Some problems arising at the theoretical solution of a problem of a photon and a mass particle interaction are considered. It is shown that calculation of such interaction cannot be executed if the photon and a mass particle are in different reference systems. It is marked that the approximated way offered by R. Feynman assumes translation of a photon in the reference system connected to a mass particle. Other approximated way of the solution of the problem suggesting translation of a mass particle to the reference system connected to a photon or in photon space is shown. The exact solution of this problem can open new ways of development of a physical science.