This issue comes up in Shiraz's lecture here on 29th October 2008.
I understand that he is saying that one can think of closed string theory as having two minima and that the ground state in the non-global minima is kind of a condensate of closed strings and open strings emerge as massless fluctuations about them. It seems that he is trying to say that open string theory cannot exist on its own and there is no sense in which there can be a low energy limit/effective action of open strings which is made up of only open strings. (also he is alluding to an interpretation of D-branes as a condensate of closed strings and closed strings as a soliton of open strings and thats what is in this second minima)
So I guess there is an interpretation that if enough energy is provided to closed strings then they will on their own produce D-branes and open-strings? (by moving to this second minima from the global minima?)
I am quite sure I said a million things wrong in the above paragraph and Shiraz doesn't provide references which derive these ideas which lets one go back and forth between closed and open string interpretation.
I would like to know as to what are are corresponding completely correct facts which Shiraz is alluding to and if someone can tell me reference which derive that (hopefully from scratch!)
He comes to this issue in trying to interprete how the appearance of D-branes in the T-dual picture of compactified Bosonic closed strings is "kind of" a breaking of translation invariance. And that this translation invariance breaking can be seen to be rooted in the interpretation of closed strings breaking up into open strings.
It would be great if someone can help explain this open/closed relationship to T-duality and hopefully give pedagogic references for that.