Though I would argue it is not about "hard sci-fi" rules but instead internally consistent rules. So Aerocontrols I will pivot and let a short video essay explain what I mean.

https://www.youtube.com/watch?v=pxuK4NQ2NHk

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Sci-Fi movies have to be careful with how they construct the internal rules and especially the first few minutes / first few parts of the story for these first few parts of the story "anchor" the viewer and their expectations. If something seems inconsistently hard sci-fi and not hard sci-fi it breaks the illusion, it takes the viewer out of the total attentional engagement they just had for they now have to think about what are the rules for this reality. Shifting the rules of a story breaks the verisimilitude and triggers an effect in the viewer that is similar to "the uncanny valley."

This is because film is by its very nature "fiction" (even when it is a documentary) you have to turn off part of your brain that says stop paying the external world as your live it (like I am in this room) and anchor your attention to something else and give your attention to this other thing.

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There are more detailed explanations of why this uncanny valley occurs but it requires philosophy that I find boring to read and sometimes even think is pure absurdity.

I am talking the dreaded Jacques Derrida and things that he likes to talk about such as presence and absence. Shivers. Well these dreaded things are more important to things like film studies than the origin of language for with film you can create realities that are so visual and hyper-real but they may have different rules than our traditional reality / our traditional understanding of reality. Now this also applies to language but it is so easy to slip someone into an external reality via film while doing so with language often takes more time.

What I am saying here is just accept it is very important how you tell a story and do not listen to the formalists or the deconstructionists explain why it is important, for it quickly turns into that teacher sound from Peanuts / Snoopy.

https://www.youtube.com/watch?v=Q4_o0dfgU