I’ve spent a lot of time pondering the connection between science and science fiction, as well as what distinguishes SF from fantasy. Of course science fiction has to have a basis in scientific reality, most will say. No unicorns or fairies (tell that to Anne McCaffrey, Roger Zelazny and others), no magic (forgetting Arthur C. Clarke’s famous quote: “Any sufficiently advanced technology is indistinguishable from magic.”) No gods, demons, leprechauns, dragons…you can carry the list as far as you like, and you’ll probably find exceptions to all of them in good, solid works of science fiction.
Many stalwarts would say that science fiction shouldn’t contain anything considered impossible by current scientific knowledge. Which rules out faster-than-light travel and time travel, two of the genre’s most persistent tropes (and dumps some of the past century’s best SF into the trash compactor). Some would say SF writers should extrapolate from current technology, rather than invent dazzling gizmos with no idea how they could possibly work. I can only say that such stick-in-the-muds must never have heard Walt Disney’s philosophy: “If you can dream it, you can do it.” Let’s remember that there are a lot of research projects around today that owe their existence to something someone saw in an episode of Star Trek.
It’s a delight to see some of the fantastic world-building that writers like Larry Niven and Canada’s Karl Schroeder can produce while playing with (and adhering to) the laws of physics. But I also get a kick out of voyagers who travel by wormhole or transporter beam.
So much depends on what we consider to be the purpose of science fiction. Canadian SF writer Robert J. Sawyer has told me, and many others, that SF is a literature of allegory and thereby a vehicle for commentary on contemporary society. I certainly agree that’s one of its primary functions, and when Pierre Boulle wrote La planete de singes (inspiration for the Planet Of The Apes movies) I doubt that he was much concerned about whether or not it was physiologically possible for apes to talk.
Am I saying that science fiction shouldn’t have any rules? No. I just think the genre is better served by not getting hung up on definitions, laws, edicts, preconceptions, or any of the other things that hamstring the imagination. Because, above all, science fiction is fiction of the imagination. It shows us where we might be going, and lets us decide whether we really want to go there. And it shows us ourselves as we are, though its mirror often requires a little deciphering.
I think those are the more important core values of what we call science fiction, rather than a set of rules that’s bound to change with each new leap forward in human knowledge.
Maybe that’s why it’s called fiction.