What is your favorite paradox from a time travel book or movie?

I love all the BACK TO THE FUTURE movies, but the paradox that has always bugged me is when Doc Brown comes back from 2015 to 1985 to take Marty and Jennifer into the future with him to straighten out their kids. Well, the problem is, if they travel to 2015 with Doc, they wouldn't have lived those years; so their kids don't exist. Of course, when they arrive in the future, there's an older Marty and Jennifer along with the younger versions. There's no way that could happen if time travel existed.

I can't accurately recall the setup but its set in a future where time travel is common and sex change operations are complete (fullu functional biologically). Completely forgetting the details of how they worked this out (its been a long time since I read it) but here goes. A man goes back in time. Has a relationship with a woman and pops back forward in time. Later he has a sex change operation and winds up going back in time and getting stuck. She meets up with a man for a brief time that who suddenly vanishes (its him) and winds up bearing his child. The child get caught up in a time mishap and she loses track of him. The child is of course the man himself.

So effectively he/she created him/herself out of the time paradox.

On edit: Found a link to some info about it. Its a Heinlen story. http://www.heinleinsociety.org/rah/works/shortstories/allyouzombies.html

I can't believe you left that great pun just laying there.

Must be the Japanese Movies and Videos we are watching tonight. Pistol Opera was one of the most avante garde existential flicks I have seen in a long time. Plus I got Eraserhead loaded in my laptop and am watching it during the slower videos. So I got plenty of excuses for missing it. :P

if they traveled forward thrity years, first they'd have to travel halfway to the future, 15 yrs, right? Then halfway from there: 7.5 yrs. Then another half of the way: 3.75 yrs.

And so on.

They need the jail keys to bust their buddies out and realize that they can steal them tomorrow because they put them under the rock yesterday, yet they decided it happened at just that moment. Weird.

Party On, Dude!

Love that scene.

I'm a big fan of time travel stories, but it drives me crazy that movies almost always handle paradoxes and time travel so badly.

Bill & Ted were the first characters I've seen who figured out how to use time paradox to their advantage - even if they think "Paradox" is "Two doctor dudes".

That scene was the movie. Everything we need to know about time travel was revealed at that one point in time - So-Crates must have helped them on that one.

Ted: "That's us, dude"

But in the case of BTTF, your looking at time as a "straight line" thinking that in order to get to 2015 they have to pass over the years leading up to 2015, when in fact they jumped directly to 2015 without passing over the other years. They would have no impact on any events between 1895 and 2015. And if you can't acept that recall that when Marty left Jennifer on the porch it was 1985.

makes everything that preceded it impossible.

(I'm not detailing what happens, for the sake of those who haven't read this excellent time travel novel.)

:D

time travel that really works. And then creates a paradox to end the paradox...

Read the book TIME AND AGAIN by Jack Finney http://www.amazon.com/exec/obidos/tg/detail/-/0684801051?v=glance

edited to get rid of the spoiler...

because that final scene is stunning when you come upon it unprepared.

Since I read the book some twenty plus years ago, I wasn't really sure that it was still in print. When I realized it was and thought about it, I took the spoiler out.

Company offers the ultimate safari deal. They research archological finds, determine exactly where prime dinasour specimens died, then provide hunters with the means of going back in time to that spot so as to shot their prey. (Have to leave the dinasour body there, of course, so that it can be found by archeologists later.)

To ensure that hunters change nothing, they are dropped onto a platform that floats a couple feet off the ground, and they aren't allowed to touch ANYTHING, except their prey with a buller.

So, this hunter goes back to shoot a T.Rex. (What else?) The hunt is strenuous, so much so that he is thrown off balance and takes a sigle step off the platform. But, despite the odds, he manages to shoot his T.Rex in the right spot at the right time. Success!

Until he returns home. Cloths, colors, fashions, governments, people are all changed. He reports this, and they launch an investigation. The only thing the investigation turns up is a single butterfly, crushed onto the sole of the hunters boot during that single step off his platform.

Ray Bradbury.

Steps on butterfly, returns to find someone like George W. Bush is President. Now you know.

:shrug:

I forget which.

My favorite time travel novel - time communication actually. James P. Hogan has become pretty much unreadable since he became a Freeper, but his early books are great science fiction. Good believable stories about scientists solving problems.

Gregory Benford wrote a similar novel called "Timescape".

Another novel I liked was "Branch Point" by Mona Clee

"Thrice Upon A Time" is one of my all time favorites. I'd love to see it made into a movie.

I almost forgot to mention it since Turtledove writes more about alternate history rather than time travel. But in this one, time travelers (South African racists) bring AK-47's to the Confederacy. A very well written novel.

I found it particularly interesting to speculate on how it would affect ones actions, if you knew that the future would judge you harshly.