VILLATA, MassimoMassimoVILLATA2020-03-252020-03-2520150003-3804http://hdl.handle.net/20.500.12386/23565Repulsive gravity is not very popular in physics. However, one comes across it in at least two main occurrences in general relativity: in the negative-$r$ region of Kerr spacetime, and as the result of the gravitational interaction between matter and antimatter, when the latter is assumed to be CPT-transformed matter. Here we show how these two independent developments of general relativity are perfectly consistent in predicting gravitational repulsion and how the above Kerr negative-$r$ region can be interpreted as the habitat of antimatter. As a consequence, matter particles traveling along vortical geodesics can pass through the throat of a rotating black hole and emerge as antimatter particles (and vice versa). An experimental definitive answer on the gravitational behavior of antimatter is awaited in the next few years.STAMPAenArticle10.1002/andp.2015001542-s2.0-84939254338000359910300008http://arxiv.org/abs/1403.4820v3https://onlinelibrary.wiley.com/doi/pdf/10.1002/andp.2015001542015AnP...527..507VFIS/02 - FISICA TEORICA, MODELLI E METODI MATEMATICIScienze Fisiche Settori ERC (ERC) di riferimento::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation::PE9_12 Dark matter, dark energy