posted
As i was driving home from the Orthodontist today i started thinking about Back To The Future for some reason. Well in BTF2 he goes into the future and there in the future is himself. Well if you were to somehow travel to the future you shouldn't be in the future. Even while writing this im not to sure but it makes sense why you wouldn't. If i traveled into the future today, and i traveled to thursday. I wouldn't be there on wensday or before i got there on thursday because that following tuesday i left. So unless i went into the past i(or you) would never meet your future self. I'm just making a theory and such, what do others have to say?
Posts: 262 | Registered: Jan 2005
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posted
So you're saying that until you actually perform the action of returning to your "proper" time, the world you visit in the future should be a world in which you vanished sometime in the past, and never returned?
Posts: 1539 | Registered: Jul 2004
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quote:So you're saying that until you actually perform the action of returning to your "proper" time, the world you visit in the future should be a world in which you vanished sometime in the past, and never returned?
To the people in that time that you left, then i would say, yea.
Posts: 262 | Registered: Jan 2005
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posted
I've had that same thought too. I would say yes, you shouldn't be able to run into your future self because you would have vanished the moment you traveled into the future. Uh... yea, does that make sense?
Posts: 1294 | Registered: Oct 2003
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posted
There are various ways around this, including parallel universes, meta-time, space-like and time-like curves, feedback loops in time, and others.
All are too complicated to put in a feature film like BTF, though many good time-travel stories, and some scientific papers, have covered them well.
If, on Monday, I travel to Friday and have a conversation with myself, and then return to Tuesday, there is no paradox. Period. Merely having absented myself from the timestream temporarily does not necessarily mean that I have done so indefinitely.
There IS a paradox if, say, I travel to Friday and get killed. But in this event, I would not encounter myself on Friday.
quote: Merely having absented myself from the timestream temporarily does not necessarily mean that I have done so indefinitely.
If you were refering to me, i wasn't meaning to say you were vanished from the time stream for (turn your head sideways cause im to lazy)8. Just until you returned.
Posts: 262 | Registered: Jan 2005
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But, again, why? To myself, the events of my voyage are contiguous: I leave, meet myself, come back, and meet myself again. There's no paradox, and no potential paradox.
Paradox: I go, meet myself, and Future Me kills Traveling Me.
Here's where your issue comes in.
Of course, this is also a perfect example of why the traditional sort of time travel is impossible.
Posts: 37449 | Registered: May 1999
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posted
That's what I meant by meta-time: an overview of local time including all discontinuities or time travel jumps.
In meta-time, a temporary absence from the local time stream is irrelevant--either you made it back home to your original time ( or near it) or you didn't. Paradox is avoided.
Some physicists have even gone so far as to speculate that the universe will not allow a time travel device to be built, even if one is theoretically possible (they probably are) to avoid any paradoxes disrupting time flow. Niven wrote a great short story based on that, the title escapes me.
You can't look at time travel with linear logic and casuality, it doesn't work. English is very clumsy describing it, too--mathematics is much better suited to it.
Posts: 327 | Registered: Oct 2003
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posted
Tom, the situation that Postman described CAN be explained away, but I think it would be COOL to read a story in which the only future you can visit is one in which you are absent, since you have not yet made the choice to return. As soon as you DO make that choice, the future changes to include you. So you can visit the future, but you can never see what it will really be like.
Posts: 1539 | Registered: Jul 2004
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quote: a story in which the only future you can visit is one in which you are absent
Geoff, lots of writers make that assumption, usually to avoid paradoxes I guess.
I think Connie Willis's To Say Nothing of the Dog(which ketchupqueen just scored at WenchCon) makes that and other assumptions to avoid paradox. The universe in her novel has defense mechanisms to minimize paradox due to time travel.
Varley's Millennium makes that assumption, too, I think--it's been years since I read it. I am a huge Varley fan but that is his weakest novel--which of course is why it was the only Varley book made into a movie.
posted
As do i, they ruin everything, like not lettin Mr.Card write his on script for the Enders Game movie. O and for Tom, you saying that youll go to friday and meet yourself, but you wouldn't be there on friday because you left on monday
posted
"you saying that youll go to friday and meet yourself, but you wouldn't be there on friday because you left on monday."
No, see, this is the problem.
Saying that you're not there because you could potentially choose to stick around in Friday is one thing. But saying that you're not there simply because you left on Monday doesn't work.
Because you came back on Tuesday.
Regardless of whether or not you knew on Monday that you would be returning on Tuesday after spending a number of weeks on Friday, the fact that you will come back on Tuesday makes it, by Friday, an inevitability that you did come back on Tuesday.
posted
I wrote a short story back when I was I think 12 about the reverse grandfather effect. Basically, my protagonist went into the future and tried to taunt his future self into killing him. I wonder if I still have that around somewhere.
Posts: 10177 | Registered: Apr 2001
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posted
As soon as you admit the possibility of stepping outside linear time, then you have to decide if this transtime is also linear, or if ordinary linear time continues as it was until you introduce an actual change.
The usual view is that "the" future includes the fact that you left the timestream, since (from the perspective of transtime) you "always" left linear time. Therefore any future you travel into will reflect the fact that you "always" left the timestream and then returned to it. Your exit does not CHANGE the future because there was no such future as one in which you did not leave the timestream.
Perhaps it's helpful to remember that there is no such thing as "time" anyway. What exists is causality. Mechanical, linear cause, which moves in only one direction (despite weird theories to the contrary). There can be (or can be the illusion of, depending on your beliefs) final causation, or motive, but it still translates, timewise, into mechanical cause: A cause B, C, and D to happen, and so on.
The rule in linear time is that an even that happens after another event cannot have caused the earlier event to happen; that is, causality is a one-way street, however much the streets might fork; they always fork "forward."
So if an Acter skips forward or backward in time, then rejoins the cause-stream at a different point, at that moment the Acter simply becomes part of the stream of causality, still making changes that only have effects in one direction.
and then it gets really complicated as you speculate on whether such a transtime Acter is still linked to that which caused his existence or his disposition to Act, or whether he is fully embedded in his new position in the timestream and is impervious to alterations that happen "after" his present position but "before" his original position.
For fiction writers, of course, we can choose whatever rules we think we can explain to our readers.
But in the real world, we have no conclusive evidence that any Acter can switch his location in the flow of causality; we all, quite literally, go with the flow, caught up in the same forward-rushing current of causality, in which there are no eddies that move one backward against the stream.
Posts: 2005 | Registered: Jul 1999
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posted
"A Brief History of Time" by Stephen Hawkings is a really great book on all kinds of time travel, space/time stuff. There is no math in it, save E=MC(2), and he makes the information pretty understandable to the average person. Then again, the great thing about writing sci-fi is that you can pretty much do anything you want as long it makes sense, or seems to make sense from a certain point of view.
Posts: 1918 | Registered: Mar 2005
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posted
Wasn't it Hawking who made the observation that clearly time travel is not only impossible but will always be impossible, for the simple reason that we aren't beset by tourists and historians every time something happens?
Posts: 37449 | Registered: May 1999
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posted
People have made that observation, Tom, but it really only implies that humans never invent time travel, not that it's impossible. The world could end tomorrow, and we would never get any time tourists. Doesn't mean it's impossible.
Also, a sufficiently advanced human time traveler could probably blend in quite well--say, by joining an internet forum to learn the ropes.
posted
I think what Mr. Card is describing is a theory of time-travel which might evolve into one which excludes the possibility for human choice. In other words "fate" exists because what appears to be human choice is in fact mechanical causation at a very small level.
This is, I think the most consistant version of time travel, because it can endure all sorts of loops without breaking down.
I believe there is a science fiction story in which a character goes back in time and eventually causes the extinction of the Dinosaurs (an event which they remembered to already have happened "before" they went back in time). Thus, they had no choice about causing the extinction, because "before" they went back in time, it had already happened.
Then there was that story by Del Rey "And It Comes Out Here" in which a man steals a time machine from a museum where he is credited as the inventor, goes back in time, ends up being credited with the discovery of the time machine which is put back in the museum. Thus he HAD to steal the time machine, because otherwise no one would have "invented" it. The paradox of the time machine never ACTUALLY having been invented by anyone if you look at the time stream linearly is cleverly dealt with by this time theory.
This theory is my personal favorite, although it puts the most pressure on the author because dealing with the concept of fate rather deflates the suspenseful aspect of a novel. However, there is obviously enough room to be amazingly creative within those constraints.
posted
What if there is an infinite array of parallel universes, all identical except at different times? Then, instead of trying to reverse time one would need only to travel across to a different universe. So let's say on Friday, you go to the universe which is still in the Wednesday before, and for example, kill your Wednesday-self. You wouldn't start to fade away, like in some annoying sci-fi movies, but instead the Wednesday-self would be unable to fulfill its role on Friday by killing the self from the Wednesday before. This would create alternating universes, one in which Wednesday is normal and you go back in time on Friday, and one in which you are killed by your future self on Wednesday.
Posts: 1 | Registered: Mar 2005
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posted
Great topic by the way. I'm reading The Time Traveller's Wife right now which is an excellent novel. Though I don't agree it is exactly "literature" as many are calling it.
Talks a lot about having free will, unless you have been to the future, which then becomes your past which you cannot change.
Posts: 3134 | Registered: Mar 2005
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posted
Oooo I love thinking about time travel. Not because I actually believe it's possible, but because there are so many physical and philosophical implications if it were.
Tyro, I've read articles by real scientists who while tossing around some ideas about time travel posed the infinite alternate universes theory to explain away paradoxes.
I personally like what I call the MADD Theory, the Modified Anomalistic Donnie Darko Theory: if you wind up somewhere in space-time that God (or physics, or fate) did not intend, it is a paradox. Paradoxes are bad, so a time-looped alternate universe is instantly created in which the paradox is solved. Within the alternate universe the only way to exit the loop is to "solve" the paradox and so the solution is ultimately self-fulfilling.
For example, you are supposed to be here reading this post. After you read it the server crashes and the post is lost forever. But instead of reading the post you decided to get up and grab a glass of milk (therefore free choice exists, sort of). While you're up, the server crashes and you never get to read the post. Your getting up to get a glass of milk creates a paradox because you are somewhere you aren't supposed to be (or perhaps two places at once?). The paradox creates an alternate universe in which a bunny rabbit appears and tells you the world will end in 28 days...just kidding. In this wacked out alternate universe events conspire so that you eventually and inevitably sit down at your computer, the universe collapses, and you find yourself in the true universe reading this post with only a shadow somewhere deep in your mind that the alternate universe ever existed. No time has passed in the true universe, and the fun thing is that at any and every moment multitudes of looped alternate universes are created but ultimately they collapse and everything follows the path that God (physics, fate, etc) intended. It applies perfectly to time travel in the sense that our true universe never intends us to travel in time, and doing so would be a paradox (even if we didn't actually kill ourselves or our ancestors). So from our perspective here in the true universe time travel will always seemingly fail, even at the exact moment it was happening.
Of course, that's just the theory I like to play around with in my mind. As far as I actually understand it, OSC is right about causality and therefore time always moving in the forward-flowing cause-->effect direction.
OSC, just out of curiosity, the Ender books are filled with science that seems based far more on true science (as we currently understand it) than a lot of other science-fiction--did you study science at all in an academic setting or did you teach yourself?
Posts: 4 | Registered: Mar 2005
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posted
It also helps if you think of "time" as a fourth dimension, and not some separate bizarre thing.
John Gribbin has some interesting essays on this topic if you're interested in a cosmological point of view. And Michael Silberstein's "Space, Time and Magic" essay in Baggett's "Harry Potter and Philosophy" is a great introduction to the subject, too.
I'm actually in the middle of writing a Neverwinter Nights module based on some of these ideas . . . it's definitely fun to think about! :-)
Posts: 11 | Registered: Mar 2005
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posted
In all logic of our feeble reality, no. You would not meet yourself in the future, due to the fact you are only there because of time travel. But in movies like "Back To the Future" it is basicly impossible to see them making sense. The directors don't direct to get facts right, they do it to be entertaining, and thus, to most people, unintelliegent.
If common sense was the 'Law of Nature' than everything would be easier. But life simply isn't easy.
Time travel is a great subject to talk about, though most people do not know enough about it, wether possible or not, to have a series discussion on it. Like myself.
Posts: 12 | Registered: Mar 2005
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posted
I feel that time travel is impossible because Time is an illusion. All time is is the observation of movement. If you ever watch a movie/tv show where someone stops "time" all it means is that everthing stopped moving at once. Even aging is movement on a molecular level. If everything were to stop at once then their would be no time. So how can you travel back in forth in something that is no more than an observation of something else? Another weird thought is that if time stopped for a million years and then restarted no one would ever know it because we would all be stopped together. Only someone outside the timestop, say God, would observe it and they could choose not to tell the rest of us.
Thinking is painfull... Posts: 832 | Registered: Jan 2005
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posted
I say it just depends on whether or not time is flexible. If time is not flexible, and you are destined to return to your "present", then you would see yourself in the future.
If time can be altered, then I guess it would depend on the most likely outcome of what you are doing.
My problem with Back to the Future was "future marty" not knowing "present marty" was there. Shouldn't "future marty" have taken the same trip when he was a teen? I guess this would be where the multiple universe theory comes in to play. Kudos to Doc in the first movie though pretending to be dead so Marty would still go back and try to save him.
[ March 25, 2005, 12:42 PM: Message edited by: Stephan ]
Posts: 3134 | Registered: Mar 2005
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posted
Me, I thought the BttF movies were very tightly plotted and easily believable, and (positing time travel is posible) I don't see a problem with the stated scenario. Attend me:
On Monday I step into my phone booth and whip forward to Friday, where I visit my future self (Me+1) and have lunch. Me+1 might be surprised or he might not, depending on the nature of reality and time. If time is linear and doesn't repeat, he would be surprised and I could prevail upon his confused state to get him to pick up the check. If it does repeat, either he has already made this trip in his past and will be expecting me (whereupon I'll probably be paying) or this could be the first time this has happened in our respective timelines and I'm starting a new loop which will be forever repeated, and I should probably order the steak.
I then hop back in my phone booth and go back to Monday. I spend the week in a normal fashion, and then when Friday arrives I am suddenly visited by Me-1 from four days previous, who will expect me to be surprised and will be sadly disappointed when he finds me already ordering cheese sticks for two. After lunch he'll pop back, and I'll go on with the rest of my life.
Where the fun comes in are the questions.
What if I don't go back, but instead stay in Friday with Me+1 and thus never live the week normally to become Me+1 myself? Will there then be two of us from that point onward? How will my wife feel about this? Or will he pop out of existence? Or will the entire universe pop out of existence since I've just violated several laws regarding conservation of energy?
What if I return to Monday, but then move to Montana and become a sheep farmer before Friday? Does that hose the whole system, or is it self-correcting since I've already experienced it from one direction and now Me-1 will have a whole new experience when he gets stood up and has to eat the cheese sticks all by himself?
What if I go to Friday and see an unblemished Me+1, who then punches me in the face for causing all this trouble? Will my black eye remain with me for Me-1 to politely ignore in four days? Will a black eye abruptly blossom on Me+1's face? Or will Me+1 somehow be unable to lay a hand on me, the universe (or, more likely, the waiter) arranging things to prevent it?
Time travel is fun. Also, fattening.
Posts: 7790 | Registered: Aug 2000
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posted
I thought of writing a story once called Thyme Travel. It turns out it would have been a Stepford Wivesian exploration of a guy who is exploring aromatherapy and discovers "the good stuff".
Posts: 2010 | Registered: Apr 2003
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posted
I remember reading a scifi story about the scandal that resulted when it was discovered that a master chef's secret was that instead of using synthetic herbs, he used real garlic...GROWN IN DIRT!!
Posts: 1002 | Registered: Feb 2005
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posted
Hmmmm. Interesting what everyone is saying. I would have to agree with DP here. I see what he is saying, but all other theories seem correct also. I think he is trying to say that if i was to leave on a Satuday, or some other day, while gone time is still moving. So while i go to friday, everyone else still had to age. I'm seeing throughout this post people saying that they go back, well since you already created a paradox by leaving the time frame, who decides that you go back they day or second you left. What if i left and never went back, see yourself shouldn't be in the future, because you left the past to go there.
Posts: 17 | Registered: Jan 2005
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posted
A little off topic, a lame idea popped into my head(happens a lot). What if you went into the future and encountered yourself, but for some reason your future self was trying to kill you, and you ended up killing him. Wouldn't you have to go back in time and prepare to be killed by yourself, or maybe you would try and kill him when the time came, but you would already know how that would end up.
Posts: 290 | Registered: Aug 2003
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