A unification of light and electrons through string-net condensation in spin models

String-net condensation in spin models gives rise to a new form of matter. The collective excitations in string-net condensed phases can behave just like the light and electrons in our vacuum. This suggests that light and electrons (as well as other elementary particles) may originate from string-net condensation in our vacuum. In addition, the string-net picture indicates how to make artificial photons, artificial electrons, and artificial quarks in condensed matter systems.