Wormholes, Worldlines and Whatnot

In the first blog in this series, I talked about the many reasons that I felt time travel stories don’t work. I specifically mentioned the main physical, metaphysical, logical and aesthetic objections. In the second blog, I bravely took up the other side, and discussed how the Many Worlds Theory effectively rebuts the metaphysical objections, and to some extent, the logical ones. However, the physical, aesthetic, and to some extent, the logical objections remain. What’s a time travel advocate to bring up in his defense now? Answer: Wormholes.

Wormholes

A wormhole functions according the idea that spacetime is curved, and there can essentially be a situation where a bridge is created cutting right through that curve, a sort of tunnel between an earlier and later time. In other words, if time were a straight line ----, it would take you a certain amount of time to get from point A to point B. But if time were more of a “C” shape, you could get from one end of the C to the other much faster by cutting through it rather than going around the curve.

This indeed solves a lot of problems. It counters the physical objection, because you can have a wormhole where objects are not moving at the speed of light inside the tunnel, although they might appear to be to outside observers (a wormhole is not simply two black holes with a bridge between them, but rather a black hole and a white hole linked by negative energy).

The show Sliders made heavy use of wormholes and the Einstein-Rosen bridges between them. Wormholes also take care of my main logical objection, the Tourist Trap, which was that if time travel is possible at one point, it becomes possible simultaneously throughout the time stream. Scientists have postulated that time travel through a wormhole would require the “stationary end” to appear first. In other words, a wormhole couldn’t open up allowing you to travel back to someplace where there wasn’t a wormhole before. The point of this being that we may not have experienced time travel yet because the first “stop,” or the first wormhole, hasn’t been created/found yet.

Worldlines

There has been another use of time travel in fiction that I haven’t mentioned yet, but that I have found to be very effective. This is the idea of the worldline. Worldlines are essentially lines that travel through space and time at once, as opposed to a timeline that simply marks the passage of time. In other words, a person’s life, drawn on a graph, would be a worldline, as it plots their movement through space and time. Some time travel stories intimate that it is possible to travel back and forth on your own worldline, since it is simply a line that exists in the universe, not something that is being created or destroyed. Under the right circumstances you should able to walk back and forth along it like the path to your tomato garden.

Whatnot
This still does not address my aesthetic objection, which you’ll remember was that time travel stories are simply messy: Specifically, it 1. disrupts continuity and makes it difficult to invest in the characters, and 2. creates the slippery slope: You go back and change something, I go back and fix it, you go back and unfix it, ad infinitum. To close out this extended rant, I’d like to take a look at how some time travel stories handle all this and how effective I think it has been.

Star Trek

I frankly think that time travel has made Star Trek a pretty big mess. You can argue with the last movie that the Romulan time trip created a new, alternate timeline, and that the initial timeline is moving forth as it always had (albeit without a Spock). That’s okay, I guess, but I suspect we will never see our “real” timeline again, and even that timeline has been removed by so many jumps it hardly matters (for example in Star Trek, First Contact, the Borg go back in time and take over Earth, radically changing its history. The Enterprise crew goes back and fixes it. However according to the Many Worlds theory, the initial timeline was unchanged by the Borg, and the Borg’s new timeline was unchanged by the Enterprise; we simply have three different universes in effect. Yes I have a headache now too).

Quantum Leap, Watchmen, Slaughterhouse Five

I lump these together because they all make what I think is effective use of the “Worldline” theory of time travel. Dr. Sam Beckett can only travel back and forth through time within his own lifetime, while Dr. Manhattan experiences different times in his life simultaneously. Billy Pilgrim has come “unstuck” in time, and experiences his life randomly through time, jumping from one point to the next without rhyme or reason (or at least without rhyme). In each case, the universe is not offended by their time travel.

Back to the Future

Back to the Future alludes to the Many Worlds theory, but not quite effectively. Dr. Brown does explain how moving through time creates an alternate timeline. However, he creates a sticky situation when he does a test run by sending his dog three minutes into the future. The dog has clearly reappeared in the same timeline, which forces us to confront the possibility that somehow moving ahead in time does not create new timelines while moving backwards does. Marty also finds that changing the past is affecting his original present (the picture with his siblings disappearing as they are “uncreated”), which gives rise to the “grandfather paradox” anew.

Sliders

Sliders handles the wormhole idea pretty well, but its protagonists are jumping through dimensions, not moving through time and space. There are no paradoxes because they never encounter the same timeline twice, although Quinn Mallory’s quest to return to his home dimension may prove impossible.

Comic Books

Members of the Legion of Superheroes travel freely back and forth through time with little concern about the consequences. The mainstream DC universe has not created a very sophisticated look at time travel although they used to have an interesting conceit where if you went back to a time where you already existed, you would appear as a wraith, since the same person cannot “be in two places at once.”

The Terminator

Terminator time travel isn’t too unwieldy for a number of reasons. The first is that only a handful of people go back before the time travel device is destroyed, and they can’t travel the other way. There are still some paradox issues, but since time travel is used so sparingly, it doesn’t interfere with the story too much.

Okay. I’m finally done with the time travel stuff. Next week I’ll go back to ranting about traffic patterns in L.A. or bad poker beats or why some Right to Lifers are psychotic or whatever.

Why You Love Time Travel Part I

In my last post, I complained about time travel as it appears in television, movies and fiction in general. I felt that there were a number of inconsistencies about time travel as to make it so implausible as to render any story based on it completely unenjoyable.

Clearly I’m in the minority in this opinion. Time travel stories continue to delight, generation after generation. Why should this be, if my objections are so irrefutable? Well, one reason is some people just like a good story and don’t care how unbelievable it is. As I pointed out in my last blog, Superman’s “impossible” ability to fly doesn’t deter my enjoyment of his adventures (although I prefer Batman). However, there's more to it than that.

The Objections to Time Travel

I raised four basic objections to time travel as portrayed in fiction: Physical: As one approaches the speed of light, required for going back in time, mass becomes infinite, effectively destroying the time traveler; Metaphysical: Specifically the Grandfather Paradox (you go back in time and kill your grandfather, therefore you are never born and cannot go back in time to kill your grandfather, etc.) and the Ontological Paradox (Future Craig hands me an envelope which he tells me to hold on to for five years. Five years later I go back in time and hand myself the envelope. Where did the envelope come from?). Logical: Specifically, the Tourist Objection; If time travel is possible, how come we don’t know about it yet? We should be being visited by an effectively infinite number of time travelers all the time, where are they? And Aesthetic: How can any story have internal consistency if someone can always go back in time and change what happened?

I mentioned that there are rebuttals to all of these objections (I excepted the aesthetic but I will stipulate that for most people, if the other objections are satisfied the aesthetic one should be as well, even if I personally am not comfortable with it), and hence, some time travel stories that work. So here goes:

Let’s start by addressing the Metaphysical objections. The famous grandfather paradox and the ontological paradox. There are two main ways that philosophers approach the problem of time travel paradoxes: The Many Worlds Theory and the Novikov Self-Consistency Principle.

The Novikov Self-Consistency Principle

The Novikov Self-Consistency Principle simply states that anything that cannot happen, will not happen. In other words, if you go back in time and try to kill your grandfather, you will always fail. Your gun will misfire at the last minute, you will have shot the wrong person, or the right person but it will turn out that he wasn’t your grandfather after all, etc. The television show LOST makes use of the self-consistency principle. Daniel Faraday repeatedly explains that no matter what they try to do, the future will not change, because whatever happened is immutable and has already happened, even if the time-traveling protagonists are at an earlier place in the timeline. Ben cannot be killed as a child, the Dharma Initiative cannot be saved, simply because it didn’t happen.

I do not find this theory particularly compelling. There is nothing in the universe to suggest that it actively attempts to sort out paradoxes at a macro level. If you shoot someone, they will die, and to suggest that the universe somehow “knows” to protect them seems to be so fanciful as to make the theory meaningless. This also does not explain the ontological paradox.

The Many Worlds Theory

The many worlds theory, popularized in D.C. Comics with their “multiverse,” and based on the Heisenberg Uncertainty Principle which says that the states of certain particles at the quantum level are not fixed until observed, and that until they are observed they exist in multiple states at once, is much more compelling. It is referenced in Back to the Future and used in comic book literature and other works of fiction, including the television show Sliders and the Michael Crichton book “Timeline.”

The idea of the multiverse is that the universe as we know it is just one of many possible universes that exist in different dimensions, and that each choice we make represents the universe that we fix in time out of the infinite universes that are possible. As it pertains to time travel, the theory goes that when we go back in time and change something, we create an alternate timeline. Our original timeline, the one that spawned us, continues on into infinity while we exist in the new, altered timeline.

This idea seems to work pretty well. It addresses the grandfather paradox: when you kill your grandfather, you create a universe where you never existed, however you, the killer, came from a parallel universe where you did exist. It addresses the ontological paradox too. In Terminator, Kyle Reese is sent back in time to protect Sarah Connor so that John Connor will be born. He ends up becoming John Connor’s father. According to the theory, there was a “prime” universe where John Connor had some other father. In that universe, Kyle Reese was sent back in time, creating an alternate universe where Kyle Reese is John Connor’s father, as we see in the movie.

How this is handled can get complicated. In Back to the Future, Marty and his siblings start to disappear when it seems that Marty may have prevented his parents from ever falling in love. If this is an alternate universe, that shouldn’t be an issue. In “Timeline” Crichton addresses this problem by suggesting that events in an alternate timeline have a “ripple effect.” That over the course of time, minor changes happen in the original timeline so that it will “catch up,” and become consistent with that timeline. In other words, events in one timeline can have an effect on others.

I feel that the many worlds theory is pretty effective in addressing the metaphysical objection, and as I stated in my first post, the metaphysical objection doesn't trouble me that much. The many worlds theory does also address the logical objection to some extent. If travelers going back in time are always creating alternate timelines, we shouldn’t expect to ever meet one in our “prime” universe. However I don’t find this entirely compelling. Somehow it seems that we still might receive a visitor from an alternate future, so that our prime timeline is their alternate one, or that the ripple effect should still produce premature time travel in our universe. I feel that there are stronger rebuttals to the “Time Tourist” objection, which is tied in with the rebuttal to the physical objection (hint: Wormholes), and I’ll discuss those in Part II.