Do all rabbit holes of knowledge eventually just lead to material science and physics? At the lowest levels of understanding, someone had to make a decision on what works best.

Computers high level programming language low level programming language assembly and processor instruction sets chip design circuit board design electricity, speed of light, quantum mechanics

Art color and light interactions, experience comes through physiology, development of pigments (historical and modern, like vanta black)

Psychology ultimately just neurochemicals and electrical synapses?

mechanical watches transfer of potential energy from the spring, friction, oil properties like viscosity, Mohs scale applied to jewels

Related to turtles all the way down.