Rewritten, or Why Time Travel With the Intent to Change is Impossible

[JunkMonkey]

Time is an invention by humans to describe the period between things happening. Once something has happened, it can't unhappen, no matter how much we would sometimes like it to.

'Time is what stops everything happening at once.'
Ray Cummings

 

[BAYLOR]

'Time is what stops everything happening at once.'
Ray Cummings

Without time planning your daily schedule would be very very difficult.

 

[Cthulhu.Science]

Without time planning your daily schedule would be very very difficult.

Oh, that is what the servants are for.

 

[BAYLOR]

Oh, that is what the servants are for.

There a time travel story you might find of interest by Poul Anderson Flight to Forever . The tv show Futurama did a homage to it

 

[Ursa major]

(I realise that this doesn't make for exciting SF )

That's why we have fantasy... and time travel is clearly fantasy (even when it's dressed up as SF).

When you time travel with their machine you create a new Universe that includes an Earth

IIRC, jumping into (or creating: the characters aren't sure how it works) a parallel universe is how the Skip Drive works in the Old Man's War series.

 

[BAYLOR]

Another book Morlock Night by K W Jeter This book is a set of sequel to H G Well novel The Time Machine. In this book , The Morlocks have gotten control of the the machine and have turned all of history into their feeding ground which having negative effects on the space time continuum.

 

[Swank]

Nearly all of SF is "fantasy" if you only allow for things we strongly believe are possible. Virtually every major SF title is suddenly fantasy.

Not a useful definition.

 

[BAYLOR]

Nearly all of SF is "fantasy" if you only allow for things we strongly believe are possible. Virtually every major SF title is suddenly fantasy.

Not a useful definition.

But pretty accurate.

 

[Ursa major]

Nearly all of SF is "fantasy" if you only allow for things we strongly believe are possible.

Given that

1. belief is for those who want to think something is true without conclusive evidence that it is, and
2. we are still a long way from knowing how the universe works (and we may always be that way, with regard to much of it),

we can't rule out things that may be possible, including in ways of which we're not aware.

The least likely of those things that may just be possible is time travel (of the type we've been discussing) as it would clearly undermine some of our most strongly held views of the way we think things are.

 

[Fiberglass Cyborg]

I remember thinking through time travel in great detail many years ago. I've forgotten most of it except this one point I got hung up on:

Never mind killing your grandad. Never mind sending a human back in time, even. If you send so much as a molecule back in time, that molecule is now in a Universe with one difference: it has an extra molecule in it. The world has been changed. From that point on, any (and I mean ANY) process that is not absolutely 100% deterministic has a chance to turn out differently from how it did in the future timeline the molecule was sent from.

Case in point: the conception of individual humans! Tiny variations in Brownian motion may effect which sperm reaches the egg. Chance variations at a molecular scale will affect the exact list of gene variants which get combined during fertilisation. Fertilisation may also not happen at all, or happen weeks or years later. The result: a different human being who didn't exist in that time-travelling molecule's original timeline. Scale that up: most, if not all humans will be slightly to very different in the new timeline. An entire world populated by our brothers and sister who never were. That's GOT to change everything.

...so if you want to kill Hitler, just send an air molecule back to the day before Hitler's mother got laid. Job done. Of course, you won't exist in the brave new world thus created. I'm not sure what happens to the orphaned futures left behind in this way. Had some ideas, but like I said I've forgotten them.

 

[BAYLOR]

I remember thinking through time travel in great detail many years ago. I've forgotten most of it except this one point I got hung up on:

Never mind killing your grandad. Never mind sending a human back in time, even. If you send so much as a molecule back in time, that molecule is now in a Universe with one difference: it has an extra molecule in it. The world has been changed. From that point on, any (and I mean ANY) process that is not absolutely 100% deterministic has a chance to turn out differently from how it did in the future timeline the molecule was sent from.

Case in point: the conception of individual humans! Tiny variations in Brownian motion may effect which sperm reaches the egg. Chance variations at a molecular scale will affect the exact list of gene variants which get combined during fertilisation. Fertilisation may also not happen at all, or happen weeks or years later. The result: a different human being who didn't exist in that time-travelling molecule's original timeline. Scale that up: most, if not all humans will be slightly to very different in the new timeline. An entire world populated by our brothers and sister who never were. That's GOT to change everything.

...so if you want to kill Hitler, just send an air molecule back to the day before Hitler's mother got laid. Job done. Of course, you won't exist in the brave new world thus created. I'm not sure what happens to the orphaned futures left behind in this way. Had some ideas, but like I said I've forgotten them.

Due to the eggs sperm disruption , you could in fact become your own evil twin or suffer an even worse fate by growing up to be a disk jockey or worse still a Public Chartered Accountant with no discernible imagination and a lion tamer career fetish .

 

[paranoid marvin]

Given that

1. belief is for those who want to think something is true without conclusive evidence that it is, and
2. we are still a long way from knowing how the universe works (and we may always be that way, with regard to much of it),

we can't rule out things that may be possible, including in ways of which we're not aware.

The least likely of those things that may just be possible is time travel (of the type we've been discussing) as it would clearly undermine some of our most strongly held views of the way we think things are.

Yes, science fiction has to have some basis in reality: spaceflight to other planets, aliens destroying the Earth, dystopian futures.

Fantasy is things that have no (or so little that it might as well be no) basis in reality. Flying carpets, sentient luggage trunks, unicorns.

Basically the diffetence between plausible and implausible. Time travel definitely falls into the implausible category.

 

[Swank]

Given that

1. belief is for those who want to think something is true without conclusive evidence that it is, and
2. we are still a long way from knowing how the universe works (and we may always be that way, with regard to much of it),

we can't rule out things that may be possible, including in ways of which we're not aware.

The least likely of those things that may just be possible is time travel (of the type we've been discussing) as it would clearly undermine some of our most strongly held views of the way we think things are.

So is FTL, materials stronger than chemical bonds, uploading minds, etc, etc. SF isn't about science, it is about possibility. The most strongly held views are that the MF made the Kessel run in 12 parsecs, not what science books imply is unlikely.


The whole damn point of SF is to propose something outlandish and see what the implications are. Not to present the film Gravity over and over.

 

[paranoid marvin]

I think this is why we have people with a difference of opinion as to whether Star Wars is fantasy or scifi, and why the lines between the two genres can become blurred.

Personally I believe that time travel is impossible, and so books that include it are fantasy. Often time travel novels are an allegory for something other than movement back and forth in time (The Time Machine for example).

 

[Swank]

I think this is why we have people with a difference of opinion as to whether Star Wars is fantasy or scifi, and why the lines between the two genres can become blurred.

Personally I believe that time travel is impossible, and so books that include it are fantasy. Often time travel novels are an allegory for something other than movement back and forth in time (The Time Machine for example).

Fantasy is not anything that is impossible. Fantasy is a much narrower genre than that - it deals largely in what we already have long accepted are outmoded ideas of the arcane. There is a very, very long list of stories with impossible things that no responsible bookseller would ever classify as "fantasy".

That said, Star Wars is SF for exactly the same reason as I, Robot, Dune, Ringworld, Fire Upon the Deep, Player of Games, Star Trek, Gateway, Starship Troopers, The Expanse, Three Body Problem, Ender's Game, Bladerunner, Foundation, Frankenstein, Hyperion, 2001, Slaughterhouse 5, Murderbot, Old Man's War, Solaris, Contact, The Stars My Destination, Cyteen, The Peripheral, Revelation Space, Eon, Pandora's Star and The Invisible Man are. So when you are ready to consign all of the best and brightest to the dustbin of Fantasy because they don't conform to known science, that will be a very stupid day.

 

[Steve Harrison]

Often time travel novels are an allegory for something other than movement back and forth in time (The Time Machine for example).

I fully agree. It's a terrific literary device to contrast directly, for example, people and attitudes in two different periods and increase the conflict in a way that would be much harder if the story was separated into those two time periods.

 

[Harpo]

Personally I believe that time travel is impossible,

See elsewhere for the details of my time travel ideas. It’s possible, but not yet.

 

[paranoid marvin]

See elsewhere for the details of my time travel ideas. It’s possible, but not yet.

I think that to accept the possibility of time travel, you have to accept that there are a myriad of branching time lines running concurrently. So every time someone goes back, there is a new time line created with the changes they have made.

Go back in time and kill Hitler in 1932, and when you return to the present you have a quite different 2025. Either that, or every time someone goes back, not only does the world around us seamlessly change but so do our memories (assuming that we still exist).

Either possibility is too unlikely (in my opinion) to make the idea of time travel work. I accept the possibility that we may be able to intentionally speed up or slow down time. I also accept the possibility that we may be able to see things that have previously occurred a kind of natural VCR). Just not that we can move backwards in time, change something, and then return to our own time to witness the consequences; or that a new time-line opens open running alongside our own.

Otherwise there would inevitably be a timeline where someone machine-gunned Henry VIII, or took modern battle tanks to Gettysburg, or jet fighters to Pearl Harbour. Or created an alternative timeline where thst happened. Because that alternative timeline would have to accept the posdibility of time travel - otherwise how could any of those things have happened?

So we are living in a timeline where no time machine was ever invented. And perhsps that is for the best.

 

[Cthulhu.Science]

I think that to accept the possibility of time travel, you have to accept that there are a myriad of branching time lines running concurrently. So every time someone goes back, there is a new time line created with the changes they have made.

Go back in time and kill Hitler in 1932, and when you return to the present you have a quite different 2025. Either that, or every time someone goes back, not only does the world around us seamlessly change but so do our memories (assuming that we still exist).

Either possibility is too unlikely (in my opinion) to make the idea of time travel work. I accept the possibility that we may be able to intentionally speed up or slow down time. I also accept the possibility that we may be able to see things that have previously occurred a kind of natural VCR). Just not that we can move backwards in time, change something, and then return to our own time to witness the consequences; or that a new time-line opens open running alongside our own.

Otherwise there would inevitably be a timeline where someone machine-gunned Henry VIII, or took modern battle tanks to Gettysburg, or jet fighters to Pearl Harbour. Or created an alternative timeline where thst happened. Because that alternative timeline would have to accept the posdibility of time travel - otherwise how could any of those things have happened?

So we are living in a timeline where no time machine was ever invented. And perhsps that is for the best.

Then there is the ability to go back in time and change anything you want.

You return to witness all the marvelous changes you've made, but, as a person out of time, you still have your memories from birth to the present moment.

On the other hand, every person conceived after the moment of your arrival in the past was never conceived. Instead different people were conceived. And so the timeline is completely altered and you, returning to 2025 might as well have gone to 3025 for all the current culture, technology and events you know about.

But you exist because you exist.

The fun thing about time travel is that we can make up anything we want about it. That is why it's called fiction.

 

[Harpo]

See elsewhere for the details of my time travel ideas. It’s possible, but not yet.

Time travel could be possible ... in the future

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And of course

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