I could explain it better, even though this guy probably knows way more than I do.
Well, perhaps :-)
Quantum mechanics predicts that completely empty space is unstable and via statistics and probability, lumps of energy and mass will coagulate within that space. As a result of Einstein's General Theory of Relativity, that will result in more space and time, which will in turn result in more matter and energy. This is the mis-named "big bang" which is really just a big expansion.
Ipad version: I dont quite recognise this explanation. If we accept inflation, an account for the origin of our universe must account for the origin of the inflationary state (field) which is thought to be different than coagulated matter (i am not sure what the coagulation refers to). Right now there are two main contenders. one is quantum gravity where space itself is quantized and thus quantum fluctuations will ( very simplified) correspond to the origin of new space in some accounts in an inflationary state.
the second main account is guth-lindes theory of Chaotic inflation where the inflationary field undergo local quantum fluctuations and thus keeps creating universets with different properties (laws)
Both accounts reflect many different variants (past eternal or not etc) and none are known to be true.