Please note that Lea (like me) is not a developer.
As a rule, things should work in ways that are familiar to a premodern observer
. So while many subfields of modern physics are up in the air, things like optics and acoustics and classical mechanics are familiar; biochemistry is up in the air, but anatomy, classical medicine, and selective breeding are familiar; and so forth.
If it helps, think of it as the difference between the real-world dichotomy between "Classical physics accurately describes how the universe works" and "Classical physics does not accurately describe how the universe works, but it's a good rule of thumb for everything with which you will personally interact on the macro level."