Roger Penrose, who mathematically proved that general relativity breaks down in black holes, believes the universe did not start with he big bang. He thinks the universe cyclically balloons and compresses and what we refer to as the big bang is merely the beginning of this aeon, the period of the universe's life that we are living thorough, rather than the actual start of everything. As he is as well qualified as anyone to have an opinion on this, and there is no reason to suggest he is wrong, this should probably be taught in schools as at least an equal hypothesis to the 'big bang was the start of everything'.