#Quarks

Mind the speed-limit sign

The speed of light is not a maximum speed through space.
It is a maximum coupling and reaction speed.

In other words, $c$ is the limit of how coherently acceleration and interaction can be shared across the universe.

First element with attribute size

Protons and Neutrons are the smallest and first entities, which can truly be assigned the property of “size”. At least spatial size as we perceive it in context of matter. Why does matter show extensions in 3 dimensions? Probably simply because electrons happen to combine 3 rotational components.