In Back to the Future 2, Marty, Doc Brown and Marty’s girlfriend all travel ahead into the future to the year 2015. During a part of the movie, Marty’s girlfriend gets trapped in her future house. She even bumps into her future self. My question is;
Why doesn’t Future Marty’s Girlfriend remember being Present Marty’s Girlfriend in her future house? Why didn’t Future Marty remember traveling from the present to the future? Or in his case, the present.
My guess is that in BTF2 all of time exsists at the same time, and the flux capacitor thingy allows them to jump from one spot to another even though things are all going on simultaneously. It’s open to alot of screw-ups, but hey, it’s Hollywood.
I usually get hit for being nitpicky like this. I dare anyone to find a time-travel movie or book that makes perfect sense.
Tricks- I always wondered that! It kept me up at night. (I was a fan.)
Well it sort of did. I would wonder about time travel, and all that good stuff. I don’t know if i pondered those exact questions. The one that plagued ME was wouldn’t George and Lorraine McFly realize that their teenage son Marty looked a BIT like “Calvin Klein”? Then again maybe because it was twenty years, they didn’t remember.
I guess it depends on whether time is a straight line or whether its like a circle.
That is, if it was set/known/determined that Marty’s g/f would go to the future, then meet herself again. Or, unless Marty’s girlfriend (Ah, what was her name?!) coming to the future was just a freak thing. That is, time’s a straight line and that’s one thing that happened, and time doesn’t repeat.
God I get too into this film, don’t i? 
12 Monkeys
No, no… young Jennifer was the product of a different timeline. Remember, in any case, that Jennifer thought it was all a dream.
As I remember it, Doc Brown describes why in the movie. He says that they could meet and cause a paradox disrupting the space-time continuum (or something to that effect), or they would simply faint and they would both think of it as a freak dream or halucination. The latter is what happens, and Marty’s Girlfriend (present) is assured it was just a dream (or at least they didn’t tell her otherwise). Even though they then travel to the alternate “Biff” time-line, she doesn’t wake up until they have set everything back to regular 1985. Thus, she thinks everything was just a dream.
Also, because Marty never gets into the accident (ending his music career) they never even move into the house Marty’s present GF & Marty’s future GF met in, so she would never experience it. I know, this seems like a paradox, but in the confines of the movies physics (I don’t know if it’s true) the future can be changes without total paradox because it hasn’t happened yet. Also, other possible paradoxes like people never being born are never really explored.
Oh, and by the way, don’t ask me how I remember any of this, cuz I don’t know.
Bricker just put my convoluted paragraphs into one easy-peasy sentence. 
Damn my slow typing…
Originally posted by RoboTR
I usually get hit for being nitpicky like this. I dare anyone to find a time-travel movie or book that makes perfect sense.
“Lightning” by Dean Koontz.
Sometimes, silent_rob, you have a lot to say… for being silent.
I love time travel discussions & movies, but hey, if you think about it too much you’ll go nuts:
If I went back in time before I was born, and killed my parents, would I immediately cease to exist? How could I cease to exist if I was never born, and therefore, never existed in the first place? And if I was never born in the first place, how could I travel back in time and kill my parents? But if I never existed I couldn’t go back in time & kill my parents, therefore they live, eventually giving birth to me. But then I do exist and am able to go back in time and kill them before I was born, but then I wouldn’t exist again, and so on.
See? It will drive you nuts. For some real fun bring this up to someone who’s stoned. They freak!
Off the top of my head: “By His Bootstraps” and “All You Zombies-” by Robert A. Heinlein (both short stories, both well worth reading). The Door Into Summer by RAH. Millennium by John Varley. There’s plenty of them out there, you just have to know where to look. Remember, Sturgeon’s Law (“90% of EVERYTHING is crap!”) was formulated in answer to a question about why 90% of sf is crap. You just gotta read the 10% that ISN’T crap.
All You Zombies– make sense? Not unless you’ve done way more drugs than I have! Besides the temporal paradox, you’ve got biological paradoces that make Jesus’ genetic structure seem obvious!
http://www.geocities.com/Area51/Rampart/6040/ Temporal Anomalies In Popular Time Travel Movies
A very strange website, indeed … the author makes up some fairly logical rules of time travel, then attempts to explain about 20 movies (Back To The Futures, Terminator, Star Treks, etc.) using those rules. For a mindfuck rating, i give this site 5 stars *****.
“All You Zombies” makes perfect sense. There is no paradox involved. It just proposes a character with a circular existence. The biological issue is a medical improbability, not a paradox.
I’d say that all of Robert Heinlein’s time travel stories make sense. Besides the aforementioned “All You Zombies”, “By His Bootstraps”, and The Door Into Summer, there is also The Number of the Beast, Time Enough for Love, The Cat Who Walks Through Walls, and To Sail Beyond the Sunset. RAH is well aware of the potential for paradoxes and worked hard to avoid them.
BTW, I totally stipulate the high “sap factor” of the last two.
Actually, Doc Brown’s explanation of how this works took care of this problem: every time they time-travel, they create another universe. So the old-Marty was not an older version of the young Marty. The young Marty never returned to the universe that he left, and therefore never developed into the old Marty. Instead, he returned to the Biff-is-a-simpering-wimp-and-Marty-doesn’t-get-into-the-accident universe. However, I recall there being a contradiction in the third movie that wasn’t resolved. It’s been so long, that I don’t remmber it exactly.
BTTF movies used the it-takes-time-for-time-changes-to-happen time travel plot. Many instances:
[ul]
[li]BTTF1: Marty and his siblings slowly disappear from his picture (and existance) instead of popping out of existance.[/li][li]The aforementioned meeting of the Jennifers.[/li][li]Old Biff changed his future, but didn’t start to fade from existance until he got back to 2015. In the movie, he staggers out of the Delorean because of it. What they didn’t show (a cut scene) was him completely fading away.[/li][li]Doc Brown in 1885 didn’t remember Doc of 1955 seeing his own tombstone, or at least immediately.[/li][/ul]
It rather puts a slight strain on the whole plot flow of the BTTFs, but it would have been a short movie had Marty instantly disappeared as soon as he pushed George out of Mr. Baines’ car’s path.
The only real problem with BTTF 3 is that they could’ve used the fuel in the DeLorean that Doc used to travel into the past, to power the DeLorean that Marty had used.
I think the scariest part of all this is that they could make a BTTF 4, 5, and 6 with Michael J Fox and Christopher Lloyd, and they’d still all look the same!