Alright, now that we got all of that boring science and “reality” out of the, it is time to move onto the fun parts of time travel. But, before we can explore the repercussions of time travel, we have to take a look at our understanding of time itself. Namely, is there a single timeline or infinite possibilities? (This is of course assuming that time is linear at all, but that is a much bigger discussion for another… time.)
There Can Be Only One!
So, let’s say there is just one timeline. One classic example of the danger here is called The Grandfather Paradox. A time traveler goes back in time and accidentally kills his own ancestor, thus ending the family line. He can’t return to his present, because he will no longer exist. The only way for him to ensure that the family line continues is to impregnate his grandmother, thus becoming his own grandfather. Personally, I find this particular thought experiment a bit silly considering that we know how DNA and the transference of genetic material works. If the time traveler did in fact kill his grandfather, impregnating his grandmother would not result in an exact copy of himself two generations later. Conversely, if killing his grandfather were to cause him to never be born, then he would cease to exist the same moment that his grandfather’s heart stopped beating, and wouldn’t have time to woo his nana (ewww). If he did not immediately blink out of existence, I suppose that grandpappy might have had some of his little swimmers on ice, but that would really be the only way around it.
But here is the thing about linear time, in a universe with only a single timeline, every decision that is ever made, has ever been made, will ever be made, is already certain. That may seem like a bit of a leap, but think about it this way. Your present is someone else’s past (let’s call her Amber), and someone else’s future (who will be known as Zoe). To Amber, the time at which you are reading this article is the future, and seems uncertain and full of possibilities. But, from Zoe’s perspective, the events of the past are set in stone, immutable and measurable. The “truth” of these events could be obscured, but the events themselves happened the way that they happened. And Zoe’s present is someone else’s past, and so on and so on. In this case, the act of time traveling is moving up or down along this single line and the actions that take place there have happened, are happening, and did happen, already.
Some authors and movie makers get this right. In Harry Potter and the Prisoner of Azkaban, for instance, Harry and Hermione end up going back in time a few hours to save Harry’s godfather. During the first time through these three hours, a few mysterious things happen. Rocks fly through Hagrid’s window, alerting the teen wizards of the Minister’s approach. Later, a howl in the distance distracts the werewolf that is attacking them, thus leading it out into the forest and saving the kids. When Harry and Hermione go back and revisit these events, Hermione realizes that it must of been she who threw the rocks and made the howling sound. She acts because she knows that she has already acted. Another series that does a lot with teleportation and time travel and handles it brilliantly are the “Dragonriders of Pern” books by mother and son team, Ann and Todd McCaffrey. If you have never read these books and are looking for a world that straddles fantasy and science fiction to fall into, I highly recommend them.
To Infinity, and Beyond!
The other side of this cosmic coin is the idea that there is one timeline for every choice made by every person who has ever lived, because reality splits based on these untraveled roads. There is world where you had strawberry jam on your toast this morning, and another where you had grape jelly. If that sounds daunting, keep this in mind: people are not special. If we follow this idea to its logical extension then there has to be a new branch of existence for decisions made by the human race, then there must one for every dog, fish, amoeba, and atom that makes up the known (and unknown) universe.
So let’s bring our time traveler into this scenario. He travels back in time, or he doesn’t. He makes it to the right time, or he doesn’t. He eats a cheese sandwich, or he doesn’t. While choking on the cheese sandwich he steps on a man’s foot, or he doesn’t. This man is his grandfather, or he isn’t. The man is angry, or he isn’t. They draw pistols at dawn, or they don’t. The time traveler kills his grandfather, or he doesn’t. Not to mention what anyone is wearing that day, whether they put on after shave, kissed their kids goodbye, or put on their pants starting with the left or the right.
For the sake of stories, people don’t generally roll with this notion to the extent that I just demonstrated, because it gets confusing and weird and bogged down in details about pants. Some people only focus life-changing events or big decisions, such as where to go to college or missing the train where you would have met the love of your life. They figure the stuff about pants will probably work itself out, and amounts to very little in the grand scheme of things, and they are probably right. It mattered very little what I was wearing or what I had for breakfast the day that my husband’s eyes met mine across the crowded lecture hall, but the fact that I signed up for a class so far outside my major made all the difference.
But, let us return to our time traveler. We can’t totally abandon everything in the multi-verse, because some choices DO make a big impact. In the case of the traveler, the fact that he traveled through time at all is a huge deal. It seems safe to assume that ripping the fabric of space and time asunder would be enough to create a new branch of the timeline. Next, killing grandpa (let’s call him Mr. Smith) would definitely count as a big deal, at which point time would bifurcate again. Aright, so in this one branch of time where the traveler went into the past Mr. Smith is dead. But, this is still linear time we are talking about here and the split between time travel and no time travel occurred AFTER the events in Mr. Smith’s day, so the time traveler would be safe from disappearing. Instead, there would be a whole new branch of time that snapped into existence to reflect the absence of Mr. Smith.
So, the time traveler will not blink out of existence. In fact, even if he went back to when the most advanced creature on the planet was a reptile and killed them all, he would still exist in the multi-verse. The biggest issue, then, becomes picking out the right timeline to land in after the trip is over.
Back to the Present
Please do not mistake these ruminations for lack of love or respect for time travel tales. I enjoy them precisely because they make me think about things like this. The idea of visiting another timeline where the choices were all different is an exciting train of thought, and exploring these meanderings through time in stories is a unique way to navigate an examination of the human condition. In a way, traveling into the distant future is a way to cheat death. Traveling into the past allows an opportunity to see our roots and find out more about what brought us here in the first place. We experience the present so clearly, looking for a way to bring the past or future into such focus is not just understandable, but laudable.
I mentioned it in Part 1 of this article, but for people interested in time travel, I cannot recommend The Time Traveler’s Almanac enough. It is an incredible collection that spans over a century of the best short stories around.
Until next time…