Science fiction, even hard SF, is filled with acknowledged tropes that many scientists consider implausible. We often take faster-than-light travel, time travel, and developments in nanotechnology for granted without worrying too deeply about the science and technology needed to bring these concepts into existence. Recent correspondence from an Asimov’s reader made me ponder the nature of another established subgenre of science fiction. The letter writer, Charles M. Barnard, questioned the publication of Harry Turtledove’s “He Woke in Darkness” in Asimov’s. Mr. Barnard wrote, “[this] is a wonderful, engaging, thoughtful story. It is, however, not science fiction. It’s not even fantasy.”

For those of you who haven’t read the story, “He Woke in Darkness” takes place in an America that never happened—at least in our universe. It features events similar to ones that occurred in the 1960s, but it turns the religion of some of the participants, and the race of all of them, on their heads. It’s a horror story, but it’s also an alternate history story.

But, what is alternate history? Some writers go to great lengths to make alternate history sound like science fiction—it’s one of those many universes next to ours that arose out of the quantum flux, or whatever—but most authors tweak the history of the world that we know and just sort of plonk their characters down. There’s no real explanation for the discrepancy, it’s just some kind of thought experiment. Does that make it fantasy? Well, probably not in the tradition of J.R.R. Tolkien or George R.R. Martin, but perhaps in the sense that “fantasy” is a term that can be used as a gigantic umbrella to describe all works of fiction—even science fiction. Does it make it mainstream? Again, perhaps in the obvious sense that fiction is always about alternate realities, worlds that aren’t truly real. If fiction were something else, it would be called nonfiction. One can make a case that alternate history is some weird off-shoot of historical fiction, but the subgenre is generally considered science fiction, and it is marketed in the SF section of the bookstore.

So, one might ask, what is science fiction? That’s not a question that I’ve ever contemplated deeply, because I have no intention of limiting my enjoyment of the field, both as a reader and as an editor. The SF writer Jeffrey A. Carver has made an honorable attempt to define it on his free online writing course <www.writeSF.com>. Jeff characterizes it as “[those] stories . . . that could not happen without some element of science, or some imagined change (futuristic or otherwise) from the world as we know it today.” He adds that, “fantasy also takes place in otherworldly settings, but in this case, the worlds are usually magical or mythical. SF stories tend to be based on, well—science, or worlds that seem possible or plausible, based on what we know or can guess about science.”

This fairly traditional definition of science fiction doesn’t seem to encompass the type of alternate history that isn’t brought about through time travel or quantum mechanics. Perhaps it could be loosely argued that alternate history falls under the “some imagined change from the world we know it today” clause. I think, though, that Jeff meant “if-this-goes-on-scenarios,” such as over-population or global warming, rather than unexplained changes in our past.

The Encyclopedia of Science Fiction may offer us a way out of this predicament. It attempts to define alternate history as speculative fiction. Alternate history tales can often be described as “What if . . .” stories. What if the Nazis had won the Second World War? What if the Chinese had “discovered” and colonized America instead of the Europeans? What if the United States had been more interested in developing rocket science than atomic weapons? The “what if” or “speculative fiction” monikers do seem to apply to many alternate history stories, but speculative fiction is another broad umbrella term that can also be used to describe much of science fiction. What if we master time travel, what if we encounter alien civilizations, what if we can travel faster than the speed of light, what about instantaneous transportation?

If we think of science fiction as speculative fiction, it’s easier to welcome alternate history into its folds with or without the quantum mechanics, parallel universes, and time-travel conundrums that are used to dress some alternate history up in science fiction clothing. With the lack of rigor in its definition, however, “speculative fiction” may, like “fantasy” or “mainstream,” be too broad a term to adequately describe the literature that makes up the canon of science fiction.

Despite the problems with terminology, Asimov’s is, and always has been, home to stories about all sorts of alternate realities. Some of those alternate realities are alternate histories. Mike Resnick has spun several stories about alternate Teddy Roosevelts, Robert Silverberg and Robert Reed have both meddled with Roman history, as has Harry Turtledove, himself, in his Byzantium series. Not long ago, Lois Tilton allowed the Persians to defeat the Athenians, and an upcoming story by Beth Bernobich will feature a nineteenth-century ascendant Ireland with emancipated women quite unlike the historical women of that era. In a Paul Melko story that will appear in our April/May issue, a young man faces his personal alternate histories.

Roads Not Taken, a collection of stories drawn from Asimov’s and Analog, and edited by Gardner Dozois and Stanley Schmidt for Del Rey Books remains our best-selling anthology. It contains such Asimov’s stories as Gregory Benford’s 1989 “We Could Do Worse” (where Eisenhower dies young and Joe McCarthy is elected president), and Bruce McAllister’s 1993 “Southpaw” (where Fidel Castro doesn’t say “no” to the New York Giants’ scout). Some of these stories have tried to explain their characters’ predicaments. Others have left the explanation for the reader to work out. I’m sure that no matter how they’re defined, alternate history stories will continue to appear in Asimov’s. At least in this timeline!