This is not as stupid a question as it might seem. Volumes have been written in attempts to define science fiction, and a brief overview is in order.
Many people define science fiction (or "scifi" as Harlan Ellison hates to hear it called) as a storytelling genre marked with laser guns, spaceships, and aliens from other planets. In many cases this is true, and suffices to nail down the genre for purposes of characters having wild adventures ... and there's nothing wrong with that. This side of science fiction is lovingly called "Cowboys and Indians in Outer Space."
There is, of course, another side to science fiction, the side that matches its abused moniker more literally: fiction based upon some premise of scientific speculation, from which arises adventure. Star Wars is NOT science fiction in this sense, for other than the Force (hardly scientific) and futuristic trappings of hyperdrive ships and lightsabres (hardly integral to the story), the epic has no foundation in speculative science whatsoever. Michael Crichton's well-known Jurassic Park, on the other hand, derives its story from a scientific idea. So does Mary Shelley's Frankenstein, which most people would rather call "horror."
Well, so much for the popular understanding of genres, eh?
The Lattice will gladly host adventures of the space cowboy type. Again, there's nothing wrong with that, despite what some science fiction purists might sneeringly claim. But it is our greater desire to provide an environment where curious scientific quirks and possibilities will give rise to the kind of adventures that Niven and Asimov and Clarke and so many other wonderful writers have gifted us with. If you don't know the difference, you are missing out! and we would be gratified if we could help you learn.
And, of course, it should not go without mention that the greatest aspect of any kind of fiction is the interplay and development of characters. Personal triumphs and tragedies far outweigh exploding planets ... and dry science only comes alive when situations arise from its application that influence our lives and loves and dreams.