In fact, all the dualities in string theory are obviously examples of unification. The electric charge is unified with the momentum of a particle; this insight was already known to Kaluza or at least Klein. That’s true because the electric charge is the generator of an isometry in a new 5th circular dimension – which is the momentum in this direction.

— Unification as a source of certainty

— Lubos Motl

2011.09.22 Thursday ACHK