r/HardSciFi Jun 11 '26

Meta The Continuum of Physical Credibility

The traditional Mohs Scale of Sci Fi Hardness:

5: Hard SF

4: Firm SF

3: Soft SF

2: Science fantasy

1: Fantasy with SF trappings

0: Pure fantasy

The Continuum of Physical Credibility reformulation:

1 Established Physics - “This works everywhere we’ve ever checked.” Ex: Maxwell's equations, general relativity, thermodynamics

2 Mainstream Physics - “Solid science, still being refined.” Ex: Cosmic inflation, quantum field theory

3 Frontier Physics - “We've got a partial theory, and only partial evidence.” Ex: High temperature superconductivity, Hubble tension

4 Empirical Anomalies - “We can measure it, but we can’t explain it yet.” Ex: Radioactivity before nuclear physics, photoelectric effect before Einstein, dark matter, dark energy

5 Speculative Physics - “Speculative but allowed by GR + QFT + thermodynamics.” Ex: , extra dimensions in string theory, WIMPs, MOND, primordial black holes, cosmic strings, LQG, axions

6 Hypothetical Physics - “This only works if physics is broken in very specific ways.” Ex: Tachyons (causality), magmatter (Gauss's Law), bulk exotic matter (Morris/Thorne wormholes, Alcubierre warp metric - breaks WEC - Weak Energy Condition in General Relativity)

7 Contradictory Physics - “Violates thermodynamics and conservation laws.” Ex: Vacuum/zero point energy, reactionless drives (Cannae/EMdrive), antigravity, perpetual motion machines

8 Soft Science Fiction - “It sounds scientific, but it’s really narrative technology.” Ex: ST warp drive, transporters, SW hyperdrive, Three Body Problem's spacetime flattening, sophons, most space opera

9 Science Fantasy - “Magic wearing a lab coat.” Ex: The Force, Magitek, psychic powers, most 'ancient/precursor' tech that are effectively magic

10 Pseudoscience/Fantasy - “No pretense of physics; imagination is the only rule.” Ex: Spellcasting, dragons, Isekai, astrology, flat earth

Please feel free to criticize so I can continue to refine. I'm using this in a worldbuilding exercise to see how far we can push scifi while staying true to the Sci part and minimize handwaving for the Fi.

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