Naturally this has already been extensively covered by tvtropes, I present the "Mohs Scale of Science Fiction Hardness" [0] The author makes some good points a

Naturally this has already been extensively covered by tvtropes, I present the "Mohs Scale of Science Fiction Hardness" [0] The author makes some good points about particular types of errors. I would not, however, call them shibboleths, that word generally refers to something quite specific and seemingly arbitrary that an in-group uses to identify itself to others in the know. Also, the idea that sci-fi is not actually sci-fi unless it's hard sci-fi reeks of No True Scotsman. Some of the author's examples were far more egregious than others; I would argue that violating conservation of energy and/or momentum is fundamentally and entirely different to a particular choice of society or political system such as a Megacorporation or Empire, In Space! [0]: http://tvtropes.org/pmwiki/pmwiki.php/Main/MohsScaleOfScienceFictionHardness http://tvtropes.org/pmwiki/pmwiki.php/Main/MohsScaleOfScienc...