Time Travel, DeLoreans and Grandfathers

 Perhaps I am biased, but I see Robert Zemeckis’ Back to the Future (1985) as one of the landmarks of American cinema, incorporating elements of science fiction, adventure, and comedy.  I have probably seen it 20 or 30 times during my life, and it is the movie that got me interested in science fiction, interested in playing guitar, and interested in movies in general.  The classic story follows teenager Marty McFly (Michael J. Fox), who is accidentally sent 30 years into the past in a time machine that mad scientist Dr. Emmett Brown (Christopher Lloyd) built out of a DeLorean.  In the year 1955, Marty runs into his parents and inadvertently prevents them from meeting, resulting in Marty’s mother (Lea Thompson) falling in love with Marty instead.  The rest of the film chronicles Marty’s quest to reintroduce his parents to each other, as well as find a way to get back to 1985.

            I think that my love for Back to the Future is apparent, but it is also important to note that the film requires a certain suspension of disbelief on the part of the audience.  Plots driven by time travel are difficult, and even though Back to the Future is a clever and entertaining film, there are numerous paradoxes and plot holes.  I remember that when I was younger, I would always argue with my dad about how Back to the Future did time travel “wrong.”  The same points that my 7-year old self was trying to make are discussed much more eloquently in David Lewis’s essay “The Paradoxes of Time Travel”, particularly in reference to the famous Grandfather paradox.  Lewis considers a character named Tim, who wishes to kill his own grandfather.  However, Grandfather died peacefully in his bed in 1957 when Tim was a young boy, so Tim builds a time machine and travels to the year 1921 so he can kill Grandfather himself.  Tim practices with a rifle and waits for the ideal conditions to fire on Grandfather, but Lewis makes the argument that it is impossible for Tim to kill Grandfather.  This is because, “Grandfather lived, so to kill him would be to change the past.  But the events of a past moment are not subdivisible into temporal parts and therefore cannot change.” (497).  Tim grew up with his Grandfather alive and kicking, which would create a contradiction if Grandfather was murdered by an unknown sniper in 1921.  Therefore, for the story to be consistent, Tim must somehow fail to kill Grandfather.

            Back to the Future treats time travel in a way such that the past can be altered, evidenced by several scenes in 1955, as well as when Marty finally returns to the year 1985 at the end of the film.  One famous scene from the 1955 portion of the film involves Marty performing a rendition of Chuck Berry’s “Johnny B. Goode” at his parents’ high school dance after he has successfully set them up together.  When another boy tries to dance with Marty’s mom, Marty begins to dramatically evaporate while he is trying to play the guitar.  Though this situation is obviously emphasized for theatrical effect, David Lewis would argue that this creates another logical contradiction.  In a given timeline, Marty can either exist or he cannot – it does not make sense for there to be a sort of “in-between” where he momentarily becomes a ghost.  When Marty returns to his proper time period, his family lives in the same place, but his house is completely transformed and his parents (particularly his father’s) personalities have totally changed.  Marty’s formerly unemployed siblings have steady office jobs and the formerly successful and arrogant Biff Tannen (Thomas Wilson) now makes his living washing cars.  At the end of “The Paradoxes of Time Travel”, Lewis maintains that the only way for this situation (as well as the Grandfather paradox) to be plausible would be if time travelers could create different branches, “separated not in time, and not in space, but in some other way.” (499).  Therefore, returning to the Grandfather example, there would be one branch of time where Grandfather lives and Tim does not appear in the year 1921, and there would be separate branch that diverts in 1921 when Tim arrives to kill Grandfather.  However, in this second branch where Tim succeeds, he has the potential to prevent his own birth.  Much like Back to the Future, depicting one branch of time where Marty’s parents are more successful than in another, at every point of Tim’s life there are two subsequent timelines, one where Grandfather lives and the other where Grandfather dies.  However, since the differing branches in this theory are not connected by space or time, this adds a whole new dimension to the concept of a time machine.  How would one be able to control which branch the time machine travels to?  Would one have to create an entirely new vessel to travel between branches?  In Back to the Future, it appears that the portrayal of time travel would have to be a lot less linear than it already is for the resulting plot to be logically feasible.  However, despite the paradoxes in the plotline, Back to the Future is extremely entertaining and my personal favorite film of all time, so I would obviously recommend it if you haven’t seen it.