When does time travel work and when doesnt it?

[Darth Ruinus]

Relativly lacking in reading some really good sci-fi (since I have only recently really taken an interest in reading) I havent read any books where Time Travel is used at all.

From what I read on these forums, time travel sounds like a cop out, ST time travel comes to mind, and sometimes just ends up sounding stupid or unneccesary.

However, I havent seen many praises of it either, and as I understand it, Xeelee-verse is filled with time travel.

So, in your opinion, when can you accept time travel? WHen do you read time travel and go "WTF Grandfather paradox" or when do you read it and say "You know, this doesnt sound stupid, pretty cool actually!"

[General Zod]

Time travel works when it's a plot device to get characters from point A to point B. (See, Doctor Who). It tends to not work as much when it's a deus ex machinae to solve problem Y (see, Star Trek).

[mr friendly guy]

If in universe Time travel "works" as a tactic to fix things despite the paradox, you need to have a reason why someone just can't keep on time travelling to fix things up and have it ending up as a deus ex machina ala star trek. Usually this takes the form of some sort of limitation.

For example in Doctor Who the paradox caused invokes the presence of the Reapers, and despite the Time Lords occasionally creating paradoxes, it can be inferred they prefer not to expand the effort to deal with the Reapers if it can be helped.

In the Xeelee verse from what I understand they just can't travel back before and wipe out the photino birds since the photino birds will ALWAYS have vastly more resources.

The other thing is, you need the other side to be able to defend against time travel either by having it themselves or some other means of defense. Otherwise fans will just wonder why one side doesn't just time travel and wipe out the other side (which will make the story really short).

[18-Till-I-Die]

In a series i'm currently working on, time travel is the entire theme there, and one way i get around the problem of deus ex machina is that it takes "time" (linear time) for changes to the timestream to spread.

I.E. if i go back and blast your infant self in the face with a shotgun, it'll take a certain amount of linear time for this to gradually work it's way "up stream" to your subjective present. You dont wink out of being, you fade slowly like Marty McFly. I figured that if you take the "timestream" thing literally it only makes sense, as nothing happens al at once, it requires a series of events that once they "happen" in a certain order have to "unhappen" in a certain order too.

Also, ALL of the bad guys have some kind of time travel to a degree, the main bad guys have just as advanced or more advanced time travel devices than the good guys, and they have a technology that can shield you against changes to the timestream. More so the more you travel in time the more aware you are of the flow of the timestream around us, even a shot voyage through the timestream makes you keenly aware of any changes or damage done and prolonged exposure results in a kind of precog called Time Sight. This means that, unless you're erased completely from history, most time travelers will be aware when and if history is changed by their enemies.

Of course i'm pretty sure most of this tosses out the concept of causality but there you go.

[brianeyci]

Who says time travel doesn't work in Star Trek?

Time travel just doesn't work the way fanboys imagine it: going back and killing Hitler on a crapper, or using it infinitely many times to correct mistakes until you win.

Anything overused sucks. Which is why most time travel in Star Trek sucks: Guardian of Forever is good, Voyage Home was only good because it was funny, and the later Star Trek just bites donkey balls because everything's already been covered by Guardian of Forever or Voyage Home.

Imagine if Voyage Home took itself too seriously.

First Contact was starship porn and an action movie. It sucks because it uses time travel just like fanboys imagine it, or at least the Borg try to: go back in time to kill the Federation because for some reason they couldn't deal with them in the present. It's a philosophical cop-out that doesn't work because it makes the antagonists seem so fucking weak as not to be able to deal with the current situation, which is lunacy considering the power of the Borg.

Time travel works best with individuals, individual needs and individual small scale issues that's just as important as saving the galaxy.

[Teleros]

It's a philosophical cop-out that doesn't work because it makes the antagonists seem so fucking weak as not to be able to deal with the current situation, which is lunacy considering the power of the Borg.

Be fair: the time travel method makes for a much less costly victory for the Borg. Course that then begs the question of why the Borg don't do it more often elsewhere, but hey, that's ST continuity for you .

[petesampras]

Relativly lacking in reading some really good sci-fi (since I have only recently really taken an interest in reading) I havent read any books where Time Travel is used at all.

From what I read on these forums, time travel sounds like a cop out, ST time travel comes to mind, and sometimes just ends up sounding stupid or unneccesary.

However, I havent seen many praises of it either, and as I understand it, Xeelee-verse is filled with time travel.

So, in your opinion, when can you accept time travel? WHen do you read time travel and go "WTF Grandfather paradox" or when do you read it and say "You know, this doesnt sound stupid, pretty cool actually!"

I quite like the idea of some 'force' correcting the changes you make - a la the remake of the time machine.

Or 12 monkeys style, where you find that the the time loop is essentially 'fixed'. There exists not past without the time loop, thus the future is not changed by it.

[NecronLord]

It's a philosophical cop-out that doesn't work because it makes the antagonists seem so fucking weak as not to be able to deal with the current situation, which is lunacy considering the power of the Borg.

Either that, or the Borg always try that, and it's their standard tactic. It probably incurs lower costs than dispatching two full warships.

[General Zod]

Anything overused sucks. Which is why most time travel in Star Trek sucks: Guardian of Forever is good, Voyage Home was only good because it was funny, and the later Star Trek just bites donkey balls because everything's already been covered by Guardian of Forever or Voyage Home.

It's not that it's overused. It's that it's overused as a deus ex machinae. Guardian of Forever wasn't an attempt to go back into the past and destroy an enemy or fix a problem they couldn't handle in the future, so it wasn't too bad. Star Trek far too frequently uses it as a "reset" button instead of something to actually create a story vehicle. Sort of like transporters really.

[Darth Ruinus]

I quite like the idea of some 'force' correcting the changes you make - a la the remake of the time machine.

Or 12 monkeys style, where you find that the the time loop is essentially 'fixed'. There exists not past without the time loop, thus the future is not changed by it.

You mean where something happens in the timeline BECAUSE of a timetraveler that goes back in time to stop it?

I was toying around with the idea of time travel, but they would always use robots to time travel, because they wouldnt want to run the risk of a person going back in time and killing themseves.

I was also thikning of a more crazy time travel wehre there were no paradoxes ie a person could kill themselves in the past and simply take their place. Though this one makes less sense than time travel in general.

BTW, in Xeelee verse, I heard that both sides have time travel, I think it was humans and xeelee, and thus wars were stalemates because each side know what the other side would do, how it would occur etc etc.

So, how does Xeeleeverse deal with the idea that a ship can "limp back from a battle that hasnt happened yet" and not cause a paradox when the crew decides to talk to their past self?

[NeoGoomba]

I'm still a fan of the Legacy of Kain concept of Time Travel. You can travel through time freely with the right means, but you can't directly alter the course of history without some extremely drastic and nigh-impossible event to take place.

[Gullible Jones]

It's a philosophical cop-out that doesn't work because it makes the antagonists seem so fucking weak as not to be able to deal with the current situation, which is lunacy considering the power of the Borg.

Either that, or the Borg always try that, and it's their standard tactic. It probably incurs lower costs than dispatching two full warships.

On the other hand, it would mean that (in most cases) they wouldn't be able to get their hands on any cool new technology.

[Ford Prefect]

So, how does Xeeleeverse deal with the idea that a ship can "limp back from a battle that hasnt happened yet" and not cause a paradox when the crew decides to talk to their past self?

When the main character of Exultant meets himself, the only thing that happens is that they dislike themselves, and they both get sent to court for retreating from a certain offensive (even though technically the past self hadn't actually been in that battle, which wouldn't happen for several years). Meeting yourself wasn't all that uncommon, apparently.

As for an sort of paradox, they just don't happen.

[Xon]

So, how does Xeeleeverse deal with the idea that a ship can "limp back from a battle that hasnt happened yet" and not cause a paradox when the crew decides to talk to their past self?

In Xeelee-verse if you go back in time and kill you grandfather you get charged for murder. It takes the "no paradox" approach which leads to some truely fruity history.

For example; human immortality nanities first "invented" in the mid-21st Century where reverse-engineered from scans from a human from 0.5 million years into the future who had them.

[Natorgator]

Did anyone see the new Futurama movie yet? I really like how they handled time travel with it:

SPOILERS:

Supposedly when you travel back through time, the second person becomes doomed (in which some unlikely event will kill them somehow, the professor proved it mathematically with the Harlem Globe Trotters) and the timeline will eventually correct itself.

[Patrick Degan]

Time travel works best in three ways:

A) a simple plot device to get the characters from A to B and nothing more...

B) closed-loop in which events turn out exactly the way they were meant, and as a corollary to that...

C) Greek tragedy SF-style, in which fate proves inescapable.

It also works best when serious if not apocalyptic consequences are attached to any attempt to alter the flow of events and thereby change reality.

The mechanics should also be kept as simple as is feasible for the story.

[bilateralrope]

Did anyone see the new Futurama movie yet? I really like how they handled time travel with it:

SPOILERS:

Supposedly when you travel back through time, the second person becomes doomed (in which some unlikely event will kill them somehow, the professor proved it mathematically with the Harlem Globe Trotters) and the timeline will eventually correct itself.

I generally prefer a closed loop setup where the past simply can't be altered. This doesn't rule out some freaky things though, like the Futurama Roswell episode where Fry finds out that he is his own grandfather.

[Atlan]

If you can, try and read "Dinosaur Beach" by Keith Laumer. It's time travel with grandfather paradox, done correctly right down to the bone.
If you're going to read stories about time travel, this one is a must.

[18-Till-I-Die]

I had an interesting thought about how to work grandfather paradoxes, and other paradoxes, that i think makes it easier but (like what i said above) kind of pisses on causality.

You can alter your own timeline, up to and including anything BUT causing your own death. IF you kill your grandfather, it wont matter, because the universe will reconcile your continued existence with your "unbirth" by simply allowing you and only you to physically live. Every future and past you will vanish but the present, single you will survive. You become the paradox.

However...this only works one way. If i go back and kill your grandpa, then you just fade away over time like Marty McFly in Back to the Future.

[Darth Smiley]

I rather like Orson Scott Card's Pastwatch. Very interesting in how it treats time travel...most of the book is not dealing with the time warp itself, but rather the characters trying to decide whether or not it is the right thing to do.

[Nyrath]

For the more fictional bent, there is a good overview at the A Guide To SF CHRONOPHYSICS

For the more scientific bent:

The Novikov self-consistency principle says the probability of any event that would create a time-travel paradox is zero. You might try to use the WAYBAC machine to killl your infant grandfather, but you are guaranteed to fail.

Three examples of Novikov's principle are Consistency Protection, Restricted Space-Time Areas, and Special Frames.


A non-Novikov fourth way of avoiding time-travel paradoxes is Parallel Universes.

Physicists Daniel Greenberger and Karl Svozil have shown that the laws of quantum mechanics enforces Consistency Protection. You can read their paper here, but it makes my brain hurt.

Translated into English, they maintain that time travellers going back into the past cannot alter the past (i.e., the past is deterministic). This is because quantum objects can act sometimes as a wave. When they go back in time, the various probabilitiesinterfere destructively, thus preventing anything from happening differently from that which has already taken place.

The boring solution to time-travel paradoxes is Professor Stephen Hawking's Chronology protection conjecture. It says that even if time travel is possible, any attempt to use it will be foiled in some magic manner.

[B5B7]

I second Laumer's 'Dinosaur Beach'. Another good one is Silverberg's 'Up the Line' [it brings up the question of why there aren't huge numbers of time-travelling spectators at historic events]. There are a huge number of other good SF novels (and short stories eg classic Heinlein 'All You Zombies', Bradbury's 'The Sound of Thunder', Aldiss's 'T' in 'STAN') that deal with time travel.

Some others are Gerrold's 'The Man Who Folded Himself', Baxter's 'The Time Ships', Anderson's 'The Time Patrol', Asmov's 'Pebbles in the Sky', Barrington Bayley's 'Collision With Chronis' and 'The Fall of Chronopolis', Dick's 'The World Jones Made' [precognition], Farmer's 'Time's Last Gift', Leiber's 'Change War' duology (The Big Time, The Change War), Ward Moore's 'Bring the Jubilee'.

Even Star Trek TNG had some good ones eg 'Yesterday's Enterprise'.

Haldeman's 'The Forever War' doesn't have time travel, but it deals well with the topic of interaction between those of different tech levels and societal interaction due to being out of own original time.

[Patrick Degan]

Haldeman's 'The Forever War' doesn't have time travel, but it deals well with the topic of interaction between those of different tech levels and societal interaction due to being out of own original time.

More specifically, it's how relativity can bite you in the ass. Hard.

[Rye]

I personally prefer the circular fate ideas put forth by 12 Monkeys and La Jetée, over the "all time you exist in is the present" version of Back to the Future, which seems to be pretty unstable. Maybe I'm just a miserable git, though.