  The connection between gravitational force and operator growth, reported in
earlier papers, is generalized to include electromagnetic forces. It is shown
how in the U(1)-invariant SYK system electric forces emerge through the same
mechanisms -- the momentum-size correspondence, and operator growth -- that
give rise to gravitational force. The unit of electric charge implied by the
U(1)-SYK theory is consistent with a Kaluza-Klein radius inverse to the
characteristic energy scale of the SYK theory.
