>>78
The most prominent one is probably the 'Big Bounce' talked about in string theory.
This is not an alternative theory to the Big Bang; it is a larger theory that comprises Big Bang. If Big Bounce is correct, Big Bang is also correct.
Also, a) Big Bounce has very little to do with string theory, and b) Big Bounce is almost certainly wrong, since as WMAP has shown, the universe is spatially flat and so will not collapse on itself.
Because of this we cannot know for sure weather our world is bigger than the planck length or smaller.
This is nonsense. There is no absolute scale of larger or smaller in string theory just as there is no preferred frame in relativity. It makes no physical difference which way you choose in calculations; pick one.
To reitterate the point I was making the Big Bang is a theory that explains the observed facts reasonably well based on current well supported scientific theory. A better theory may come along at any moment.
Of course. This happens all the time in science; for example Newton's laws of Gravity were replaced with General Relativity at high energy scales. This doesn't mean Newton was wrong; it just means General Relativity has a larger scope of applicability than Newtonian gravity.