"Physics of the game world" is a less ambiguous term; it refers to how events unfold in the game. It is usually dependent on the adjudication of the GM. If it is in violation of RAW in certain places, this is generally a good thing. If it is in violation of player expectations, then while the rules of the game aren't serving as the physics of the world, that lack is indicative of a problem. Really, the root cause of the problem is a lack of shared assumptions; if one set of players is thinking "We can trivially defeat this encounter in a nonheroic manner, but aren't going to because that isn't fun." and another set of players is thinking "We're going to find interesting and thematic ways for the rules to intersect and see what happens when they do, because playing every encounter out according to exactly what the GM planned isn't fun.", you will have a violation of player expectations.
OH GOD MY BRAIN STOP PLEASE NOW