On a Rational approach to TimeTravel paradoxes.

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On a Rational approach to TimeTravel paradoxes.

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Aug 18, 2010, 12:58am

Dear Group,
I was wondering if you have any recommendations for SF stories
which try and handle the various Paradoxes in TT, reasonably.

I have always been anoyed with, say, such simple problems as the atoms in the TT heros body. Do they simultaneously exist in 2 places?
The gold in his/her ring came from a supernova and if they travell far enough back...?

I suppose the "many worlds" approach might work but it is rarely explicitly mentioned.

I did enjoy timescape by benford and accept the sheer escapism of most TT tales but most of the genre is just that.

I suppose I'm looking for something a bit "meatier".
Yes I do have various popularizations of Physics which are almost SF but would be interested in your thoughts.

Yours, Guido.

Aug 18, 2010, 3:27am

You might try Cowl. In it, paradoxes (or just generally changing your history) push you off your original timeline into an alternate one. Getting back is all a matter of how much energy you put into getting you back to your original timeline. Killing your grandfather would require such vast amounts that it's not feasible, stranding you on that new timeline. But just going back and shaking his hand makes such a small change that it's doable. It still involves a bit of hand-waving and pseudoscience, but it was a good read.

Aug 18, 2010, 6:26am

How to Build a Time Machine should address any scientific detail about the possibility of time travel.

On the fiction side, I found Robert Silverberg's Up the Line very funny, and internally consistent with regards to its approach to time travel and the inherent paradoxes.

I tend to look on time travel in a story as simply a tool to help tell a story and only find it irritating when the tale is inconsistent or self contradictory.

There is another novel I'm thinking of that involved time travel by archaeologist back to medieval times. I will try to find/remember its name. It did have a good treatment of the paradoxes.

Aug 18, 2010, 10:05am

Larry Niven's Flight of the Horse is a collection of funny short stories dealing with the problems of TT.

Aug 18, 2010, 11:29am

4> Just avoid Rainbow Mars, which is a novel-length work with the same characters/setting. The writing was simply dreadful. And I saw this even though Niven is one of my favorite authors.

Aug 18, 2010, 12:41pm

>3 pgmcc: Were you thinking of Timeline?

Aug 18, 2010, 12:48pm

#6 You got it in one!

Thank you!

Edited: Aug 18, 2010, 1:49pm

Connie Willis has published some novels and stories, beginning with Fire Watch, in which graduate study in history includes actual visits to the period being studied. In To Say Nothing of the Dog, a traveler accidentally brings back an artifact from the past, resulting in some amusing worrying and discussion about its possible effect on the chaotic system.

In Gene Wolfe's Book of the New Sun, certain adepts are able to enter the corridors of time, which permits them to travel to the past or future.

Aug 18, 2010, 2:23pm

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Aug 22, 2010, 12:15pm

Replay by Ken Grimwood is a good story that presents the many paradoxes of time travel as the central source of conflict.

Aug 22, 2010, 10:51pm

A classic, which is fun but doesn't address your mechanics, is Heinlein's The Door into Summer.

Aug 23, 2010, 7:05am

The most serious limitation of time travel tales is that they usually ignore that fundamental predicament (called 'life' - hah!) that we are all in. I mean, here we are, riding in our little boats down time's stream, from our births to the moment of our personal extinction.......

If the wish to travel in time is the ultimate escapism, along the lines of "Stop the world - I want to get off!" then being able to 'slide' through the dimension we call time without also being able to significantly extend our own short life-spans wouldn't really be of much use to us.

Comments, please.

Aug 23, 2010, 5:44pm

Dear Group.

Thanks for your thoughts, "Honestly, I would totally agree if it wasn't for the hairy-nosed wombats."

Sorry my brain went sometime else :-)

I am surprised how many of the "older" TT tales mentioned I had already read.
And here I was thinking I didn't really like TT or perhaps rather that it annoyed me.

I WILL look up/read/borrow some of the newer ones but please don't expect any reviews etc. I doubt my reviews would be of any interest other than to myself.

Guido, with thanks.

Aug 24, 2010, 7:04pm

@ 12

If time didn't pass for a time traveller, he wouldn't exist. So there isn't any way of extending your own personal duration in any of the "likely" time travelling stories that I have read. You live X hours or days while sitting in your time machine, just as you would live that many hours sitting in your house. Subjective time passes.

You start in 1990, travel back to 1980, "live" normally until 1990, and "voila" you are ten years plus however many seconds you spent in the machine travelling back, older. If the method of time travel dictates that you have then stayed in your own timeline coming "forward", then your house isn't ten years older then when you set out, but you are.

I have read a lot of very unsatisfactory TT stories where the author bluntly states that a time traveller "can't" die in a time that is before his/her birth date. Or implies somehow that travelling backwards in time is some how different physiologically to travelling forward in time. Or implies somehow that your atoms can't be in close proximity to the younger atoms taht are in your body when you set out, so "You mustn't see yourself whatever you do!, The Universe will blow up!! ! !! !"

On a side note, the clearest proof to me that time travel will never happen, is not as the man said "Where are all the time tourists" but, "how come someone from the future hasn't nobbled Hitler".

Aug 24, 2010, 10:08pm


Alternative Universes semi solve those issues.

Although I don't really understand that buisness of "NOT DYING" in TT.
I must confess that, that idea, had never come up in my readings :-)

Can you point me to a Tale which explicates those ideas?


Aug 25, 2010, 10:00am

15 > Many Waters has a strange argument that is completely stupid along those lines. A couple kids get sent back in time to Noah and one argument used to get the seraphim to help them is that if they die in the past they would never be born and that would change the future (and these beings are supposed to understand space/time) ???WHAT? How can that make ANY Sense? anyway it's not the 'Can't die because I'm in the past' but a similar stupid thing.

Aug 25, 2010, 2:57pm

I think one can pare the question of time travel down to, "How can that make ANY sense?" Aside from the paradoxes there is no actual past or future. All there is is the present. That's it. The present. While we use a lot of spatial metaphors to move forwards and backwards in time, time has no backwards and forwards. Time, in reality, stands still, is buried within and informs only the instant. It is always now, always Present. That fact is why time travel bores me. Once you've suspended your disbelief enough to accept the idea of time as a road rather than a spot, why quibble about which paradoxes make sense and which don't?

Edited: Aug 25, 2010, 2:59pm

Robert Heinlein's longish short story or novella "By His Bootstraps" is one example of a person getting all tangled up with himself through time travel.

His short story "All You Zombies" takes the idea even further.

Both can be found in his collection Off the Main Sequence.

Aug 25, 2010, 9:11pm


Well, Alternate universes might semi solve the problems, but then they are not the same thing as "straight" time travel stories, so it is kind of a non-sequitur for us to talk about them. Again, or otherwise.

As for giving you a list, I USUALLY throw memories of books I hated out of my skull, but , I will try.
Poul Anderson wrote a couple where the people couldn't die "out of their time" I think, maybe one was called Time Out of Mind?. Not sure at all about that.

Phillip Jose Farmer wrote an otherwise cool story called "Times Last Gift" that of course had Tarzan in the cast, and Lar of Opar too, naturally :P where scientists go back and find themselves "stuck" in the stoneage and find that only accidents can kill them, they don't age "because of time" or something.

And that is about the limit. I can remember a story where a guy gets an unreliable time belt, and then he loses his diary, so is always panicking when he travels to somewhere because "It might be somewhere I already "exist" and our atoms will explode the universe", but have discarded the rest of the experience in disgust.

Aug 25, 2010, 9:13pm

"Time, in reality, stands still, is buried within and informs only the instant. It is always now, always Present".

Nice theory geneg. Care to offer conclusive proof?. I mean, you seem so certain, that I guess someone has proved the point you make.

Aug 25, 2010, 9:20pm

One thing I know about time travel: If Jean-Claude van Damme kicks your present self into your past self, you'll turn into weird goo and then explode.

Aug 25, 2010, 9:29pm

I've always enjoyed Crawford Kilian's chronoplane series (The empire of time) This is a combination of multiple dimensions and time travel as I recall. Dated before PC's but well crafted and consistent.

Aug 25, 2010, 9:48pm

A particular I worry about {in case aliens offered me a time trip} is your position in space when you travel through time. Earth and everything else is moving through space so if you go back in time would you pop out in space {the vacuum} at the physical co ordinates of your starting point and the earth would be some distance away where it is traveling to your position?

I think the tv series 7 days addressed this issue a bit when the guy's sphere would pop out into space and then glide to earth in some kind of trippy montage but I don't remember any explanation.

Timeline got around this by having a wormhole that happened to join two areas, not just a jump to the past. Anyone know of real live physics or sf constructions that address this issue? Or are those aliens just trying to get rid of me and fondle my coin collection?

Aug 25, 2010, 9:55pm

If I were writing a TT story I'd say this: As long as you were in an inertial frame of reference when you turned on the time machine, you'd pop back out into the "same" place as where you left. But if you were under acceleration, then...you'd end up in outer space or the middle of the earth, or something?

Wait, what? Hmmm, not sure that makes sense. Let's try to figure out what monkeys sound like when they collide at near lightspeed.

Aug 26, 2010, 2:19am



Aug 26, 2010, 4:20am

Is the "LHC" now using monkies rather than "quarks or some such substitues"
in their experiments?

The WORLD MUST be told the truth.!


Aug 26, 2010, 4:20am

The only person that I know of who says "Ook", also bounces people on their head if they use the 'M' word. Just saying.

Aug 26, 2010, 4:27am

#26 My daughter's boyfriend works at CERN. I must challenge him on his animal cruelty. He claimed he was only looking for a Higgs Bozon. Does that sound like a name for a monkey to you? I think it could be.

"Tarzan, Cheetah and Higgs Bozon swung though the trees!"

It does have a ring to it. Monkeys and apes unite.

Aug 26, 2010, 4:28am

Dear "JUST" I do believe the "librarian" has been known to look after his own reputation rather well, but thanks for looking after his good name.
And from ALL us "primates", I thank you.

Edited: Aug 26, 2010, 4:43am

Hmm, #28, A "higgs Bozon" does not sould like the sort of chap I would like to meet in a Pub after midnight.
Although a Miss. Boson might be a different matter.

Aug 26, 2010, 5:50am

#17 "The present. While we use a lot of spatial metaphors to move forwards and backwards in time, time has no backwards and forwards. Time, in reality, stands still, is buried within and informs only the instant. It is always now, always Present"

Time does have a forwards direction - the entropy of the universe continually increases. You may only subjectively experience the presence, but around you the universe is absolutely increasing in time.

I'm not sure that this automaticlly implies that there is a backwards direction, but it seems to me that it should.

I too am a big disliker of timetravel stories, precisely because it is so frequently handled so badly.

Aug 26, 2010, 9:57am

We discontinued funding the super monkey collider, yet we call ourselves an "advanced" society.

Aug 26, 2010, 9:59am

>31 reading_fox: I believe the standard position is

statistical mechanics + observed increasing entropy = objective time.

Time is real; it's not just a construct (as if that needed to be said). The gods created it to prevent everything from happening at once.

Aug 26, 2010, 10:10am

So it's true #32, it's ON THE NET and thus must be true.
As a mother of 3 I am horrified.
Oh wait I am a single guy with NO kids.
Oh dear, can someone explain those "quark thingies"?

Your, male, confused,


Aug 26, 2010, 10:29am

Oh by the way,
I just bought cowl on Amazon.
So I guess this type of web discussion does work!

Aug 26, 2010, 10:36am

So it's true #32, it's ON THE NET and thus must be true.

Well, I'd like to believe that it's not true, because, to quote the article, "...with funding cut off, the future of our nation's monkey collision program looks bleak."

Edited: Aug 26, 2010, 12:06pm

Time, in a way, precipitates out of the quantum soup. A direction to time only becomes apparent at a particular level of complexity. Prior to reaching that level time has no arrow. Without a direction it isn't what we conceive of as time at all. Once the necessary level of complexity is reached, time moves forward (is this time orientation driven by entropy or is it entropy?). Is it possible to move forward along the arrow of time without the universe actually proceeding in time to the point at which you wish to arrive? I'll let you answer that question. Is it possible to move backwards in time to a point the universe has moved beyond? You can answer that question as well. The only place one can be in time is where the entire universe is at the instant you wish to measure. The universe has not yet arrived at a future point and has passed forever points in the past. Without arranging every quanta, every string, every whatever the smallest element of existence is in exactly the same pattern it was or will be at the time you wish to find yourself, you will not get there. The only way to travel to the future is to wait for it. There is no past to travel too. It's gone. The entire universe expends all of its energy just getting to the next instant. Where would you find the energy to rearrange the universe? Even if you could rearrange the universe, the act of rearranging it would render a different result than just waiting for it, thus it would not be "the future", but someplace else, someplace outside the normal flow of time. The space-time continuum would have been disrupted and heaven only knows what that would entail.

With my layman's popular knowledge of physics, I don't see room for time travel. Managing the quanta is impossible for all kinds of reasons, not the least of which is the ever-shifting nature of the quanta itself.

Aug 26, 2010, 12:22pm

#37 I think the Australians have it linked with "Quantas".

Aug 26, 2010, 2:23pm

23> Earth and everything else is moving through space so if you go back in time would you pop out in space {the vacuum} at the physical co ordinates of your starting point and the earth would be some distance away where it is traveling to your position?

I don't think this question makes sense. Didn't the famous Aether experiments prove that there is no way to specify a grid as being at rest compared to everything else in the universe. As Einstein pointed out, everything is relative, so what reference would the Universe use to locate your point in space when you go back in time. You can choose the center of the Earth, the center of the Solar System, the center of our Galaxy, or somewhere random, they all make as much sense.

So, it you were writing a TT story, you might as well make it easy and say that you will end up in the same position relative to the closest mass (the Earth). But you still wouldn't wind up at the same spot on earth since it rotates and if you go back far enough there's continental drift. If you had your time travellers go to the South Pole and not go too far back into geological time you eliminate some of the difficulties.

Aug 27, 2010, 1:25am


No U in Qantas mate, isn't actually a word. Stands for Queensland And Northern Territories Airline Service.

# 37

So it wasn't a fact you are quoting, more an opinion about time travel, which is fine mate, don't take that as critical, I really did want to know if you had "an established fact" with references, to your idea of "the past' and "the future" not existing like you said.
You said "Aside from the paradoxes there is no actual past or future. All there is is the present" and that last part seemed quite likely to me, I just wanted you to tell me where I could go to see the reasoning of it, if it "was fact".

And seeing as certain physicists have suggested ways of BUILDING time machines, stands to reason THEY don't think you have to re-arrange all the quanta in the universe to go back in time.
In fact it seems inelegant to go about it that way. :)

Aug 27, 2010, 2:20am

#40 where you refering to "Greens" book?

Aug 27, 2010, 9:25am


On a side note, the clearest proof to me that time travel will never happen, is not as the man said "Where are all the time tourists" but, "how come someone from the future hasn't nobbled Hitler".

Maybe it would make things worse! See Making History by Stephen Fry

Aug 27, 2010, 10:06am

#42 How do know Hitler wasn't a time traveller and that he didn't nobble someone who would have made things better and that we are just living in the timeline that ensued?

Aug 27, 2010, 4:56pm

Well, seeing as my parents would not have met if it hadn't been for World War II, I've got a very vested interest in stopping any time travellers nobbling Hitler!

Aug 27, 2010, 4:57pm

Edited: Aug 27, 2010, 4:57pm

>44 RobertDay:
You've gotta take one for the team, Robert.

Aug 27, 2010, 5:01pm

Hell of a time to put the "many worlds" theory to the test!

Edited: Aug 27, 2010, 7:29pm

You reminded me of a "family" story which shows how opertune our existance is.
My Grandfather fought in WWI and subsequently in the Russia Revolution.
He became a POW and as was the wont in that theatre he was being lead out to be SHOT. In lots of 10. Yes, always shoot the privates not the generals :-(
Well, so the story goes, an officer on horseback came up to this operation waving a sword and just said "...not this lot..."
This was a few years before my Mum was born.

Obviously, the why's will never be know.
Though I am sure that each and every reader has a similar "serendipity" in their history. (splng?)

Yours, Guido.

I worked out how to spell "serendipity.

Aug 27, 2010, 9:28pm

I am sure that each and every reader has a similar "serendipity" in their history.

oh so!.

Members of my family survived the Napier Earthquake in 1931 because they were out of town at a funeral. People didn't/weren't able to travel far as easily as we do now, very unusual for them to be away from home in a whole family lot. The house was empty. Luckily too, most of a hill fell on the houses in their street.
250 or so people died in the town.

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