Hm? Old thread you say? hmmm..... eh. I'll post anyway.
A solar system has a center, as all do, the center of a solar system is a star. The high mass and gravity of the sun, keeps the planets swirling around it. But, if we go beyond the solar system, we reach the galaxy. Which contains thousands, if not millions of stars, if not BILLIONS of stars and solar systems. The galaxy is held together by, what is assumed a black hole. The high mass and gravity of the black hole keeps all the stars and solar systems together. But, when we go beyond the galaxy, we reach the universe. The universe contains Trillions of galaxies, but... thats as far as we go. Truethfully, I think the universe is just another expansion in the great "Final Frontier". I think, that very far off, there is a large object or clump of mass and gravity, that keep all the galaxies together. And if we go beyond the universe, we will find another expansion of space, that contains tons more universes.
So I believe that the universe has an end, its just very far off, and we haven't been able to see far enough to catch a glimps of an end, or the great center of the universe. Sorry, I'm only fourteen, this is the best I can shove out.