Given that the definition of "matter" is slightly ambiguous, it's not really wrong, but it's not really correct either. Traditionally, matter usually has to ha

Given that the definition of "matter" is slightly ambiguous, it's not really wrong, but it's not really correct either. Traditionally, matter usually has to have mass, but if you just think of matter as a volume of particles, then a collection of photons could be defined loosely as "matter".