At this point we are going to take a step back from the ebb and flow of the narrative to provide you with an entry in my Journal about the basics of time travel. If you cannot wait to find out how the story will unfold or, more likely, you do not give a flying whatever about the inner workings of time travel, skip ahead until the next chapter. Fulfillment and enlightenment are not for the likes of you.

Still here? Excellent! I shall try to reward you by not bludgeoning you to death with my mastery of the subject. For those with severe cases of masochism, feel free to go to the Archives and ask it to explain time travel. Be sure to bring lunch (and dinner and breakfast, for the next several days). Time travel is a hideously complex topic described and explained by millions of words, pages of formulas and diagrams, video presentations with animated cartoon figures and somber scholars (not infrequently in the same video), and tables of data that would de-forest the world if committed to paper.

What you will find here is the story that the Arisa tell Shepherds and cognitively-challenged children (presuming that such children could exist in the infinitely perfectible society of Arisa). So far as I know, what I am about to present is all true, but it glosses over everything that would trip your mental circuit breakers. Of course, the vast majority of Arisans, while aware of time travel, actually know less than I do (or that you will know when you finish the chapter).

What follows is a series of relatively short topics, each of which builds upon the proceeding topics, that will infuse you with a basic understanding of how time travel works and what some of its limitations are.
The Metaphor of the Rope
Metaphors are essential for teaching complex concepts to simple minds. If you are a “smart person”, you get to talk about mathematical models or theories, which are the same idea, rhetorically, but dressed up in formal clothes. In any case, we need to talk about “time”: the flow of events; the transformation of the future into the past. We could think about time as a river or a branching tree, but we are in the cheap seats here, with limited resources, and, for our purposes, “time”, with all of its aspects, is a rope. If we look with a critical eye, a physical rope is made up of several braids, each of which contain several strands, which in turn are made up of multiple fibers. Our metaphorical “rope of time” realizes this nesting within nesting, with layering that is much more extensive: the universe is made up of galaxies, galleries break down into star systems, star systems consist of suns and planets, planets encompass people, rocks, bacteria, plants, animals, paintings and so on. If we were trying to stretch the point, even atoms and their component sub-atomic particles would have their place in the “rope of time”.

The life of each individual element is represented by a fiber in this rope of time. Each point along the fiber defines a place and time where the individual exists. The beginning of the fiber is conception and birth; the end is death. Alice whose only exposure to time travel is to follow the flow of time from future into past has a simple fiber. Bob who, for a while loved Alice, has a fiber that comes to parallel that of Alice and then drifts away. And what is the shape of the fiber of Carl, the time traveler? Patience, we will get there in a while.

The rope of time supports multiple viewpoints. The common experience of human conscious is to perceive our passage along the fiber, starting at the beginning until the inevitable end. Our internal clock may tick slowly and then quickly, but it always ticks. The expectant future rushes toward us and quickly recedes to become the remembered past. We are always “in time” and “of time” without the possibility of escape.

Oh, I see you over there. You are thinking that we can escape from the tyranny of time through the use of time travel. I am unfortunately the bearer of cruel tidings. There is no escape. Oh, we can bend and twist time and, for a little while, make it appear that time has no meaning, but when the sums are totaled up, time stands first in line to collect what it is due. Perhaps it is the case that other beings have a different experience of time, but we are human and our humanity is bound up with the inevitable passage of time.

Stretching our metaphor, we can step outside of the rope of time to view it stretching out from our vantage point into the past in one direction and into the future in the other direction. A word of caution here: it is unwise to ask questions about the where, when or how of our vantage point; the answers exist but your head will hurt for hours after you hear them. Looking at the past, present, and future of the “rope of time” in this way suggests that they are all equally accessible. It turns out there are problems visiting the future and coming back to the present. No one knows how to make that happen. In other words, if we travel in time, we can only travel in time into the past.
Adding In Time Travel without the Big Complications
And why do we want to visit the past? There are three reasons: the first reason is that we want to get information that we don’t necessarily have about what happened in the past. The more distant the events of the past are, the more likely it is that we have incomplete and even contradictory information about these events. Traveling through time to the past makes it possible for us to see and record what actually happened. The Arisa have a need to understand fully the events that have produced the present. The second reason is that we want to retrieve objects from the past. The Archives is stuffed with art, great and not-so-great, examples of technology, and many other items for which no justification exists other than it was just there for the taking. The third reason is that we want to change the events that make up the past. This last purpose is definitely associated with “big complications”; we will defer our discussion of it to later chapters.

This section is about visiting the past to collect information. We are going to assume that the intent of the visit to look at but not alter the past. Our journey follows this path: we start out from “right now” on the rope of time, travel back in time to experience a particular temporal and physical region of the rope of time, and then return back to “right now” plus a few minutes with new information and memories.

In other words, in terms of our rope metaphor, we need to tease out a fiber for Carl, our time traveler from above, elongate that fiber so that we can pull the fiber as a loop back along but just outside of the rope of time to the temporal region that Carl is to visit. Once the loop of the fiber is long enough, we can attach the fiber to the rope of time at the earlier point. As long as that fiber is attached to the earlier section of the rope of time, Carl experiences time as if he were in the past. After Carl has achieved his purpose, we detach the fiber and then pull it back to the region that we referred to as “right now.”

The path of the fiber represents the journey of Carl. Before the visit, he moves along the fiber within the rope of time in the usual fashion. The mechanics of the visit pulls his fiber back and allows him to experience time at an earlier point along the rope, and then detaches the fiber and brings him back to the present. Carl has traveled in time to the past and returned. From Carl’s perception, there is a continuous and contiguous experience of time flowing by. The passage through the parts of the fiber that are not attached to the rope of time are experienced without duration; the traveler is outside of time; the clock cannot and does not tick.

Now, understand, there are many different complications that we can introduce here but we will hold off on most of them because we don’t want you to run away shrieking and speaking of demons. Even given the risks of gibbering madness, there are some complications that we must address.

The first complication requires that we must balance the books: the amount of matter and energy in the rope of time at any given time is a constant. When we attach the fiber to a past region of the rope of time, we are adding matter and energy, violating this rule. We are compelled to remove an amount of energy and matter equal to what we inserted to keep everything squared away. When the traveler leaves the past, we have to swap the removed matter and energy back in.

The above doesn’t even begin to convey the complexity that’s involved here. If I venture into the past, I must breathe the air, quite possibly drink the water and eat the food, excrete wastes (thank you so much for the delicacy), heat and cool the environment, and in so many other ways interact with the past environment. At the end of the visit, it is very difficult to draw of crisp boundary between what belongs in the past and what must accompany the exiting time traveler back to the future. The machines of time travel expend an enormous amount of computing power to keep all that straight and make sure that the books balance up at the end of the visit. It is a difficult task which is relieved greatly by the fact that one oxygen atom looks a lot like another oxygen atom.

A key insight here is that time travel involves the movement of physical things back in time. In our metaphor, we can “stand outside” of time and see the rope of time stretching out from past to future. It is tempting to think that we could just “look in the windows” and avoid all manner of complications springing up from the act of entering the rope of time. It is not to be. Entities from the temporal realm have no place in this “outside”. It is only through tricks and deception that we can secure safe passage. Oh, the “windows” exist but, even with the tricks, the shades are lowered and the drapes are closed. We can see shadows moving about and hear murmurs of conversations but to experience the past we must be securely inserted into the rope of time.

Every time you inject a machine or a person into the past, you take the risk that you will change the past. As we will see most changes are of no consequence but a risk is a risk. It is less risky to send back a simple machine that has a minimal interaction with its environment, but situations arise that call for a person to handle the uncertainties and complexities of the past. That is why I, as a Shepherd, exist.

A second complication is that the rope does not wait silently for us to find it. It twists helically in time and space to reflect the orbit of the earth around the sun, to reflect the orbit of the sun around the local galaxy, and to reflect the whole host of other movements that add complexity to the visit. The machines expend even more computing power to keep all this straight and to make sure that the time traveler does not arrive in the middle of outer space or traveling a thousand miles an hour relative to the target location. Neither outcome is a happy one.

The third complication is that while machines make the transition back into the past without any kind of adverse effects, the same is not true for human beings. Complex formulas predict how severe the nausea of a time jump will be, but in the simple terms that we are using here, the more energy that is used for the time jump, the more nausea that the time traveler is going to suffer just after each jump associated with a visit. The susceptibility to nausea is accumulative, dissipating only slowly over weeks. That notion that you had about a mountain hide-away tucked away in the Rocky Mountains of 100,000 years ago. Forget about it! The commute would kill you.

The final complication is that the act of attaching and detaching a time traveling object to a past time, adds a particular kind of temporal energy to that past time. The more material that is attached, the greater the amount of energy that is imparted to that past time. The greater the energy imparted to that past time, the more difficult it is to attach subsequent time traveling fibers. This is called saturation. Two opposing factors struggle with each other: one is the desire to know as much about the temporal region as possible before sending back a real-life time traveler. Not even the most courageous time traveler wants to go in to a temporal region completely blind. That is a good way to get dead in a hurry. On the other hand, each probe into the past adds temporal energy to that temporal region and increases the saturation. Send enough probes, and the temporal region becomes too saturated to be reachable.

Dealing with all these factors and complications means that time travel takes an enormous amount of power and equally enormous amount of computation to make it happen properly. Time travel is the province of the large machines and of large staffs of humans and machines. The practice of hundreds of visits back into the past has smoothed out a lot of the wrinkles, but it is still an extraordinarily complex and difficult thing to accomplish.
Stealing Treasure from The Past
The past contains objects that the present does not. There are material objects deemed vital that have been lost. There are documents, corrupted or destroyed, that have value to historians and to the time Mappers and behaviorists. There is artwork and other collectibles that provide motivation to travel to the past.

The overwhelmingly most popular purpose for a visit to the past is to collect information. Part of the reason for this popularity is that such a visit is comparatively simple. We jump a very small machine that has very powerful recording capabilities to the right place and the right time in the past, turn on the recorder, wait for a while, turn off the recorder, and jump back to the present time. Carefully done, we get exactly what we need. These machines can be very small and have essentially no impact upon the past that could ripple into the present. This is very much in keeping with the values of Arisa.

But there are times in which the purpose of the visit requires more than simply recording information. The entity to be recorded may be too complex to capture in the time that is available. Biological objects often fall into this category. To get an accurate record, it would be necessary to send back a full analytical lab. Such labs are of good size and require much more energy. And then there is the potential problem of having that lab fall into the hands of people in the past, triggering all sorts of paradoxes. The Arisa fear time-travel paradoxes and are prepared to go to great lengths to avoid them.

Let us suppose that we have established by various means that a famous painting was destroyed by fire at a particular place and at a particular time. In such cases, it’s often much simpler to pull the painting back to the future, leaving in its place ashes that are indistinguishable from the destroyed painting. The beauty of this is that there is no uncertainty. The Arisa do love their certainty.

Contrast this with a work of art that has been “lost” to the people of the past. The amount of uncertainty here is substantially higher. To steal a painting that is about to be lost requires the certainty that this painting never shows up anyplace in the subsequent histories. We are not speaking the histories that they teach in school; such histories are, of necessity, incomplete and biased. We must be sure that the painting is never part of a transaction, never inspires a hero or villain to take action, and stays buried forever. That is a condition that the Arisa can establish, but it is an enormous complication. It is almost always the case that the Arisa will opt for making an extremely detailed record of the treasure, and then, in present time, meticulously reproduce an object identical in every way except for the notion that one is the “real thing” and the other is not. I, along with most of Arisa, cannot tell the difference and thus do not care.

None of what we have covered should have any effect on the history subsequent to the visit. It is possible, in a visit of the third kind, to change the past, triggering all sorts of complications. These complications deserve their own chapter.
The Nature of the Time Portals
So far we have been presenting generalities. Now it is time to cover the mechanics. Virtually all time travel involves the use of time portals, the first of the time travel devices to be invented. The basic notion of the portal is that you place people and material inside of the portal, set a destination defined in terms of a particular time and geographic location, fire up the machine, and watch it push the people and material back to the past and then pull them back.

The time portal is responsible for dealing with all manner of complications: movements through the physical universe and balancing matter and energy being the primary ones. Most of the complexity of the time travel portal involves massive amounts of computing power to figure out all of these movements and adjust the time travel so that the traveler ends up standing on the ground with zero angular momentum relative to the ground. It is almost always the case that the planners of a visit send expendable machines back to the past first to establish where everything is. The farther that the time portal has to send travelers back to the past, the more likely it is that errors can creep in.

One or more of the travelers carries a medallion. The time travel portal maintains a connection through time to this medallion. The medallion can be used to signal the time travel portal that the travelers are ready to return to base time. While the instructions given to travelers include the admonition to never, ever lose the medallion, it is technologically possible to locate travelers who drop their medallion in the river. Trust me, it happens. The past is unpredictable. The people who plan visits try as hard as they can to eliminate risks, but did I mention that the past is unpredictable?

It is theoretically possible for a time travel portal to move a traveler from one point in the past to another point in the past. In practice, it is never done. Given the structure of energy consumption and command-and-control activities, it is much simpler to pull the traveler back from the past to the base time and then re-transport them to the new location and time. This approach is slower, at least in theory, but much safer. There are two factors that challenge the safety of the visit: First, the computational complexity of keeping track of movement and balancing matter and energy grows exponentially, as does the chance for errors. Second, the questions about what should exist and when during a multi-step visit increase the risk that the visitor will appear to know a fact before they could know it. The Arisa like the notion of “safer” very much.

An important characteristic of how the time travel portals are used is that there is more or less a continuous thread of existence relative to base time. The visits to the past can be thought of as little side trips that always bring the traveler back to the base time, a little bit older and perhaps a little bit wiser.

Another important characteristic of how time travel portals are used is that there is substantial energy that is needed to transport anything in time. The longer the distance in time, the greater the energy that must be used to transport the travelers. The greater the mass that is to be transported, the greater the energy that must be used to transport the travelers. Some of that energy ends saturating the destination temporal region. The more energy that is used, the greater the saturation. It is difficult to transport into a place on the time branch that is already saturated. The greater the saturation, the greater the difficulty. What this means that if you transport several tons of traveler and supporting materials to March 4, 1741 BC, you have effectively shut off time travel to any point within of weeks of that date. In simple terms, it means that if you forgot to pack something for your visit to the past, be prepared to do without. The next time that they can send you the toothbrush that you forgot might be weeks away in local time. And if you are thinking that the portal operators can just send it earlier in the time branch, that too has its own problems. Here be paradoxes and such. It is possible but it is something that tradition strongly suggests should be avoided.
Subjective Time
Our last topic is subjective time, the perception of the time traveler as to how long has it been since some past milestone. For a person that does not travel in time, subjective time and objective time are the same. For a person that travels in time, subjective time and objective time are quite different.

Take my case. In 1943 I was 42 years old, minding my own business in the North Atlantic, dying of cold after my ship was sunk by the Germans. The Arisa transported me into the year 4039. By the calendar, I was 2,138 years old, but I had experienced only 42 years. This is a serious discrepancy. But wait, there is more. I have made visits that lasted for weeks or months in the past, only to arrive back in the present minutes later. The calendar says that I am not significantly older but my memories say otherwise. Another serious discrepancy.

Let’s see if a little “show and tell” can clear this up. We have two characters for our play: Sam and Al. Sam is the time traveler. Al is the person operating the time travel portal. The set for our play is very simple. There is a box structure in the center of the stage that is perhaps 10 feet tall and 20 feet wide. In the center of this box, facing the audience, is a door. There are all sorts of dials and blinking lights and levers and whatever else makes you think of time travel decorating this box. This is our time-travel portal. It is nothing like the real thing but who cares. On the top of the box are two displays. One display is labeled “Al”. It shows the current date in time and displays an age in years, months, days, hours, and seconds. The other display is similar but it is labeled Sam. It shows the same values for the date and age. Al and Sam start out being the same age.

The action begins. Our players enter from stage right. Both men look the same, short hair and clean-shaven. Sam is wearing a backpack suitable for traveling in time. Al has a clipboard. He uses the clipboard to check on how well Sam is prepared for his visit to the past. Shots? Check. Local currency? Check. Fake credentials? Check. Return medallion? Check. Finally Al decides that Sam is ready to make the visit. Al opens the door that is serving as our surrogate time travel portal. Sam waves to the audience and walks in. Al closes the door and presses a big green “Go Back” button. The lights blink. An extremely attractive woman in a skimpy outfit parades across the stage from stage right to stage left holding a sign that says, “Sam is in the past.” She points at the display that is labeled Sam. The audience gasps as it realizes that that display now is showing a date and time some 100 years in the past. Someone in the audience who is a little bit more observant and has consumed more than his share of alcohol while waiting in the lobby for the play to start, calls out, “My God, Sam is aging faster than we are!” And indeed the display of Sam’s age is advancing faster than that of Al’s.

A few minutes pass while Al makes a point of looking at dials and jotting down data on his clipboard. Then a big red rotating light on the box, I mean, time travel portal, starts blinking on and off. The attractive young woman in the skimpy costume parades from stage left to stage right holding a sign that says, “Sam has just activated the medallion and wants to come back home.” Al makes a big show of rushing over to the big red button that says “Return” and pressing it. There is a puff of totally gratuitous smoke. Al opens the door of the time travel portal and out steps Sam. But this is a different Sam. He is deeply tanned. He has a full beard and his hair is quite long. He is clearly older than he was when he went into the time travel portal. Sam went into the time travel portal being the same age as Al. He came out of the time travel portal being a year older subjectively. From Sam’s perspective, he has experienced a year of visit time that Al and the audience have not. The display for Sam confirms that he is now a year older than Al.

I mention this concept to show you that the life of the time traveler is not easy; confusion abounds everywhere. In another sense it does not matter too much. The machines keep track of subjective time. In the rare instance that I or anyone else wants to know, the machines can lay out the entire history of my subjective life. Then again, there is the notion that one is as old as one feels. In Arisa, I can feel as young or old as I want; with the medical capabilities of the machines, age is truly only a state of mind.
Crescendo Primus
The material in this section only touches on the most basic of concepts of time travel. If you are confused, it is likely that you are trying too hard to understand what is going on. Don’t feel bad about it. Other than a handful of clever people who have spent centuries mastering the topic, no one in Arisa understands it any better. There is a substantial body of rules and procedures that make up a process that just works. I understand what I understand. Understanding the rest will just have to wait until I have a lot more free time.

There are, of course, more things to learn about time travel. Look for more Journal entries to come.

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