So Is It Not Possible For Marty To Return Home Ever?
Yes It is!
It can be seen that when travelling through time you can arrive in an alternate timeline. This is evident from Doc’s theory about the alternate 1985 where Biff is in power.
But it is also seen that after leaving Powerful Biff 1985 and going back to 1955, they could “change time” to then arrive back in a version of 1985 which looked to be the same as the Good 1985 where Marty’s parents were successful as seen at the end of the first film.
This means that it is possible to go from the Good timeline to a bad reality and still make it back to the Good Timeline.
However, it could be argued that the Good 1985 they returned to isn’t the same good reality that Doc, Marty and Jennifer had left at the end of the first film and was itself another alternate reality! This would once again mean there is another reality where Marty just disappears!
All the successful parents would know is that car waxing Biff saw Marty and Jennifer get into a flying car with Doc Brown and flew off never to be seen again!
But let’s assume for a moment that it was the same 1985 as the Good 1985.
By this same token it could be said that Marty would be able to do something to one day find his way back home to the Original timeline where his parents were losers in life.
But Hold On Does This Mean Time Can Be Changed Or Not?
Once again yes and no.
As explained earlier it can be argued that Marty clearly could change his own timeline by travelling back to his own timeline’s past and affecting his potential birth. The evidence is that he started to disappear.
But the evidence is also that any time travel he did after this didn’t take him back to the Original 1985, but did in fact take him to the future of alternative timelines as Doc explained on the chalk board in Part 2.
Loose Ends?
So what about the Marty and Doc who already existed in the Powerful Biff 1985? We know very little about these versions of Marty and Doc. We hear that this version of Marty is supposed to be in Switzerland.
The Marty we are watching in the film obviously has no memory or knowledge of being in Switzerland, but why is this? Because it wasn’t him that went to Switzerland. It was an alternate version as this is clearly an alternate reality. He also had no knowledge of Biff being in power or his father’s death. The reason for this is because it didn’t happen to the Marty we are following and happened instead to the alternate Marty.
We do know that time can take a while to alter as we witness with Marty’s siblings slowly disappearing. But we also see newspaper headlines quickly change to show Doc no longer committed and that George is still alive. this of course is plot convenience for the filmmakers to show these changes fast, but the slowness of the siblings isn’t just something to show the audience as it is central to the plot of Marty’s race against time to bring his parents together before time runs out and he no longer exists.
This is therefore evidence that Marty was in an alternative reality where two Marty’s exist. Could it be possible that Marty arriving in that timeline could cause the one in Switzerland is disappear and be erased? It’s not impossible, but we see no evidence in the series that this would definitely happen. Likewise could it be possible that if Marty had stayed in the Powerful Biff timeline long enough he would start to gain Switzerland Marty’s memories? Would time heal itself in this way the same way that the siblings slowly started to be erased?
We do definitely see that two Doc’s and Jennifer’s meet each other, so two can co-exist to some degree. But it should be noted that the Doc theorises that the two Jennifer’s meeting could cause a catastrophe for the space time continuum.
When the two Jennifer’s meet they both pass out and it doesn’t blow up the universe, but Doc clearly didn’t know what may happen. And just because it didn’t happen with old and young Jennifer meeting doesn’t mean it couldn’t ever happen.
So maybe Marty arriving in the Powerful Biff timeline did cause his Switzerland version to disappear, and maybe Marty may have been at risk of disappearing himself…but there’s not enough evidence to say either way.
Likewise by this same token we see a photo of Doc being committed which obviously didn’t happen to the Doc we are watching. We almost have to assume that this other Doc and Marty still existed and there were just doubles of our heroes also out in this timeline.
