it's stated that general theory of relativity describes gravity a consequence of the curvature of spacetime caused by the uneven distribution of mass/energy...what caused the uneven distribution of mass/energy? And if the universe is said to be expanding what is the universe expanding to, and how does the space that allows the expansion of the universe look like, is this space infinit or does it have a size? im quite confused with many things such as the expansion of the universe...amongst other things. If the universe is expanding shouldn't it collide against something? it's like inflating a baloon in open space verses inflating it in a box eventually it runs out of space...so shouldn't there be some kind of space out there in order for a thing to expand?