Back to the Future

I am making this post because many of youmisunderstand BTTF time travel.

BTTF has a single, non-branching, mutable timeline. Changes to the timeline propagate to the future slowly, at some sort of undefined meta-time rate. This is why Marty and his siblings start disappearing from the photo one by one (although why they do so in parts is nonsensical). If it used branching or multiple timelines, the photo would be unchanged, just from a different timeline. If the timeline was immutable, there'd be no fading problems, no mall sign change, no change in his parents' lives, etc.

A single, mutable timeline with non-instant change propagation is the only way to explain those films. It's nonsense in reality, but it's pretty consistent in the films.

You're a single, non-branching, mutable timeline.

Okay Tim,

re: my point in t'other thread abot Doc having a bullet-proff vest all along. Is it possible that the Doc we see at the start of BTTF1 had already met BBTF1 Marty and BTTF3 Marty and it was only the appearance of BTTF3 Marty that convinced him to read the letter but he decided to never tell young pre-BTTF1 Marty so the timeline would be maintained?

Also does BBTF3 Cowboy Doc still have the knowledge of meeting BTTF2 Marty in BTTF2 and BTTF3 or just meeting BTTF1 Marty in BTTF1? So is BTTF3 Doc a different DOC than in BTTF1 and BTTF2? Or is BTTF3 Doc the same as BTTF1 Doc but BTTF2 Doc is in another timeline and for our Marty no longer exists?

Ryan McAvoy said:

Okay Tim,

re: my point in t'other thread abot Doc having a bullet-proff vest all along. Is it possible that the Doc we see at the start of BTTF1 had already met BBTF1 Marty and BTTF3 Marty and it was only the appearance of BTTF3 Marty that convinced him to read the letter but he decided to never tell young pre-BTTF1 Marty so the timeline would be maintained?

No, he didn't. At that point, Doc was not wearing a bulletproof vest. However, by the time Marty gets there at the end of the movie, Doc-without-vest never existed, except in Marty's memory. Why Marty's memory seems immutable, while the timeline changes around him, is never addressed. Apparently that's just how time travel works - Your physical body can be affected by change-propagation (see: Marty's disappearing hand), but your memories remain intact, as long as you are a time traveler.

I concede that it makes no sense, obviously.

Also does BBTF3 Cowboy Doc still have the knowledge of meeting BTTF2 Marty in BTTF2 and BTTF3 or just meeting BTTF1 Marty in BTTF1? So is BTTF3 Doc a different DOC than in BTTF1 and BTTF2? Or is BTTF3 Doc the same as BTTF1 Doc but BTTF2 Doc is in another timeline and for our Marty no longer exists?

 I need to re-read the plots of 2 & 3 to answer this question, because it's been awhile since I saw them.

Oh I almost forgot!

doubleofive said:

You're a single, non-branching, mutable timeline.

I branched your mothers' timelines last night!

timdiggerm said:

Oh I almost forgot!

doubleofive said:

You're a single, non-branching, mutable timeline.

I branched your mothers' timelines last night!

Oh shit!!!11one

http://www.mjyoung.net/time/

That is all I have to say about that.

Not!

Seriously folks, Marty Prime is ending variations of everybody all the time.  

What happened to the loser versions of his parents and siblings?  Gone!  What about 1985 jerkwad Biff?  Gone.  The 2015 version of pretty much all of his friends/family- gone.  Bifftastic 1985?  All gone.

And to Ryan's question, I don't think 1885 Doc has any memories of what 1955 BTTF3 Doc did- or else he wouldn't be surprised to see Marty show up in 1885.  Unless, as is somewhat suggested by the films, these things can take some time to propagate throughout space-time.  Perhaps by the end of BTTF3, 1885 Doc does remember sending Marty back in time to 1885 from 1955.

Regardless of whether you're a time traveler or not, there is an official timeline and that official timeline includes 1955 Doc sending Marty to 1885.

However, the official 1985 now has awesome McFlys, but does Marty ever remember any of that?  Again, he is surprised to see awesome McFlys upon his return to 1985... but do those memories fill in a week later?  Memories of things he didn't experience, but should?  Or did those memories go back to 1955 with "Awesome" Marty McFly at the end of BTTF1?  

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Back to ending variations of these people, it's really no different from cause and effect in our linear existence.  We all end possible versions of people by interacting with them.  We just never get to see what could have been if our actions were different, and Marty does.