Maybe conclusive to you (and many people)... but until we know for fact what did come before (if anything): there will always remain some reasonable doubt. (Also, i don't get how entropy equates to closed system... in some iterations of the universe: it could be true... but it is an assumption that this iteration is not one of many envisionable systems in which entropy is just a stage in the system.) The question of 'How did the Big Bang get there?' becomes all the more important if this universe is not the original.
Please give me a home where cloud buffalo roam
Where the dear and the strangers can play
Where sometimes is heard a discouraging word
But the skies are not stormy all day
