But I'm writing one now.
Which has been interesting, considering how I don't know what I'm doing. Fortunately, the husband loves the sci fi, and so I often go bother him on subjects like cryogenic freezing and the speed of light. He has been very helpful, so I guess I'll keep him for another year.
Meanwhile, I found the text of Robert Heinlein's form fan letter rejection (much like query letter rejection, but for his fans). In it, he mentions a definition of science fiction:
Science fiction: stories that would cease to exist if elements involving science or technology were omitted.OK, so admittedly, that's a bit obvious. But also, it's not. Think about my beloved Star Wars*. Are lightsabers necessary to the plot? Not really. The story could have been just as easily set in the Middle Ages as in outer space. Replace hyperspeed with Spanish galleons and light sabers with swords, and we're there. Leia's metal outfit in the second movie probably wouldn't have flown so well in the Middle Ages, but... The science/technology isn't particularly necessary.
Meanwhile, you have books like The Adoration of Jenna Fox, where, without science, the story simply would not exist. The story revolves around science. That is the plot. There is no possible way for the story to exist without the scientific elements.
Or, how about a story such as Ray Bradbury's "All Summer in a Day." It's brilliant, and if you've not read it, go here. Read it first, you'll like it better that way.
So, see how the story wouldn't exist without science? The entire plot exists because of the scientific reasoning behind the sun being visible only one day every seven years. That's the plot. What the characters do with the science is essential--but you cannot have the plot with the characters without the science behind them. Science fiction, by definition, requires this formula: characters + science = plot.
*Please note: the only acceptable, worth viewing Star Wars in existence is the original three. Return of the Jedi is the best. It's a fact. Look it up.