Strange Paths offers a robust essay on the topic of interstellar arks, one that considers our future among the stars without warp drives or other breakthroughs that get us past the speed of light barrier. Star Trek and its ilk offer familiar, short-term travel analogous to our own relatively brief journeys in the Solar System. The real thing may be different:
The way toward stars becomes however quite unfamiliar if we consider that such Triumph of Physics could possibly not happen, and that the famous constant of Einstein c, the speed of light (3E8 m/s), represents an horizon speed which is impossible to exceed and which is even extraordinarily difficult to approach, so that we would begin to see outer space like it is seen by astronomers: a vastness compared to which that of terrestrial oceans is nothing.
The author looks at two alternatives, the first being a relativistic rocket able to take advantage of time dilation at velocities close to light speed so that the crew experiences a much shortened interstellar journey. Such a craft (the author assumes a vehicle driven by antimatter) is well beyond our technology, but it offers up the kind of mind-bending travel Carl Sagan was among the first to describe. Says Strange Paths, “Thus, in just 12 years of proper time (but 113,243 years for the stationary observer), which is a long time but still bearable in a comfortable spaceship, one could traverse the whole Galaxy, whose diameter is 100 000 light-years.” The relevant mathematical arguments are supplied.
But what energizes the essay is the long-haul ark, a vessel driven by a what the author calls thermonucleoelectric propulsion, channeling fusion plasma through a magnetic conduit for thrust. The beauty of the ark is that it is a self-contained world, housing its own society and capable of maintaining itself in stellar systems unlike our own. Thus the author’s choice of Epsilon Eridani as a target, it being relatively close to the Sun at 10.5 light years and, as a K2 star, not terribly dissimilar from ours.
Could a gas giant around Epsilon Eridani, even one in as eccentric an orbit as the one we now know to be there, provide satellites that could be used as a resource base for an interstellar ark? There seems to be no reason why not, though I think the author is overly pessimistic about the possibility of nearby terrestrial worlds, the Centauri stars now looking more and more promising in that regard, especially as we consider Proxima Centauri’s possible role in delivering volatiles to inner system planets around both Centauri A and B (if they do indeed exist).
But it will take another decade or so before we start to accumulate enough terrestrial-style worlds to draw even the most preliminary judgments about their frequency. Until then, speculation like this, richly detailed and backed by solid mathematical description, offers us a look at how humans can reach the stars with technology that could reasonably develop absent major breakthroughs in our understanding of physics.
On the societal level, the discussion of human psychology in such enclosed spaces is fascinating, and I would also offer up a paper by Edward Regis Jr. called “The Moral Status of Multigenerational Interstellar Exploration.” This one was in the Finney and Jones volume Interstellar Migration and the Human Experience (Berkeley: University of California Press, 1985). Regis considers the psychological and ethical questions interstellar arks present and finds no show-stoppers:
We conclude then that just as no rights of Earthlings are infringed by their not being included as passengers on a space ark leaving for the stars, no rights of star voyagers are infringed by their not living their lives on Earth. A multigenerational interstellar expedition is no more and no less morally permissible than the very existence of human life on our own planet.
Strange Paths has more to say about how life aboard an interstellar ark would be conducted, and how the ark can be constructed in such a way as to maximize livability in terms of environment and social interaction. And here’s something to ponder that may awaken old memories:
Compared to the Present, the spiritual horizon is identified to the horizon of social activity previously discussed. Arkonauts live a morally new situation, in lived and in long-term aims. They should develop an original mentality. The need of getting along would come first. The word trajectory reminds of “transient”. But such transient is a whole life and a whole civilization, with the result that the stellar goal will become almost secondary. The majority of individuals populating this travel will belong to a generation “not leaving, not arriving”. For this majority, the end of the way would just appear like a distant future. Certainly, in background the reach of targets will structure the community, but the stake making the happiness of the travellers will remain for the humankind its present.
The science fiction trope from way back is the interstellar ship whose inhabitants have forgotten their mission; indeed, they no longer recall that they are on a ship at all. Think Heinlein’s story ‘Universe’ (later part of Orphans in the Sky) or Aldiss’ Non-Stop (published here in the US as Starship). But we can hope for outcomes better than this. Alan Bond and Anthony Martin, of Project Daedalus fame, have written about so-called ‘worldships’ powered by nuclear pulse engines or solar sails, and Gregory Matloff has speculated on sail-driven craft on a 1000-year journey to the Centauri stars. These are voyages that may one day prove viable with manufacturing help from nanotechnology.
Strange Paths concludes this energizing essay with the thought that no matter how extravagant the propulsion and structural demands of an interstellar ark may be, the examination of its parameters now may somehow contribute to a future in which it happens. So it is with interstellar studies, which routinely posit technologies that are, at the least, next-generation, and extrapolate from them to show what could be done. We are in the lengthy but critical stage of base-building, creating the intellectual framework from which great things may one day grow.