(The following is drawn from a speech delivered at Brown University in Providence, Rhode Island, on February 3, 2019, during the Space Horizons 2019 conference.)
There’s a theory, which I happen to share, that science and SF comprise a never-ending feedback loop, one that’s been going on ever since Jules Verne decided to pick up a pen and write his first novel, Paris in the Twentieth Century (which he wrote before 20,000 Leagues Under the Sea but which wasn’t published until 1996). According to this theory, just as SF writers peer over the shoulders of scientists and technologists to gain inspiration, so scientists and technologists are often inspired by SF to explore new ideas or develop new inventions.
It works this way: if a SF writer notices that a scientist has discovered a new means of luring a mouse into a trap and uses that knowledge to write a story about a better mousetrap, another scientist may read that story, decide that the idea is feasible, and use it to theorize a better way of killing mice. The technologist takes that information and uses it to invent a better mousetrap. Whereupon a different SF writer notices the existence of Mousetrap 2.0 and concocts a story about one that’s even better, Mousetrap 3.0, which is noticed by yet another scientist, and so forth.
Nowhere is the feedback loop better illustrated, or has lasted longer, than the co-relationship between interstellar SF and interstellar science. Space travel was one of the very first topics SF writers explored—Verne again, with From Earth to the Moon and Around the Moon. Robert H. Goddard of Worcester, claimed to have been first inspired to create the liquid-fuel rocket from reading H.G. Wells’ The War of the Worlds. As a child, Goddard wanted to visit Mars to see if Martians lived there, and he spent his life devising the means to do so. Why, I haven’t a clue; Wells’ Martians were murderous cannibals who came to Earth to eat us alive. Nonetheless, every liquid-fuel rocket ever built and launched owes its existence to Goddard’s work, including those that eventually sent probes and rovers to Mars.
It’s hard to pin down which came first, science fiction about interstellar travel or real-life scientific speculation about the same. I’m something of an armchair SF historian, and I haven’t yet been able to answer that question to my own satisfaction. It took a long time for early science fiction to move beyond our Solar System, and it also appears that scientists didn’t seriously consider the possibility of interstellar exploration until around the same time the first interstellar SF stories appeared.
For example, take the idea of generation ships, aka worldships. Most people familiar with both the technological concept and the SF stories dealing with the same would probably tell you that it was Robert A. Heinlein who first developed the idea with his novellas “Universe” and “Common Sense,” published in Astounding in 1941 and later reprinted in 1964 as a novel, Orphans of the Sky. Yet the idea was out there long before Heinlein hit on it. British scientist J.D. Bernal first described what he called “globes” in his monograph The World, the Flesh, and the Devil, published in 1929. Just two years later, in 1931, the first so-called “space ark” appeared in the comic strip “Buck Rogers in the Twenty-Fifth Century,” when Buck, his girlfriend Wilma Derring, and their egghead scientist pal Dr. Huer fly to the asteroid Ceres and discover that it’s actually an enormous worldship built by the inhabitants of Ganymede (and incidentally, the illustrations of Ceres’ interior look a great deal like the interior of the worldship described by Arthur C. Clarke in his 1973 novel Rendezvous With Rama).
Did Philip Francis Nowlen and Dick Caulkins, the co-creators of Buck Rogers, derive inspiration from Dr. Bernal’s essay? Impossible to know today . . . and, in fact, it is possible that the idea originated with neither party, and someone else came up with it first. But both Heinlein and Clarke kept up with scientific literature, so I have little doubt that they were familiar with The World, the Flesh, and the Devil, and if my old pen-pal Arthur was still around, I bet he’d tell me that he was a Buck Rogers fan from way back.
Another favorite means of achieving starflight is the reactionless interstellar drive. We can safely say that the idea originated in 1928 with The Skylark of Space by Edward E. Smith, which he developed further with the Bergenholm interstellar drive of his Lensman series in the 1930s, beginning with Triplanetary and Galactic Patrol. But Doc Smith’s Bergenholm drive, while highly imaginative, was also impossible; his ships were capable of attaining velocities hundreds of times the speed of light, making it possible for a character to travel not only to another star, but indeed another galaxy, within just hours or days.
And Smith wasn’t consistent with this either. In First Lensman, a prequel to Galactic Patrol published in 1950, Lensman Virgil Samms makes the trip to a distant extrasolar planet in just hours . . . but when the time comes for him to land his spacecraft on that world, he walks back to the engine room and cranks up the Diesel engine his vessel is equipped with for takeoffs and landings.
Faster-than-light drives became commonplace in SF after Doc Smith introduced them. His colleagues Edmond Hamilton, Jack Williamson, C.L. Moore, and others began routinely inserting FTL starships into their stories. Some early writers made an effort to explain how these vessels might work, even if their explanations were rather unlikely. For instance, in Williamson’s story “The Galactic Circle,” published in Astounding in 1935, every inanimate object aboard an experimental starship is made of uranium, right down to the dinner plates. Once the ship lifted off from Earth and traveled out into interstellar space, accelerating ever faster as it left our system, these objects were used as fuel just as coal is fed to a coal-fired steamship engine.
Atomic energy was often mentioned in early SF, but the principals of nuclear fission weren’t generally known yet, or at least not by most laymen. Nevertheless, atomic FTL drives were accepted as a given, with little or no pretense at scientific accuracy or verisimilitude. So we have to give Williamson some credit: at least he tried.
As science and technology advanced through the twentieth century, so did science fiction. By the late ’60s, FTL ships had not only become commonplace in SF, but also more credible. The most famous starship of all, the U.S.S. Enterprise of the original Star Trek, didn’t resemble the starships of just twenty years earlier. The show’s concept designer, Matt Jefferies, kept in mind the fact that a starship doesn’t need to be streamlined, and although the NCC-1701 looks like (to quote a late friend of mine, an aerospace worker and SF fan) “a spaceship designed by committee,” Jefferies, Gene Roddenberry, and the show’s scriptwriters established certain limitations, which Chief Engineer Montgomery Scott managed to finesse constantly if not consistently. When the Enterprise got above a certain warp factor—the maximum varied from episode to episode—it began to shake like a leaf in a windstorm, and if it kept up that speed for too long, Scotty would get on the blower and tell Kirk that the engines “canna take the strain much longer.”
Because Star Trek’s audience was not only larger than the average readership of a science fiction novel, but also generational, it popularized an idea that’s been with us for many years: the warp drive. Something like the Alcubierre drive may or may not be feasible given its extraordinary energy demands, but a number of theoretical physicists with whom I’ve spoken don’t consider it to be flat-out impossible. Such a warp drive may one day be built, tested, and perfected; just because we don’t know how to achieve this at present doesn’t necessarily mean that we’ll never achieve it in the future.
The warp drive’s second-cousin, the traversable wormhole, began making its appearance in the early ’70s, not long after their existence was theorized in scientific literature. For instance, Analog published quite a few stories and novels in which vessels traveled instantly from one star system to another via wormholes; the notable ones were Joe Haldeman’s 1972 novella “Hero,” which formed part of his classic novel The Forever War, Stephen Robinette’s (aka Tak Halus) 1974 serialized novel Stargate (no relation to the movie and TV series of the same title), and George R.R. Martin’s 1972 novella “A Second Kind of Loneliness.” Like warp drives, traversable wormholes may or may not turn out to be feasible; either way, they continue to be investigated by astrophysicists.
Today, the propulsion system that appears to be most likely, at least in the short term, is the lightsail. The origin of this idea is hard to pin down, mainly because there are several variations on the same general principle, a vessel that uses an enormous sail to harness the solar wind and carry the vessel across space. In one of those instances in which two SF authors simultaneously hit on the same general idea, in 1964 two short stories were published that not only described spacecraft propelled in this manner, but even had the same title: “Sunjammer” by Poul Anderson (as Winston P. Marks) in Analog, and “Sunjammer” by Arthur C. Clarke in Boys’ Life, subsequently retitled “The Wind from the Sun.”
Because the solar wind was later found to be inadequate for propelling large payloads—my old college astronomy professor dismissively called it “the solar breeze”—lightsails gradually evolved into something different: spacecraft that utilize focused energy such as lasers or microwaves. The first SF novel to describe such a vessel may have been The Mote in God’s Eye by Larry Niven and Jerry Pournelle, published in 1975; my own novel, Arkwright, published in 2016, describes an unmanned variation of such a craft. The lightsail represents the current state of the art in theoretical interstellar propulsion; Breakthrough Starshot will likely utilize this technology in one form or another when it launches an interstellar probe sometime in the near future.
However, unless some revolutionary new theory in astrophysics emerges that undermines or discredits Einsteinian physics—not likely; people have been trying to outguess Uncle Albert for many years—the speed of light will remain an absolute limit. And if nothing can travel faster than light, then even a ship capable of generating and utilizing a warp bubble will take years, decades, or even centuries to reach its target. While generation ships may seem to be the answer to this problem, bear in mind that, even in science fiction, most worldship missions end in a bad way, usually with the crew either collectively losing their minds and turning on one another in homicidal rage or their descendants forgetting who they are, where they came from, and what they’re supposed to be doing.
This is one of the reasons why I’ve often said, again and again, that space exploration, whether it be within our own Solar System or beyond, is not just about propulsion. Unless we never intend to visit distant worlds ourselves but send unmanned probes instead, we need to always consider the human factor and never regard the people aboard these ships as little more than cargo or puppets. It won’t do an interstellar mission any good if a starship arrives at Alpha Centauri, Bernard’s Star, or another nearby target only to have half the crew murdered and the other half crazy as outhouse rats.
On the other hand, if science fiction teaches us anything, it’s that everything changes. Something that seems unfeasible, unlikely, or impossible today may become quite possible tomorrow. Given the rapid pace of development in theoretical physics, we may be just one major breakthrough away from discovering the key that will make interstellar exploration possible not just for unmanned probes, but for humans as well. And even if the sheer enormity of space makes such voyages nothing more than the basis for a good science fiction story, the work we put into it might make it possible for us to colonize the worlds of our own system. We may never be able to leave our home system, but wouldn’t it be great if we could travel to Mars in just days . . . or even hours or minutes?
I suspect that something may occur that opens the space frontier like never before, and sooner than we think. We might even find ourselves in a position where we can send a manned vessel beyond the Kuiper Belt before we even set foot on Mars. Science fiction usually depicts interstellar travel as something that isn’t accomplished until the twenty-second or twenty-third century, but it would be wild if we could build and dispatch our first starship within our lifetimes, or perhaps within the lifetimes of our children or grandchildren.
That’s our mission. That’s why we’re here, science fiction writers and scientists alike.
Let’s go to work.
Allen M. Steele seems to be making a sideline of going to interesting places and delivering speeches related to the history of science fiction. His most recent engagement was in Beijing, where he was a Guest of Honor at APsfcon 2019, a major Pacific Rim science fiction convention.