Luis Gonzalez-Mestres Cosmological implications of a preonic vacuum (I) (350K, PDF) ABSTRACT. The mathematical and dynamical structure of standard Physics at very short distances can be significantly modified by and underlying preonic structure. But the implications of such a new dynamics can produce important effects well beyond the directly concerned domain. Preons can, in particular, be the constituents of the physical vacuum as postulated two decades ago with the superbradyon (superluminal preon) hypothesis. Indeed, if a fundamental form of matter or pre-matter beyond standard particles exists, there is no reason to assume that its critical speed is equal to the speed of light c. The propagation of superluminal signals in vacuum can in particular be at the origin of the observed quantum entanglement. But the strongest implication of a preonic vacuum would be the possibility that it actually drives the expansion of the Universe. If an unstable (metastable) vacuum permanently expands, it can release energy in the form of conventional matter and of its associated kinetic energy. Then, the cosmological energy density of standard matter may be able by itself to accelerate the expansion of the Universe making useless dark energy and the standard cosmological constant. The spinorial space-time (SST) we introduced in 1996-97 can be the expression of such an expanding vacuum at cosmic level. In the presence of a preonic vacuum, the structure and properties of black holes can be modified in several ways by the interaction between the content of the black hole and the vacuum dynamics. The emission of superluminal preons through the black hole cannot be excluded if such objects can exist as free particles in our Universe. Besides gravitational waves, astrophysical events such as black hole mergers may also emit preonic waves. Similarly, the preonic vacuum may have nontrivial implications for gravitational waves propagating at very large distances. We briefly discuss these and related issues, as well as relevant open questions.