paper draws upon and analyses is a very important series of lectures from 1884, lectures which have only recently been published and have thus hardly been taken into consideration by scholarship. The space envisioned by Hertz in this context is a purely relational space. It is not a vacuum that contains or transports forces and matter, rather it is ubiquitously connected with masses and forces. This perspective represents a crucial step towards a new concept of space.