#@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 a 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.