I reject the big-bang theory. I'm not a theoretical physicist I just have a hard time imagining that the universe started with a single point in time. The child in me asks, "Well, what happened before the big bang?" As far as I can tell 13.7 Billion years ago the principals of conservation of mass were still valid. If matter can not be created or destroyed then matter should have all existed one second before the big bang. You can't make something out of nothing, even if you have vast amounts of nothing.
Let's think about time. Now imagine one second into the future. There's always a future second and it seems preposterous to imagine that somehow future time could stop. In the same realm I believe you can always go back one second in time. If we believe in time as a dimension then like the other X,Y & Z dimensions it should expand out infinitely in both directions.
Where did the universe and everything come from? The answer is that it has always been here, infinitely into the past and infinitely into the future. Interestingly enough I can't fathom an infinite past but it somehow seems more plausible then a past that stops at a somewhat arbitrary point.
My theory happens to be compatible with a big-bang event, I just don't view that event as the start of everything. It was just a very loud day on an infinite timeline.