“Vacuum is a physical medium capable of transporting electromagnetic actions. It is characterized by three physical constants:
1. Permittivity of the vacuum, ε0 = 8,854,187×10−12 F.m−1 (Faraday per meter),
2. Permeability of the vacuum, μ0 = 1,256,637×10−6 H.m−1 (Henry per meter),
3. Speed of light in the vacuum, c 0 = 299,792,458 m.s−1 ”.
Here we have, displayed once again in clear and precise terms, the extraordinary ambiguity that contemporary physics maintains with the meaning of the word “vacuum”. The above definition can be read in the volume dedicated to physics, l’Encyclopédie scientifique de l’univers, edited at Gauthier-Villars in 1981 by the Bureau des longitudes. We cannot doubt either the seriousness or the competence of the editor or the commissioner: Gauthier-Villars is to science what le Goncourt is to literature. Meanwhile the Bureau des longitudes, created in 1795 during the Revolution and which still today remains in the shadow of Henri Poincaré, has remained an institution that is as atemporal and symbolic as the Ecole des mines. But how is it possible to conceive that an individual of ordinary intelligence, only a little interested in physics, would not be puzzled by such a formulation? Vacuum, in the current understanding of the term, is the absence of everything, the nothingness, nothing, unless we specify it: vacuum of air, vacuum of matter, etc. To attribute an arbitrary property to something whose existence as a physical object we deny seems therefore ...