"It's been said that science fiction and fantasy are two different things: science fiction the improbable made possible; fantasy, the impossible made probable..."
As a literary genre, Science Fiction (a subset of
Speculative Fiction) is broad and incorporates subgenres ranging from
Steampunk to
Cyber Punk, running headalong through
Space Opera on the way.
Science Fiction depends on asking "what if?" (Not quite the same thing as
What If?.) Or as an obscure 1930s
Science Fiction musical asked, "just imagine"...
The one defining(-ish, definitions differ) trait of Science Fiction is that there is technology that doesn't exist
in the time period the story is written in. Consider
20,000 Leagues Under the Sea. The story was written in a time when submarines were still at the prototype stage, so
20,000 Leagues Under the Sea falls within the boundaries of Science Fiction.
However, Science Fiction is as much a genre as a
setting. Often, the technology is a means to explore a concept, and the story could be a detective story focusing on how advanced technology affects crime and policing. This story would be both Science Fiction and
Detective Story.
In general, without getting too much into the advanced and diverse subgenres of Science Fiction, there are two schools —
"hard" and "soft". While the distinction isn't always clear cut, there are a few key differences. Hard science fiction relies on using already established science or justifying it's fictionalized science using carefully calculated predictions. Hard SF tries to use the advanced technology as something that is important in itself, with its consequences, limitations and new uses being the main plot points. Due to the heavy focus on the scientific aspect, this is a rather niche market. Soft science fiction falls under two main schools - adventure/pulp science fiction and social science fiction. The former uses technology as a means to an end, merely a backdrop that allows
The Captain to fight for Justice™ with a
Stun Ray against the evil aliens and have
space sex with the
Green-Skinned Space Babe. In the latter, the science is used as a means of exploring characters and the social/psychological effects of the new technology. In both schools of soft science fiction, it usually doesn't matter whether the technology used is actually plausible or not, and there is little to no explanation as to how the technology would actually work. Otherwise, it may rely on such devices as
Technobabble to maintain a "science-y" atmosphere without the author actually having to use actual science. Because hard science fiction tends to focus more on scientific detail and soft science fiction focuses on well developed characters and/or adventure, there is a divide between certain sections of the fandom. This divide has been around since, essentially,
the very beginning of the genre
. However, "hard" and "soft" say nothing about quality or literary value, just the level of science used.
As with everything, there is often a
blend of Hard and Soft Science Fiction. It is perfectly possible to write a hard Science Fiction story about
The Captain running around shooting people with miniaturized microwave emitters designed to incapacitate people without killing them, shooting aliens and having sex with
Green Skinned Space Babes, (with no chance of conception because green aliens are biologically incompatible with humans) just as one can go into considerable detail justifying otherwise implausible technology that is
much like magic (usually accomplished by making a few minor changes to mathematical formulas) and its effects on science.
This can often lead to
Hidden Depths, as a story might be "
cyborg police bust crime in the grimdark future by hacking people's brains", which sounds like soft Science Fiction, but further
exploration shows next to everything to be based on technology that is currently available, and the consequences of such technology is explored in depth.
Science Fiction authors and fans are
notoriously cranky about
how their work is not taken seriously by the literary community, and especially resent being lumped in with
the fantasy genre. (
Speculative Fiction, an umbrella term for all varieties of imaginative literature, has an an analysis page that explains the
differences between Fantasy and Science Fiction.) Note also that many Science Fiction fans dislike the term
Sci-Fi: to them it suggests the
flanderized conception of the genre in popular culture, with green-skinned aliens, giant space battles and hammy production values. Therefore,
they will insist on calling it SF for short.
Subgenres of SF include:
(Exact definitions of these genres, including whether they're really SF, and how much they overlap with fantasy, will vary from person to person.)
See:
Speculative Fiction Tropes,
Speculative Fiction Series,
Speculative Fiction Creator Index,
Technology Marches On.
