I've been reading some speculative articles about the possible quantum arrow of time which emerges through collapse and irreversibility. My question is: does collapse in the Copenhagen interpretation (or perhaps in a objective-collapse model) allow the spontaneous decrease of entropy where an improbable event like reforming of a broken glass can happen? As far as I know, the only thing that is irreversible in Copenhagen (which isn't in MWI or BM) is the loss of branches when measurement occurs. But does that imply that for some reason entropy cannot go in reverse in the branch we observe, if it's in fact the only one? My bet would be that - yes, the entropy can decrease and that is compatible with collapse and the Sch. equation, but wavefunctions cannot reinterfere. So in one way, entropy can decrease, but in a global sense considering lost branches - it cannot. Therefore, I don't understand the attempt to define the arrow of time through collapse since collapse doesn't disallow the spontaneous decrease of entropy. All opinions are welcome, thanks in advance.