The Time Travel Fallacy, part 3

This is the third article in a mini-series on time travel. To read the first two articles click here and here.


Issue 3: What happens to a person who time travels?

There are two main questions I want to look at with regard to a time traveler's person. First, how does one's body time travel? This is much like the question of how one can teleport, as bodies are broken up into pieces of matter or energy and reassembled upon arrival--is the person who arrives the same as the one who embarked? And second, assuming the person remains the same after travel, what does the differing passage of time do to the traveler? Not only does time pass more slowly the faster one is traveling, but the process of time travel would mean that one who spends significant time in the past would return to the present measurably older than he left.

Now this is starting to get ridiculous...

Starting with bodily effects of time travel, the result would depend on what manner of travel is used. There are two main methods I can think of: travel by vehicle that moves beyond the speed of light and travel by "teleporting through time" in a stationary (or sometimes rotating) machine. While I can feasibly see the vehicle method resulting no physical changes in the traveler, I am more skeptical about the results of travel by teleportation.

As I understand it, such time travel involves the traveler being teleported from a particular place and time to another. I'm not sure how such a machine would accomplish the "time" portion of the teleportation, because it seems most theories of time travel require massive physical velocities to accomplish the slowing and reversal of time. Nevertheless, let's assume it's possible to be instantaneously zapped from one time to another. Even so, how does that work? Because such teleportation requires the disassembling and reassembling of matter at the molecular level, it would seem reasonable that--even if the same human form emerges on the other side, it would not be the same body of consciousness. In other words, outside observers would see the same person (and for all intents and purposes it would be the same person), but the consciousness and awareness that exists in that body would be different.

To break it down further, think of a person as an "original." When the atoms that make up that original are teleported, they must, theoretically, be broken down into energy (or at least to the smallest atomic structures possible). The thinking is that you can't pass a 160 lb. person through time and space in its entirety. Then, the body is reassembled on the other side (this would be the work of a retrieval machine that has scanned and stored the structural data of the traveler, e.g. the Transporter in Star Trek). In essence, the time traveler is scanned in the copy machine at the take-off point and printed out at the destination in another time and place.

Here we come across the troubling question: who is this "printed" person? I have to believe that consciousness can't travel across time in the form of atoms or energy in the way that a body can. If this is true, the person arriving would have the mental knowledge, wherewithal, and capabilities of the original, but it would not be the original in the true sense. This is of little consequence to the outside world, because your friend Dave would still be Dave--he remembers your trip to Vancouver, can still recite the Shakespeare he learned in college, and has the same character and personality traits as Dave has always had. But the original  "consciousness of Dave" is now gone. This may not matter to the larger world, but to the original Dave it's a pretty big deal!

Putting aside this concern, let's look briefly at the effect of the passage of time on the time traveler. We already know that time passes more slowly the faster something is traveling--at least, relative to its slower-moving counterparts. This has been observed in astronauts who spend large amounts of time aboard the International Space Station, who are a few seconds younger than they would have been on Earth during that span. Consequently, it seems reasonable to believe that a time traveler would age significantly slower during his travel, relative to time's passage on Earth. Because time travel theoretically requires movement beyond the speed of light, it would exhibit the ISS effect to the extreme.

However, what about one who spends time in another era? Presumably they would age at the normal rate of a being at rest in that time (that is, they would age at a 1:1 ratio with what is standard on Earth, if that's where they are). However, their age upon return depends entirely on (1) how long they were in that other era, and (2) what time they choose to return to, relative to their departure time. This second point means that  a person who spends a few years in another time and then returns to his contemporary time at even the exact moment he left will suddenly appear much older. Taken to the extreme, someone who chooses to return sometime before he left will compound the effect and age before he left.

As far as I can imagine, this aging phenomenon will only go one direction--forward. So time travel for long periods of time would become an "at your own risk" scenario, where one would essentially choose to live his live at normal speed and time in his contemporary age, or spend time traveling throughout the years. The more time travel a person undergoes, the less time he will have to spend in his contemporary time due to the ongoing aging. This doesn't account for the time slowing effects of extremely fast travel in a time machine that actually moves. However, even in such a case, the person will age once he reaches his time destination. That aging can't be undone, no matter when he chooses to return to the present.

In sum, it seems that time travel is a risky proposition for the one doing the traveling, even if all of the possible kinks are worked out. I'm not sure that I would volunteer for such a trip.

The Time Travel Fallacy, part 2

This is the second part of a multi-part series on time travel, posted weekly on Tuesdays. For part 1, click here.

A sequel? Well, all right...

Now that we've discussed the problem with time travel's effects on reality and events, I'd like to move on to the issue of why no one has ever been outed as a time traveler. (I think the closest we've come is Nicolas Cage, the immortal / time-traveler).  Are time travelers that stealthy? What's the deal? Without further ado, let's dive in.

Issue 2: If time travel were possible, we would have already encountered travelers at some point in history.

This one is pretty easy to wrap your head around, even if its implications are pretty far-reaching. If, at some future time, humans gain the ability to time travel, why have there been no confirmed (or as far as I know, officially reported) instances of encounters with time travelers? One could easily imagine a situation where someone heads back in time and is unable to hide their identity as a future-person, thus tipping off those of us in the past. For instance, if future time travel becomes a new recreational activity (like the time vacations that are so common in the future in Family Guy), it would seem inevitable that someone would slip up and let the cat out of the bag. Because this has never happened, it leads to one of three possible results:

     (1) time travelers have been unfailingly diligent in covering their tracks,
     (2) time travelers have rarely to never visited a time in which humans exist, or
     (3) time travel simply is not possible.

I would argue that possibility (3) is the most likely on this list. The chances that no one will ever slip up while time traveling is all but impossible, even if authorities are somehow able to restrict its use to "official, non-commercial use only," like the military tries to do with a lot of groundbreaking new technologies today. Only an outright ban on all time travel (before it even begins to be used) will prevent a foul up in traveling to the past. Possibility (2) is also very unlikely, because the thought of traveling to times in which past, historically recorded events have occurred is essentially the main draw to the ability to time travel. There is very limited utility in only traveling to times in which trilobites roamed free and humans were millions of years in the future.

This list of possibilities ignores the possibility that is always looming in the margins of such things: that the answer is "we can't comprehend it with current understandings." I'm willing to accept that as a possibility, it just doesn't make for a very interesting discussion. Perhaps there is some future technology that renders it impossible to unmask a time traveler, or perhaps there is some aspect of the time travel process that perfectly disguises the fact of travel. But while that is possible, remember that the simplest explanation is usually the right one. And in our case, the simplest explanation is that, given the concerns above, time travel is not possible.

I recognize that an argument could be made that relates the fact that no one has verifiably encountered aliens. The gist would be that, the above scenario, when applied to alien encounters would essentially mean that there are no intelligent life forms on other planets. That is a logic leap I am less willing to make for a few reasons. First, there is a difference between the two subjects because aliens would travel (presumably) in their contemporary time, so there's nothing that says we would have to have already encountered them if they are out there. Think: if they are progressing technologically at the same rate as humans (from the same starting point), we would not have encountered them at this point because we have not been able to travel intergalactically ourselves.

If he can become a flaming skeleton, time travel's a cinch.

The other key difference is the application of Occam's Razor. In the time travel situation, it is indeed simpler to say we have not encountered time travelers because time travel is not possible. But with regard to aliens, the unimaginable vastness of space tilts the scale, leading me to believe that the simplest explanation (which is usually the right one) is that we haven't encountered visitors because (1) we haven't expanded our own universal footprint enough to find them ourselves and (2) there is simply a lot of empty space out there.


To summarize: if time travel is possible, where are the travelers? Is Nicolas Cage the only one who has been allowed access to time travel? Or is he the only one who (may have) slipped up? I suppose we just don't know (yet).

The Time Travel Fallacy, part 1

This is the first in a multi-part mini-series on time travel. I plan to release three segments--one per week--over the next several Tuesdays. However, that's not a concrete situation, and I may add more if more aspects of interest arise.

Time travel, as I see it, has a few problems. I'm not going to wade into any physics issues, or the concern about the ability to surpass the speed of light, but rather simply discuss a few issues that I perceive in a metaphysical manner. There are two specific issues, possibly mutually exclusive, with time travel in general. Because of the length of discussion that can go with each, I've chosen to break this post up into three parts. The first will concern how any changes that are made via time travel would have already occurred in the present from which the time traveler came. The second part will discuss the argument that, if time travel were possible, how come we've never exposed anyone in history to be a time traveler? The final segment is slightly different, briefly examining the implications of time travel for the person doing the traveling. Without further ado, let's dive into the first issue.

Issue 1: Changes made in the past would already be perceived in the future as "normal," and hence no changes could subsequently be made.

Roads? Where we're going we don't need roads.

There are dozens of movies, books, and TV shows that use time travel as a main plot tool (and, as it turns out, many more TV shows that use time travel as a device in at least one episode). The most common situation has the protagonists going back in time to interact with characters that are presumably baffled by the appearance and existence of the time travelers. However, under the theory of time travel to which I subscribe, none of these stories would go quite as they're depicted for one key reason: time travel that changes a past reality in any way will be reflected in the future from which the time traveler came, and thus whatever changes he or she may make in the past would have already happened in the reality as it exists in their contemporary time. 

This doesn't mean that one can't necessarily change something through time travel. I think it's silly to say that, if time travel is possible, one cannot actually perform any action in the past that would have a future effect. But you can't have the present exist in one form, go back in time, and return to a completely different present--at least, not in the "universe" that the previous present exists in.

What does this mean? Stay with me, because I fear I'm losing you, if not myself. Let's look at an example in order to try and hash it out. If I'm disappointed that I'm not financially well-off in the present (2012), but I inexplicably also have access to a time travel device, I may decide to go back in time and set myself up with some great investment. I could go back to 1980 and buy into the Apple IPO, reaping huge rewards when I return to 2012. Sounds good, right? Well I don't think it's quite that simple.

First of all, from a purely economic perspective, if this could be done, people would flood back in time to invest in things that turn out to be big, and as we see, not many people actually have the foresight to start early on with a big winning investment (i.e. we would probably see many more people win big in great investments). Similarly, people would pull this trick with Powerball by learning the numbers and going back in time to buy the winning ticket. Not only would this ruin the value of such lottery games, it would have been noticed by now (to be discussed in segment two).

Now, to examine the example from a time travel perspective. Let's say I have a time machine and use it to go back in time and buy into Apple. I also have a friend who agrees to run the machine and wait in my basement, manning the controls while I'm gone (although if performed correctly, I should return to the present at the same time I left, or even before, which could open up a whole different can of worms). How does that friend perceive this supposed shift in the "truth?" It's easy for one to picture the change from the traveler's perspective, because the time travel event functions as the change point, where on one side I don't have the money and on the other I do.

But for people who are in the present, how do they see it? Do I return from my trip (imperceptibly, as I said) and he suddenly knows I have several million in my bank account? Where does the trigger event happen where he goes from "knowing" I'm broke in 2012 to "knowing" I'm rich in 2012? Nothing will have changed for anyone who didn't make the trip, right? Perception of events as they exist (or passed before) are pretty black and white. My friend, who knew about the time travel mission beforehand, will not be able to perceive the difference between "before I left" and "after I got back." No time will have passed in his perception, and there will be no triggering event for him.

It is partially for the above reason, a paradox of sorts, that I have trouble conceiving of time travel. To people who did not make the trip (if indeed such a trip is possible), there is never a trigger moment at which reality changes. Assuming, arguendo, I succeed with my Apple IPO mission, from my friend's perspective (as well as everyone else's), I have always had the fortune I gained in 1980--just as Oceania has always been at war with Eastasia.

I suppose this isn't to say that changing events isn't possible. All it says is that events that are changed will have always been changed, and hence no change will be made. This subtle distinction may in fact be self-defeating, because if any time travel changes will have always been "reality," how will I know to go back and change them? In a circular way, if I go back in time to change something, it will never have existed in any other way upon my return, but if it never existed, how can I need to change something, hence what purpose would time travel serve?

To avoid tying my brain in any knots, I'll end here. But after parsing all of this out, it appears to me that time travel--at least for the purpose of changing past events--is not plausible. If changes made through travel are imperceptible in the "new" present, and have always been as they become after the trip, how can one time travel to make those changes in the first place? I also avoided getting into the "multiple universes" theory of time travel and teleportation, because that will make heads explode.

The post is best read with this song playing in the background.