Read that same cracked article this morning, ynvaser
I love that site.
Anyways, turns out the universe is finite.
There are definite edges, persay. However, accoring to some thoeries, those edges are just "our" universey massive place, and there are more. Space itself is infinite, for sure. which is a neat concept. However, the amount of crap in space is limited by the creation of said mass. Therefore, by calculating exactly how much of what was created in the big bang (And i remember reading something about that happening), we can estimate how much matter is in space, and therefore how far out this "big bang's" effects have reached, and therefore define our area.
Also, in that cracked article, it mentioned the theories of the gravity well that pulls everything closer. My personal theory is a supermassive black hole, but really we have no farking clue.
Gg's, universe.