Are there terms that describe a science fiction story that strictly adheres to, I guess, plausible science concepts and technology versus science fiction were the science is really just made up and is theoretically impossible? I know a lot of sci-fi TV shows, like Battlestar Galactica, employed physicists and other scientists as consultants to make sure things were accurate, whereas other shows that I won't name employed people solely to fill in technical- and sciency-sounding words in the script.

  • 1
    For reference, related question: scifi.stackexchange.com/questions/675/… Commented Jan 21, 2011 at 19:23
  • 1
    You may have heard of the Mohs scale of hardness for minerals. The TV Tropes site (WARNING! Can be addictive and time wasting!) has a page called The Mohs Scale of Science Fiction Hardness, giving numbers from 1 to 6 going from the least scientific SF up to real life. tvtropes.org/pmwiki/pmwiki.php/Main/… Commented Apr 7, 2018 at 17:43
  • Duplicate comment. The Mohs scale of hardness for minerals has inspired the addictive TV Tropes website to have a page called the Mohs Scale of Science Fiction Hardness number various works from 1 to 6 according to the hardness of their science. tvtropes.org/pmwiki/pmwiki.php/Main/… Commented Apr 7, 2018 at 17:48
  • Interesting choice of Battlestar Galactica. While it has some interesting aspects to it (e.g. projectile weapons, no energy shields, shaky cam for battle scenes) there's plenty of fantasy as well (angels, religion, apparitions, and of course -- "jumping" spaceships, plus the shape of the ships and fighters makes no real-life sense).
    – Andres F.
    Commented Dec 20, 2023 at 23:11

4 Answers 4


The usual term is "hard science."

If that's not what you're looking for, can you narrow down what you mean by "plausible science concepts and technology"? For instance, FTL drives aren't based on any known scientific concepts, so are you ruling out all SF with FTL travel?

  • 1
    It's my understanding that current theory puts faster than light travel as an impossibility, so ... I guess, yeah. Or, again with Battlestar -- they incorporated FTL travel and the theory of relativity (Time slowed for the Final 5 as they traveled to warn the 12 colonies). So, that would be an example that's ok.
    – Slick23
    Commented Jan 21, 2011 at 2:23
  • 1
    FTL is not often 'hard sci-fi' in my opinion, unless the author does a really good job of explaining it. Commented Jan 21, 2011 at 18:59
  • 2
    I think you mean hard science fiction. :)
    – Lexible
    Commented Sep 9, 2018 at 4:08

"Hard SF" is a sub-genre that basically try to keep within the accepted parameters of known science.

But it can still be pretty out there. Consider Alisdair Reynold's Revelation Space universe. FTL travel is impossible, but far-out stuff like nanotech, life extension and AI is not.

  • I suppose the difference is that FTL is definitely contrary to the laws of physics as we know them, while nanotech, life extension, and AI are compatible with such laws. Commented Jan 22, 2011 at 15:29
  • 1
    FTL hasn't been definitely ruled out. Hard SF authors typically get around the limitation by proposing that the space dimensions of our spacetime are rolled up in some higher dimensional macroverse and we can use the higher dimensions to take short cuts. SF readers know this scenario well, we call it hyperspace. Or the author might suppose that exotic matter has been found with negative energy density, which would permit wormholes to be held open. See Robert Forward's Timemaster for an exploration of that. The good authors don't ignore special relativity, they look for loopholes.
    – Kyle Jones
    Commented Jan 21, 2012 at 3:58
  • Hal Clement is considered the quintessential hard SF writer. Yet there is FTL travel in many of his novels. Hard SF usually has scientific sensibility, but that doesn't preclude a few way-out concepts like time travel, teleportation, & other exotic phenomena. There isn't a simple cut-off.
    – a4android
    Commented Nov 7, 2019 at 8:18
  • 1
    12 years later, AI is commonly available science that creates pure fiction... :(
    – FreeMan
    Commented Dec 20, 2023 at 18:05

Just adding to the other answers, TV Tropes has the Mohs Scale of Science Fiction Hardness, acknowledging that there's a continuum with a few notable points.

  1. Science in Genre Only: The work is unambiguously set in the literary genre of Science Fiction, but scientific it is not....
  2. Physics Plus: Still multiple forms of Applied Phlebotinum, but here the author aims to justify these creations with natural laws both real and invented—and these creations and others from the same laws will turn up again and again in new contexts....
  3. World of Phlebotinum: The universe is full of Applied Phlebotinum with more to be found behind every star, but the Phlebotinum is dealt with in a fairly consistent fashion despite its lack of correspondence with reality, and in-universe, it's considered to lie within the realm of scientific inquiry....
  4. One Big Lie: The author invents one (or, at most, a very few) counterfactual physical laws and writes a story that explores the implications of these principles.....
  5. Speculative Science: Stories in which there is no "big lie"—the science of the tale is (or was) genuine speculative science or engineering, and the goal of the author to make as few errors with respect to known fact as possible. ....
  6. Real Life (a.k.a. Fiction in Genre Only): A Shared Universe which spawned its own genre, known as "Non-Fiction". Despite the various problems noted at Reality Is Unrealistic, it is almost universally agreed that there is no other universe known so thoroughly worked out from established scientific principles....

Another sub-genre is called Techno-thriller. Stories in this genre include many (relative to other genres) technical details. The specific abilities of technology often drive the plot. There is a big emphasis on real-world or plausible near-future technology. This genre often overlaps hard sci-fi, military fiction, and spy fiction.

Notable authors include Michael Crighton, Tom Clancy, Douglas Preston, and Neal Stephenson.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.