John C. Wright points us to a wonderful little essay called Grading SF for Realism, that explores what different grades of science fiction look like when judged by the realism of their content. All the way from diamond hard science fiction that looks like it comes from the pages of tomorrow all the way through to extremely mushy soft science fiction that makes Star Trek look scientifically rigorous. The author offers the following on a graduated scale
The Hard-Soft Sci Fi Gradational Scale
On the basis of rating of common sci fi tropes from ultra-realistic to pure soft sci fi unscientificness, one can posit a grading of the genre from Ultra Hard to Very Soft. This is not intended as, and should not be taken as, a list of absolutes. It is simply one interpretation of what is more and what is less likely, given the current understanding of the universe and how it works. Future discoveries in physics, AI, etc may very well change the placement of some of these stories – some things that are here listed as implausible may become very plausible, and vice versa. However even if, say, warp drive turns out to be viable and wormholes not, there is no way that the Star Trek “bumpy-headed humanoid of the week” galactography could in any way be possible. Hence some things are patently absurd, no matter what future advances in technology or exploration of space reveal.
However, this should not be taken as a value judgment, because no grade is “better” than any other. So soft science SF as a genre is just as valid as hard science SF. Moreover, you may have a completely different, but equally valid, approach to these things. Other standards might equally well be used to define various levels of “hardness”, and we in no way wish to claim that our interpretation is the only or the best one! In addition, to reiterate, we are not trying to suggest that “hard” science fiction is in any way “better” than the soft sci fi, or pop sci fi franchises. All that is simply a matter of personal taste, opinion, and preference. None of what is written here should be taken as any sort of value judgement.
before offering this extremely helpful chart.
|Major Categories||Rating used here||Common Tropes||A few examples|
|Hard Sci Fi||“Present Day Tech”||Cutting edge Present Day Tech, some developments and speculation, but nothing major that has not been attained today (so no AI). Basic space exploration, very near future||Technothrillers, Allen Steele’s Orbital Decay|
|Ultra Hard (Diamond Hard)||Plausible developments of contemporary technologies – AI, Constrained Nanotech, DNI, Interplanetary colonisation, Genetically engineered lifeforms. Nothing that conflicts with the laws of physics, chemistry, biology etc as currently understood||William Gibson, Neil Stephenson, Kim Stanley Robinson’s “Mars” Trilogy, Robert Forward|
|Very Hard||Plausible developments of provocative contemporary ideas, bot nothing that conflicts with the known laws of physics, information theory, etc – Assembler Nanotech, Nano-Goo, Uploads, Interstellar colonisation, Relativistic ships, vacuum-adapted life||Greg Egan, Linda Nagata, Greg Benford’s Galactic Center series, Stephen Baxter’s Manifold Series, GURPS Transhuman Space|
|Plausibly Hard||The above but with the addition of some very speculative themes, some of which may well turn out to be impossible, others may be possible. Requires some modification of current understanding, but nothing that is logically impossible, or has been conclusively proved to be impossible (so no FTL without time travel) – Wormholes, Reactionless Drive, Sub-nanotech (Femto-, Plank, etc), Domain Walls, exotic matter, FTL drive with time travel, etc||Stephen Baxter’s Xeelee universe, Greg Bear’s Forge of God series, Orion’s Arm|
|Firm||As realistic as the above categories were it not for unrealistic/impossible plot devices (e.g. FTL without time travel paradoxes), although these are kept to a minimum as much as possible||Asimov’s “Foundation” Series, “Giants” series by Hogan, Vinge’s A Fire Upon the Deep and A Deepness in the Sky|
|Medium||Similar to the above but with a larger number of unrealistic plot devices; e.g. FTL without real explanation (ore with pseudo-explanation), alien biota in some instances very similar to terragen life, psionics, a great many alien civilizations. However still preserves plot and worldbuilding consistency, and the science is good and consistent.||Niven’s “Known Space” series, Robert Heinlein’s Starship Troopers, Banks’ “Culture” novels, David Brin’s “Uplift” series, Frank Herbert’s Dune, Traveller RPG|
|Soft Sci Fi||Soft||A number of unscientific themes – e.g. aliens as anthropomorphic “furries”, handwavium disintegrator guns, Alien Cultures and psychology all extremely uniform, and so on. However, still retains story consistency.||Various TV series: Babylon 5, Farscape, Andromeda, Matrix, StarGate for the most part|
|Very Soft||As above but either even more unscientific elements (humanoid of the week, lifeless planets with beathable atmosphere, etc), and story with less consistency||Various TV and movie series; for the most part the Star Trek Canon and Star Wars Canon|
|Mushy Soft||As above but even more unscientific (alien races never before encountered speak perfect English without a translator, animals too large to stand in Earth gravity (Godzilla), weapons that make energy beams without putting energy in, interstellar travel without FTL or centuries long voyage, mutants with super energy powers, etc)||Godzilla, Comic Book Superheros, badly written TV sci fi, elements of some franchises|
Checkout the rest for a description of each category.