The Arisa are obsessed with understanding what is going on in the timeline. That means that they want to map out each of the time branches and understand what event triggered the split that created that time branch. There is a particular role within the Arisa called the “Time Scape Topologist”. Almost no one actually uses that title. Rather they refer to “time Mappers” or just “Mappers”. The time Mapper is responsible for understanding all of the various time branches that make up the timeline. In theory, this means that they are interested in literally millions of different time branches, but, in practical reality, they all focus most of their attention on those time branches which are “closest” to the time branch that everyone calls the “main” or “mother” time branch. In other words, if it is not feasible to reach a particular time branch from the main time branch, the interest in that time branch diminishes greatly.

These “close in” time branches are of interest because they are potential places that a time traveler can visit. It is possible for a time traveler from one time branch to visit a different time branch. From the perspective of the amount of effort it takes to travel in time, going back in time along the same time branch is significantly easier. It is also significantly more risky in that it might cause a new time branch to occur when one does not want such a time branch to occur. The visits to the past along the “mother” time branch are almost always pure observation. There are visits to the past where works of art are retrieved just prior to their destruction but the expectation is that these retrievals will not cause any significant shifts in the time branch. While it is more expensive to go to a different time branch, it is also likely to be safer. Changes in that in another time branch will not affect the “mother” time branch, even if they trigger a branching.

The further that one travels back in time, the more difficult it becomes. One factor is simply taking into account all of the “fuzziness” that is caused by the micro branching and merging that happens every second. Think of time travel as involving well over 1000 different dimensions, all of which must be accounted for in order to deliver people and equipment into the past successfully. The longer the jump into the past, the more computations that must be made to track how each of those dimensions has changed throughout all the fluctuations that can occur because of the “fuzziness” that is an inevitable aspect of each time branch. Miscalculating even just one of these dimensions can result in a dead Shepherd. The second factor is that the greater the “distance” in time to be traveled, the greater the effort that must be expended. This second factor is relevant when you are crossing from one time branch to another time branch. The longer the time between when the fork occurred that created a two time branches, the more likely it is that the two time branches have gotten out of sync with each other. The machinery of time travel must compensate for this. Again, failure to compensate is another way for a Shepherd to end up dead. The third factor is simply the amount of energy it takes to move through time. There is an exceedingly remote possibility that even if the first two factors are handled properly, the power conduits of the time portal could leak and fry the Shepherd.

It is the responsibility of the time Mapper to understand all these factors and provide sufficient data to the machines that control the actual mechanics of time travel to ensure that the people and material arrive in the past and return successfully. The time Mappers are also responsible for laying out in considerable detail the constraints and requirements on the time travelers. For some trips, the time travelers can pretty much go wherever they want to go. For many of the trips, there is an intricate set of dance steps to control where the time traveler can and cannot be at various times during the visit. It is not uncommon for a trip to be proposed and planned only be canceled because the dance steps required to be successful are too complex to be executed without exceeding the tolerance for risk.

The time Mapper has enormous banks of data but the typical interaction of the time Mapper with the Shepherd is graphical. The first form of a graphical display shows the main time branch as well as the relevant side time branches. The display looks like a tree where some demented painter has splashed bright neon color over each of the time branches. Each of these colors represent some factor or characteristic that is of interest to the time Mapper. In truth the number of factors that have to be represented is far too great for the colors to be useful to distinguish all of them at the same time. The time Mapper must select the specific factors that are of interest for a particular review and make sure that the audience looking at this understands which view is being presented. I know this because I had embarrassed myself the first few times that I was at one of these presentations by misinterpreting what the colors meant. In spite of this embarrassment on my part, I have found that the multicolored tree structures are a useful way of introducing the differences of the time branch that is the target of the visit.

I sat through a number of these presentations as an “almost a Shepherd” where it was clear that I was to keep my ears open and my mouth shut. As I got more responsibility, I started asking questions about why it was that the time Mapper was showing all of these time branches when we were only going to one time branch. The time Mapper in question was delighted that I’d asked the question and spent nearly 2 hours explaining to me what the answer was. In very general terms, a specific visit to the past is proposed to accomplish some specific goal. It might be to retrieve some artwork that is about to be destroyed, or to capture the details of some technology that has been developed in an alternate time branch, or in very rare instances to intervene in the time branch to ensure that a branch occurs or does not occur. In the first two instances of retrieval of art or technology, there might be a dozen or more different time branches, all containing essentially the same material, in which the visit could occur. It is the responsibility of the Mapper to determine what the cost and constraints would be for making a visit to each of these time branches and to select the specific time branch that the Shepherd will visit.

Much of the data that is used by the Mapper to compare and contrast the various time branches as the potential candidate for a potential target of a visit is collected by machines that are injected into the timeline. These machines are designed to be passive and unobtrusive. These machines are in effect invisible to the inhabitants of the time branch, even if those inhabitants have access to extremely sophisticated sensors. The data that these machines bring back from the timeline is analyzed and contributes to the data that the time Mapper uses to sort through the various time branches that might be visited. There might be as many as 40 or 50 such passive visits to the time branch that ends up being the final target time branch. The Arisa in general and the time Mappers in particular have a strong distaste for uncertainty. More data collection is always regarded as a good thing. There are limits to data collection however. Too many visits to a time branch can result in the time branch being saturated.

A reconnaissance probe is no more than 2 to 3 inches across. The typical approach is to identify an existing native rock or stone in a building that can be replaced by a machine that looks exactly the same. After the rock or stone is inserted into the past, it will spawn hundreds of machines the size of flies that blanket the surrounding area for hundreds of miles. Just prior to the point where the probe is to be retrieved, the small machines will return and reassemble themselves as a single unit. The machinery of time travel will retrieve the probe and replace the original rock or stone, bringing the time branch back into to balance once more.

Each instance where anything is inserted into the past, either in the main or home base time branch, or some other time branch, is called a visit. The overwhelming majority of visits involved only very small probe machines such as I have described above. These are referred to as passive visits. There is a substantial body of evidence that these passive visits to do not affect the time branch in any way. The probes do not in and of themselves make any changes to the time branch and the inhabitants of the time branch cannot detect these passive probes. Even these visits are planned in detail, and then analyzed and reviewed by both other time Mappers and specialized machines before any action is actually taken. This might sound very cumbersome but it is surprisingly fast and efficient. There is widespread understanding that these passive probes are absolutely necessary to gather the data necessary to make decisions about more intrusive visits. The machines that analyze this data are well understood and trusted. There are built-in safeguards that practically guarantee that no unintended consequences will occur because of these passive visits.

The complexity goes up when the visit is intended to retrieve something. The something that is to be retrieved might be a physical object such as a work of art or a document of historical importance that is about to be destroyed. Or that something might be data about a technology that is of interest. In both cases, the Mapper must ensure that the retrieval can be done without affecting the time branch. In general that means that, a combination of machines and people can be inserted into the timeline, procure the “something” that is the target of the visit, and exit the time branch without being observed, either by people or by machine sensors. In an ideal visit, the visitors would consist only of machines. Machines can be made much smaller than people and are more likely to escape observation than people. If it is possible to have perfect knowledge about the circumstances around the visit, all the visits would use only machines. The problem is that, in certain circumstances, there is a trade-off between having perfect knowledge and being able to make another visit to the particular time. It might take quite a number of visits to achieve perfect knowledge. That number of visits could easily saturate the time branch to such an extent that another visit might not be possible. Sending in a Shepherd to make the visit under these circumstances oftentimes makes more sense. A highly-trained Shepherd is capable of dealing with incomplete and possibly incorrect information much more readily than a machine is. There is more risk, however, but that is something that Mappers and Shepherds deal with all the time.

When the purpose of the visit is to intervene in the time branch to effect a change, that might or might not cause the time branch to split into multiple time branches, the complexity goes up by several orders of magnitude. Whereas the surveillance probes inserted into the time branch for a retrieval might bracket the point of the retrieval by several years on each side, the surveillance probes for an intervention visit might bracket the time branch by centuries. In addition, the amount of information that is captured about the time branch at a given point goes up by a substantial amount. The computational load, as all this information is analyzed and all the possible outcomes are analyzed, is staggering.

A time Mapper never lacks for things to do.