if it was another day... this would have been another world!!!

  If that thing would have happened on another day, this would have been another world. How many times I think even if an event would have occurred a moment early or a moment late, the world would have been drastically different. Is this the reason, Einstein said, god do not play dices? The current world, time frame, point of references, predictions, conclusions are result of so many things, events and person occurring on that particular time.
  Hugh Everett, proposed a theory in 1957, called theory of Many Worlds Interpretation, which some what explains, every event on a particular time line triggers another set of event and happening not necessarily impacting the same time line. The many-worlds interpretation regards possible futures as having a real existence of their own. The same way, the theory of multiple histories reverses this in time to regard the many possible past histories of a given event as having real existence.
  So with this in mind, if timing of a single event is changed even by a minute fraction of second, it could have triggered another history, another future and altogether different present.
  Since "other times are just special cases of other universes" , the temporal granularity of personhood through time is a special case of being spread out through worlds. In addition to one's identically time-stamped copies at a moment across parallel worlds transversely, there are the differently time-stamped copies across parallel worlds longitudinally, linked by natural law so as to give the individual's experience of one world and a continuous self. The implications for the theory of personal identity are not yet clear, but Derek Parfit's Reductionist view seems to be favored: The concept of personal identity ceases to apply when branching is taken into account, but branching maintains what's important about personal identity, such as psychological continuities having to do with memory, desire, character, and so forth. If we track the closeness transversely as well as longitudinally, the tracked slices of "me-copies" would be the continuing person. Deutsch would seem to favor some such approach. There are "multiple identical copies" of me in the multiverse. Which one am I?  "I am, of course, all of them."