Thursday, September 10, 2009

Time Travel

So I was watching Terminator Salvation the other day and found myself actually laughing a bit at one of the plot points involving time travel, when it dawned on me that I probably have a stranger way of looking at the concept than most. Exactly what does time travel entail? Is it even possible, and if it is, how exactly does it work?

It's all theoretical of course, and no one can really tell you how it works because it's never been done before (well who knows maybe there really are time travelers out there but who would ever believe them anyways), so about all we really have to go on is just hammering away at the logic of the subject, what might or might not actually be possible. For however much I'd like to try and keep this note grounded in science and logic, I can't help but think it's gonna veer more towards the movies as much as anything else, but in the end, hasn't time travel fueled more science fiction plots than serious discussions anyways? And after all, an hypothetical example is about the only way we have of demonstrating our points since this, it would seem, is pretty untestable.

How?

First, I suppose the question of whether or not its even possible should be explored. Most books and movies have a habit of creating some kind of a plot device or another to explain away the problems posed over how it'd be possible to travel through time. This can take the form of say a flux capacitor (Back to the Future series), a magical ring, book, talisman or spell of sorts, or whatever kind of special time machine the writers have dreamed up. Superman even flew around the world and made it spin backwards in his first movie to achieve his time altering goals, though I'm pretty sure that would just cause a whole slew of natural disaster that'd kill everyone on the planet, not turn back time...

As far as distorting time goes, we know that the faster someone is traveling the slower they age. For example, if someone gets into a plane that travels twice as fast we are spinning on this planet, it will reach the same place in half the time (24 hours could have expired for the people who stayed on the ground, but for those in the plane only 12 hours would have passed). Alas, this is not distorting time in a big way. What benefit could you get from this other than to slow aging slightly, and even then you'd have to spend all that time on a craft of some sort moving faster than everyone else which would be boring as hell most likely. Even if you got on a space craft and returned after what would be a short period of time for you but years for everyone else, what gains would one get? Perhaps the sick could be put on such a ship in the hope they could return much later in the future when a cure were available though it might end up being merely a costly gamble. Anyone curious enough just wanting to see the future could do so this way, but they'd miss out on everything in between including the lives of family and friends who stay behind. I suppose you could age wine faster in this way, but it'd be a pretty stupid way of doing it.

In terms of a serious, scientifically possible way that would make time travel a reality though, the closest I've seen to it comes from the idea that black holes have a gravitational power so great that they can actually suck in and distort time. Nothing else I've ever heard of can distort time in quite this way. Even this has been used as the plot device for at least a couple of movies involving time travel: "The Sphere", and the recent "Star Trek" reboot which featured a younger version of Kirk and an older version of Spock who gets sucked into a black hole and back into time.

Paradoxes and Alternate Timelines

I suppose the real meat of the topic, however, is answering how time travel could actually work assuming it is even possible, and can time even really be changed? As far as I can believe, the idea that time can be changed is barely even conceivable. The word we need to define right now is: paradox. To put things quite simply, how can something be and not be at the same time? Sometimes you really can't have it both ways.

Let's assume for the sake of argument that you have a time machine. Creating a paradox would be as simple as say: Going back into time and killing yourself at a younger age so you'd never exist beyond that point in time. This would be a very glaring paradox, because if that were the case then how on earth could you have been around to go back into time and do it in the first place? If you subscribe to the "Back to the Future" way of thinking, I'm pretty sure that Doc Brown is telling you right now that this would have to be one of those events that'd destroy the entire universe. Some might ask, "Who would ever want to do that anyways?", and I guess the answer would have to be: "Someone who'd want to destroy the entire universe might wanna do that", but keeping in topic with this note...

Where does the phrase alternate universe come in? I suppose now would be the time to introduce it. The idea behind an alternate universe is simply that you've made what was once a possibility that didn't occur into a reality into one that did, and that there are now quite simply put, two realities (or alternate universes). I have a lot of problems with this idea that there could be multiple universes out there for every single possibility. Despite the fact that its stirring and cheerfully hopeful to think that we could right the wrongs of the past and make new choices, aren't there just too many possibilities out there at the end of the day? Wouldn't there not only have to be an alternate universe for the World War II never occurring, but also one for me buying a Coke this morning instead of tea? I suppose, in the end, one would have to say that only the possibilities that someone was really willing to put the effort into to go back in time and change would create alternate realities (unless of course going back to change their breakfast this morning were that important to a person and they actually went back and did it).

Putting aside all the problems I have with there being multiple realities let's assume now for the sake of argument that you did go back in time and kill yourself. Wouldn't you then have created an alternate universe where you no longer existed from that point on? Assuming for a second, that time is now recording a new version of events splitting away from the old (by the way, Doc Brown drew this on a chalkboard in the middle of Back to the Future Part 2), what happens to the old version of events you once knew? The one where you gained access to a time machine and decided to go back and kill yourself.

For starters, I'm pretty damn sure that if it is even possible to go back into time and kill yourself, it wouldn't mean that you never existed to go back and do it. This after all would be a paradox, and I think quite impossible. So then assuming we've created a new alternate universe by doing this, doesn't time as we once knew it still have to be out there somewhere, floating around, and not the reality as you know it anymore, but a reality nonetheless that must still exist in some shape or form because if it didn't a person could never even have existed to go back and kill themselves in the first place? Does this mean then that everyone who stayed back in the reality you once knew, and didn't go back in time with you, does this mean they're all still out there living their lives as if you disappeared when you went back in time? It would seem to me that it would have to, if I believed this were all possible (which I don't, by the way, more on that later). What then would be the ramifications of all this then?

A lot of people seem to think it would be a great idea to go back into time and take out Hitler when he was still young and vulnerable, if it were possible. Seems noble enough, his actions later caused an incredible amount of death, misery, and hatred. Who wouldn't want to go back and change that? But let's think about this again... if we changed things so that Hitler never was able to do what he did, well then we never would have even become upset about it in the first place, and thus never even resolved to go back and change things. Assuming that we could go back and change things and that this would create an alternate universe, wouldn't this mean that everyone who stayed behind and didn't travel with us back in time would still be out there, in the version of history where Hitler did do what he did, still bitter and wishing they could change things? Perhaps they'd be forever separated from those who went back in time and would assume the whole thing failed even if it succeeded. It seems to me that only those who actually went back in time and did the deed would be reaping the fruit of their labor. This by the way was the plot point that made me laugh to myself when watching Terminator Salvation. Seeing John Connor get all riled up and desperate to save Kyle Reese (his father whom he sent back in time from the future) kind of didn't make sense to me, because assuming that even if the machines killed Kyle Reese wouldn't John Connor simply go on existing anyways?

The way things were "Meant to be"

There is one other possibility for how time travel might work, and it doesn't include the possibility of alternate realities or even changing time for that matter. The idea behind it all, is that the version of events as we know them, are the only reality, and that any kind of time travel is simply a part of it all. To put things simply, there is a fate for us all, and there's no way to change it. In keeping with the way this note has been written, the movies: "Sphere", "Harry Potter and the Prisoner of Azkaban", and the TV series "Gargoyles" all used this form of timeline.

Perhaps the easiest way of demonstrating this concept is to take directly from "Sphere". In it, three scientists discover a spacecraft deep under the ocean and while exploring it, discover that it was made by the U.S. military in the future, got sucked into a black hole, crashed in the ocean, and nobody survived. At one point, one of the scientists turns to the other as says simply, "We're all gonna die down here, you know. If we lived to tell people about this, the military wouldn't have launched the ship in the first place. It would have done something to stop it all from happening. We're not meant to make it out of this and warn them..." Thinking about what this all means, while time travel is possible, changing things isn't. Things are all connected, and all is (for lack of a better way of saying it) meant to be.

Kind of a frightening thought in a way. We can't change things, we're at the mercy of fate. Though I suppose that since we've no way of knowing anyways it all amounts to about the same thing when it comes right down to it. But assuming it were all true and we could travel through time, then we would know for a certainty how things were meant to turn out. We couldn't change anything, but we'd know at least. We would know, for example, that going back in time to try and kill Hitler would end in failure, because history has been written, we see the outcome, we know he lived to do what he did. In the end, it really seems to me that this method of explaining things is the most likely. I honestly believe it precludes paradoxes, although it certainly has its share of detractors or those who have never thought about it, or just can't comprehend it.

The Terminator Movies

I'm putting this in here as a bit of an after thought, might seem a bit excessive to dedicate a small section to this, but its still fresh on my mind right now and I feel like getting into it. One example I failed to mention earlier was the first "Terminator" movie. You could say it followed this "one timeline" kind of philosophy as well. There was no changing the future, everything was meant to be. Reese was always meant to go back and father John Connor. It is usually at this point that people begin to ask: "But how could Reese have been sent back in the first place by John Connor to father... John Connor? How could John Connor have known? Isn't that a paradox?" I suppose the only answer is: "He knew to do it because he knew how the past turned out and that he was meant to do it." You might say that if a future version of yourself showed up and talked to you one day, that you'd know your destiny would be to one day be in the shoes of the person across from you, having the other side of the same conversation with your younger self. Again, you'd just know it was meant to be.

Getting back to the Terminator movies though, one might also ask why the machines didn't see the whole endeavor of sending a terminator back in time to kill the Connors as being doomed to failure. Them being such smart, aware, thinking machines and all, shouldn't they already have known how history turned out? Perhaps even the machines didn't know how time travel works, although that kind of makes them look stupid when you think about it. But then the second movie managed to explain this fairly well by showing that the first terminator to go back was actually the basis for the Skynet computer that ruled the machines. And so the machines would therefore have known they were meant to send back their terminator to fulfill this. The second movie would go on to include its main characters attempting to change the future and then end in a pretty ambiguous way so as to leave things open as to whether they succeeded or not. The first two movies were the creation of James Cameron, and while I can never entirely be certain if he intended to keep with this formula of time being monolithic, unchangeable, and fated, the fact is we'll never know (although an alternate ending of that movie suggested otherwise). The third movie tore down any possibility of with the "one timeline" theory with their whole: "You only delayed Judgement Day" schtick and, well, the rest is history. Kind of weird how the series as a whole is inconsistent in its ideas, though I suppose its bound to happen when you change creators mid-way through. For all the ideas time travel is worth, there really is no way for us to know how exactly it works, and putting how I think it actually does aside, I still enjoyed "Back to the Future", "Star Trek" and whole bunch of others whose ideas on time travel I had trouble believing.

1 comment:

John said...

We hardly understand what "time" might be, and only understand it enough to venture the occasional wild guess about how it might be manipulated. Because of that, I've never understood how people could use our current understanding of time to say with certainty that the manipulation of time was possible or impossible.

The same with black holes, you can say that anything at all happens when you enter one, because no one is going to be able to conduct an experiment that proves you wrong.

I've not read too much on the subject, but my understanding is that although 2 black holes could interact and merge to create a wormhole between them, that would happen at random and probably be uselessly rare. I would think that for it to be useful at all, black holes/ wormholes would have to be created and manipulated, and then fed with enough energy to be maintained while the link was kept up. I'd be surprised if we were able to collect enough energy over the next 1000 years to begin to experiment with something like that... and it might turn out that there simply isn't enough energy in our solar system to power such a process even if it is possible.