Konstantin Tsiolkovsky is the first person I know of to talk about worldships and their ramifications, which he did in an essay originally published in 1928. “The Future of Earth and Mankind” was the rocket pioneer’s take on the need for enormous ships that could reach the stars in journeys taking thousands of years. The notion percolated quickly through science fiction, and by 1940 we have Don Wilcox’s “The Voyage that Lasted 600 Years,” which ran in Amazing Stories. Wilcox, who taught creative writing at Northwestern University, imagined a ship’s captain who, though kept in hibernation, wakes up every 100 years to check on his ship, watching the gradual degeneration of the successive generations of the crew.

It’s a bleak take on worldship travel that has often been echoed in later science fiction. But would a worldship actually be this horrific, a cruise from hell that lasted entire lifetimes? See Ken MacLeod’s Learning the World: A Novel of First Contact (2005) for the worldship as a place of unlimited opportunity, and consider reading some of the many worldship stories covering the entire range of possibility that SF has produced, from Lawrence Manning’s “The Living Galaxy” (Wonder Stories, 1934) all the way forward to Gregory Benford and Larry Niven’s Bowl of Heaven (2012), which depicts what might be described as a traveling Dyson Sphere, though one with unusual design parameters.

Population Density Enroute to the Stars

Stephen Ashworth’s papers on worldships, recently published in the Journal of the British Interplanetary Society contain his speculation that reasons of economic efficiency will produce colony vessels and then worldships with high population densities, supporting thousands of inhabitants per square kilometer. What to do with a human spirit in need of open spaces? One solution is virtual entertainment in which the crew — or colonists, or whatever we choose to call them — could tap into the experience of their choice, perhaps mixing Earth-like desert, jungle and ocean adventures with customized fantasy according to whim.

When Gerard O’Neill wrote about colony worlds in The High Frontier (1976), he imagined a different outcome. Huge communities like his Island Three would not necessarily need to be space-going versions of Manhattan, but might take advantage of the abundant resources of the Solar System to provide living room in a variety of settings:

…as colonists from various countries of Earth arrive to settle the many communities in space, there will be a great variety in the ways in which land area will be used. Some immigrants may choose to arrange their land area in small villages, with single-family homes, the villages being separated by forests. Others may prefer to build small, intimate towns of high population density, to enjoy for example the color and excitement and human interaction that is so much a feature of small villages in Italy. With many new communities to choose from, the emigrants from Earth will settle in those they like best.

Of course, O’Neill was not talking about worldships but what might be their predecessors, the kind of colony worlds that would define a truly system-wide economy. Even so, we can imagine scenarios where the inhabitants of such a colony, having produced several generations of space-adapted descendants, may decide that long journeys are not a problem if their entire world goes with them. Imagine, then, a truly sylvan setting like O’Neill’s:

I would have a preference, I think, for one rather appealing arrangement: to leave the valleys free for small villages, forests and parks, to have lakes in the valley ends, at the foot of the mountains, and to have small cities rising into the foothills from the lakeshores. Even at the high-population density that might characterize an early habitat, that arrangement would seem rather pleasant: a house in a small village where life could be relaxed and children could be raised with room to play; and just five or ten miles away, a small city, with a population somewhat smaller than San Francisco’s, to which one could go for theaters, museums, and concerts.


Image: The vast interior of an O’Neill cylinder presents a more spacious view of what a worldship might become. Credit: Rick Guidice/NASA.

Requirements for the Journey

The idea that we might one day build such artificial worlds, whether or not we translate them into star-voyaging worldships, seems fantastic. And for a bit of sobering up, Ashworth’s papers are just the ticket. In “The Emergence of the Worldship (II): A Development Scenario,” he looks at the requirements for sustaining human life on a vessel whose travel time might be measured in millennia. Space precludes running through all of these, but many are obvious:

  • Closed cycle production and recycling of food, water and oxygen;
  • A source of electrical power independent of Sun or planets and sustainable over the course of the journey;
  • Thermal management through radiation of waste heat to space;
  • Full control over the microbiological environment;
  • Viability of all food and ornamental species in functional reproductive health at stable population sizes over an indefinite number of generations

and so on. The list is understandably extensive, and includes factors like ensuring social and psychological stability, the need for continuing maintenance of all systems, and the long-term stability of the gene pool. None of these are factors that could be resolved in short time frames, and Ashworth believes they may emerge through a series of colonies set up at progressively greater distances from the Earth. Eventually such colonies learn how to operate independent of planetary surfaces and a manned starship — the worldship — may emerge, seen here as the logical endpoint of a lengthy period of technological and social growth. From the paper:

Viewed as a government research programme such a demonstration seems implausible, due to both its complexity and the timescales required to achieve operational maturity. Viewed as a gradual evolution of humanity into space, however, aimed not at starflight as such but at space colonisation within our own Solar System, and motivated by the large energy and material resources available for expansion, it seems likely that after a timescale on the order of centuries the preconditions listed above may be fulfilled in the course of normal economic growth.

We’ve come a long way in our conception of worldships from Robert Heinlein’s “Universe” (Astounding, 1941) and its sequel the following month, “Common Sense.” Published in book form as Orphans of the Sky, the story follows a ship’s crew that has long forgotten the nature of the voyage and no longer realizes that its world is a ship. The result is social deterioration and a rigidly stratified society of the sort Brian Aldiss explored to much greater effect in his 1956 novel Non-Stop. One can only imagine how the inhabitants of a worldship structured more or less along O’Neill lines might fare over the course of a similar journey, and we can assume that science fiction isn’t yet through exploring the ramifications of this intriguing concept.

The citation for Stephen Ashworth’s paper is “The Emergence of the Worldship (II): A Development Scenario,” JBIS Vol. 65, No. 4,5 (2012), pp. 155-175.