Matter and antimatter in the same universe?

Abstract

The question of what amount of primary antimatter exists in the universe is still open. At the present stage of the research, no claims for a really well established scenario can be accepted, because of the incertitude of the very few existent experimental data. In fact, we can speculate, with some experimental arguments, only about our galaxy or, maybe, about our cluster of galaxies, while the extrapolations over greater dimensions are still very difficult. Nevertheless, the very useful theoretical work of many physicists has led to pictures of the highest interest (concerning the mechanisms of propagation, the exotic hypothesized sources, the existence of new elementary particles and new cosmological scenarios) in such a way that new experiments, discriminating between models, can lead to radical and very interesting changements in our conception of the physical world. What we need now are experimental data and the next (10 – 12) years will maybe provide a beginning of solution, but we need also to understand more and more about our ≪obseryab1e≫ universe and, first of all, if it is coincident or not with the universe conceived in the traditional philosophical way as the ≪whole≫.