Today, I have a guest blogger, Will Finlay, writing about Time Travel. Will is a retired Electrical Engineer/Quality Assurance Engineer. He’s an avid reader of science fiction and science non-fiction. He’s also my editor and my husband.

Time Travel by Will Finlay

John sits on the edge of his bed, at the end of a pleasant day, thinking about time travel and time machines. John likes science fiction and just returned home after watching a good sci-fi show at the theater. In his head John is thinking about what it would be like to have a time machine. He envisions a great adventure traveling into some other time. He thinks how cool it would be to see what the future holds. Mulling over the possibilities it occurs to him that being able to travel to the future would presume time to be fixed, predestined, no one having any choice in their destiny. John realizes that if true, what we do today, what he is doing this very moment is also predestined. John frowns, not liking that thought at all. Why then are we striving to do anything if it’s all scripted, he thinks? Why not just sit quietly and do nothing for the rest of my life. Then he thinks, If my life is predestined, that is what I am destined to do. John decides he really doesn’t like this train of thought and decides this is not the case. So if our future is not predetermined, John realizes there must be an infinite number of future time lines, associated with an almost infinite number of choices yet to be made by him and the rest of the world. If he travels to the future, which potential future would he end up at? Would it be a different future each time he travels forward? If so, there isn’t really a true future, just some fantasy future, so why go there? Rats!

Remaining undaunted he decide there is always the past. And that truly is fixed (or is it?). John decides he could travel back in time to some special event that has happened, or maybe visit someone famous that he knows about. He thinks, yep, maybe I’ll visit Albert Einstein. He’s famous. In his head he rushes off to the library to find a specific time and place to meet Mr. Einstein. Since his time machine travels in time, but not through space, he must also make plans to travel to the appropriate locale. Wouldn’t do to end up at the right time, but be in the wrong place.

Ah, but then another serious rub occurs to him, thinking about where to meet Albert in the past. Is time travel somehow fixed to locations on the Earth? That seems to be what all the science fiction stories presume. What is a true ‘time’ location? Is finding a location and time on the Earth enough? The Earth constantly rotates around the Sun in space, while the Sun is in constant motion in an arm of the Milky Way galaxy. Is the Milky Way galaxy location in the universe even fixed? Crap! He suddenly realizes that without a true coordinate location he could move back in time and find himself floating around somewhere in outer space, asphyxiated, when all he wanted to do was have some fun and meet Albert. He realizes there may be more to this time translocation and decides that even buying a space suit wouldn’t help. He could still be stranded somewhere in space with limited air, still doomed to a somewhat slower asphyxiation. John decides that any true time machine must also incorporate a space craft capable of getting back to Earth pretty darn quickly (hopefully not translating into a sun or into an asteroid somewhere). John decides to call it a day and go to bed, dismissing his imaginary travel for the night.

Time travel has long been an enthralling topic of speculation among science fiction writers, capturing the imaginations of avid science fiction readers and sometimes even scientists and science buffs. Some, not so starry eyed, totally scoff at the thought, greeting proponents with utter disgust and haughty derision. For others, the idea of traveling in time (other than the day to day forward time travel we living beings are all already doing) is met with a kind of hopeful romantic affection, opening a world of infinite possibilities.

For me, one knotty problem associated with time travel is the ‘time paradox’. According to Webster’s Dictionary a paradox is an inconsistency or contradiction, a statement or event that is seemingly contradictory or opposed to common sense and yet is perhaps true, or an argument that apparently derives self-contradictory conclusions by valid deduction from acceptable premises.

One simple example of a time paradox would go like this: You travel back in time and eventually meet your younger self (having not asphyxiated in space and somehow winding up at the right place on Earth). You buy a gun and shoot and kill your younger self (apparently always hating some affectation or characteristic about your younger self). As foolish and stupid as that might seem, you kill younger you. But wait, there is a problem. If you shoot your younger self, your older self would not exist, except as a rotting corpse in the future, obviously not able to time travel back and shoot your younger self (excepting as a zombie, but that is another discussion for another time, no pun intended, that we will not deal with here). This, my friends, is a paradox. If you can indeed go back in time, you might find your younger self (considering you know all about younger you) and there is nothing prohibiting you from actually performing this really stupid act. So does your younger self get shot by some future wraith that then disappears? Because if younger self is indeed killed, older you does not exist. And in fact older you should be realizing at this point that you do not remember somehow being dead, someone shooting and killing you. What are we smoking here? Maybe there is something wrong in this equation.

Some gutless authors make their stories fly by writing silly prohibitions into their time travel stories whereby the traveler is severely counseled against changing any past events or causing any harm, screwing up the future and creating one of these insoluble paradoxes. Yeah, like that’s going to happen. You go back in time, you breathe the air, walk on things, touch things and take up space, minimum; How long before some inconsequence or combination of inconsequences becomes consequential. Maybe the author of those books should have restricted his traveler to only looking through a video portal screen at the past, to avoid the traveler making changes to the past. Then no one is actually traveling in time, just making a new kind of History channel (But I guess that book would be rather boring). A few authors sidestep the paradox potential by claiming that only key events are historically pivotal, just avoid those (hopefully someone has made a list of pivotal things to avoid). And some authors simply do not try to explain the paradoxes at all, forging ahead as if logic and reality are of no consequence (Quality control problem).

Other than shooting oneself (a rather a glaring psychological problem), what if the time traveler actually changes some pivotal event? In most stories, the tellers depict the traveler eventually going back to their original time and finding that some things or everything has changed. You may no longer be married to your spouse (for better or worse), your job may no longer exist (again, for better or worse), or you may no longer exist, having been killed along the time line back when (Rats! Yet another paradox to explain; or at least a problem with the IRS). Or if the time machine suddenly ceases to exist because it has not been invented in this present, you may be in serious trouble (At least the sanity of the author may be in question at this point. Questions involving time travel and paradoxes can cause severe headaches, at the very least and lead some to throw up their arms in derision and join the other team). However, most time travel authors seem to slog on, refusing to give in, some changing their tack and claiming in their novels that ‘one cannot influence events that have already happened’ (The ‘universe’ somehow actively interdicts to prevent change).

Another phenomenon common in time travel yarns is the “mini-loop” which creates a “divergent” universe. John lives in spacetime “TA”. John, it turns out, is an amazing scientist, having just built a prototype time machine, he calls his Chronocraft. To avoid being asphyxiated, buried alive, crushed, imbedded in walls, exploded or experiencing other such ‘untimely’ outcomes, John’s craft flies into space before jumping through time and prohibits reemergence into other solid objects. Being anxious to try it out, John climbs in, closes the door, performs pre-flight checks, establishes a chosen time in the past, flies into space, and then engages his time travel circuitry. Moments later (or is it earlier), after determining he remained alive and presumably intact, John flies his Chronocraft back to Earth to the site of the event or person he wishes to experience. Unfortunately, unbeknownst to John, being inexperienced, over enthusiastic and a bit careless in his interactions with past history, during his sojourn he manages to change some historically significant factor in the past. John returns to his hidden Chronocraft, and travel forward to what he presumes is his present, only to discover he is no longer in the present (“TA”) he remembers. Some subtle and some not so subtle changes have occurred and John is delirious with fear, shaken and aghast at what he has wrought upon himself. We shall designate this John as John “B”. Unnerved, John quickly gets back into his Chronocraft and returns a few moments earlier into the past, in hopes of correcting his mistake. He awaits his earlier self (John “A”). When John “A” arrives, he is surprised to meet John “B”, who quickly explains the situation. John “A” races back to his Chronocraft without interfacing with the past and returns home, and thus avoids changing history (or so they think). This loop travel to warn oneself may allow John “A” to return to his own time-stream, but what of John “B “ who conveniently popped out of some micro-dimension to warn John “A”. Does he cease to exist (POOF!) once John “A” returns without changing the past? Or, does John “B” continue to exist and go back to the divergent timeline “TB”. If John “B” goes back to “TA” there would be two Johns (rather awkward, especially to his wife and family).

The idea of time travel makes time seem flexible, not a fixed forward marching time stream, but a dimension we can get into our cars and drive around in. Without explanation of time’s characteristics, we can suddenly ‘move through’ time. Many current time travel entrepreneurs address this flexibility dilemma by whipping up alternate time streams and multiverses to address glaring paradoxes. If a time traveler changes some historically relevant event, when he/she returns to his/her present, the traveler jumps or winds up in a parallel or divergent time line. This idea of parallel dimensions (although parallel is a two dimensional misnomer here) or a multiverse, if you will, actually describes some glimmer of thought regarding time as a dimension. If time is truly a dimension, we may use our three familiar dimensions (as Mr. Einstein often did in his musings) to begin posing ideas about how the time dimension might function. We shall awaken and utilize John again for this.

John walks out his front door, turns and closes the door. He finds himself outside now, standing on a plane, stretching to infinity in all directions. He picks some intricate combination, avoiding obstacles like houses and lakes (houses hurt to smash into and it is too cold for a swim) and begins to walk, also perceiving himself as moving forward in time, John’s mind recording his chosen choices and the journey. John is free to walk wherever he wishes on that plane. (That is, within any physical barriers encumbering those two dimensions. We use two dimensions here for ease of discussion, though three dimensions could also be applied.) In kind, John’s choices define a path in time that he also walks, called his life. At every moment John makes choices that create John’s time line. However, at every choice, every moment, there is also phantom Johns that make different choices. John “A” walks one direction, John “B” walks another, John “C” yet another and on and on. Just as there are an infinite number of paths John could walk, there may be an infinite number of Johns walking an infinite number of divergent timelines in the time dimension. Our John, alas, with his limited capabilities is restricted to only walk one path, his mental chronograph only recording this one chosen sojourn. But in the time dimension, an infinite number of choices depict infinity John, those infinite number of choices all existing, just as the two dimensional plane allows an infinite set of paths. As another dimension, all those paths may exist in the time plane, allowing John to pick a journey (Without time, one can go nowhere in our three dimensions).

Our three dimensions create an almost (if not actual) infinite physical universe in which we can travel. Could the time dimension be ‘choices’ existing and giving reality to an infinite number of universes, with its own set of time ‘houses and lakes’ in our path? Envision our lives as time lines where at any given moment we make divergent choices, propelling us through an infinite number of parallel life paths or universes, along with billions of others. In time traveling to the past, instead of making divergent choices (already made moving forward in a linear manner), perhaps when we influence (change) the past we instead jump across to a different linear time line, causing the trip forward to land us into a different future. So time traveling could entail jumping across time lines, perhaps getting us lost in time forever. Food for thought.