I love (and write) science fiction, but there are a bunch of things that show up a lot in SF movies, novels that have become such a part of the furniture of the genre that nobody bothers to ask whether they make any sense. An unquestioned assumption is not necessarily something that’s implausible or impossible but something that gets plugged into stories like a widget, without any thought on the part of the writer.
Bionics: Or, as we say in the real world, prosthetics – which are, of course, becoming increasingly common and sophisticated. What they’re not doing is making anyone superhuman. Go take a look at a VA hospital (and by the way, how much of an opportunity did the people behind Bionic Woman remake miss by not making her an Iraq vet?). Nobody there is lifting cars or taking spy photos with their camera eyes; they’re lucky if they can get anything like the former abilities of the limb or body part being replaced, and even if they give an advantage in one area (as Oscar Pistorius’ legs supposedly did) it’s pretty limited. Even if you could make a bionic limb super-strong, of course, the problem is that the hand bone’s connected to the wrist bone, the wrist bone’s connected to the arm bone, and so on, and that whole chain is only as strong as its weakest link. So superhuman strength is pretty much off the menu (you could conceivably build a bionic hand with superhuman crushing power that wouldn’t stress the wrist too much, but that’s about it) unless you replace basically the whole skeletal structure, which brings us to…
Uploading, or cloning for that matter: Not that either of these things are necessarily impossible (though both involve a fair bit of handwaving, especially the copying-memories part of the latter), but neither are they any kind of ticket to immortality for the simple reason that neither an uploaded version of your mind nor a clone with all your memories is you: they are both copies of you, which will no more prevent you from dying than having children will. With that in mind, it baffles me why anyone would want to do either of these. Who would want to have an immortal or, worse, much younger copy of yourself around? How would that take the sting out of aging and death? Not to mention the fact that you would be made to suffer Robert Burns’ most terrible curse: to see ourselves as others see us. Most of us can’t stand to hear a recording of our own voices; imagine that magnified by a factor of a million and you’ll get the idea of just how annoying and uncomfortable it would be to have a simulacrum of you wandering around.
Sensors: Such an innocuous bit of technology, those machines that let Mr. Spock or whoever tell you what’s going on down on the planet. Unfortunately, nothing like them actually exists. For example, one thing people can always tell with sensors is the presence or absence of “life signs.” How do they do that? It can’t be through infrared or heartbeats, since neither of those would be detectable from space (well, infrared could be, but not individual heat signatures) – but the magical sensors usually can not only detect individual life forms but tell you what species it is! Sensors are practically the definition of the unquestioned assumption; they’re such a background element that hardly anyone bothers to think before plugging them into a story. (This goes double for tractor beams.)
Space combat: This is probably the most commonly appearing one on the list, but think about it for a minute. Actual combat mostly consists of one person trying to get to a target, and the other one trying to stop them; a fighter-interceptor trying to stop a bomber, for instance (or disabling the bomber’s fighter escort.) That works all right when your battleground is the sky, because there are a limited number of possible approaches and escape routes. But when the target is a planet that limited number increases until it approaches infinity – so it’s likely that your fighter-interceptors will simply be unable to intercept anything.
Aside from that, though, the notion of space war is equally unlikely. Even if we assume the existence of FTL travel (something that would have been on this list thirty years ago, but which writers have more recently made more of an effort to justify), it’s almost certainly going to take a lot of energy to get from star to star; what could be waiting there that would be worth the effort involved? You might argue, of course, that war pretty much always takes a lot of energy and that’s never stopped anyone, but the fact is that almost everything of value on an inhabited planet can also be found on uninhabited planets, asteroids or comets. Sure, you can come up with some other reason for an interplanetary war – an ideological difference, some genuinely unique resource, a pathological hatred of the colour blue – but by this point you’re either handwaving or actually giving the matter some thought, which means it’s no longer an unquestioned assumption.
Sol III: This is a pet peeve of mine. SF writers figured out a long time ago that aliens wouldn’t call our planet “Earth,” so you often see it referred to as “Sol III,” which sounds much more science-fictiony. The problem, of course, is that “sol” is Latin for “sun,” which means that instead of calling the planet “Earth” you’ve called it “Sun III” – so much less geocentric!
None of these are bad ideas, necessarily – except for that last one – but I’m tired of seeing them recycled over and over like so much dorm room furniture. So here’s my challenge to everyone who writes SF in novels, movies, comics or wherever: the next time you’re about to use one of these ideas, think it through – odds are good that after a few minutes’ consideration you’ll wind up with a more interesting and original story.
Now if you’ll excuse me, I have a dynamite idea for an epic about bionic space marines I need to work on…