Science fiction is the literature of change. More precisely, science fiction is the kind of literature that most explicitly and self-consciously takes change as its subject and its teleology. This essential presupposition holds as true for the earliest works to explore the new vantage point afforded fiction by scientific and technological developments, works such as Mary Shelley's Frankenstein and H.G. Wells The Time Machine, as for the genre's most recent runs through cyberspace in novels by William Gibson, Pat Cardigan, and Rudy Rucker. This centrality of change was most firmly voiced by twentieth century science fiction's most influential author, Robert Heinlein.

I think, claimed Heinlein in a 1941 Denver, Colorado speech to the Fourth Annual Science fiction Convention, that science fiction, even the corniest of it, even the most outlandish of it, no matter how badly it's written, has a distinct therapeutic value because all of it has as its primary postulate that the world does change. Some forty-five years later, science fiction greats Jack Williamson, Frederik Pohl, and Brian Aldiss still invoked the concept of change to explain their common project. I take seriously this notion that technology is changing the world and the future is going to be different, explained Williamson to Publishers Weekly writer Rosemary Herbert. Even more emphatically, Frederik Pohl specified: The biggest reality in the world today is change, and that's what (science fiction) is about and other kinds of literature are not. And, suggesting the almost obsessive quality of this phenomenon, Aldiss identified science fiction writers as the ones who are prodromi cally moved to write of change. What each of these writers left unspoken was science fiction's even stronger commitment to the postulate that the world can best be understood through change, whether rapid and radical or evolutionary over great periods of time.

The extent of this commitment can perhaps best be seen in Octavia Butler's Parable of the Sower (1993), where her protagonist Lauren O lamina constructs Earth seed, a secular religion around the credo All that you touch, you change. All that you change, changes you. The only lasting truth, is change. God, is change. Butler's novel dramatizes the two key corollaries to a worldview built around the concept of change: (1) If you believe in change, you can prepare for it, and (2) If you believe in change, you damn well better prepare for it. In this sense, all science fiction is preparation.

There is an odd tension almost a contradiction in the notion of a genre devoted so strongly to the idea of change. Most popular genres depend on a view of the world frozen in time, a world whose features and rules remain fixed from book to book, but science fiction rises from change in the referential world, envisions change in fictional worlds, and paves the way for change in the worlds of its readers. Indeed, in exploring the kaleidoscopic human implications of science and technology science fiction in the twentieth century has been not just the literature of change, but has become more an epistemological force, an ideology having much more in common with the revolutionary project of modernism and now, some would argue, with the cultural dominant of postmodernism than with other popular literary genres. The century that has seen science fiction first codified as a genre and perhaps more important as a publishing category has also seen that genre develop through distinct stages, mutate in innumerable and unpredictable directions, and finally overflow the limits of genre to become a meta-genre so broad and so pervasive as to be a concept and force quite outside the boundaries of fiction, and of art itself. As modes of science fiction have increasingly become the new realism of technological society, the world itself has grown science fictional. The scientific, technological, and industrial developments of the nineteenth century that made the rise of science fiction possible have inexorably led to twentieth century conditions in which manifestations of science fiction have become inevitable and inescapable.

It is not too much to claim that in the fifty years following Heinlein's frequently cited comments about change that something one might loosely call science fiction thinking has clearly overflowed the formal bounds of literary genre to sustain both an identifiable science fiction subculture and a broad complex of science fiction-shaped cultural assumptions about science, technology, and the future. Change– usually constructed as progress has become the distinguishing mode of, as well as the subject of, science fiction in the twentieth century. Since 1900 one has seen the initial codification of futuristic stories into what Hugo Gernsback first effectively called science fiction, have seen Gernsback's and John Campbell's prescriptions for this new genre fulfilled and then challenged and surpassed as writers turned science fiction in a dizzying swirl of new directions. Moreover, in recent years the genre has begun to shed its genre identity as it has increasingly disappeared into or significantly enveloped mainstream fiction.

Many critics and science fiction writers alike explain this conflation by claiming that the felt experience of science and technology has so permeated contemporary life as to render our culture itself science fictional. In the twentieth century the literature of change has itself never stopped changing, never stopped mutating, moving away from its European roots in satire and social criticism, moving closer and closer to the paradigms of first modernism and then to those of postmodernism. The audience of science fiction has repeatedly shifted as it has grown, ranging between intellectual and popular extremes. And the positivism and optimism of science fiction writing in the 20's and 30's has been tempered, if not supplanted, by questioning and frequently apocalyptic pessimism in the years following WWII: science fiction is the only genre to truly feel the fallout from Hiroshima. Some of the genre's most dramatic and most significant changes have seen the dime novel, boy-engineer appeal of pulp magazine scientifiction being wrestled into a useful and compelling vehicle for feminist expression, ecotopian protest, and wide-ranging explorations of difference and marginality of every imaginable kind. Both in popularity and in function the status of the genre has also changed, with science fiction texts and science fiction thinking becoming important influences in a self-replicating process– a feedback loop– involving science fiction cinema, TV, video games, music videos, computers, and comics, all sharing and developing science fiction assumptions, themes, and icons.

This extraordinary feedback loop has made science fiction the first truly multimedia genre and, more important, the only popular genre to have a clear cultural impact. At the very least, science fiction is at the heart of a well-codified subculture; at its most influential, science fiction is what William Sims Bainbridge describes as a popular cultural movement that develops and disseminates potentially influential ideologies. Seeing in science fiction no less than the attempt to create a modern conscience for the human race, Eric Rankin and Robert Scholes have observed that science fiction has appeared in every medium of artistic creation, developing through dialectical stages focusing on the popular medium of the moment, in great part simply because science fiction is itself a major force in the continuing development of our culture. Only the eclectic and expansive sense of literary genre advanced by this series can account for the many stages in the development of science fiction and only an understanding of the importance of science fiction's unique extra textual dimension can account for its phenomenal growth in popularity and cultural influence in the twentieth century. Against the broad sweep of twentieth century science fiction, my task in this necessarily brief study is a difficult one, sure to be incomplete, sure to be shaped by my personal reading preferences, sure to be weakened by the hundreds, if not thousands, of fine science fiction stories and novels that, even after a lifetime of enthusiastic reading, one does not know.

To give in a brief single work an accurate and systematic view of science fiction near the end of the twentieth century is, of course, impossible. In the first place, science fiction is no longer just fiction, but has become a universally recognized category of film, television, music, music videos, electronic games, theme parks, military thinking, advertising, and its concepts and icons are now routinely appropriated for the development and marketing of products ranging from breakfast cereal to pickup trucks. Science fiction is not even only science fiction any longer, but sci-fi (a term hated by most science fiction writers) to those who consciously or unconsciously minimize its importance, and science-fiction to its well-informed fans and critics, some of whom see those initials standing for speculative fiction, implicitly suggesting the contested status of science in twentieth century science-fiction, particularly that written since the 1960's. Some of the difficulty in describing science fiction is revealed in the sheer number of names that have been advanced for it: scientifiction, science fiction, science-fiction, sf, stf, speculative fiction, speculative fabulation, structural fabulation, science fantasy.

Additionally, the science in science fiction is no longer just science. Discoveries in quantum physics have increasingly challenged science fiction's early identification of science with certainty and its positivistic optimism that everything could be known and all problems solved if only one thinks long enough and well enough. The easily identifiable big science of rocket ships, robots, and atomic bombs has more and more in the twentieth century been augmented by what Bruce Sterling calls science that sticks to the skin, the little science of a technological environment or techno sphere that surrounds and involves everyone in the culture. Not only is science-fiction not fiction about science, but also it now rests more on debate than agreement about what it is that constitutes science.

Even if one considers science fiction exclusively as a print phenomenon, its size and range of permutations demand encyclopedic rather than essentializing analysis. One of the most complicating variables in a study of twentieth century science-fiction is that while it has flourished since the 1940's in both short stories and novels, the genre's golden age had limited access to the novel format, and many of the genre's writers and critics argue that its strengths are most apparent in the short story rather than in the novel– another aspect that separates science fiction from other popular genres. Moreover, science-fiction has more than any other popular genre been presented to its readers through the publishing hybrid of the fix-up, novels more or less smoothly cobbled together from short stories sharing the same worlds – themes, characters, settings, etc. As a result, even an exhaustive study of twentieth century science fiction novels would give a very incomplete and misleading picture of the genre. A Borges might imagine a thoroughly satisfying overview of the genre, but even such a heroic encyclopedic effort such as John Clute's and Peter Nicholls magnificent, 1370 page The Encyclopedia of Science Fiction (1993) must acknowledge its many omissions and curtailed discussions. In the excellent volume that precedes this one Paul Alkon uses the title of Arthur C. Clarke's The Nine Billion Names of God to suggest the plenitude of science fiction works written before 1900; consider my task when the actual count of science fiction novels published in 1992 approached three hundred, and the sheer volume of science-fiction novels and short stories made it virtually impossible for anyone to keep up with all developments in the field.

A recent guide to science fiction that confined its attention to the most significant English-language titles and further limited itself to books that have largely remained in print during the past twenty years still found itself surveying over 3000 titles. The Third Edition of Neil Barron's indispensable Anatomy of Wonder: A Critical Guide to Science Fiction (1987) now contains annotated entries on over 550 critical works devoted to science-fiction or science-fiction authors, in addition to entries on some 2,000 works of science-fiction, including 476 works of foreign language science-fiction. The recent Fourth Edition (1995) drops coverage of foreign language and many older titles, and still contains over 1000 entries on primary works. It also now annotates over 150 works of history and criticism of science-fiction, not counting works devoted to individual authors. And finally, some of the most experienced writers in science fiction writing and scholarship have already tried their hands at such a single view of twentieth century science fiction, with persuasive results almost uniformly at odds with each other in some significant respect. For the twentieth century has seen the dramatic proliferation of science fiction criticism just as surely as it has seen the flowering of science fiction writing, and even the attempt to survey this body of criticism would invoke, if not the number of Clarke's Nine Billion Names of God, the number and frustration of R.A. Lafferty's equally classic Nine Hundred Grandmothers.

Anyone who hazards generalizations about science fiction can ill afford to forget the laughter of the ultimate grandmother at spaceman / anthropologist Cer an Swicegood's efforts to discover how it all began. Accordingly, my goal in this study is not to attempt a representative sampling, much less a comprehensive overview of science fiction since 1900, but is instead to suggest some of the concerns that have allowed science fiction to become what J.G. Ballard claims is the main literary tradition of the twentieth century, and what Istvan Csicsery-Rona y persuasively describes as an attitude toward life, a way of being in the world. Following the wise example of Paul Alkon in Science Fiction. Unlike other popular genres such as the hard boiled detective story, the western, or the romance, the megatext for science fiction holds concepts that have no close approximation in the referential world: there may be no detective like Philip Marlowe, but there are detectives in the referential world; there is no similar referential analogue for time travel, matter converters, or faster than light drives. In this respect, science fiction would seem to be similar to fantasy, which also has no referential analogues, but fantasy's concepts are anything but unfamiliar, drawing as they do on thousands of years of myth and superstition.

In contrast, science fiction is in the process of creating myths grounded in science and technology– myths familiar to science-fiction readers, but unfamiliar to those not informed by the science-fiction megatext. Consequently, science-fiction tends to make much more sense to and to appeal more to readers who have more extensive knowledge of the science-fiction megatext, a kind of chicken-and-egg proposition that seems much more obvious and redundant than it really is, since the megatext for science fiction is arguably broader and more varied than for any other literary genre or mode. Science fiction, more than other literary genres, is itself intensely process ual; in science-fiction the dynamic interplay among writers, audiences, and conventions have operated at higher and higher rates of change.