From the little I understand of the big bang It states that the universe was in a very high density state and then expanded.
This is commonly used as a proof that the world had a beginning and thus torah tradition and science are not at odds. Dr. Gerald Schroeder wrote a book claiming this very position.
However, I was just thinking that the theory itself claims that there was a pre-existing kernel of mass that exploded and expanded. Thus, it was not a creation out of nothing. Also that there was a "space" for it to expand into. Again, another previously extent object or matter.
Why is this a proof? Am I wrong I my understanding of the theory?