Hard SF

Definition

Hard SF is less a genre than a contract: the author promises not to cheat with what we currently know, and the reader accepts some cognitive effort in return. Liberties are rare, flagged, and often justified in-text or in an appendix.

What it's for

It turns rigor into a narrative engine: physical constraints become obstacles, hence tension. Gravity, delta-V, chemistry, thermodynamics force painful choices. Hard SF also speaks to the present — it tests our relation to knowledge, engineering, and scientific collaboration.

Variants by genre

• Classic: Asimov, Clarke, Benford — ships, exoplanets, relativistic paradoxes.
• Mundane SF: no FTL, no first contact, no singularity (Geoff Ryman, 2004 manifesto).
• Biological hard SF: Peter Watts, Greg Bear, Greg Egan — cognition, evolution, genetics.
• Rigorous climate fiction: Kim Stanley Robinson — The Ministry for the Future, sourced climate data.
• Operational hard SF in space: Andy Weir, The Martian / Project Hail Mary.
• Chinese hard SF: Liu Cixin — The Three-Body Problem, fundamental physics as engine.
• Francophone hard SF: Sylvain Neuvel, Laurent Genefort (implicit technical encyclopedias).

Common pitfalls

• A physics lecture disguised as a chapter — see Infodumping.
• Flat characters sacrificed to scientific demonstration.
• Boasted rigor but one major inconsistency that breaks the contract (unowned FTL, impossible ecosystem).
• Opaque technical vocabulary that excludes without nourishing.
• Confusing hard SF with anti-humanism: rigor doesn't require coldness.

Examples

• Andy Weir — The Martian: accessible hard SF, every rescue is an engineering problem.
• Greg Egan — Diaspora, Schild's Ladder: radical, mathematical hard SF.
• Kim Stanley Robinson — Aurora: generation ship with a realistic biosphere.
• Liu Cixin — The Dark Forest: cosmic sociology drawn from physics.
• Peter Watts — Blindsight: extrapolated neuroscience, consciousness as evolutionary bug.
• Becky Chambers — The Long Way to a Small, Angry Planet: gentler hard SF, social engineering of a multispecies ship.
• Sylvain Neuvel — Sleeping Giants: giant mecha, engineering treated seriously.

Writing tips

From book 1, keep an "owned scientific liberties" document — two columns: what is plausible today, what is extrapolated (and on what basis). Cap it at three major liberties: beyond that, you're not writing hard SF anymore, you're writing soft SF in disguise. Then apply the visible physical cost rule: every technical scene must cost a character something measurable — fuel, oxygen, sleep, margin for error. If no cost is embodied, you recite instead of dramatize. Finally, test the translation-into-action rule: every technical term introduced must reappear in a concrete action within the next 20 pages, or cut it. In beta, hunt the orphan inconsistency — a single quietly broken law ruins the contract; the collapse patterns are listed in the 7 worldbuilding sins. Rigor alone doesn't create tension: pair it with the techniques in narrative tension and suspense.

Revision checklist

• Is every scientific liberty owned (footnote, dialogue, afterword)?
• Is science embedded in action (problems, failures) rather than recited?
• Do physical constraints actually cost a character something?
• Is technical vocabulary translated into action (we see the consequence)?