Rotation around an "axis" is an illusion brought on by the fact that we live in three dimensions. Rotation is really around 2D planes.
In 2D, there is one plane: the space itself. So rotation is more of a back and forth.
In 3D, every 2D plane corresponds to a perpendicular direction and vice versa. This direction is the "axis".
When you rotate around the z-axis, you're really rotating around the xy-plane. The xy-plane itself is naturally invariant under this rotation.
In higher dimensions, you can rotate around more than one plane simultaneously.
Rotation around an "axis" is an illusion brought on by the fact that we live in three dimensions. Rotation is really around 2D planes.
In 2D, there is one plane: the space itself. So rotation is more of a back and forth.
In 3D, every 2D plane corresponds to a perpendicular direction and vice versa. This direction is the "axis".
When you rotate around the z-axis, you're really rotating around the xy-plane. The xy-plane itself is naturally invariant under this rotation.
In higher dimensions, you can rotate around more than one plane simultaneously.