#split-axle design

[isomorphismes]

Here's a physically intuitive reason that rotations ↺

(which seem circular) are in fact linear maps.

If you have two independent wheels that can only roll straight forward and straight back, it is possible to turn the luggage. By doing both linear maps at once (which is what a matrix or Lie action does) and opposite each other, two straights ↓↑ make a twist ↺.

Or if you could get a car | luggage | segway with split (= independent = disconnected) axles

to roll the right wheel(s) independently and opposite to the left wheel(s)

, then you would spin around in place.