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Ansibles in Traveller

This article originally appeared in the October 2011 issue of the downloadable PDF magazine.

The classical Traveller setting is one where Charted Space is filled with large multistellar polities, with communication being slow, no faster than travel. The problems of managing empires on this scale are obvious from historical analogy, especially the examples of the British and Spanish empires. If you add faster-than-travel communications (FTTC, henceforth) to such setting, you increase the ability of the home government to centralize control. The faster such communication is relative to the speed of travel, the greater the tendency toward centralized control. Traveller deliberately limits communication to travel speed to minimize the ability of a polity to centralize control (and thus maximize game opportunities).

One of the consequences of the lack of FTTC in Traveller is that the various worlds are largely independent, with the Imperium providing limited interworld services, such as defense or protection of commerce. But is an Imperium—or rather, any multiworld polity—really necessary on the player-character scale?

The practical independence of worlds and canonical levels of anticommerce activity such as piracy suggests not (though it could be argued that the threat of Imperial response is itself a factor in low levels of anticommerce activity), and in a setting where imperial polities do not exist, FTTC can be introduced without ruining the essential “Traveller-ness” of the setting. As is common in SF, I will assume that such communication is instantaneous between stations and refer to it as an “ansible”.


There are a number of ways to introduce the ansible into a story setting, ranging from telephone-like (anyone can make an ansible call to anyone else, and interact in real-time) to something more like electronic mail (where messages are stored and forwarded for later retrieval). The particular model used will, naturally, depend on the needs of the story, and it is not unknown for the described use of the ansible to be inconsistent with the described model.

If we assume that “scientific consistency” will be maintained—that is, if our ‘story’ does not use the ansible in ways that our definition would not allow—in a no-multiworld-polity setting, I believe that the following model/constraints will allow a campaign setting to remain recognizably “Traveller”:

  1. Ansible hardware is large enough (and expensive enough) that mounting an ansible aboard a ship is impractical at best. Perhaps a hull from a High Lightning-class ship could be gutted and an ansible mounted to create a poorly-armed communications ship, but in a setting lacking large multiworld polities, it is unlikely that such large ships will be constructed, and would be difficult to justify in any case.
  2. Ansibles can only operate at a distance from gravitationally-significant masses. For simplicity, assume that the ansible platform must be outside the 100-diameter limit of any such masses. (Yes, this means space-based. It is more reasonable to construct a platform that is not independently mobile and which can be defended by smaller but well-armed ships than it would be to mount the ansible in a ship.)
  3. (for re-emphasis) Multiworld polities do not exist. Customs unions, postal unions, trade combines, and the like may exist, but in no case is there any centralized legal, political, or military multiworld authority.

General Implications

It should be noted that the strength of any effects described here will depend in part on the cost of an ansible call/message—the higher the cost, the lower the overall traffic, and with lower traffic—that is, less exchange of information—the more conducive to the ‘standard Traveller model’ the setting will be.

The expense of the ansible means that only the richest systems—and of them, only those that have settlements significant in their own right off the mainworld—will consider construction of more than one ansible. However, the benefit of FTTC will be enough to ensure than all but the poorest and smallest of systems will have one, and economically marginal systems will be willing to go into debt to build or purchase an ansible.

Even aside from the gravitational-significance standoff distance, prudent system governments will establish their own standoff distances (or, if the ansible is a commercial monopoly of a single company, the company will mandate such standoff distance) for gravitationally-insignificant bodies (such as ships) such that space traffic or debris in space traffic lanes will not present a danger of damage to the ansible. Additionally, provisions are likely to be made for some level of defense against deliberate attack, and standoff distances will be sufficient to reduce the ansible’s target profile.

If the ansible is capable of ‘streaming’ data, and the standoff distance allows for light-lag delays of less than about a second (thus allowing real-time interaction), it is nearly certain that large space stations will develop at the standoff distance, and those stations—which will rapidly develop into cities—will take over the role of the system’s primary trade hub, with businesses that depend on interstellar trade being the principal ‘residents’ and employers. Any port facilities farther away from the ansible will be relegated to acting as feeders for the primary ‘OutPort’ at the ansible standoff. If, because of technical or regulatory constraints, ‘streaming’ data is not possible, such space hubs are less likely to develop, as the communications model will be, in effect, store-and-forward, and the impact of light-lag will be far lower.

Implications for Trade

Speculative trade as currently understood will not exist—when one can contact a destination system before making a purchase of cargo, it becomes possible to determine whether there will be a market at the destination, and possibly for several destinations ahead. To the extent that anything similar to speculative trade exists, it will likely be a market analyst with good sales ability taking goods on consignment from a manufacturer trying to break into a new market, or developing a new product line.

The same factors that operate to reduce speculative trade will operate to favor the development of standard shipping routes, with ships operating according to fixed schedules. The majority of ship ‘trade’ will be the buying and selling of space for shipping goods, and shipping companies will compete on the basis of reliability, efficiency (how quickly is hold space going to be available on any particular segment to be traversed), and price. Hold space will often be scheduled weeks or months in advance.

Military Implications

Recall that there are no multiworld polities. A world’s defense forces will be only what that world can muster on its own, plus whatever other nearby worlds might contribute to a mutual defense pact. In the event of an attack on a world, relief forces will be potentially only one week away (instead of two weeks)—but the ansible represents a single point of failure for communications, and it will be a target for takeover or destruction by an attacking force. Takeover will be more desirable than destruction, as an ansible in control of the attackers can be turned to their purposes. A failure to prevent the target system from using the ansible means that other worlds in the immediate stellar neighborhood will have very early warning of hostile operations in the region. If, as is permitted in some versions of Traveller, an actual destination can be determined from analysis of the outbound ‘jump flash’, the almost instant notification of the destination system means that mutual defense pacts can be activated prior to the actual attack, and supplemental forces can be available to the defenders almost as soon as the attack commences.

Tweaking for Effect

How strong the effects of the ansible are on a campaign setting will depend on how easily accessed the ansible is. That in turn will be defined by two factors: message capacity, and message cost. Both factors are left to the referee to control for his campaign; in general, making the ansible less accessible will lessen the effects of the ansible on the setting. Additionally, how any restrictions are imposed will play a role in shaping the setting; referees are thus cautioned—as always—to consider carefully the effects of any fiat.

A Note on the Origin of the Idea

In various Traveller forums and mailing lists, there is always a perennial thread on books, movies, TV shows, and so on that ‘have a Traveller feel’. While no two individual lists will ever match perfectly, certain examples are repeatedly mentioned by multiple people. One of those is the Vatta’s War series of books by Elizabeth Moon, and I used that series as a jumping-off point for the idea. A few days of discussion following the posting of an earlier draft of this article to the Traveller Mailing List revealed some considerations not addressed in the series, and I have incorporated my thoughts on those into this article, with thanks to the various list members that opened them up for consideration and discussion.