Is it scientifically possible that God created the universe in only 6 days?

There is no stronger source for doctrine than the texts of revelation. Science does not negate the possibility of Allah creating whatever He wills at any time or for any duration, because that is related to the power of Allah, Whom nothing incapacitates. He says: "And Allah is over all things competent" and "And Allah was over all things competent." So Allah is able to create all creatures in less than a moment, and everything to which His will is directed occurs as He wills and at the time He wills, confirming His saying: "Indeed, His command, when He intends a thing, is that He says to it, 'Be,' and it is." And He, Glory be to Him, informed that He created the heavens and the earth and what is between them in six days, as stated in His saying: "And We did certainly create the heavens and the earth and what is between them in six days, and there touched Us no weariness."