Yeah, how do you know there were any, eh? This is stupid.
We don't, but he specified "this one" because there may be others. (Assuming commander has not kept me misinformed of inverted's meaning.)
A theory is that the universe cycles between Big Bangs and Big Crunches, when it accrues enough central gravity (via black holes) to pull everything back in or something, I forget specifics. Someone post the theory if you like.
According to this, there were possibly infinite cycles of Bangs before the one that created the universe as we see it now.
I mean, it makes sense. Where else would all the matter come from to make another bang?