icant writes:
As I understand the string theory it is an effort to show what was before the big bang.
This is a big misconception that many many laypeople have about the universe. There is no 'before' the big bang. Time did not exist prior to the event, at least according to all modern theories.
There are others here (cavediver, son goku) that are FAR more learned in this department then I. They have discussed it many times in the past with others on other threads here. Have a read and post on those threads (or start a new one) if you have any questions.