Consensus is what separates science from philosophy. It's created by the theory with the most support that can stand up to attacks from all sides. What people forget is consensus is built by convincing highly intelligent and highly educated people with their own pet theory's that they are wrong. Unlike elections there is not ballet stuffing and no theory needs to win.

PS: Ask a astronomer happened before the big bang and they will say "we have no clue" but wait or prod for a little bit and each will provide their own little pet theory.