The world of anti-matter sounds like something only for fiction stories because scientific professionals seem to have not found enough reason to believe it yet. I in fact is not a professional in physics (I am a philosopher) but I like to read physics. I see the world of anti-matter to be quite possibly real, not by fictitious imagination, but by reason. Some scientific professionals have been telling us that there were huge amount of anti-matter during the early period of this universe, much more than the total amount of matter we are having today in the observable universe. And then, according to the scientific professionals, most anti-matter collided with matter then turn back to energy together, and the rest of a litter amount of anti-matter just disappeared, and left the matter to form the universe today. For the mysterious reason of the disapearance of the rest of anti-matter, scientific professionals have made some assumption that they just decayed, which seem have not been universally accepted among scientific professionals. However, in the mean time, scientific professionals have also been telling us that the space is expanding, and the rapid expansion have created some physically isolated regions, which could not communicate with each other AT ALL because their recession speed is greater than speed of light. Well, this IN FACT provides a much cleaner and better explanation for the disappearance of the rest of anti-matter: at the very beginning, there were matter and anti-matter, but their distribution in space-time was not completely absolutely homogeneous, at the different remote sides of the "cloud", some was occupied by excess of matter and some other was occupied by excess of anti-matter. When most matter and anti-matter were colliding with each other and turned back to energy, those remote orphan matter and anti-matter were left out because their counter-parties were in the region with recession speed relative to them greater than light speed. And then these matter and anti-matter cooled down to form their own universes, which would not communicate with each other due to the greater than light speed recession speed. If what I laid out above is the truth, then a world of anti-matter would exist somewhere and would not communicate with our universe in non-quantum manner. Maybe we don't need to worry about their coming back. But would that possible for us to meet with them in some quantum way and then together turn back to energy?