Creation of the universe: THE BIG BANG

the quran contains the following verse,regarding the origin of the universe..

''Don't the unbelievers see that the heaven n the earth were joind togethr(as one unit of creation),before we clove them asunder.....al-quran 21.30'"

the striking congruence b/w the quranic verse n the big bang is inescapable ! Hw could a book,whc 1st apprd in the deserts of arabia 1400yrs ago,contain ths profound scientific truth..??