Photon: history, mass, charge, L.B. Okun, hep-ph/0602036 v2 13 Feb 2006
The talk consists of three parts. "History" briefly describes the emergence and evolution of the concept of photon during the first two decades of the 20th century. "Mass" gives a short review of the literature on the upper limit on photon's mass. "Charge" is a critical discussion of the existing interpretation of searches for photon charge. Schemes, in which all photons are charged, are grossly inconsistent. A model with three kinds of photons (positive, negative, and neutral) seems at first sight to be more consistent, but turns out to have its own serious problems.