I've looked and I don't think this has been asked before. In Back to the Future 1, after Marty changes his parent's future, its obvious that he changes his own life and the life of his siblings drastically. He owns an awesome truck, has a date with Jennifer to go to the lake, etc.

So why doesn't he have any memories of these things? Shouldn't his memories be altered in the same way the photo of his siblings changes? Or an even better example: Doc's memories are different in that he now remembers Marty from the past and wears a bullet proof vest to the mall. And don't say that Doc always remembered Marty from the past and its a time loop because if that were true then Marty's family would always have been successful and his dad not a loser.

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    Seems the IMDb FAQ addresses this, might be a good place to start.
    – Walt
    Jul 21, 2015 at 7:01
  • @Walt You might want to put that into an answer then.
    – Napoleon Wilson
    Aug 3, 2015 at 17:15

3 Answers 3


Marty was in the time machine when he came back. The definition of the time machine is that the machine (and what it contains) travel through time unaltered.

(My real question would be, why is there just ONE Marty when he comes back to 1985 after fixing his family. There should be one Marty that was born from his parents on his normal birthdate, and one that came back from 1955 to 1985. But that's another story!)

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    I have not watched movie but i believe the Marty who born from his parents on normal birthdate , will need to take time machine else there will be no Marty changing past :-). Time travel loops rocks and sucks at same time.
    – Panther
    Jul 21, 2015 at 8:45
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    What @Panther said. Alternate timeline Marty would also need to go somewhere in alternate timeline Doc's time machine (at some point before the time that original timeline Marty reappears), and ideally meet with an unfortunate accident so that the alternate timeline is left with only one Marty and one time machine. Take that, causality!
    – aroth
    Jul 21, 2015 at 14:17
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    We see the alternate Marty traveling back in time from the Lone Pine Mall, when "our" Marty comes back a little bit early. Also see "The Other Marty McFly?".
    – Josh
    Jul 21, 2015 at 19:22
  • @Josh absolutely correct! Jul 21, 2015 at 19:53
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    @fabriced There are two Martys. Main Marty and the one going back in time when main Marty goes to save Doc. Based on the rules of time travel in the BTTF universe my guess is that the second Marty DOES have all the new memories, which brings in a whole new set of issues such as, how can they be sure that a Marty who grew up in a completely different home setting would go back in time and do all the same things that the first Marty did. Heck why did he and Doc ever meet in the first place? His entire life should have been full of experiences different than the first Marty.
    – sanpaco
    Sep 15, 2016 at 16:51

Just so everybody noticed the memories don’t really matter. Marty could only change his perception of the past because if he goes back in time and his other stuff goes back in time just like he did it’s just like going back in time to look at your past self except you are going forward in time and you watch your past self go back in time. Just because he’s in another timeline that doesn’t mean the other timeline is nonexistent. He’s actually creating new histories from his point of view and the original histories still happen meaning that every non linear timeline also happens chronologically. Otherwise it would be a paradox if it was linear.


Marty's memories does and has changed. In fact, not only this, but Marty actually has two sets of seventeen years worth of memories. He remembers the childhood from which his mother was an alcoholic and he also remembers the childhood in which his father is a sci-fi writer and his mother is happy. According to my theory, sometime after Marty went to 2015 in Part II, these new memories caught up with him. Furthermore, the problem he had with being called chicken is a trait from the new timeline, as this didn't occur in Part one. By the end of Part III, Marty even commented how everyone was back to normal, indicating that his memories have completely caught up to him. But as a time-travelers, he'll always have the old memories, no matter what, as the old memories are dependent on him going back to 1955 in the first place.

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    What's the evidence to support Marty having memories of events he didn't experience?
    – T.J.L.
    Jan 7, 2019 at 15:31

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