# Time-travel fiction with rules that make sense **URL:** \ **Category:** Cafe Society\ **Created:** [October 1, 2008, 8:07pm UTC](https://boards.straightdope.com/t/time-travel-fiction-with-rules-that-make-sense/466062 "2008-10-01T20:07:57Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [October 1, 2008, 10:23pm UTC](https://boards.straightdope.com/t/time-travel-fiction-with-rules-that-make-sense/466062/21 "2008-10-01T22:23:29Z")
> [@appleciders](#): > > I think _All You Zombies_ is better liked by Heinlein’s fans partly because it’s more complex, partly because it comes to a more interesting end, because there really aren’t more than one or two characters in the story, and partly because it’s less well known. It’s like an “indie” band- fans will only admit to liking the music if it’s still underground. Once it’s mainstream, it’s crap. It’s become a shibboleth for Heinlein fans to think that _All You Zombies_ is better- it proves you’re a real fan, not a dilettante. “Zombies” is well-liked probably because it ties the time-loop tighter, in fewer pages, and because the main character is more appealing (the main character in Bootstraps is a bit of a jerk - at the beginning of the story he’s padding out his philosophy thesis, in the future, his reaction to the servile humans of the future is on the order of “Cool - slave girls,” and his treatment of the girl he’s seeing in the present is nothing to write home about) ---
**Author:** ![Tom\_Tildrum](https://avatars.discourse-cdn.com/v4/letter/t/e95f7d/32.png) [@Tom\_Tildrum](https://boards.straightdope.com/u/Tom_Tildrum)\ **Post date:** [October 1, 2008, 10:33pm UTC](https://boards.straightdope.com/t/time-travel-fiction-with-rules-that-make-sense/466062/22 "2008-10-01T22:33:57Z")
In _[Absolutely Inflexible](http://www.fictionwise.com/ebooks/ebook1176.htm)_, Robert Silverberg expressly violates causality (an object in an infinite loop has no creator), but he crafts a great story. Connie Willis’ comic masterpiece, _To Say Nothing Of The Dog,_ avoids paradoxes by positing a universe that actively forbids them. You can only travel backward in time if your actions will be inconsequential to the continuum. You can visit quiet times and places in England, but if you try to visit the Battle of Hastings or the execution of Lady Jane Grey, the time travel machine simply won’t work. Or it will dump you somewhere far from your intended destination, and various coincidences and other flukes of circumstance will prevent you from traveling back to your goal. It also prevents you from traveling to a time where you would meet yourself. Much of the plot concerns unexpected balkiness from the time-travel machine, and the need to deduce why the universe thinks that a particular time and place is so crucial. ---
**Author:** ![Lamia](https://avatars.discourse-cdn.com/v4/letter/l/8e7dd6/32.png) [@Lamia](https://boards.straightdope.com/u/Lamia)\ **Post date:** [October 1, 2008, 10:39pm UTC](https://boards.straightdope.com/t/time-travel-fiction-with-rules-that-make-sense/466062/23 "2008-10-01T22:39:07Z")
> [@Lute Skywatcher](#): > > I believe it’s explained that changes in the past take a while to affect the present. As for old Biff returning where he was, I think the plan was for him to visit 1985 and be disgusted with what his younger self did to Hill Valley so he returned to 2015 but the filmmakers couldn’t figure out how to get it to work. In the first movie it is established that changes to the past somehow do not instantly change the future timeline. It’s not clear why this is[li], but the whole plot relies on it. When Marty inadvertently prevents his parents from falling in love, he doesn’t instantly wink out of existence. He has several days to set things right. I believe Doc points this out, and the way first Marty’s brother and then his sister fade from their family photo indicates that there’s a kind of forward ripple effect once the past is changed.[/li] When Marty’s parents do fall in love then Marty and his siblings do instantly reappear in the photo, but as this has no effect on the plot then I’d consider it cinematic license (or see below for my invented explanation). [\*]I think it was best for the movie not attempt an explanation, but if I had to invent one I’d say it had to do with probability. When Marty prevented George from being hit by the car he changed the event that had originally caused Lorraine to fall for George, but he hadn’t actually made their future relationship impossible…only unlikely. Marty’s siblings faded from the photo as the odds against their ever being born increased. His oldest brother was the first to go because his birth relied on George and Lorraine getting married (or at least having sex) fairly soon. The less Lorraine thought of George the less likely this was to happen. If George had blown it at the “Enchantment Under the Sea” dance then Lorraine never would have given him another chance, but until then possible futures still existed where they married a little later and had one or two kids. Once George developed a spine and he and Lorraine had their first kiss, it became 100% certain that they would soon be gettin’ busy. This is why Marty and his siblings instantly reappeared in the photo. ---
**Author:** ![Voyager](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/voyager/32/133_2.png) [@Voyager](https://boards.straightdope.com/u/Voyager)\ **Post date:** [October 1, 2008, 11:12pm UTC](https://boards.straightdope.com/t/time-travel-fiction-with-rules-that-make-sense/466062/24 "2008-10-01T23:12:47Z")
> [@Andy\_L](#): > > “Zombies” is well-liked probably because it ties the time-loop tighter, in fewer pages, and because the main character is more appealing (the main character in Bootstraps is a bit of a jerk - at the beginning of the story he’s padding out his philosophy thesis, in the future, his reaction to the servile humans of the future is on the order of “Cool - slave girls,” and his treatment of the girl he’s seeing in the present is nothing to write home about) I agree. Zombies is a later and far more elegant work, and shows that Heinlein was growing as a writer. My example is Asimov’s **The End of Eternity.** At the end of the book the hero prevents time travel from being invented at all, which is the only stable state given the many changes caused by the Eternals. Alternate timelines, like Lafferty’s **The Men Who Murdered Mohammed** make sense, but are less interesting. ---
**Author:** ![Grumman](https://avatars.discourse-cdn.com/v4/letter/g/43a26b/32.png) [@Grumman](https://boards.straightdope.com/u/Grumman)\ **Post date:** [October 1, 2008, 11:21pm UTC](https://boards.straightdope.com/t/time-travel-fiction-with-rules-that-make-sense/466062/25 "2008-10-01T23:21:46Z")
> [@Tom\_Tildrum](#): > > Connie Willis’ comic masterpiece, _To Say Nothing Of The Dog,_ avoids paradoxes by positing a universe that actively forbids them. You can only travel backward in time if your actions will be inconsequential to the continuum. You can visit quiet times and places in England, but if you try to visit the Battle of Hastings or the execution of Lady Jane Grey, the time travel machine simply won’t work. Or it will dump you somewhere far from your intended destination, and various coincidences and other flukes of circumstance will prevent you from traveling back to your goal. It also prevents you from traveling to a time where you would meet yourself. Much of the plot concerns unexpected balkiness from the time-travel machine, and the need to deduce why the universe thinks that a particular time and place is so crucial. I don’t think that _does_ make sense. Without some sort of God of Stopping Paradoxes, how can the universe stop you from going some time and place earlier and/or further away, and just travelling to the Battle of Hastings by conventional means, and why does it stop you visiting events that are utterly insignificant on a cosmic scale? ---
**Author:** ![Dogzilla](https://avatars.discourse-cdn.com/v4/letter/d/e480ec/32.png) [@Dogzilla](https://boards.straightdope.com/u/Dogzilla)\ **Post date:** [October 1, 2008, 11:46pm UTC](https://boards.straightdope.com/t/time-travel-fiction-with-rules-that-make-sense/466062/26 "2008-10-01T23:46:40Z")
> [@Justin\_Bailey](#): > > The original **Terminator** is actually comepletely sound and an example of meddling with the past just creates the future that already exists. I have to disagree because Terminator was the first time-travel movie that presented a huge plot hole/paradox to me that bugs the crap out of me and killed the movies for me forever. Let me 'splain. When Reese finds Sarah Connor and starts explaining to her that her future son sent him back from the future to find her and protect her, he tells her that her son’s name is John Connor (eventually). So, at the end of the movie, you see that Sarah has conceived John and she’s making a little video diary for him as she’s driving in Mexico. Obviously, she names her kid John because in T2, of course, her son is John. But she only named him that because Reese told her that was her son’s name. Couldn’t she have averted the next three awful movies by simply naming her kid Billy or something? Who really named John? _Nobody_. Sarah played into the “prophecy” and made it self-fulfilling by making sure her kid was named the same thing as the name Kyle told her. I’ve gone around and around with this, but AFAICT… nobody named John. ---
**Author:** ![Zsofia](https://avatars.discourse-cdn.com/v4/letter/z/7bcc69/32.png) [@Zsofia](https://boards.straightdope.com/u/Zsofia)\ **Post date:** [October 2, 2008, 12:01am UTC](https://boards.straightdope.com/t/time-travel-fiction-with-rules-that-make-sense/466062/27 "2008-10-02T00:01:11Z")
> [@Grumman](#): > > I don’t think that _does_ make sense. Without some sort of God of Stopping Paradoxes, how can the universe stop you from going some time and place earlier and/or further away, and just travelling to the Battle of Hastings by conventional means, and why does it stop you visiting events that are utterly insignificant on a cosmic scale? Because it does. Them’s the rules of the game in those books. They’re not all Battles of Hastings - the continuum keeps you away from plenty of stuff the importance of which is not understood. ETA - and you can’t get temporally OR physically close to those events. You can’t land in Japan in time to make it to Waterloo. Just part of the rules. For example, at the end of _To Say Nothing of the Dog_, characters find they’re allowed to take things forward into the future when they thought it was impossible. It’s possible… if the thing is about to be destroyed, so it doesn’t matter. You can steal anything you want from a burning cathedral, for example, or rescue kittens thrown into the river. But you’ll never be allowed to do anything that would make any real mark on the past. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [October 2, 2008, 12:29am UTC](https://boards.straightdope.com/t/time-travel-fiction-with-rules-that-make-sense/466062/28 "2008-10-02T00:29:49Z")
> [@](#): > > I believe it’s explained that changes in the past take a while to affect the present. As for old Biff returning where he was, I think the plan was for him to visit 1985 and be disgusted with what his younger self did to Hill Valley so he returned to 2015 but the filmmakers couldn’t figure out how to get it to work. This is the explanation people give, but I don’t buy it – Biff’s changes were efectively instantaneous. When Doc and Marty got to their own time an entire world had been transformed. It’s simply the necessities of plot and timing. And, despite **Interrobang** ’s disagreement, I hold it’s still a discrepancy, but needed for the venue. ---
**Author:** ![Balance](https://avatars.discourse-cdn.com/v4/letter/b/ccd318/32.png) [@Balance](https://boards.straightdope.com/u/Balance)\ **Post date:** [October 2, 2008, 12:40am UTC](https://boards.straightdope.com/t/time-travel-fiction-with-rules-that-make-sense/466062/29 "2008-10-02T00:40:48Z")
I’ve been quite pleased with the way Aaron Williams has addressed time travel in his comic book [PS238](http://nodwick.humor.gamespy.com/ps238/index.htm). He makes no effort to explain how time travel is possible–the time travelers are mostly metahumans who can do it innately, or who can build time machines, and the rest are the people those characters haul around with them. The time travel parts of the story have a nice, solid internal consistency, and make sense even when characters are encountering each other in reverse sequence. They can change the past, and the changes seem to take effect immediately, but no one has done anything paradoxical yet. The shakiest thing, from a logical point of view, is the barrier event in the future. There’s a point beyond which the future is too unstable for current time travelers to travel into, because too many events beyond that point depend on a single, crucial decision. (This has just been resolved in the print comics, but is still a ways off in the online version.) ---
**Author:** ![Grumman](https://avatars.discourse-cdn.com/v4/letter/g/43a26b/32.png) [@Grumman](https://boards.straightdope.com/u/Grumman)\ **Post date:** [October 2, 2008, 12:41am UTC](https://boards.straightdope.com/t/time-travel-fiction-with-rules-that-make-sense/466062/30 "2008-10-02T00:41:37Z")
> [@Zsofia](#): > > ETA - and you can’t get temporally OR physically close to those events. You can’t land in Japan in time to make it to Waterloo. What’s stopping you from landing 100 years before Waterloo, on Mars? Or X years before Waterloo, anywhere less than X light-years from earth? Unless you are defining “close” in terms of the speed of light, you are attempting to treat relative terms as if they are absolute, and if you _are_ defining “close” in terms of the speed of light, the time machine is, practically, almost useless. > [@](#): > > characters find they’re allowed to take things forward into the future when they thought it was impossible. It’s possible… if the thing is about to be destroyed, so it doesn’t matter. You can steal anything you want from a burning cathedral, for example, or rescue kittens thrown into the river. But you’ll never be allowed to do anything that would make any real mark on the past. Nothing is ever destroyed. A painting may be reduced to ash, but that ash, and the heat energy released as it burned, remains. ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [October 2, 2008, 12:48am UTC](https://boards.straightdope.com/t/time-travel-fiction-with-rules-that-make-sense/466062/31 "2008-10-02T00:48:56Z")
I can’t think of the name but there was one time travel story that postulated that you could only travel in time if you were a split-second away from dying, since at that point your further interaction with history would be virtually nill. The discoverer of time travel built a time ship that became a sort of temporal Flying Dutchman, snatching doomed people away at the last possible instant. ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [October 2, 2008, 12:51am UTC](https://boards.straightdope.com/t/time-travel-fiction-with-rules-that-make-sense/466062/32 "2008-10-02T00:51:44Z")
> [@Voyager](#): > > Alternate timelines, like Lafferty’s **The Men Who Murdered Mohammed** make sense, but are less interesting. Alfred Bester, not R. A. Lafferty ---
**Author:** ![KneadToKnow](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kneadtoknow/32/3999_2.png) [@KneadToKnow](https://boards.straightdope.com/u/KneadToKnow)\ **Post date:** [October 2, 2008, 12:55am UTC](https://boards.straightdope.com/t/time-travel-fiction-with-rules-that-make-sense/466062/33 "2008-10-02T00:55:15Z")
> [@Rysto](#): > > The use of time travel in Harry Potter and the Prisoner of Azkaban was completely logical, although Rowling was quite subtle about it(the movie threw all subtlety out window). A nice touch was when Harry et al. are sneaking out to see Hagrid underneath the invisibility cloak. They wait until they can’t hear anybody in the Great Hall before going through it. The last people they hear leaving dash off and slam a door closed behind them. Later, when Harry and Hermione travel back to try and rescue Sirius, they appear in the Great Hall, and they quickly run and hide in a broom closet before they can be spotted, slamming the door behind them. I concur fully. Rowling really out-did herself with the Time Turner. And I appreciated from a storytelling standpoint why she had to do what she did to them in _Order of the Phoenix_. ---
**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\ **Post date:** [October 2, 2008, 1:11am UTC](https://boards.straightdope.com/t/time-travel-fiction-with-rules-that-make-sense/466062/34 "2008-10-02T01:11:55Z")
“Year of Hell” on _Star Trek: Voyager_ mostly made sense, I thought: an alien scientist uses a timeship, which is insulated from any changes he makes, as a weapon to change the course of history and try to bring his family, which died in a war he could have prevented, back to life in a new (or restored?) timeline. He can never fully figure out the complexity of each timeline, or how events unfolded across dozens of worlds, and over and over again cannot achieve his goal. Audrey Niffenegger’s novel _The Time Traveler’s Wife_ features a man who inadvertently travels through time over and over again, almost as if he were having seizures. He can’t take anything with him, can’t control when or where he goes, and finds that time passes at different rates for him and for those back in his “present.” When he is in the past, he apparently cannot make lasting changes; the past seems set in stone. ---
**Author:** ![erislover](https://avatars.discourse-cdn.com/v4/letter/e/71e660/32.png) [@erislover](https://boards.straightdope.com/u/erislover)\ **Post date:** [October 2, 2008, 1:36am UTC](https://boards.straightdope.com/t/time-travel-fiction-with-rules-that-make-sense/466062/35 "2008-10-02T01:36:17Z")
I thought Primer was a time travel movie that made sense, but as the focus of the movie was the breakdown of a relationship and not the science of time travel, we cannot say for certain. There are real questions about events in the movie that the film does not answer directly, though I believe there is a consistent theory of time travel behind them. (The questions being, namely: when did we/Abe meet the Aaron clone, and whence Granger?) My theory of how time travel works was not (generally) accepted at the primermovie message board, but not for any inconsistencies anyone could find. I think they just didn’t like it. I often fancy rewriting primer as a time travel story instead of a drama, but I cannot write. Damn that was an awesome movie. ---
**Author:** ![WarmNPrickly](https://avatars.discourse-cdn.com/v4/letter/w/d78d45/32.png) [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)\ **Post date:** [October 2, 2008, 1:44am UTC](https://boards.straightdope.com/t/time-travel-fiction-with-rules-that-make-sense/466062/36 "2008-10-02T01:44:10Z")
> [@CalMeacham](#): > > Robert L. Forward, noted hard-core SF writer, churned out **TimeMaster** because he wanted to see a time-travel story done _right_. He didn’t believe in the Grandfather Paradox. There’s only one past, and whatever happens there is what happened. If you go back into the past and interact with yourself, then you already know what’s going to happen, and you can’t change it. It is what it is. He challenged people to come up with a mathematical proof of the grandfather paradox. And in his book, he has an older version going back in time and interacting with younger versions of himself. Of course you can eliminate the Grandfather Paradox in the completely opposite way by making nothing you do in the past have any consequence at all. You simply create a new timeline from which you didn’t originate. ---
**Author:** ![Askance](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/askance/32/8281_2.png) [@Askance](https://boards.straightdope.com/u/Askance)\ **Post date:** [October 2, 2008, 2:38am UTC](https://boards.straightdope.com/t/time-travel-fiction-with-rules-that-make-sense/466062/37 "2008-10-02T02:38:38Z")
> [@Elendil\_s\_Heir](#): > > Audrey Niffenegger’s novel _The Time Traveler’s Wife_ features a man who > > inadvertently travels through time over and over again, almost as if he were having seizures. He can’t take anything with him, can’t control when or where he goes, and finds that time passes at different rates for him and for those back in his “present.” When he is in the past, he apparently cannot make lasting changes; the past seems set in stone. Not dissimilarly to Billy Pilgrim in Slaughterhouse 5, now I come to think of it! He’s described as being spastic in time, and can appear at any point in his own life only. ---
**Author:** ![Zsofia](https://avatars.discourse-cdn.com/v4/letter/z/7bcc69/32.png) [@Zsofia](https://boards.straightdope.com/u/Zsofia)\ **Post date:** [October 2, 2008, 2:46am UTC](https://boards.straightdope.com/t/time-travel-fiction-with-rules-that-make-sense/466062/38 "2008-10-02T02:46:29Z")
> [@Grumman](#): > > What’s stopping you from landing 100 years before Waterloo, on Mars? Or X years before Waterloo, anywhere less than X light-years from earth? > > Unless you are defining “close” in terms of the speed of light, you are attempting to treat relative terms as if they are absolute, and if you _are_ defining “close” in terms of the speed of light, the time machine is, practically, almost useless. Yeah, and what are you going to do about it from Mars? The time machine is not going to let you take your spaceship. Look, time knows if you’re going to go fuck something up and it just doesn’t let you do it, because to it it’s either happened or not happened already. It’s not like it doesn’t know what you’re going to do. It’s a predestination time continuum. That’s the world - it’s the rule you start with. ---
**Author:** ![RealityChuck](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/realitychuck/32/195_2.png) [@RealityChuck](https://boards.straightdope.com/u/RealityChuck)\ **Post date:** [October 2, 2008, 2:59am UTC](https://boards.straightdope.com/t/time-travel-fiction-with-rules-that-make-sense/466062/39 "2008-10-02T02:59:21Z")
In films **12 Monkeys** was quite consistent. ---
**Author:** ![Grumman](https://avatars.discourse-cdn.com/v4/letter/g/43a26b/32.png) [@Grumman](https://boards.straightdope.com/u/Grumman)\ **Post date:** [October 2, 2008, 3:03am UTC](https://boards.straightdope.com/t/time-travel-fiction-with-rules-that-make-sense/466062/40 "2008-10-02T03:03:24Z")
> [@Zsofia](#): > > Yeah, and what are you going to do about it from Mars? The time machine is not going to let you take your spaceship. Why not? Do the laws of the universe apply equally in all cases except where m=spaceship? > [@](#): > > Look, time knows if you’re going to go fuck something up and it just doesn’t let you do it, because to it it’s either happened or not happened already. It’s not like it doesn’t know what you’re going to do. It’s a predestination time continuum. That’s the world - it’s the rule you start with. This is a thread about time-travel fiction with rules that make sense. If the story revolves around arbitrary and ill-defined rules, then it isn’t a piece of fiction with rules that make sense. [Previous page](https://boards.straightdope.com/t/time-travel-fiction-with-rules-that-make-sense/466062.md?page=1) [Next page](https://boards.straightdope.com/t/time-travel-fiction-with-rules-that-make-sense/466062.md?page=3)