Leuchs, GerdHawton, MargaretSánchez Soto, Luis Lorenzo2023-06-222023-06-222023-032624-817410.3390/physics5010014https://hdl.handle.net/20.500.14352/72352© 2023 by the authors. This research was funded by the Spanish Ministerio de Ciencia e Innovación (Grant PGC2018-099183-B-I00).The debate about the emptiness of space goes back to the prehistory of science and is epitomized by the Aristotelian 'horror vacui', which can be seen as the precursor of the ether, whose modern version is the dynamical quantum vacuum. In this paper, we suggest to change a common view to 'gaudium vacui' and discuss how the vacuum fluctuations fix the value of the permittivity, e(0), and permeability, mu(0), by modelling their dynamical response by three-dimensional harmonic oscillators.engAtribución 3.0 Españahttps://creativecommons.org/licenses/by/3.0/es/journal articlehttp://dx.doi.org/10.3390/physics5010014https://www.mdpi.comopen access535Fine-structure constantUncertainty princibleQuantumFieldEnergyÓptica (Física)2209.19 Óptica Física