I am wondering about the gravity of loose groupings of matter, such as galaxies. Stars and other objects have their own gravity but when you look at groups of galaxies you see that the galaxies have the combined gravity of all the matter that makes up the galaxy. My question is not about the combined affects of gravity in galaxies but of the Universe as a whole. So what I want to know is if it is possible for all the gravity from all the matter in the Universe to be combined. Could this have an event horizon effect at the "edge" of the Universe, forming an invisible unbreachable barrier around the Universe that doesn't allow light or matter to "escape" and instead just sends light or matter around the "edge" of the Universe? I don't know if I have formed my thoughts into the proper words so that you understand what I am trying to say, but I figure some of you will get it.