Cosmology, physics, biology, etc

Physics

The world is flat, specifically an infinitely tall cylinder with a flat top. The sun and moon go around it. They are the same size and distance away and are always opposite each other. Polaris is a sphere that hovers over the North pole and goes up and down. It exudes cold and causes seasons. Stars are five-pointed stars on the shell of the universe (and also dead people, see https://glowficwiki.noblejury.com/link/630). There is air everywhere inside the shell of the universe.

Gravity needs air to get into somewhere.

Science generally

The universe has opinions about the natural order. The first few times something "unnatural" happens, it is much more difficult than it should be, but then the universe gets used to it and stops objecting. For example, the first few times someone tried to make vacuum, the containers crumpled even though they were as strong as containers that worked for that later.

Biology

Genetics runs on quadruple helixes.

The respiratory systems of local humans are worse than those of Earth humans.

Local humans age at the same rate relative to their years as Earth humans do relative to ours. That is, a local sixty-four year-old looks the same age as an Earth sixty-four year old despite the disparity in year length (though that might be because the disparity is not actually that large).

The hearts of local humans are slightly differently located than Earth humans' hearts, and are more in the place usually more metaphorically associated with putting one's hand over their heart.