quaternion

Halfway through the episode, Urmson is describing the mathematical model his company chose: quaternions.

In his 1865 treatise 'A dynamical theory of the electromagnetic field', Maxwell laid out 20 equations using esoteric mathematical expressions known as quaternions.

But science is full of them - my favorite being William Hamilton using his pocketknife to carve quaternion equations on a bridge abutment after inspiration hit when he had no paper or pencil.

In particular he explained the principle of least action, first advanced by P. L. M. de Maupertuis, and developed by Sir W. R. Hamilton, of quaternion fame.

Every pulse pushes nature's quaternion along life's currents recreating us afresh; the morn feeding the morn, Memnon's music issuing from every stop, as if the Orient itself had sung.