The Problem of Parallel Universes

In 1957, a 27-year-old physicist named Hugh Everett pioneered a new interpretation of quantum physics.  Everett theorized a universe of many universes, where separate universes represented all possible outcomes of a given event.  This came to be known as the Many-Worlds Interpretation (MWI) of quantum physics.
Science inspires fiction, and fiction inspires science, so I don’t know if this idea was a natural outgrowth of Everett’s studies in physics, or if science fiction stories inspired it.  After all, H.G. Wells, Edwin Abbott, C.S. Lewis, Isaac Asimov and others used some variant on the many-worlds idea in their novels, and it’s possible Everett read these.  Whatever inspired him, he brought scientific rigor to a very intriguing idea.
He also opened a giant can of space slugs.  Strangely, I think the effect on fiction has been larger, and more damaging, than the effect on physics.  In science, it’s often the case where competing theories co-exist until one gains proof, or at least popularity.  For now, MWI exists along with other interpretations.
However, the effect on fiction is rarely addressed.  What triggered this thought is the recent online debate among Star Wars fans as to whether the novels that take place after “Return of the Jedi” will still be part of the official canon when the new Disney Star Wars movies come out.  Likewise, you have similar debates among fans of comic books and the movies that derive from them.  What happens when the Scarlet Witch in the Avengers movies is different from the Scarlet Witch in the X-Men films? Why is the movie Nick Fury the Fury of Marvel Ultimates instead of the classic Marvel books? What is canon? What takes precedence?
Even the source material can be a problem.  I recall a time when DC comics juggled a variety of parallel worlds of Earth 2 or Earth B, with some of the same heroes, or variants of traditional characters like Green Lantern.  The latest storyline of Marvel’s New Avengers addresses the gloomy idea of how to save our world when parallel Earths are being destroyed by creatures able of travel between the many worlds.
Does this dilute, well, everything? Is the death of Darth Vader less meaningful if in a parallel world he lives and takes over the throne from the emperor? What about Obi Wan’s noble sacrifice? Does Frodo’s journey to Mount Doom have the same impact when we know that in the universe next door, Frodo stayed home to plant an apple orchard until orcs overran the Shire?
If there is always another place where a given event didn’t happen, does it rob the events we know of meaning? Perhaps there are people that find the idea comforting.  In another universe, their spouse who died in a car accident is still alive, and they’re happy together.  That’s somewhat reassuring.  But to the one subjective observer (you), our lives are a series of events that happen in a fixed sequence, with no jumps backward or forward, and no splits onto other routes or branches.  We race through life like toy cars on a racetrack, at maximum speed and without deviation.
So when we read fiction that presents us with alternate storylines of familiar characters, not only can it confuse us, but I worry that it weakens the original material.  For me, Batman has only one tragic origin, and he exists in only one Gotham.  Frodo did throw the ring in Mount Doom, and Darth Vader died saving his son from the emperor.
I wish that creative people would stop reworking the material of others.  I don’t need to see a re-imagining of a movie I saw 20 years ago.  Or a new novel that takes a classic work from Jane Austen or Tolstoy and inserts zombies. 
As creative people, we should be making up our own characters and our own universes.  Will these be derivative of past works? Certainly.  Everything is.  But we can put our own stamp on them, and maybe even add something to the mix.  Let’s leave the parallel worlds to the physicists.
(Note:  I found the pic at:  http://www.lightspeedmagazine.com/issues/apr-2011-issue-11/)