The Two McFly problem

Let’s talk about cinematic time travel.

If you ask anyone from my generation to list their favorite movies, chances are decent that Back to the Future is going to be on that list. If you want to go by today’s ratings, it has a 96% fresh rating on Rotten Tomatoes. I could go on a rant about how much I love that movie, and have for over decades. I know it pretty much by heart.

So, back in my college days, it came as a great surprise when one of my friends, Lindsey, told me that she didn’t understand the ending of the movie.

In case you’ve forgotten (and if you haven’t seen it – STOP RIGHT NOW AND GO WATCH IT), at the beginning of the movie, Doc Brown is gunned down by the terrorists whom he stole the plutonium from in order to power his time machine, leading Marty to jump into the car to escape, accidentally sending himself back in time 30 years. Throughout the movie, Marty tries to warn the past Doc about his fate, but Doc deems it too dangerous to know about his personal future. Having given up all other options, Marty decides to return to the future a little bit before he left, hoping he could warn Doc about the attack. Unfortunately, the DeLorean breaks down upon its return to 1985, so Marty has to run to the earlier scene, only in time to see the events from the beginning, including Doc being gunned down and his own past self fleeing back in time. He then finds that Doc survived the attack, having actually gone against his own advice and reading Marty’s warning.

Here’s the whole scene if you’d like to see it again.

For years, I didn’t give much thought into the matter. Marty arrived earlier than he left, and thus witnessed the beginning of the movie. What was so confusing about that? But my friend was insistent, with the question “But what happened to the other Marty?” It didn’t seem complicated to me. He went back in time, then returned to be the Marty we now know. Full circle. I dismissed her for being silly.

But then, years later, I began hearing a bunch of nerd chatter wondering about “the two Martys”, and I started giving the matter some thought. Like a lot of thought, much to my cohort JR’s disdain because he’s spent far too much time listening to me to go on and on about it. It comes down to how time travel works in Back to the Future (let’s not get into a debate about time travel is covered in any other medium – this is an enclosed story), expanding to the entire trilogy.

The issue at hand is set up in the second movie, when Marty comes up with a scheme to use future knowledge to make money in the past, which while shot down by Doc, is actually done by main villain Biff Tannen, who steals the time machine to give his younger self a book that has every sports statistic from 1950 to 2000. So when Doc and Marty return to 1985, they’ve found that Biff’s action has turned their town of Hill Valley into a dystopia, with Biff Tannen ruling atop his ivory tower.

When Doc and Marty discuss what has happened back at Doc’s lab, Doc uses a chalkboard to explain what’s going on.

The top line is the original timeline, marked with their home of 1985, along with where they had been in 2015. Doc has discovered that Biff made his millions using the plan Marty had come up with, and realize that when Old Biff gave Young Biff the sports almanac, he created an alternate timeline, which they were now in. Marty suggests going back to the future to stop him, but Doc tells him they can’t because they will just go further into this timeline, so they have to stop it in the past.

And with that explanation, I understood the problem Lindsey was having with the end of the original movie.

When Marty travelled back in time to 1955, he himself created an alternate timeline in which all of his actions occurred. For example, in his original timeline, he had not been there when his father George was struck by his grandfather’s car, thus allowing George to meet Lorraine and go to the dance at their school. Likewise, Doc had never met Marty in 1955 and thus was unable to save himself when gunned down by the terrorists. But Marty’s actions in 1955 created an alternate timeline in which George won Lorraine’s heart through bravado rather than sheepishness, Biff was put into his place, and Doc got set on his path earlier than originally planned.

Thus, when Marty returned to the future, he did not go back to his original 1985, but this new alternate version that had been created through his actions. This 1985 had its mall named Lone Pine Mall instead of Twin Pines Mall (because Marty ran over one of the pines), and the McFly family were successful and healthy through the better path his parents had been set upon.

So what’s the problem? It begins with Marty’s reaction to the changes in his house when he wakes up the morning after returning from the past. He has no idea that his home is different, his family is successful and popular, nor that his relationship with Jennifer Parker is now encouraged by his mother. His reaction to all of this is seen as strange by his family. What that means is that up until that point, they have been living with a Marty McFly that was raised in this environment and was aware of everything that had happened up to that point. Thus, our protagonist that we have been following through the film is not actually back in his home, but rather an alternate version of it.

So, if that is the case, what happened to this version of 1985’s Marty McFly? The Marty we saw our Marty witness went back into the past in the DeLorean, but did not return to this timeline. Where is that Marty?

This is what I’ve been pondering over. Because in this reality, our Marty’s actions was in that Marty’s past. A mysterious stranger had appeared in Hill Valley, got his parents together, then vanished that very night, never to be seen again. That Marty no doubt had been told about the mysterious “Calvin Klein” (Marty’s false identity in 1955), especially since his father had written a novel based on the experience.

So, in theory, the past that Marty went back into was the same one that our Marty changed. So why weren’t there two Marty’s? The best answer I could come up with on my own (and going down that rabbit hole on the Internet is NOT recommended) is that both our Marty and that Marty went back in time to November 5, 1955 at 6:28 AM. In theory, they both arrived at the exact same point of time at the exact same place, the place where our Marty’s timeline changed due to his arrival, meaning that two DeLoreans and two Marty McFlys overlapped each other. So why did our Marty keep going and the other didn’t? My guess would be that our Marty’s actions were essential to that Marty’s existence. He could not exist with his own past without our Marty affecting the timeline, so our Marty was the one that didn’t blink out from the overlap.

Or maybe the 1955 that Marty went into was changed on its own by the arrival of a Marty who had the knowledge that Calvin Klein had existed, but was unaware that he himself was the mysterious figure. Thus, he still managed to save his father from the car and was introduced to his mother, found Doc, and then worked to keep the timeline as he had remembered it. So would that Marty return to this timeline? Well, no, because chances are having the knowledge of Calvin Klein’s actions made that Marty act differently than our Marty, and thus he returned to another alternate 1985 that had been made due to his actions, and he probably watched THAT world’s Marty vanish.

Of course, this is all theoretical and best left for nerds like me to ponder and pontificate about. And as for Lindsey? I called her years after we both had left college and told her I finally got what she had been talking about and apologized if we had teased her about it. My own little better future.



  1. I’ve never put that much thought into this even though I know the BTTF timeline rules. This has sent me down a rabbit hole too. Here’s what I’ve been mulling over: 1) We never see the original timeline again. It either ceases to exist or goes on with a deceased Doc and a vanished Marty. 2) it seems unlikely that the alternate 1985 Marty would end up hanging around Doc which would mean that he never would’ve been there for the shooting and went back in time, yet we see that. I had ideas about the blip and maybe the reality not changing until Marty went back in time, but the mall being Lone Pine mall when he runs up means it has definitely already changed and yet Marty is still with Doc. Great brain exercise!


    • There is a Back to the Future comic (with Bob Gale helping plot) that deals with Marty questioning the existence of the other Marty, but I’m so far behind on it I never saw what happened. I’m not a big fan of expanding the story beyond the three movies, because I feel like it wrapped itself up so nicely…but once I get to it, I’ll probably follow up.


  2. A never-ending time loop is created a mobius strip where it’s ongoing for infinity with time traveling Marty always appearing at Lone Pine Mall to see himself blast back to 1955 then he sees Doc is alive and well. When Marty wakes up in his new family household it’s all new to him which is why his family is confused at how he’s reacting. He won’t have any memory of growing up with successful and healthy parents and siblings why would he?


  3. The only logical answer to this paradox is that just like we see in the movie, the original Marty returned to 1985 in the new timeline created when he altered his parents future, found the Doc alive, returned home to find the new 1985 Marty asleep in his bed, brutally murdered him in his sleep, buried the body, then pretended to be him from that point on, even though he has no memory of growing up in the successful family he created. This missing yet brutal scene should have been included in the DVD extras.


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