This may seem crazy...

yes, I believe it is possible. I believe this because it is possible to create alternate timelines based on our decisions, eg. You went on to do university, that's a decision, whereas, if you chose not to go, a new set of oppurtunities await, though others will be closed off. Think of life as a set of doors, branching off into the unseeable distance. You can only choose one. There is no way that the timelines could be in one dimension, as there would be a paradox. So maybe?